Method Statement: Engineering Department - Asset Integrity [PDF]

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METHOD STATEMENT



Belzona® Repair of HBG-3270/3470 Tubesheet



Engineering Department – Asset Integrity



Method Statement – Belzona® Repair HBG-3270/3470 Tubesheet



Contents 1 2



Introduction ............................................................................................................. 3 Objective.................................................................................................................. 3 2.1 Application Instructions ................................................................................... 3 2.2 MSDS .............................................................................................................. 3 3 Tools and Materials .................................................................................................. 3 3.1 Materials/Consumables ................................................................................... 3 3.2 Tools ............................................................................................................... 4 4 Repair Preparation ................................................................................................... 4 5 Application of Belzona® 1311 Ceramic R-Metal ......................................................... 5 6 Application of Belzona® 1391 Ceramic HT Coating ..................................................... 5 7 Job Completion ........................................................................................................ 6 Appendix A Instructions for Use ................................................................................... 7 Appendix B Material Safety DataSheet ......................................................................... 8



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Method Statement – Belzona® Repair HBG-3270/3470 Tubesheet



1



INTRODUCTION



Inspection of the HBG-3270/3470 shell/tube heat exchangers has identified general corrosion metal loss on the process side of the tubesheets. Each of the heat exchangers has two tubesheets, denoted ‘east’ and ‘west’ as per the vessel orientation. The tubesheet is constructed from SA-516 Grade 70. The tubesheets will be repaired by filling out the metal loss with Belzona® ‘ceramic R-metal’ (1311), and finish coated with Belzona® ‘Ceramic HT’ (1391). This method statement describes the preparation and application for the repair of a tubesheet. If both tubesheets on one vessel are to be repaired according to this method statement, then all phases of the repair (preparation, application, and curing) must be completed on one tubesheet prior to commencing repair of the second tubesheet.



2



OBJECTIVE



The following reference documents must be made available prior to commencing the repair:



2.1



Application Instructions Belzona® 1311 ‘Instructions for Use’, Publication 10-2-07 (Appendix A) Belzona® 1391 ‘Instructions for Use’, Publication 1-4-07 (Appendix A)



2.2



MSDS



Refer to Appendix B. SDS Ref



Description



10585



Belzona® 1311 Base



10312



Belzona® 1311 Solidifier



10579



Belzona® 1391 Base



10473



Belzona® 1391 Solidifier



10417



Belzona® 9111 Cleaner/Degreaser



3



TOOLS AND MATERIALS



3.1



Materials/Consumables •



Belzona® 1311 (refer to reference document for quantities)



•



Belzona® 1391 (refer to reference document for quantities)



•



Belzona® 9111



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Method Statement – Belzona® Repair HBG-3270/3470 Tubesheet •



Blasting abrasive medium and fine (use an angular abrasive, suitable to achieve a 3mils profile)



•



Cork tube stoppers for blanking tube apertures (ID radius = 0.292”)



•



Rags/Cloth for Degreasing



•



Plastic bags for waste collection



3.2



Tools •



Blasting machine



•



Wire brushes



•



Wet film thickness gauge



•



Tools and receptacle or surface for mixing



•



Stiff bristled brushes for application



•



Spreader/applicator



•



Sharp knife



•



Tarpaulin – to protect non-repairable areas of the exchangers



4



REPAIR PREPARATION 1.



Insert cork stoppers in to the tube apertures to create an ‘air-tight’ fit ensuring that the inserted length is at least 2”. Using a sharp knife or small saw, trim the cork tube stoppers extremity flush with the tube end.



2.



Once all tubes apertures are blanked off securely with the cork tube stoppers begin removing all loose debris and scale with a wire brush.



3.



Cover the non-repairable areas with tarpaulin material. This should include covering the flange and shell areas.



4.



Blast clean the metal bonding surfaces to a finish of SA 2.5, according to ISO 8501-1.



5.



Remove/clean-up all blasting debris from the area.



6.



Thoroughly clean and degrease the tubesheet with Belzona® 9111, applying by clean brush between the tube gaps and clean cloth soaked in Belzona® 9111. The 9111 does not leave a residue, wipe clean any pooled degreaser with a clean cloth and allow residue to evaporate from the surface.



7.



If application does not immediately follow the preparation, protect the cleaned area from contaminants with new tarpaulin cloth.



8.



NOTE: It is advisable to repair Belzona® 1311 on one part of HBG-3270 and one part of HBG-3470 at the same time. After curing, upon application of the Belzona® 1391 coating, start repairing the second part of both exchangers.



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Method Statement – Belzona® Repair HBG-3270/3470 Tubesheet



5



APPLICATION OF BELZONA® 1311 CERAMIC R-METAL



Refer to the Belzona® application Instructions for more detailed information regarding the mixing and application of the product.



1.



Once mixed the Belzona® 1311 has only a limited working life, so it should be mixed only when the repair is ready to be carried out, and should be mixed and applied in a timely and effective manner. In ambient temperatures of 15°C and 25°C, the working time from commencement of mixing is 25 and 15 minutes respectively.



2.



Transfer the Base and Solidifier to the mixing receptacle or surface and mix thoroughly until a smooth, streak-free paste is achieved. Ideally the product should be mixed in its entirety, i.e. one full unit of base to one full unit of solidifier. Should smaller quantities be required a base to solidifier ratio of 3 to 1 by volume, or 5 to 1 by weight should be used.



3.



Apply the mixed 1311 directly to the tubesheet using the plastic applicator taking care to completely fill out the small areas around the tubes. Press the product firmly in to all gaps to remove trapped air and ensure maximum contact with the prepared surfaces. Build the product up to fill out the tubesheet area to the leading edge of the nozzle raised face, paying particular attention not to contaminate the mating face. Using the plastic applicator smooth across the entire repair to create a smooth flush finish across the tube sheet and take care to clean away any build up on the cork tube stoppers.



4.



Remove the cork tube stoppers immediately after the application is complete. This is to prevent the cork tube stoppers from getting stuck in the tubes during the curing period.



5.



Initial curing should be achieved in 2 hours given ambient conditions on Miskar, and full mechanical cure should be achieved in approximately 24 hours. Follow up coat of Belzona® 1391 should not be applied until at least the initial cure is complete.



6.



Clean all mixing and application tools with Belzona® 9111 cleaner/degreaser and bag up any waste/soiled rags for disposal in special waste.



6



APPLICATION OF BELZONA® 1391 CERAMIC HT COATING



Refer to the Belzona® application Instructions for more detailed information regarding the mixing and application of the product.



1.



Allowing at least 12 hours since the application of the Belzona® 1311, the repair should now be finish coated with Belzona® 1391.



2.



Ensure all the tubes apertures are blanked off securely with the cork tube stoppers.



3.



Cover the non-repairable areas with tarpaulin material. This should include covering the flange and shell areas.



4.



Flash blast the surface of the cured Belzona® 1311 with a fine grit and a moderate blast pressure to achieve a ‘frosted’ surface appearance.



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Method Statement – Belzona® Repair HBG-3270/3470 Tubesheet 5.



Remove and clean away all blasting debris using clean rags soaked in Belzona® 9111 degreaser.



6.



Commence mixing of the 1391 only when the application is ready to begin. Given Miskar ambient conditions, the mixed product should remain workable for 30 to 40 minutes. The product should not be applied if the ambient temperature is below 10°C. For mixing, pour the entire contents of the solidifier into the base can, and mix thoroughly until streak-free. Refer to the application instructions for further guidance on mixing.



7.



For this application a single coat of thickness 800 to 1000 microns is required, and should be confirmed using a film thickness gauge during application.



8.



Begin applying the mixed product to the tube sheet using a stiff bristled brush or the plastic applicator provided, starting from the fine edges around the tube apertures and out to the nozzle raised face edge, again taking particular care not to contaminate the mating surface.



9.



Use the film thickness gauge at several locations to confirm the coating thickness and visually inspect for any missed areas.



7.



Finish the application with a brush to achieve a uniform coverage.



8.



After finishing, immediately inspect the coated surface for any missed areas or pinholes, if any are identified brush out immediately.



9.



Remove the cork tube stoppers immediately after the application is complete. This is to prevent the cork tube stoppers from getting stuck in the tubes during the curing period.



10. Once the coating has cured, conduct a detailed visual inspection to identify any missed areas, pinholes, or signs of mechanical damage. If any are found, refer to the application instructions for guidance on repair. 11. Clean all tools with Belzona® 9111 and bag up any waste for special waste disposal.



7



JOB COMPLETION 1.



If any of the cork tube stoppers were not removed and stuck in the tubes, isolate the area around the exchanger and clear any people from the area. To remove the tube stoppers apply low pressure compressed air to the open side of the tube bundle, gradually increasing the air pressure until the stoppers begin to release from the tubes.



2.



Once the repair products have been fully cured and satisfactorily inspected, isolate the air supply and the channels are reinstated.



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Method Statement – Belzona® Repair HBG-3270/3470 Tubesheet



Appendix A



INSTRUCTIONS FOR USE



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Method Statement – Belzona® Repair HBG-3270/3470 Tubesheet



Appendix B



MATERIAL SAFETY DATASHEET



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