Corrosion in pipes is common and complete pipe wall loss or through-hole defects are a regular occurrence within many facilities.
In the Oil & Gas and Offshore industry where flammable gases are present, it is necessary to fix these types of pipe leaks and pipe defects with cold curing repair. The reason is because hot works are generally prohibited.
Composite repair system using composite wrap must meet the minimum requirements and perform at the expected level under extreme conditions. Numerous composite repair materials are available on the open market today, but there are few that have the testing and capability to perform at the elevated temperatures which may be experienced.
Gathering Pipeline Data & Information
When performing online pipe leak repairs, it is necessary to follow in accordance to ASME PCC2 and ISO 24817 standards and requirements. All data for the pipeline operating pressure, temperature, pipe size and pipe medium should be gathered and reviewed.
Detailed Engineering Calculation and Application Method of Statement
A detailed engineering calculation and report specifically to the pipe leak shall be generated to determine the quantity and type of materials to be used. The method of application (method of statement) detailing a step-by-step repair technique shall be provided and approved by the client.
Site survey should be conducted prior to work commencement, so that all risks are assessed and detailed into risk assessment report. All Personnel Protective Equipment should be worn and risk mitigating/ reducing steps employed to minimize or avoid all unnecessary risks.
Surface Preparation of Affected Pipe Section
Before work commencement, always try to shut off or reduce the pipeline pressure and temperature as much as possible. Commencing surface preparation by using the grit blasting technique – clean affected pipe surface to SA 2.5 standard whenever possible. At locations where grit blasting is not possible, these locations shall be cleaned with appropriate non-spark tools. The length of surface preparation should be in accordance to the Engineering Calculation Report provided. While performing surface preparation, pipe surface should remain dry throughout the repair application. Prepare the pipe surface roughness to approximately 60 to 80 microns. Use a surface roughness tester to confirm the prepared surface roughness has been achieved.
Commencement of Pipe Leak Repair Works
Commence pipe repair procedure – pipe leak repair process should commence within 4 hours after the surface preparation has been completed. Before commencing of pipe repair works, ensure the leak location is properly marked.
Put on the latex gloves and knead appropriate amount of SS106 Seal Stic underwater epoxy stick to cover the area of the leak. Apply the mixed Seal Stic onto a stainless steel sheet metal. Meanwhile, prepare several sets of SealXpert stainless steel clip by cutting an appropriate length of the steel clip. Connect the cut-off length of stainless steel clip with adjustable fasteners. Wrap the connection with adjustable fastener with a PVC tape. Place the stainless steel backing against the SealXpert stainless steel clip while the Seal Stic faces the pipe surface, away from the leak location. Tighten the adjustable fastener of SealXpert stainless steel clip slightly and slide the several sets of clip to the leak location. These SealXpert stainless steel clips should be seated next to each other, securing both the centre and edge of leak location. Continue to tighten the adjustable fastener of SealXpert stainless steel clips while ensuring that the Seal Stic is covering the leak hole.
Rebuilding of Affected Pipe Section
Once the leak is arrested, apply SealXpert PS102 metal repair putty. Mix the hardener portion of PS102 metal repair putty into the resin container and apply the mixed repair putty over the prepared pipe section (around pipe length and circumference). The applied coating thickness should be in accordance to the Engineering Calculation Report provided. Allow the coated SealXpert PS102 repair putties to cure for sufficient time (curing time is dependent on pipeline operating conditions) and observe leak condition. Use a barcol hardness tester to confirm the cured putty has obtained at least 85 Shore D hardness.
Composite Pipe Wrapping
Put on the latex gloves and tear open the Wrap Seal PLUS fiberglass repair tape and immerse it in water for 10 seconds; squeeze the roll while immersing it in water. Remove the fiberglass tape from the water and start wrapping the Wrap Seal PLUSTM fibreglass repair tape. The wrapping of fiberglass tape should start at least 100mm to 200mm before the leak area. Wrap the pipe as tightly and evenly as possible, pulling slightly after each round of wrapping. Apply the entire roll over the pipe surface with at least 50% overlap for the entire pipe repair length. Total length of wrapping should be in accordance to Engineering Calculation Report. Repeat the wrapping for a specific number of layers of Wrap Seal Plus fiberglass repair tape and finally tapering off with approximately 25mm over each wrapping layer. The wrapping direction should be done in one direction.
Inspection of Repair
Allow the repaired area to be cured for several hours (duration is dependent on pipeline operating condition). Check to confirm the final Barcol hardness measurement.
Repair job is completed and the repaired system can be operated back to normal operating conditions.
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