Wednesday, October 13, 2010

Pipecoating Part 1



BASIC
FAMILIARIZATION GUIDE
FOR PIPE COATING
QUALITY CONTROL
TESTING & INSPECTION
PRODUCTION
SPECIFICATIONS
OTHER RELATED ITEMS


INTRODUCTION
Why you need to know about pipe coating? Pipe Coating represents a very large global industry that has expanded 20 fold in the past 20-30 years and is continuing to expand internationally. It provides for a very substantial workforce throughout the world which usually allows for above average remuneration.
To those who are considering this type of a career I will outline some aspects of the pipe coating industry commencing with Quality Control of pipe coating. As the title of this document dictates the document is a "guide only" and is not a basis for gaining accreditation or any form of qualification, it’s purpose is to familiarize you and give you an insight on some aspects pertaining to the pipe coating industry. Should one seriously wish to pursue a pipe coating career I would suggest you participating in one or more of the several professional and well recognized courses e.g. NACE and others, which can provide both training and certification for courses attended.
To go forward, pipe coating has been an substantial industry for nearly a century and spurred ahead at the advent of the Oil & Gas industries back in the 1960’s and in later years the middle east water transmission industry.
Common materials or types of coatings used for pipe coating today include a wide range which I will address as we go through this guide:
Typical Generic Type Applications include:

Reinforced Coal Tar Enamel For external pipe coating
Reinforced Bitumen Enamel For external pipe coating
Liquid Epoxy Coatings For Internal & External pipe coating
Liquid Epoxy Urethane Coatings For internal & external pipe coating
Fusion Bonded Epoxy Coating For internal & external pipe coating
Multi Layer Polyethylene Coatings For external pipe coating
Multi Layer Polypropylene Coatings For external pipe coating
Internal Flow coatings For internal efficiency
Polychloroprene (Rubber) Coatings For external splash zone coating
Internal Cement Mortar Coatings For internal water pipe coating
Concrete Weight Coatings For external stabilization coating
Insulation Coatings For extreme surface temperature conditions
Sacrificial Anodes For cathodic protection purposes
(Manufacture/Installation)

THE GUIDE

I have prepared this guide in modules each module addressing a particular element in regard to pipe coating. In this edition the first five modules will look at quality control aspects of the generic pipe coating activities.



MODULE 1
INCOMING BARE PIPE RECEIVED AT A COATING FACILITY
ELEMENTS IN THIS MODULE:
Pipe receipt
Pipe traceability
Pipe condition
Contamination, Vegetation, Oil
Excessive Corrosion
Bevel damage
Pipe wall defects, Gouges, Pitting, Dents, Out of Round
Chloride/Conductivity testing

1.0 PIPE RECEIPT (Load In to a storage area)

Part “1” describes the requirements for inspecting and recording the identity of pipe when received at a coating facility.

When receiving pipe it is normally expected that the pipe condition and the pipe identity markings are such that the pipe is in a fit condition to be passed through the coating facility and that the pipe identity is correct and is clearly legible.

The pipe shall be free from excessive vegetation and oil contamination and the identity established and verified. Each pipe shall be visually inspected for steel damage which includes bevel damage, gouges, dents, out of roundness and excessive corrosion and/or pitting.

      Vegetation type contaminant Oil Contamination



Oil Contamination



Bevel damage


Bevel Damage



Typical Gouges



Typical Pitting



Example Heavy Rust



Example excessive rusting



Example Dents Example



Steel Laminations



Example Out of roundness





REMEDIAL ACTION:

Pipe that do not comply with incoming inspection criterion, shall me marked on the bevel end in accordance with the typical marking legend contained in section 4.0 below. Any defective pipes should be segregated as soon as possible and preferable stored separately. Unresolved pipe defect problems should be subject of a Non conformance report (NCR) until the disposition of the offending pipe is established.

Note: See also item 8 in Module 2

REPORT

Mark the pipe body in accordance with the marking legend example contained in section 4.0 below. Record the type and details of the defect on a designated Quality Control Form. If the pipe is considered to be a permanent steel reject (PSR) the offending pipe shall be subject of a non conformance report (NCR).

2.0 RANDOM SALT CONTAMINATION CHECKS.

It is often a requirement that salt contamination checks are to be carried out during the load in of the bare pipe (as well as in production) to determine the levels of salts that may exists on the pipe and to determine if pre water washing of the pipes is required. The testing for salts is carried out in accordance with an agreed Laboratory practice or method statement.

Typically the equipment used to determine chloride levels on steel substrates is an industry recognized instrument identified as a SCM 400

Using tweezers remove a sample absorbent paper from a protected pack of test papers and inject up to 2 ml of deionised water onto the paper surface using a syringe. Place the wetted paper on pipe and press firmly into the substrate ensuring as much air as possible is excluded.

Note: deionised water is not normal tap water it is specially processed water.

Chloride tester SCM 400





Wetting paper



Placing paper on the pipe



Switch the SCM 400 on by pressing the RED button. Press the button again to start a two-minute cycle timer. After two minutes remove the test paper from the pipe and place over the SCM

Picture showing switching location



Picture showing reading



On completion of test, lift the lid, remove the paper and clean the electrode with a high purity water soaked tissue.

Note; After use, the red button shall be pushed twice to switch off the instrument and the magnetic catch engaged.


REMEDIAL ACTION

Where salt readings are outside of the tolerances specified, the supervisor of the coating line shall be informed of the non conformance who will decide on what corrective action is to be taken.

REPORT

Record all test results on a designated Quality Form.

Record:

Sample Date
Pipe number
Location of tests
Chlorides detected expressed in µg/cm/2

3.0 RESIDUAL MAGNETISM

With some pipe coating projects there is requirement to check the pipe for residual magnetism which can affect welding operations downstream from the coating activity. Residue magnetism is measured in units of Gauss and is detected using an instrument called a Gauss meter.

The type of Gauss meter described in this module is a F.W.BELL 5070GAUSS/TESLAMETER. This is typical of the instrument required for residual magnetism testing.

Test for residue magnetism can also be required on the completion of pipe coating activities to determine if or the extent of residual magnetism being introduced during the coating activity. Prior to using this instrument a calibration procedure is required and the results documented.

Calibration of the Gauss meter

Prepare the probe zeroing, then rotate the function selector to the ZERO position.The “ZERO” legend will flash and actual dc flux density readings will appear on the display. The meter will select the lowest range regardless of which range was in use prior to using the ZERO function.

Recall that the maximum flux density level that can be zeroed is 30mT (300G or 23.88k Am). The meter will switch over to the dc mode of operation during zeroing. Recall that the zeroing operation affects dc errors only.

Press the AUTO push button and the process will begin. The “ZERO” legend will also flash.

Once automatic zeroing begins it must be allowed to complete. During this time all controls are disabled except for the POWER switch. The process normally takes from 5 to 15 seconds.

The meter selects the lowest range and adjusts the nulling signal until the net result reaches zero. The final zero values will remain in effect until the meter and probe are zeroed again, if the probe is disconnected or if the meter is turned off and back on again.


Zeroed



Initial electrical offsets in the probe and meter will be interpreted as flux density signals. To remove these errors place the tip of the probe in the Zero Flux Chamber and press the ZERO push button. Once the zeroing operation has completed, use the MANUAL ZERO mode to make fine adjustment as needed.

Stray magnetic fields from nearby equipment, magnets and the earth will also affect accuracy. To remove these errors place the probe in a fixed position and press the ZERO push button. The ZERO function can be used in static (DC) fields not exceeding the lowest full-scale range.





REMEDIAL ACTION

Gauss readings that do not comply with the tolerances specified shall be reported to the supervisor who will determine what action is to be taken.

REPORT

Report all the Gauss readings as required by the relevant ITP and record calibration details and report on the designated Quality Form.

Record:

Sample Date
Pipe number
Location of tests
Magnetism detected in Gauss

Note: "Be aware" that in checking for residual magnetism one must ensure that the testing racks or adjacent pipes or steel work is not affecting the Gauss readings (hall effect)

4.0 TALLY AND PIPE TRACEABILITY

Each pipe arriving at the coating facility shall be tallied upon reception. It is a "most important" activity that must be carried out in a diligent and accurate manner. All pipes when loaded into the coating facility must be properly identified. Usually the pipe number, heat number and length are to be recorded however in instances more details may be required
.
Legible pipe stencil


illegible pipe stencil



REMEDIAL ACTION:

Pipes that cannot be properly identified (ID is not legible), shall be marked in accordance with the typical marking legend contained in section 4.0 below and quarantined. The details of the problem shall be recorded and passed onto the Tally Coordinator. Unresolved pipe identity problems shall be subject of a Non Conformance Report (NCR)

Note: If a pipe looses its identification (traceability) and cannot be correctly identified it is often the case that the pipe cannot be used by the end user.

REPORT:

Complete record of each pipe shall be recorded on the designated incoming Tally Form.

Record.

Pipe number
Length
Heat Number
Wall Thickness
Weight

Typical colour code charts:

It is normal practice on most projects to have a colour chart included in the Manufacturing Procedure Specification (MPS) See typical chart below












MODULE N0. 2
INCOMING RACK & ABRASIVE BLASTING
ELEMENTS IN THIS MODULE:
Incoming rack traceability
Incoming Rack Inspection
Climatic Conditions
Blast Grade, Profile, Cleanliness
Pipe wall defects, Gouges, Pitting, Dents and Out of Round
Wall Thickness Measurements

Module “2” describes the requirements for inspecting and recording the identity of pipe when pipes are loaded into the coating facility incoming racks.

1.0 INCOMING RACK TALLY & TRACEABILITY

Pipes transported from the pipe storage yard and placed onto the incoming process racks shall be tallied and the pipe identity confirmed as being correct. This usually entails checking the pipe identity to that of the shipping manifest.

When pipes arrive at the incoming rack, they shall be checked for any mechanical damage and/or contamination. Also the pipe number, length and heat number shall be recorded on the relevant Inspection & Tally Forms.

Pipe Conditions:
Oil contamination



General Contamination


REMEDIAL ACTION:

Pipe with excessive damage, contamination or pipe marking irregularities shall be quarantined. A Non Conformance Report (NCR) shall be raised for unresolved damage/marking issues.

REPORT:

The tally and any damage shall be recorded on the relevant incoming rack Tally & Quality Forms and the defects marked up in accordance with the marking legend contained in section 4.0 of Module 1.

2.0 CLIMATIC CONDITIONS

Prior to abrasive blast cleaning a check must be made for the ambient relative humidity conditions at the blasting area. Normally the accepted local Dew Point level is for the pipe temperature to be a minimum of 5° C above Dew Point (DP) although in many instances a minimum of 3° above “local” Dew Point is sufficient. The Relative Humidity (RH) conditions shall be carried out in accordance with an agreed Laboratory Practice/method statement.

The equipment required for checking the relative humidity is a Whirling Hygrometer a two disc calculator and calibrated digital thermometer. The Whirling Hygrometer contains two thermometers, one for wet temperature and one for dry. The hygrometer is swung in the air for approx. 30 seconds, the temperatures are noted and the two disk calculator is used to establish dew point and relative humidity.

Note: As an Alternative to the above, an approved Electronic Dew Point/Relative Humidity Meter can be used. (Where electronic devices are used they shall be suitably calibrated and operated strictly in accordance with the manufacturer’s instruction).


Examples of typical equipment used for checking DP & RH conditions


REMEDIAL ACTION

Where the Dew Point or Relative Humidity criterion is not being met, the process parameters shall be adjusted to correct the irregularity. If these parameters cannot meet the specified tolerances for DP & RH the supervisor shall be informed and the problem resolved before continuing with production.

REPORT

The DP and RH shall be recorded on a designated the incoming rack Tally/QC Form.

Record:

Time
Pipe number
The relative humidity (RH) expressed in percentage
Dew point (DP) expressed in °C above DP.

3.0 ABRASIVE ANALYSIS & CONDUCTIVITY OF ABRASIVE

On a regular basis (once per 8 or 10 hour shift minimum) the abrasives mix used for cleaning shall be analyzed in accordance with an agreed Laboratory Practice/Method Statement to determine:

1.) The amount of fines contained in samples of grit/shot taken from the working mix of the
centrifugal abrasive blasting equipment.
2.) That the working mix is free from unacceptable oily type contaminants.
3.) The conductivity of the abrasives is within the specified limitation.
The equipment required for the various analyses includes: a calibrated weighing balance, a sieve assembly, a sealable container. A conductivity meter and probe and a plastic beaker.

Sieve analysis

From the working mix a 200 gram sample shall be taken for sieve analyses, the sample shall be accurately weighed and the weight recorded. The weighed sample shall then be placed in the sieve assembly; the assembly shall consist of one large mesh sieve 1.18mm, one fine mesh sieve 425 µm. and a bottom pan. The sieve sample shall be shaken in the assembly for a minimum of 30 seconds.

On completion of shaking, the sieve assembly shall be dismantled and the contents of each sieve and the bottom pan weighed. The weight left in each sieve shall be recorded then a calculation shall then be made to determine the amount of fines that is retained in the bottom pan (fines) The acceptance criteria shall be a maximum 16 % fines.

Grit sample


Sieves


REMEDIAL ACTION

Should a higher % of fines than that specified be determined, the working mix shall be topped up with fresh material until an acceptable level of fines can be demonstrated.

REPORT

The abrasive sieve analyses shall be recorded on a designated Quality Form.

Record:

Time
Date
Sieve analyses details.
Pass Yes/No

Contamination

To check the abrasive working mix for contaminants, a 100 gram sample shall be taken from the working mix and placed in a sealed container filled will a sufficient amount of solvent to fully saturate the sample in one third of the total solvent placed in the test container. The sample shall be vigorously shaken then the contents allowed to settle (2 minutes) The solvent in the test container shall then be observed to determine if any oily residue or other substance is apparent (floating at the top of the liquid).

Grit sample (No Contaminants)


Grit sample (With Oily and other Contaminants)


REMEDIAL ACTION

Should the abrasive be contaminated, the supervisor shall be informed and the whole working mix shall be changed.

REPORT

The abrasive contamination shall be recorded on designated Quality Form.

Record:

Time
Date
Pass Yes/No.

Conductivity

For conductivity testing of the abrasive a grab sample of the working mix is placed in a plastic container. Distilled water (which is conductivity calibrated) is then place into the container to fully saturate the abrasives and allow room to cover the holes on the conductivity test probe.

The conductivity probe is then immersed in the solution, making sure that holes are completely submerged. After two minutes the probe is placed on the bottom of the beaker making sure that no air bubbles remain trapped in the sleeve.


The conductivity meter is then switched on by activating the by ON/OFF button. The temperature coefficient knob then set to 2% to compensate for the temperature effect of average solutions. Select the prescribed 19.99 ms/cm range by pressing the appropriate range key and adjust the calibration trimmer located on the side of the instrument using the calibration screwdriver until the display shows “12.88 ms” (i.e the conductivity reading @ 25 0C) All subsequent measurements will be compensated to 250C (770F). If preferred calibration can be compensation to 200C (680F) rather than 250C (770F), to do this adjust the trimmer to read “11.67 ms”. All subsequent measurements will then be compensated to 200C the calibration is now complete and the instrument is ready for use.

Conductivity testing




REMEDIAL ACTION

Should the abrasive conductivity be outside of the specified tolerance, the supervisor shall be informed and appropriate action implemented. If the contamination problem cannot be resolved the whole working mix shall be changed.

REPORT


The conductivity analyses shall be recorded on a designated quality form.

Record:

Time
Date
Conductivity levels expressed in ms/cm

END PLUGGING (Required prior to external blasting only)

Prior to the bare pipe being indexed onto the blast line conveyor, both end of the pipe shall have internal end plugs inserted to prevent ingress of the blasting materials and to protect internal coatings (If applied)

Incorrectly fitted end plugs


Correctly fitted end plugs


4.0 PIPE INSPECTION AFTER BLAST CLEANING

After blast cleaning, all pipes should be visually inspected for steel defects. In cases where defects are deemed to be of a small nature i.e. small burrs, lamination's and/or minor pitting shall be lightly ground out (if required) to remove the defect.

Small lamination's


Minor Gouges


Minor pitting


Defects that are of a more serious nature shall be brought to the attention of the client prior to rectification work being carried out i.e. deep gouges, pits and or lamination's. An agreed procedure to rectify this type of damage must be approved prior to any repair taking place.

Deep gouges


Deep lamination's


Significant pitting


REMEDIAL ACTION

Should the steel defects be outside of the allowable steel defect tolerances the pipe shall be classed as a permanent steel defect (PSR), quarantined and be subject of an NCR’


REPORT

The details of all steel defects shall be recorded on a designated quality form and if necessary photos and sketches should be appended to the report.

Record

Date
Pipe number
Defect type
Location
Status Accept/Hold/Reject

5.0 SURFACE PROFILE

On completion of surface preparation activities, the abrasive cleaning has to be assessed for surface profile in accordance with an agreed laboratory practice/method statement.

Surface profile is defined as the average peak-to-valley depth that is created during surface preparation. It sometimes is referred to as “anchor pattern”, “tooth”, “surface amplitude”. Surface profile when observed under high magnification resembles lunar craters or a series of peaks and valleys in the surface of the steel. These peaks and valleys can be sharp, or “angular,” or they may be rounded or a mixture of both.

Surface profile or anchor pattern is generated by abrasive blast cleaning and by some power tool cleaning methods. The adhesion of the coating system to the underlying steel surface is greatly enhanced by generating this “peak and valley” pattern in the steel, which effect actually increases the total surface area for the coating material to adhere to.

Surface profile is quantified by measuring the depth of the “valleys” in relationship to the top of the “peaks.” Inadequate surface profile depth may not properly “anchor” the coating system (and disbonding may occur), on the other hand an excessive surface profile may cause rogue peaks that can potentially protrude through the coating film and cause pinpoint rusting and/or accelerated corrosion to occur.

There are three methods that are most practical and routinely used (both on the shop floor and in the field) for quantifying the depth of the surface profile after surface preparation.

  • Method A: Replica Tape
  • Method B: Surface Profile Depth Micrometer
  • Method C: Visual Surface Profile Comparator
  • Method D: Stylus/Rugotest 
METHOD A (REPLICA TAPE METHOD)

Burnishing Testex Sample



Measuring Testex Sample


Knuckle Gauge & Testex Burnishing tool


Use of a replica tape in conjunction with a spring-loaded micrometer (Knuckle Gauge). This method of surface profile measurement entails generating an “impression” of the anchor pattern and measuring the impression using a spring-loaded micrometer.


The “Testex” replica tape itself consists of a non-compressible 2-mil-thick polyester film bonded to a compressible layer of foam, which is attached to the underside of the film). On all testx types,the film remains a constant 2 mils, but the amount of bonded compressible foam varies depending on the range of the replica tape. The compressible foam is pressed into the anchor pattern, effectively creating a mirror image of the surface profile in the foam. The peak-to-valley impression is then measured using a calibrated spring micrometer.


Step 1: Selecting the Appropriate Replica Tape

Prior to obtaining a surface profile measurement, select the range of the replica tape to be used. There are four ranges to choose from, including:

  • “Coarse,” which measures surface profile depth from 0.8 (20 µm) to 2.0 mils
  • “Paint Grade,” which measures surface profile depth from 1.3 to 3.3 mils (33 to 84 µm)
  • “X-Coarse,” which measures surface profile depth from 1.5 to 4.5 mils (38 to 114 µm)
  • “X-Coarse Plus,” which measures surface profile depth from 4.0 to 6.5 mils (102 to 165 µm).
Note: Replica tape typically is selected based on the specified surface profile depth being specified.

Step 2: Preparing the Surface for Measurement

Unlike other methods of surface profile measurement, the replica tape method can be adversely affected by residual abrasive and dust remaining on the abrasive-blast-cleaned surface. Therefore, prior to obtaining a measurement, ensure that the measurement area is free of dust and abrasive debris by lightly sweeping the surface with a clean brush.

Step 3: Preparing the Replica Tape

Remove a piece of the tape selected for use from the roll. Carefully remove the replica tape from the paper backing, this exposes the adhesive on the tape. Discard the paper backing and the small black and white protective circle attached to the paper backing. Ensure that the protective circle does not remain attached to the replica tape. Firmly attach the replica tape to the surface to be measured, leaving one corner folded over to create a pull-tab.


Step 4: Burnishing the Replica Tape

Using the rounded tip of the plastic burnishing stick provided with the micrometer, burnish the white, 3/8-in. (0.6-cm)- diameter circle located in the center of the replica tape until it turns uniformly gray. After verifying that there are no visible white streaks, use the pull-tab to lift the replica tape carefully from the surface.


Step 5: Adjusting the Micrometer

Adjust the micrometer so that the indicator needle rests on “0” with the micrometer anvils closed. 

Step 6: Measuring the Replica Tape and Determining the Surface Profile Depth

Insert the replica tape containing the surface profile impression into the anvils of the micrometer and release the lever. This allows the top and bottom anvils to close in the center of the 3/8diameter film/foam circle.

The micrometer indicates both the thickness of the non-compressible 2-mil film and the peak/valley impression in the compressible foam. To determine the surface profile depth you must subtract the 2-mil polyester film thickness from the micrometer reading.

To eliminate the need for constantly deducting the film thickness you can set the micrometer needle on “8” rather than “0” in Step 5. This effectively presets the micrometer allowing for the –2 deduction.


Using the X-Coarse Plus Range of Replica Tape

The X-Coarse Plus replica tape can be used to measure very deep anchor patterns—up to ~6.5 mils or more. To use this tape, confirm that there is sufficient compressible foam mounted to the film before trying to obtain a measurement.

Prepare the tape as described in Step 3. Prior to attaching the tape to the surface, however, set the needle on the micrometer to “8” (effectively –2 mils). Insert the unused piece of replica tape into the anvils of the micrometer and release the lever. The micrometer reading is the maximum surface profile depth that can be measured with that piece of replica tape. Follow steps 4 through 6 above from this point forward.


Step 7: Recording the Measurement

Document the area tested and surface profile measurement on the test tape itself in the sections labeled “No.” and “Reading,” respectively. Always record the surface profile depth after the 2 mils has been deducted for the polyester film. Finally, verify that the recorded surface profile depth falls within the range of the tape chosen for measurement. If it does not, then the reading may be invalid.

Calibration of Surface Profile Measurement Equipment


It is not necessary to calibrate the visual surface profile comparator. If the comparator discs become tarnished, however, they can be difficult to use. A soft pencil eraser can be used to remove the tarnish without disturbing the electroformed pattern on each segment.


Calibration of the surface profile depth micrometer was described earlier. Conduct this “zero-verification/ adjustment” procedure prior to and after each period of use.
Although the replica tape itself needs no calibration, routinely confirm the micrometer’s level of accuracy by inserting shims of known thickness into the instrument and verifying a correct measurement. Plastic shims used to calibrate coating thickness gauges can be used for this purpose. Recognize, however, that these shims may not represent an exact thickness.

METHOD B (The Surface Profile Depth Micrometer)



Method B uses a surface-profile-depth micrometer. For this method, one measures the depth of the “valleys” using a conical-shaped metal tip. The surface profile depth appears on the gauge dial or on the digital display depending on the model.

Step 1: Verification of “Zero”

Before using the depth micrometer, verify the zero reading by placing the micrometer base onto a piece of plate glass. The gauge should indicate “0.” If it does not, adjust the dial gauge or the digital display until attaining a zero reading.

Step 2: Obtaining Surface Profile Measurements

Place the base of the calibrated gauge onto the abrasive-blast-cleaned steel and push downward. Do not slide the gauge as this will dull the protruding pinpoint and affect gauge accuracy. Read the scale or digital display and record the surface profile depth. The gauge reading represents the depth of the valley in a very small area. Therefore, it is important to obtain multiple measurements in a given area and to obtain measurements in multiple areas. Record each individual gauge reading in order to calculate the average and range of the anchor pattern.

Step 3: Re-verification of “Zero”

After using the depth micrometer, verify the zero reading again by placing the micrometer base onto a piece of plate glass. The gauge should indicate “0.” If the zero adjustment is off by a significant amount, it may be necessary to measure the surface profile again.

METHOD C (The Visual Surface Profile Comparator)


Method C uses the Visual Surface Profile Comparator method. For this method, one visually compares the prepared steel surface to an electroformed nickel disc containing known anchor patterns through a 5-power illuminated magnifier.


Step 1: Understanding the Comparator Disc Stencils


Each comparator disc contains five segments. Each segment of each disc is stenciled with a code identifying the surface profile depth, the disc type, and the year that a master disc was generated (the discs are electroformed copies of a master disc; they are not prepared individually by abrasive blast cleaning). The first stencil on each segment indicates the surface profile depth depicted in mils (e.g., 1, 2, 2.5, 3 mils [25, 50, 64, 76 µm], etc.). The second stencil on each segment indicates the abrasive type (S for Sand, SH for Shot, and G/S for Grit/Slag)

Your choice of disc will depend on the abrasive media used to blast-clean the steel surface.

Step 2: Selecting the correct Comparator Disc

Select the comparator disc that matches the type of abrasive used to blast-clean the surface. Use the S disc to compare surfaces that were prepared using silica sand; use the SH disc to compare surfaces that were prepared using steel shot; and use the G/S disc to compare surfaces that were prepared using grit or slag abrasives. G/S can represent a variety of abrasives, some of which include steel grit; copper, coal, and nickel slag’s; garnet; aluminum oxide (Al
2O3); and others.

Many fabrication shops use an operating mix of steel shot and steel grit in their centrifugal blast machines. Because this is a visual assessment of surface profile depth, the G/S disc likely is the best candidate as it depicts angular peaks and valleys.


Step 3: Attaching the Comparator Disc to the Illuminated Magnifier

Choose the disc that represents the abrasive used to prepare the surface, then attach the disc to the viewing head of the 5X illuminated magnifier (face up, centered). The magnifier head is equipped with a magnetic strip that holds the disc in place during prepared surface examination.

Step 4: Examining the Prepared Surfaces


Turn on the magnifier’s light switch and place the magnifier with the attached disc directly onto the abrasive blast-cleaned steel (Figure 2). The hole in the center of the disc reveals the prepared surface. Compare this surface to each of the five segments and select the segment that is the closest match to the surface profile depth. If the surface falls between two segments, do not interpolate but simply record both segments as a range (e.g., 2 to 3 mils). Record the type of disc used and the surface profile depth (in mils). If the specification refers to surface profile depth in terms of µm (micrometers or microns), convert the surface profile in mils to µm by simply multiplying that amount by 25.4 (e.g., 3 mils is 76 µm). Therefore, accurately assessing the surface profile depth for compliance with the governing specification is paramount to a successful coatings project.


Method D (Stylus/Rugotest)


Surface Roughness can be assessed using electronic and stylus type instruments. Parameters commonly used when these instruments are utilized instruments:

Mean roughness Ra (ISO 4287, DIN 4768) The mean roughness Ra matches the arithmetical mean of the absolute values related to the profile deviation y within the reference length l.

Max. profile valley depth R max (DIN 4768) The max. profile valley depth R max counts for the most significant single roughness depths Zi within the total length lm.

According to ISO 4288 and DIN 4287 - Part 1, this parameter is also  specified as Ry max.

Mean roughness depth Rz DIN (DIN 4768) The mean roughness depth Rz is the arithmetical mean of single roughness depths of successive sampling lengths le. According to ISO 4287 and DIN 4762, the parameter Rz DIN is also  specified as RY5 .

Since Rz changes its name in both DIN 4768 and ISO 4287, this parameter is also specified as Rz DIN or Rz ISO
.
If the parameter Rz is measured according to DIN, it is generally admitted that the extreme value specified by ISO is matched providing that Rz  ISO does not exceed Rz DIN

REMEDIAL ACTION

Where the surface profile is found to be out with the specified requirements the production line supervisor is to be notified and remedial action to be implemented. Pipe that has been found with profile depth defects shall be rejected and re processed.

REPORT

The surface profile determinations shall be recorded on the designated Quality Form.

Record


Date
Time
Measurements
Method
Average of the measurements expressed in µm.

6.0 BLAST CLEANING STANDARDS

The blast cleaning standard shall be determined in accordance with an agreed Laboratory Practice/Method Statement.

The blast cleaning standard is designated by the letters “Sa” e.g. common standards used are Sa 2.5 or Sa 3

Prior to blast cleaning, any layers of rust shall be removed by chipping. Visible oil, grease and dirt shall also be removed.

After blast cleaning, the substrate surfaces shall be cleaned from loosely adhered dust and residues.

Note: for descriptions of surface preparation methods by blast cleaning, including treatment prior to, and after the blast cleaning process see the relevant industry standard ISO 8504-2

Sa 2 Light blast cleaning

When viewed without magnification, the surface shall be free from visible oil, grease and dirt, and from poorly adhering mill scale, rust, paint coatings and foreign matter. See picture, Pictorial Standard No. 1

Sa 2.5 Thorough blast cleaning

When viewed without magnification, the surface shall be free from visible oil, grease and dirt, and from most of the mill scale, rust, paint coatings and foreign matter. Any remaining contamination shall be firmly adhering. See picture, Pictorial Standard No. 2

Sa 3 Blast cleaning to visually clean steel

When viewed without magnification, the surface shall be free from visible oil, grease and dirt, and shall be free from mill scale, rust, paint coatings and foreign matter. It shall have a uniform metallic appearance. See picture, Pictorial Standard No. 3


Typical pictorial standard



Pictorial Sa 2


Pictorial Sa 2.5


Pictorial Sa 3


The blast standard is visually monitored on every pipe and is randomly checked throughout the working shift against the relevant pictorial standards.

REMEDIAL ACTION

Where the blast standard is found to be out with the specified requirements the production line supervisor is to be notified and remedial action to be implemented. Pipe that has been found with blast standard defects shall be rejected and re processed.


REPORT

Record the blast grade on the designated Quality Form:

Record

Date
Time
Pipe number
Blast standard observed

7.0 SURFACE CONTAMINATION

The surface contamination shall be determined in accordance with an agreed Laboratory Practice/Method Statement.

To check the level of surface contamination after abrasive blast cleaning apply a suitable size strip of clear plastic adhesive tape on the area of steel substrate to be tested, pressing evenly and firmly onto the pipe and into the profile at the test area.

The tape is then removed carefully and placed (adhesive side to paper) on a white paper background (or pre formatted area of the inspection report).

The amount of contamination is then evaluated after displaying against the industry standard ISO-8502 Standard Chart for surface dust and contaminants.

Tape on pipe



Tape on Report


REMEDIAL ACTION


Where the surface contamination is found to be out with the specified requirements the production line supervisor is to be notified and remedial action to be implemented. Pipe that has been found with contamination defects shall be rejected and re processed.


REPORT

Record the surface contamination on the designated Quality Form:

Record

Date
Time
Pipe number
Contamination level 1-5

8.0 STEEL WALL DEFECTS (After Abrasive Cleaning)

Pipes that are segregated for pipe wall defects that require grinding are usually subject of an
NCR.

Before grinding the wall of a pipe the operator must be in possession of an agreed procedure and have a instruction from the owner of the pipe prior to carrying out the work.. This agreement however can be in the form of an approved action included in an NCR.

ASSESSMENT OF DEFECTS (general)

Pipes stood aside with steel wall defects shall be examined after surface preparation and the defects assessed according to the applicable Inspection and Testing Plan criteria, this criterion is usually in reference to a particular standard for steel pipe. E.g. API

Wall defects, pits, gouges, lamination's etc shall be clearly identified and marked up accordingly. Under some circumstances photographs shall be taken prior to any rectification work is carried out.

GRINDING OF DEFECTS

The grinding of defects shall be carried out using a hand grinder fitted with an appropriate cutting type disc. Care must be taken not to over grind defected areas; excessive over grinding may cause the loss of wall thickness to the extent that the pipe wall thickness no longer meets the requirements of the steel manufacturing specification.

Grinding shall be carried out in stages, a light grind followed by a wall thickness measurement check (Pit Gauge or UT) keep repeating this process and till either the defect is removed or when it is apparent that the pipe wall thickness tolerance will be breached.





REMEDIAL ACTION

Grind areas to remove defects within the pipe wall thickness tolerances. Note where grinding of the parent steel is close to the pipe wall thickness minimum tolerance the grinding shall not continue and the Client shall be informed of the problem.

DO NOT CONTINUE GRINDING

REPORT

The defects shall be recorded on an agreed Quality Form, sketches and photos are to be appended if required.

Record

Date
Type of Defect
Location
Status Accept/Hold/Reject

WALL THICKNESS CHECKS (USING ULTRASONIC THICKNESS and/or PIT GAUGE)

UT GAUGE - The ultrasonic thickness gauge shall meet the following requirements:

Type of instrument shall be approved by the client
Range of measurement: not less than 50mm
Accuracy of measurement: ±0.1mm
Application temperature: 0 0C to + 40 0C

Prior to wall thickness measurement, dust, dirty and rust in area to be measured shall be removed. The area to be measured shall be smooth and free of visible corrosion pitting.

The ultrasonic wall thickness measurement shall be taken according to the following steps:

Note: Measurements shall be taken on clean unaffected (defect free) areas of the pipe wall as close to the identified defect that is practical. 

A minimum of two (2) measurements shall be made for each test zone. If slight difference in WT is noted the thinnest WT reading shall be used. If larger difference is noted, the reason shall be established before the unaffected WT is determined

Plug the probe into the UT gauge. Turn on the gauge. Start measurement after the gauge displays no indication of low power, input error etc.

Calibration

The gauge shall be calibrated each time when it is turn on and when the probe or battery is changed. Prior to calibration, reset the gauge to make the gauge into calibration status. Put some coupling agent onto the standard plate. Make the probe vertically and well touched with the plate until the gauge reads 4.mm to finish calibration.

If the gauge does not display expected number, move the probe away. Reset the gauge to make the gauge into calibration status and repeat the above steps until calibration is completed. The tolerance of the UT gauge shall be zeroed during calibration.



Measurement of Steel Pipe Wall Thickness

Evenly spread coupling agent onto the surface of area to be measured. Diameter of the coupling agent shall not be less than 15mm. vertically touch the probe to the surface to be measured. When the gauge is ready and displays a value, read and record the value to finish measurement.

Coupling Agent

To be washed and cleaned, coupling agent shall be of water-based solvent, such as composition glue and detergent. Its viscosity shall meet measurement requirement. Before measurement starts, the coupling agent shall be tested on the standard plate of the gauge, and shall be used only when the test result satisfies calibration requirement.

PIT GAUGE - The Pit Gauge shall be approved by the client.

CALIBRATION

Calibrate (or "zero") the pit gauge dial indicator. Place gauge on a flat reference surface. This surface should be true and without pits or other variations, and gauge should be oriented in a similar manner as surface to be assessed. Loosen locking mechanism, and rotate dial face until "zero" is aligned with large needle. Tighten locking mechanism.

Place gauge on surface to be assessed. "Feet" should be positioned on a true surface and should span the pit. If the feet of the gauge do not span the area being assessed then a bridging bar shall be utilized. Place dial depth surface on the flat surface as shown in figure (glass slide) Twist the movable scale until needle indicator reach to ‘0’ digit Dial depth gauge is ready to use








MODULE N0. 3
APPLICATION of COATING
ELEMENTS IN THIS MODULE:
Internal Flow Coating Application
Asphalt Enamel Application
INTRODUCTION PIPE COATING

Module “3” describes the requirements for inspection and recording the identity of pipes when being processed in anti corrosion coating facilities. Coatings described within this module include Internal Flow Coating and Asphalt Enamel

1.0 INTERNAL FLOW COATING

Internal Flow Coating is usually undertaken using specially formulated water based or epoxy coatings that can be applied to pipe internal surfaces. The coatings are usually applied to improve the flow efficiency of the pipeline rather than a protective coating, although in some instances the coatings are of a dual purpose.

Typical Internal Coating



1.1 MATERIALS:

All incoming materials should be checked against the material manufacturer’s certification and any other specification requirements. The incoming materials receipt report (IRF) must be completed when materials are received.

REPORT

Record

Material certification,
Batch numbers
Date of manufacture.
The form shall also outline the incoming tests required for the material (If required)

Note: All materials shall be stored strictly in accordance with the manufacturer’s instructions

Prior to the commencement of internal pipe coating it is imperative that all the fundamental requirements are assessed and checked out. This includes the testing of the raw materials to verify that they are in compliance to the specified requirements for the particular type of materials used.

The processing system must also be checked out to ensure that the material mixing and metering equipment is correctly calibrated and all application parameters are correctly set.

1.2 INCOMING PIPE


Pipes that are received at the incoming racks shall be inspected for contamination and/or pipe defects that prevents acceptable coating and cannot be repaired at the incoming rack or grinding area. See Module 2

1.3 PREHEAT & BLAST CLEANING:


Prior to abrasive cleaning, the pipes re be pre-heated (if required) to eliminate any moisture from the substrate. The internal surfaces are abrasive blast cleaned to remove rust and mill scale in accordance with the specified requirements for surface preparation. The typical blast standard requirement is a minimum of Sa 2.5.

The pipe surface temperature shall be monitored prior to blast cleaning using a hand held surface contact pyrometer or optical pyrometer. The preheat temperature should be checked as a minimum each hour. The steel surface temperatures to be blast cleaned shall typically be of 3° C above the local dew point, the dew-point should be checked at the commencement and twice per shift. All climatic conditions shall be recorded on an agreed Quality Report.

See Module 2

The blast cleaning is carried out using an internal blast unit that travels through the pipe interior at a controlled even speed that allows for the correct grade and blast profile to be achieved.

Internal Blasting

Pipes Prior to Blasting


Pipe after Blasting

On completion of abrasive blasting, the internally blasted pipe surface is visually inspected for surface imperfections.

Note: Suitable lighting must be available to assist with this inspection.

Where practical access is available, the imperfections shall be removed by hand filing or light grinding in a manner that does not adversely compromise the pipe wall thickness tolerances.

Where surface defects are observed that are not accessible to be repaired the pipe shall be stood aside and NOT coated.

The pipes should also be inspected for both surface cleanliness and surface roughness (Profile). The acceptance criterion and inspection frequency is found within an agreed project inspection plan (ITP)

See Module 2

It is normal practice that salt contamination checks are carried out at the commencement of production followed by two tests daily. The Maximum acceptable salt contamination level and test frequency is contained within an agreed project inspection plan (ITP)

See Module 2

After the inspection process, the cutback ends are prepared by placing self-adhesive masking tape of correct width to the internal cutback sections of the pipe.

Note: Where test panels or slides are required, they shall be affixed (if possible) in the cutback area of the test pipe.

The pipe is then lowered onto an a clean air blow out station where a high pressure air lance travels through the pipe and removes unwanted residue dust and blast media from the pipe internal. After the blow out station the pipe is then indexed to the coating application line and placed upon rotating buggies.

Responsibilities:

The Abrasive Blast Line Supervisor should ensure that the blast boom speed is travelling at the correct rate and that surface amplitude and cleanliness standards are maintained within the specified tolerance. He shall also be responsible for ensuring that all processing is performed in the safest possible manner.

The QC Inspector/Auditor shall be responsible for verifying that the specified climate, salt contamination, cleanliness, surface roughness and blast grade condition are monitored and recorded. He shall also ensure that samples of the abrasive are checked by the laboratory at the test frequency as specified.

The laboratory Technician shall be responsible for receiving the abrasive samples and for performing and recording the required tests.

1.4 MATERIAL APPLICATION


On completion of the surface preparation a counter levered material application boom (fitted with a material application head) travels at a pre determined travel rate within the pipe applying the coating material.


The constituent material components are mixed together (for normal airless application) at the mixing station, the mixed material is fed through the application boom and applied to the internal steel surfaces using an airless application head. ( for plural spray systems the materials are mixed at the application head on the paint boom just before the spray head tips).


The material application takes place whilst the pipe is steadily rotating and whilst the boom supporting the material application head retracts from the pipe at a pre-determined speed. After completion of coating, the freshly coated pipe is checked for the wet film thickness (WFT). The pipe is then rotated for a while at a higher rotation speed to reduce the risk of runs or sags occurring.


Paint Mixing Station



Internal Coating Application


Typical Airless Application


Typical Plural Mixing Head


Immediately after the application of the coating and removal of the cutback masking paper, the pipe is transferred to the post curing station. To accelerate curing of the freshly applied internal flow coating, warm re-circulating air is introduced to the pipe interior.


After the pre curing process, the initially dried coating is visually inspected for uniformity. In the event of bad weather, accepted pipe have their ends temporary covered with clear light gauge plastic sheathing which is perforated to allow egress of the solvents during the curing process. The plastic sheathing also protects the coating from dust and/or moisture while in the pipe storage area.


REMEDIAL ACTION


Non-conforming pipe are typically marked with white paint or applied masking band across the bevel ends to ensure pipe will be re-processed. Any defects (porosity/holidays) disclosed by visual and/or by wet sponge testing and other obvious defects shall be repaired by the applicator.


Pinhole type holidays shall be repaired using material similar to the parent coating materials and shall be touched up by hand using an artist soft brush in accordance with procedures approved by Client.


In cases where the damage coating of a larger nature the area shall be prepared by power wire brushing to ISO St 3. The sound parent coating surrounding the repair area shall be cleaned by removing all surface contaminants and loose or disbonded coating. The surface shall then be wiped clean and touch-up with a premixed material taken from the parent material application tanks.


See typical repair section procedure item 1.7 below.

Internal defective coating (under thickness) or damaged coating due to handling, shall be re coated within the manufacturer’s allowed re-coating time.


Note: Re coating can only be carried out if allowed and approved by the Client. If not approved, the pipe shall be rejected marked up as above and re processed.


REPORT


The coating details shall be recorded on an agreed Quality Form or Forms


Internal blast cleaning report

Internal coating report

Internal coating repair report


Record


Pipe Number

Sequence number (if required)

Pipe Length

Pipe OD

Pipe Wall Thickness

Coating Wet Film Thickness (WFT)

Cut back distance

Pipe Status (Hold Reject etc)

Repairs

Test Pipe YES/NO


Responsibilities

The coating supervisor should ensure that all coating is carried out under controlled conditions. If unsure about the disposition of pipe defects, he should contact the QA department with any queries. He should also be responsible in ensuring that the task is conducted in the safest possible manner.

The QC Inspector should be responsible for recording disposition of pipe exhibiting defects and raising NCR report. He shall also perform periodic testing in accordance with an agreed Inspection Test Plan (ITP)

The Tallyman should ensure traceability of all pipes and correct records of defective pipe movement and disposition.


1.5 INSPECTION AND TESTING

Visual Inspection


On completion of the coating and curing process each pipe are visually inspected. The coating should be a continuous smooth uniform even textured and coloured coating and should be free from runs, sags, pinholes and others imperfections indicative of incorrect coating application.


Cutback


All cutback distances are be checked and no tape residue should remain on the substrate.


Tape Adhesive Contamination




Thickness checks


Check the wet film thickness (WFT) using a comb-type gauge. Check the dry film thickness (DFT) either by using pre-calibrated magnetic lift off device and/or an electronic thickness gauge approved by Client.


Note: The Wet Film (WFT) measurement shall allow for the percentage (%) solids of the material for e.g, a 50% solids material shall have a WFT that is twice as thick of that of the required Dry Film Thickness (DFT)

The dry film thickness shall also be checked on metal test panels (Type B samples) coated within the test pipes and also on significant areas inside the test pipes. See off-line tests below

Holiday Detection

Normally it is a requirement to test significant areas inside test pipes for holidays using a low voltage wet sponge method.

1.6 OFFLINE TESTING

Besides the online testing and inspection requirements there are a series of “Off Line” tests that have to carried out to confirm compliance of the coating system against the specified requirements of the project. Test include the following practices:

Porosity Adhesion
Coating removal resistance
Curing Test

Bend Test

Salt Spray

Water Immersion

Gas Blistering


Typical method of affixing test sample plates to cutback area


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Porosity - API RP 5L2

Porosity Check (wet and dry) - Pinhole Check


Note:This practice may be modified by the requirements of the customer’s specification, see relevant Project Inspection Test Plan (ITP)


Scope


Carry our 100% visual examinations through a glass slides prepared and coated with the pipe during the coating process. Glass slides (Type A samples) both wet and dry shall be prepared and viewed with 100W bulb according to API RP 5L2


Typically a maximum of 5 pinholes shall be allowed on a test slide.


Equipment

Glass slide panel
Cleaning Solvent
100-watt light bulb and test box

Procedure

Attach solvent washed glass panels with roughened surfaces (size approximately 25mm x 75mm x 2mm) to the internal test areas of production pipes used as test pipes. On completion of coating the test pipes the glass slides shall be removed and examined. The panels shall be checked (by naked eye) both wet film and subsequently dry film for pinholes.

No pinholes shall be visible when viewed with the naked eye against the normal sunlight. There shall be no more than 5 pinholes on the glass slides visible when viewed against a 100-watt common household light bulb.

Porosity Checks






Report


Record



Date

Pipe number (test pipe)

Sample Number

Porosity (sunlight)

Porosity (lamp box)

Pass YES/NO


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Adhesion test - API RP 5L2


Note:This practice may be modified by the requirements of the customer’s specification, see relevant Project Inspection Test Plan (ITP)

Scope


To determine the adhesion of cured internal coating


Equipment

Sharp Knife or cross hatch cutter
Metal test panel
Transparent Adhesive tape

Procedure

Prepare metal panels (abrasive cleaned) Type B samples and placed in different test pipe heads prior to coating. On completion of coating and when coating has cured carry out a Crosscut adhesion test. The test area is prepared on an area of the panel that is a minimum of 13 mm from the panel’s edge. Using a sharp knife or purpose made grid cutting tool cut the coating through to the metal with 16 lines over 25 mm. Then make a further 16 cuts at 90º through the previously made cuts. (This will produce 225 squares)

On completion of preparing the grid sample firmly place a self-adhesive backed tape (adhesive side contacting the coating) on the test area, then remove in a snapping action.

Evaluation


The coating is considered acceptable if no coating (other than cuttings) is removed from any of the grid area.



Report


Record

Date

Test Pipe Number

Sample Number

Pass YES/NO


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Coating removal resistance - API RP 5L2


Note:This practice may be modified by the requirements of the customer’s specification, see relevant Project Inspection Test Plan (ITP)


Scope


To test the internal coating material sample for resistance to removal


Equipment

Stanley Knife or similar

Procedure

Place a prepared Type B test panel (size approximately 75mm x 150mm x 2mm) onto a firm flat surface (coated side facing upwards).

Using the same samples as used for the Cross-cut test, carry out a coating removal test whereby “X” or “V” cuts are inscribed through the cured coating down to the bare steel using a sharp knife. A sharp knife is then held at approximately 60º to the surface and pushed so that the blade has a tendency to lift the coating.

Evaluation

The coating shall not be removed from the test panel in strips but should flake off. The flakes when rolled between the thumb and forefinger, shall produce powdery particles.





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Curing Test - API RP 5L2/ ISO 4628-1 rating 0 to 2.


Note: This practice may be modified by the requirements of the customer’s specification, see relevant Project Inspection Test Plan (ITP)


Scope


To test the internal coating material for cure.


Equipment

Solvent (MEK) or thinner
Glass container

Procedure

Attach prepared (blast cleaned) Type B metal panels (size approximately 25mm x 100mm x 2mm) to the internal test areas of production pipes used as test pipes.

After the coating and when he coating is cured, Immerse the cured metal test panel into solvent (MEK or thinner used in thinning paint). Soak the test panels in the thinning material for a period of 4 hours at ambient temperature.

Evaluation

After 4 hours remove panels from the solvent and allow the coating to recover for a period of 30 minutes prior to evaluating the results., The cure shall be acceptable if no softening, wrinkling or blistering of the coating film are observed.


                                                                        Cure Testing




Report


Record


Date

Test Pipe Number

Sample Number

Pass YES/NO


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Bend Test - API 5L2/ (ASTM D1737)


Note:This practice may be modified by the requirements of the customer’s specification, see relevant Project Inspection Test Plan (ITP)


Scope


To test material for flexibility after coating application and coating cure.


Equipment


Cylindrical mandrels with diameters of 3mm to 13mm.

Procedure

Attach prepared (blast cleaned) Type B metal panels (size approximately 25mm x 100mm x 2mm) to the internal test areas of production pipes used as test pipes.

After the coating and the coating has cured, the test panels (from different pipe heads) shall be bent around cylindrical mandrels (API RP 5L2 Clause 5) with diameters of 13mm and 3mm.

Evaluate result visually; there should be no rupture/crack or loss adhesion of the coating to the plate when bent over the 3mm diameter section of the mandrel.


Bend test





Report


Record


Date
Test pipe Number
Sample Number
Pass YES/NO


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Salt Spray - API RP 5L2 Appendix B


Note:This practice may be modified by the requirements of the customer’s specification, see relevant Project Inspection Test Plan (ITP)


Scope

To test the internal coating material sample for resistance to salt spray.


Equipment

Salt spray container
Clear plastic tape

Procedure

Place a prepared Type B test panel (size approximately 75mm x 150mm x 2mm) onto a firm flat surface (coated side facing upwards)

Using a Stanley knife the panel shall be scored down to bare metal in a diagonal configuration on the coated side. The inscribed side of the panel shall face the salt spray for a minimum period of 500 hours.

Evaluation

The test result shall be satisfactory if after 30 minutes of drying upon removal from the fog and spray, the coating exhibits no blistering, and not more than 3.2 mm of coating can be removed in any direction from the area surrounding the scribes with a pull by clear plastic tape.

Record

Date
Test Sample Number
Pass YES/NO


------------------------------------------------------------------------------------------------------------------------------


Water Immersion API RP 5L2 (5.2.4.6)


Note:This practice may be modified by the requirements of the customer’s specification, see relevant Project Inspection Test Plan (ITP)


Scope

To test the internal coating material sample for loss of adhesion, softening, wrinkling and blistering


Equipment

Fresh water or aqueous solution
Glass container

Procedure

Attach prepared (blast cleaned) Type B metal panels (size approximately 25mm x 100mm x 2mm) to the internal test areas of production pipes used as test pipes.

After the coating and when he coating is cured, Immerse the cured metal test panel into the water or solution for a period of 4 hours at ambient temperature.

After 4 hours remove the panels from the test glass and evaluate results.

Evaluation

There shall be no loss of adhesion, softening, wrinkling or blistering of the coated film observed after 30 minutes following removal from the glass container.

Report

Record

Date
Sample Number
Pass YES/N


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Gas Blistering - API RP 5L2 Appendix 5 (E)


Note:This practice may be modified by the requirements of the customer’s specification, see relevant Project Inspection Test Plan (ITP)


Scope

To test the internal coating for resistance to gas blistering


Equipment

Pressure container (autoclave)
Dry nitrogen Gas

Procedure

A Type B sample to be prepared and placed internally in the pipe. (size approximately 75mm x 150mm x 2mm) onto a firm flat surface (coated side facing upwards).

The cured coating sample shall have the uncoated sections protected from the atmosphere.
He sample shall be placed in a suitable pressure container

Using dry nitrogen gas, the pressure within the container shall be raised to 1200 ± 100 psi.
The temperature shall be adjusted to 25± 6 ° C

The pressure shall be maintained for 24 hours after which the pressure is released during a period of not more than 5 seconds. .

Evaluation

The coating shall be examined within 3 minutes of the time that the pressure was released. Any blistering found shall constitute a failure.

Report

Record

Date
Sample Number
Pass YES/NO

1.7 REPAIR PROCEDURES


Repair procedures shall be in accordance with the Manufacturer recommendations. A typical example of acceptable area for repair is, a maximum of 100 cm/2 of the total internal pipe surface with allowing up to 3 repairs per pipe within the 100 cm/2. Repair material shall be the same material used in the factory applied coating.


Note: Tests points on pipes are not considered to form part of the repair criterion.


2.0 ASPHALT ENAMEL COATING


Asphalt Enamel Coating is undertaken using a hot molten petroleum bi product “Bitumen” commonly known as Asphalt Enamel, during its manufacture the material is oxidized (known as blowing) to various specific qualities suitable for pipe coating.

The Asphalt Enamel coating system consists of a primer followed by alternate layers of hot applied Bitumen and glass fiber inner wraps and finally an impregnated reinforcing outer wrap.

Primer Layer


Primer Thickness Check

Prior to the commencement of Asphalt coating it is imperative that all the fundamental requirements are assessed and checked out. This includes testing of the raw materials to confirm their compliance to the specified requirements for the correct application of the coating.

The processing system must also be checked to ensure that the heated bitumen material can consistently be maintained at the correct holding and application temperatures and the metering of the material remains constant. Failure to check these parameters can cause inconsistent coating thickness during application and/or degradation of the material due to excessive heating.

2.1 MATERIAL

Primer

The primer used for Asphalt enamel coating is commonly a synthetic primer complying to the requirements contained in industry standard BS 4147 Type B. Each batch of primer shall be checked against the specified requirements and the certification for each batch shall be checked for compliance.

The primer is tested on receipt for the rate of flow (Viscosity) and for volatile matter in accordance with the specified frequency rate detailed in the project Inspection Test Plan (ITP). The test for flow rate and volatile matter is carried out in accordance with and agreed Laboratory Practice/Method Statement.


Volatile Matter





--------------------------------------------------------------------------------------------------------------------------------


Volatile Matter Primer – BS 4147


Note:This practice may be modified by the requirements of the customer’s specification, see relevant Project Inspection Test Plan (ITP)


Scope


Determine the volatile percentage mass of the primer.


Equipment

Round circular dish 75 mm in diameter Oven Procedure Weigh to the nearest milligram between 1.0 and 2.0 g of the primer into a tared flat bottomed circular dish, about 75 mm in diameter. Heat the dish and its contents in an oven at a temperature of 105-110C for three hours. Allow the dish to cool to room temperature in a desiccator then reweigh to the nearest milligram.


Evaluation


Calculate the volatile matter


V/matter = 100 x M1 – m2/M1


Where


M1, is the mass of the sample prior to heating
M2, is the mass after heating


Report


Record


Date
Batch Number
Volatile Matter expressed in % mass


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DETERMINATION OF VISCOSITY / FLOW TIME – BS 4147


Note:This practice may be modified by the requirements of the customer’s specification, see relevant Project Inspection Test Plan (ITP)

Scope

Determine the flow characteristics of the primer

Equipment

Flow Cup No.3
4mm Flow Cup
Stop watch
Ice cubes (for cooling)
Support stand
Certified Thermometer

Procedure

Adjust the temperature of the primer sample and the flow cup to 23 ± 0.5°C or to an alternative
temperature agreed by the Client.

Place the flow cup on the support stand and level to the top of the cup.

With orifice closed by the finger, fill the sample until it just begins to overflow into the gallery.
Pour slowly to Avoid formation of air bubbles. Ensure the level of the sample coincide that of the
top of the cup.

Place a suitable receiver under the flow cup, remove the finger from the orifice and
simultaneously start the timing with the stop watch, stopping it when the stream of the sample
first breaks.

Evaluation

The time taken shall be recorded and reported as the viscosity in seconds. The results of
successive Determinations should not differ from their mean by more than 2.5%.

Report

Record

Date
Batch Number
Viscosity expressed in seconds


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Asphalt Enamel

The Asphalt enamel is supplied in clean bulk containers and is usually required to comply with the requirements of industry standard BS 4147 Type 2 Grade B.

Each batch of Enamel shall be checked against the specified requirements and the certification for each batch shall be checked for compliance.

The enamel shall be tested on receipt for the following conditions:

Softening Point
Filler Content
Penetration
Specific Gravity

The tests shall be carried out in accordance with the specified frequency detailed in the project ITP. The test shall be carried out in accordance with an agreed Laboratory Practice/Method Statement.

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Determination of Softening Point (Ring and Ball) - BS 4147


Note:This practice may be modified by the requirements of the customer’s specification, see relevant Project Inspection Test Plan (ITP)

Scope

To determine the softening point of the bitumen material

Equipment

Two brass tapered rings
Ring Support
Two steel balls
Certified thermometer
Glass beaker
Tripod with draft screen
Gas burner
Moulding plate
Melting pot
Sharp knife
Tongs

Procedure

Break approximately 300 g of the bitumen material into small pieces, then slowly heat the material in a melting pot until the material has melted, stir continuously to avoid local overheating and loss of vapour, thereafter stir occasionally. (always keep lid on when not stirring)
Heat the brass rings to approximately the same temperature as the heated sample material, after heating place ring (inverted) one within each of the guiding pans which should be placed on a polished moulding plate.

Fill the rings with the melted sample material heated to 60 or 70C above the expected melting point of the material. Take care when filling the rings to avoid the inclusion of bubbles and use sufficient material for each ring so that after cooling for 20 minutes a slight access of material remains above the level of the top of the rings. Allow the filled rings to cool to room temperature then remove the access material using a slightly warmed sharp knife.

Pour neutral glycerol into the glass beaker then fit rings into the support and place assembly concentrically within the beaker. Insert the certified thermometer and adjust it so that lies along the vertical axis of the beaker, ensuring that the bottom of the rings and the bulb is level with the bottom of the rings and that the bulb is central with the central hole of the ring supporting plate.

Set the apparatus up so that the ring supporting plate is horizontal. Bring the the apparatus to, and maintain it for 15 minutes at a temperature at least 45C below the expected softening point of the sample material. After 15 minutes place the steel balls (Using tongs) centrally on the upper surface of the sample material in the rings.

Place the gas burner under the beaker then apply heat in such a manner that the temperature is raised by 5C each minute: maintain this rate within +/- 0.5C over each one minute period. Rigidly adhere to this heating rate and reject all tests in which the rate of any one minute period after the initial first three minutes.

Evaluation

Note 1; the softening point temperature at which the coating material surrounding each steel ball first touches the the lower plate of the support, and report the the result as a mean of the two balls.

Note 2; If the two steel balls fall at temperatures that differ by more than 1C Discard the test and repeat the test.

Report

Record

Date
Batch Number
Softening Point expressed Ball A in C
Softening Point expressed Ball B in C
Average Softening Point in C




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Determination of Filler content of bitumen – BS 4147


Note:This practice may be modified by the requirements of the customer’s specification, see relevant Project Inspection Test Plan (ITP)


Scope


Determine the filler content as a percentage by mass of the coating material by ignition.


Equipment


Tared pre ignited silica crucible 40 mm in diameter x 30 mm high

Cold muffle furnace


Procedure


Weigh to nearest milligram between 1g and 1.5 g of coating material into the crucible. Place the crucible into the furnace and raise the temperature to 700-750C over a period of 2 hours then maintain that temperature for a period of no less than 2 hours. Remove the crucible from the furnace and allow to cool in the desiccator.


Evaluation


Weigh the crucible and ash to the nearest milligram and calculate the filler content.


Filler = 100 x M2/M1


Where


M1, is the mass prior to heating
M2, is the mass after coating


Report


Record


Date
Batch Number
Filler content expressed in % mass




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Determination of density – BS 41 47

Note: This practice may be modified by the requirements of the customer’s specification, see relevant Project Inspection Test Plan (ITP)

Scope

Determine the specific gravity of the coating material

Equipment

Polished brass mould

Melting pot (steel) 80 mm in diameter x 100 mm high

Balance

Beaker

Procedure

Heat about 100g of sample material slowly in the melting pot to between 60-70C above the softening point of the material, keeping the lid on when not stirring. Heat until the material is completely fluid, stir continually to avoid local overheating and excessive loss of vapor.

Pour the fluid material carefully into the mould, avoid inclusion of air bubbles, until the mould is almost full. Allow the mould and material to cool to ambient temperature then part the mould.

Suspend the moulded sample from the hook on a balance using a suitable length of nylon thread and weigh the sample to the nearest milligram.


Add a few drops of wetting agent to a small beaker of water at 25C. Place the beaker on a bridge across the the balance pan. Suspend the moulded sample from the hook on the balance so that it is fully immersed in the water in the beaker about 25 mm from the bottom of the beaker. Carefully remove all the air bubbles adhering to the sample and the thread.


Evaluation


Weigh the sample to the nearest milligram whilst suspended in the water and calculate the density


Density at 25C = Ma/Ma – Mw


Where


Ma, is the mass of the sample in air
Mw, is the mass of the sample in water at 25C


Report


Record


Date
Batch Number
Mass in air
Mass in water
SG of sample






Mould for sample for density determination




















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Determination of Penetration – BS 4147


Note: This practice may be modified by the requirements of the customer’s specification, see relevant Project Inspection Test Plan (ITP)


Scope


Determine the indentation value of the material


Equipment


Penetration Needle
Penetrometer
Constant Temperature Water Bath
Bath thermometer
Transfer Dish
Sample Container
Timing Device
Melting Pot
Brass Plate


Procedure

Break approximately 300g of the bitumen into small pieces and heat them slowly in the melting pot until the material is fully molten: stir continuously to avoid local overheating and excessive loss of vapors. Place the sample container on the polished brass plate so that close contact is maintained between the rim and the plate.

When the temperature of the sample material is approximately 60 to 70C above the expected softening point of the material, give the material a final stir. After discarding the first two or three grams pour the material into the sample container (approximately two thirds full) then allow to cool to room temperature.

Place the container (Inverted) in a transfer dish immersed in a constant temperature water bath at 25C for one hour.

Clean the penotometer needle with solvent, dry and insert into the penetrometer: load the the needle holder to bring the total moving mass to 100 g. Place the transfer dish containing the sample container and filled with water from the constant temperature water bath onto the table of the penotrometer. Slowly lower the needle until the tip makes contact with its image on the surface of the sample. Position the needle at least 10 mm from the edge of the dish and 10 mm from any previous hole.

Evaluation

Set the dial reading to zero, then quickly release the needle holder. Leave it for 5 +/- seconds and then lock the needle. Read the depth of penetration in tenths of a mm from the dial and record the result.


Report


Record


Date
Batch Number
Sample Number
Result expressed in tenths of mm





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Glass fiber reinforcement

The Glass fiber Inner wrap (reinforcement) shall be supplied in accordance with the design data supplied by the client.

Each batch of Inner wrap shall be checked against the specified requirements and the certification for each batch shall be checked for compliance.

There is normally no requirement for receipt testing.

Outer wrap

The Glass fiber Outer Wrap shall be supplied in accordance with the design data supplied by the client.

Each batch of Outer wrap shall be checked against the specified requirements and the certification for each batch shall be checked for compliance.

There is normally no requirement for receipt testing, however the properties included on the manufacturer’s batch test certificate shall be checked for conformity to the specified requirements.

Inner Wrap


Outer Wrap



2.2 PROCESS DESCRIPTION:

Incoming pipe

Pipes are received at the incoming racks. Any contamination or pipe defects that prevents acceptable coating and cannot be repaired at the incoming rack or grinding area shall be cause to hold the pipe. The held pipe shall be removed from the process and clearly marked (HOLD or REJECT) and placed into the appropriate holding area for adjudication by the client representative as to its disposition. The criteria for steel defects shall be generally in accordance with API (The practical detail to be agreed by both parties).

See Module 2


Preheat & blast cleaning

Pipes shall be placed onto the incoming blast line rack where bevel protectors (if fitted) shall be removed and end plugs fitted. The pipes shall then be indexed and lowered onto the blast line conveyor and conveyed through a pre-heat oven to the required pipe temperature. The pipe surface temperature shall be monitored prior to blast cleaning using a hand held surface roller contact pyrometer or melt sticks. The preheat temperature shall be checked as a minimum every two hours and the temperatures recorded. The steel surface temperatures shall be a minimum of 3°C an agreed above dew-point to a maximum of 50 ° C.

The pipes shall then be progressed through a centrifugal abrasive cleaning machine; the Blast Machine Operator shall continually monitor the blast effectiveness via visual inspection. Abrasive samples (100 ml) shall be taken from the working mix(s) once per shift. The sample shall be passed through 1.18 mm & 0.425-mm mesh sieves. No more than 16% shall pass the 0.425-mm sieve. Should the amount of fines exceed this figure, fresh grit shall be added to the working mix. Each abrasive sample shall be tested for chlorides and other contaminants. The results of the analysis shall be recorded on the agreed Abrasive Contamination Test Report.

See Module 2

Responsibility:

The Incoming Tally man shall be responsible for the recording and traceability of all the incoming bare pipes. He shall also be responsible in ensuring that the task is conducted in the safest possible manner

The abrasive line supervisor shall be responsible for ensuring that the end plugs are positioned correctly and that the specified preheat temperature is constantly maintained. He shall also ensure that the conveyor line speed is constant and that the surface amplitude and pipe cleanliness is maintained within the specified tolerances. He shall also be responsible in ensuring that the task is conducted in the safest possible manner.

The QC Inspector/Auditor shall be responsible for verifying that end plugs have been positioned correctly and that the specified preheat temperature is maintained. He shall also perform climatic conditions testing at the specified intervals and review laboratory testing of abrasive materials.

The Laboratory Technician shall be responsible for taking samples of the abrasive and analyzing.


Grinding area

On completion of abrasive blasting the pipes shall be indexed onto the transfer holding rack and inspected. All pipes are to be checked for any steel imperfections i.e. sliver, scabs, lamination's, burrs or bristles. Defects shall be repaired by grinding or by hand filing. Pipes that fail to meet the specified requirements shall be clearly marked (HOLD or REJECT), removed from the process and placed on the reject rack for adjudication by the client as to its disposition. Details of pipe defects shall be recorded on an agreed the Daily Grinding Inspection Report.

See Module 2

A salt contamination check of the blasted pipe surface shall be checked using an SCM 400 and the results are usually recorded twice per shift on an agreed Salt Contamination Test Report.

See Module 2

A dust contamination check shall be carried out on the blasted surface and rated in accordance with ISO 8502-3 and shall be recorded on an agreed Dust Contamination Report.

See Module 2

The blasted surface shall meet or exceed the requirements of the blast specification pictorial standard ISO 8501-1.Sa 2.5 The blast standard shall be monitored and the standard achieved recorded usually every 4 hours.

The surface profile shall be checked in accordance with ISO 8503-1 using the Testex replica method and shall be recorded on the agreed Surface Profile report.

The elapsed time shall between surface preparation and coating shall be monitored; the maximum elapsed time shall be 4 hours. No rust blooming shall be apparent prior to the application of the primer.

Responsibilities:

The Blasting line Supervisor shall ensure that all repairs grinding and filing is carried out under controlled conditions. If unsure about the disposition of pipe defects, he should contact the QA department with any queries. He should also ensure that the pipe has been cleaned of residue blasting matter, both internally and externally. He shall also be responsible in ensuring that the task is conducted in the safest possible manner.

The QC Inspector/Auditor shall be responsible for recording disposition of pipe exhibiting defects and raising NCR report. He shall also perform periodic testing in accordance with the project ITP.

The Tally man shall ensure traceability of all pipes and correct records of defective pipe movement and disposition.

Primer application

After the blast cleaning process, the pipe is transferred to the coating rotating station where the primer application (normally by airless spray) to the rotating pipe takes place.


Primer thickness check

The Dry Film Thickness (DFT) is checked and shall typically between 25 µm and 50 µm and shall be determined at the beginning of each shift and periodically thereafter. Control of primer thickness shall be by regular Wet Film Thickness (WFT) checks.


Visual inspection of primer

The applied finish of the primer shall be free from runs, sags or drips.


Pipe ends cleaning

Primer shall not be applied within the specified cutback length as specified inan agreed project Inspection Test Plan (ITP)

Primer Thickness Check Cutback Area



Enamel application

The Enamel is supplied either by road tanker which is equipped with a heating system or in solid form. If in solid form the Enamel is physically chopped into manageable pieces before being loaded into the melting kettles. The melted enamel stored in kettles is maintained at a temperature recommended by the manufacturer and must be constantly agitated to prevent “coking up” of the material.

Note: “Coked enamel” can cause serious defects within the enamel coating. Where coking is apparent the offending supply kettle should be taken off line and cleaned of the coked material.

When the enamel is to be applied, it is pumped to a holding kettle and heated to the required application temperature. From the holding kettle the material is pumped to the application weir. Any excess enamel during coating activities is re-circulated from the coating weir flood box back to the holding kettle via an in line filter.

It is important that the asphalt enamel coating is applied to the primed pipe prior to primer degradation or becomes dead and is usually applied within four hours of the primer application.
A typical coating usually consists of the following constituent layers:-

a) A primer coat
b) A first layer of asphalt enamel
c) A first layer of glass fiber reinforced inner wrap
d) A second layer of asphalt enamel
e) A second layer of glass fiber reinforced inner wrap
f) A third layer of asphalt enamel
g) An asphalt impregnated glass fiber reinforced outer wrap

Water quenching

Immediately after coating, the coated pipe enters the quenching station where it is showered with water to cool the coating in readiness for handling and inspection.

Water Quenching



Responsibility:

The Coating Line Supervisor shall ensure that the enamel heating equipment is maintained in satisfactory operating conditions and settings are commensurate to the particular pipe size and wall thickness pipe being processed. He shall also be responsible in ensuring that the coating activity is conducted in the safe manner.

FINAL INSPECTION (COOLING BOARDS)

Immediately after cooling the coated pipe shall be transferred to the outgoing padded pipe rack where the pipes are positioned on the end cleaning rotators where the coating shall be visually inspected any detrimental coating defects and the cutbacks shall be established.

Visual inspection

All coated pipes are visually inspected for detrimental wrinkling, voids, lamination's, mechanical damage and dry wrap.

Outer wrap overlap check

The outer wrap overlap shall be constantly checked and should be between 12mm and 25mm.

Pipe end (cutback) cleaning

The coating shall be cut back and trimmed to provide a chamfered end. The cutback length shallbe as per the Client’s specified requirements.

Holiday Detection

After end cleaning the entire coated surface of each length of pipe shall be inspected for holidays using a high voltage (pulse type) holiday detector previously set and calibrated to the correct voltage. The circumferential search electrode shall maintain intimate contact around the entire circumference of the coated pipe at all times. The voltage shall be checked and recorded hourly. The travel speed for holiday detection shall be at a rate of 300 mm per second maximum. Any holidays or surface defects shall be clearly marked and recorded on an approved Anti corrosion coating inspection report.

Test voltage shall be based on NACE Standard RP0274-93 with the following formula except that in no case shall the voltage exceed 18,000 volts.

V = 7900 √ T

Where V = Voltage setting in volts
T = Coating nominal thickness in mm


The holiday detector shall be calibrated at the start of each shift with a crest voltmeter.

Thickness checks

The coating thickness is usually determined by taking the 4 equidistant measurements (3 on the body and 1 on the weld) at the lead end middle and tail end of each pipe ( a total of 12 measurements). The measurement shall be conducted using either magnetic lift off or electromagnetic thickness gauge. Records of the thicknesses shall be recorded on an agreed Coating and wrapping inspection report.

Note: isolated under thickness shall not normally be cause for rejection.

Thickness Checking


Responsibilities:

The cooling Board Supervisor shall be responsible for ensuring that the holiday detection of each pipe is carried out in a correct manner and at the correct voltage. Also he shall ensure that the pipe cutbacks are correctly established and that the pipe ends and pipe internals are sufficiently cleaned. He shall also be responsible in ensuring that the task is conducted in the safest possible manner.

The QC Inspector/Auditor shall be responsible for visual inspection of the coating and physical testing. He shall also monitor the coating thickness, holiday detection and cut back length. He shall also be responsible for calibration of thickness gauges and holiday detection equipment prior to the start of each shift.

The Tally man shall be responsible for checking the pipe identity and maintaining pipe trace ability on the computerized pipe tracking system. He shall also ensure that coating thickness checks are being carried out and being recorded correctly for each pipe.

Pipe Marking and Identification

The identity of each pipe shall be established and entered into the pipe tracking system such that traceability is maintained. Accepted pipes will be released for transportation to the stockpiles or other processes.

Responsibility

The Load Out Tally man shall ensure that the correct pipe markings are applied in accordance with the agreed marking system. He shall also be responsible in ensuring that the task is conducted in the safest possible manner.

2.5 OFF LINE AND LABORATORY TESTS

Adhesion test

Adhesion test shall be in accordance with ANSI/AWWA-C203 – Usually once in every 50 pipes. Tests shall be performed on ¼, ½ and ¾ positions along the pipe length. For pipe with weld seam, one of the tests shall be made at a position perpendicular to the longitudinal weld seam.

Using a sharp knife or chisel cut 200 mm x 50 mm test strip in the parent coating, then from one end lift enough of the sample to be able to grip by thumb and finger, in a snapping manner pull the sample from the pipe. The test should be carried out at 25º C

If the peel breaks or does not expose the underlying metal, adhesion shall be considered satisfactory.





Coating distribution test

Distribution of reinforcement shall be determined through visual inspection on cross-sectional segment of the test samples. Using a sharp knife or chisel cut 200 mm x 50 mm test strip in the parent coating, then from one end lift the coating sample from the pipe.


On visual inspection the first layer of glass reinforcement (Inner wrap) shall be within the middle 33% of enamel coating thickness. The glass reinforcement shall not touch the primed surface nor exposed to the outer wrap. Note: this is based on only one inner wrap being used.

Tapping out test

Sound test shall be performed along the selected pipe length to detect presence of voids. The sound test shall be by tapping with a mallet or wooden handle of a scraper at random over a large number of locations along the length and around the circumference of the pipe.


Any voids detected during sounding shall be repaired.




2.6 COATING REPAIR

Repairs to the coatings shall be carried out in accordance with an approved Repair Procedure. Coated pipes that cannot be repaired shall be rejected, stripped and re coated. Unacceptable pipe shall be marked up with Red/White hazard tape and recorded on the NCR system

Typical repair procedure


Repairs of holidays, damage or inadequate coating shall conform to the following criteria:-

a) The total damaged, defective or disbonded areas not exceed 5% of the overall
coating area.


b) The maximum individual defect areas shall be limited to 5 areas unless otherwise agreed by
the client.


c) The criteria may be relaxed subject to client approval

d) Dirt, corrosion products and defective areas shall be removed with the aid of a heated sharp
scraper. Care shall be exercised when removing the wrap in order to prevent disbondment to
 the adjacent coating.

e) Molten enamel shall be applied to the prepared area (s), ensuring that the hot enamel is flush
with the existing parent material. Felt outer wrap is placed onto the hot enamel areas and
neatly feathered to bond with the parent coating. The overlap shall be a minimum of 25 mm.


f) On completion of the repairs (after sufficient setting time) the repaired area (s) shall be
checked for electrical resistance using a holiday detector set at 15 Kv.

Repair Process





Responsibilities:


The repair foreman shall be responsible for coating repairs and shall ensure the correct equipment and repair method is used for coating repair. He shall also be responsible in ensuring that the task is conducted in the safest possible manner.

The QC Inspector/Auditor shall be responsible for checking the preparation and the completed repair. 


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