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Discussion Forums - The Hendrix Group
HomeHomeDiscussionsDiscussionsOil Refinery Co...Oil Refinery Co...Pressure vessel repairPressure vessel repair
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4/20/2010 9:00 AM
 
We had a severe internal corrosion in the 16" Pig Trap barrerl portion away from the manway closure. Due to above ,it has been planned to cut the adjacent C-Seam weld and carry out weld build-up at corroded location and join the barrel portion again after carrying out necessary Inspection & Testing. I would like to know the above proposed refurbishment works (cutting the barrel portion and rewelding) will comes under repair or modification or alteration category as per pressure vessel code. Any reference to code for the above work is highly appreciated. with advance thanks,
 
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4/20/2010 9:00 AM
 
Krish123 16" Pig trap barrel portion is away from pressure vessel man hole. Technically this 16" should come under piping code modification / repair jobs. Your description of intended / proposed repair job had not made clearly made which C-seam you intend to cut, build up at corroded portion and join with the barrel portion. From the description, it appears that the C seam is that of trap pig barrel which comes outside the pressure vessel. If it is only the 16" pig trap pipe C seam outside the man hole, your repair could be quite simple of cutting the C seam (outside the man hole nozzle) build up the corroded portion and re weld the same C seam of the 16" pig trap barrel pipe. Such repairs, corrosion weld re-building and re-welding of C seam will come under piping code for repair, inspection and testing. If the proposed repair (intended) is to cut the C seam of the pressure vessel at the top or bottom crown (which should include the man hole and other nozzles at the top crown of the vessel), then repairing this will come under Pressure Vessel code (ASME or BS or DIN etc under which the vessel was originally constructed). Refer to Code related practices for such repairs. If the intended repair is connected with pressure vessel weld ( C seam) you are governed not only of the pressure vessel code but also other statutory rules for repairs of the same (For Ex: you may have to get statutory clearance of the proposed repairs /rectification from appropriate statutory authorities like IBR for Boilers / Explosive inspectorate for vessels coming under SMPV(U) Rules, Factory inspectorate before even commencing the repairs) Please make clear your intended scope whether it is outside the pressure vessel or will cover the pressure vessel top or bottom C seam. Hope this helps. C.V.Srinivasan Nishi Engineers Pvt Ltd India April 20, 2010 E-mail: nishi@vsnl.com > We had a severe internal corrosion in the 16" Pig Trap >barrerl portion away from the manway closure. Due to above >,it has been planned to cut the adjacent C-Seam weld and >carry out weld build-up at corroded location and join the >barrel portion again after carrying out necessary Inspection >& Testing. I would like to know the above proposed >refurbishment works (cutting the barrel portion and >rewelding) will comes under repair or modification or >alteration category as per pressure vessel code. Any >reference to code for the above work is highly appreciated. > >with advance thanks,
 
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4/21/2010 9:00 AM
 
Normally pig traps are fabricated under B31.3 or Sec VII Div1/2. Our case it is Sec. VIII Div.1. In pig traps the end closure is being used as a manway for internal check. In this case we cut the barrerl at reducer section C-Seam weld to carry out weld build-up at corrded location. I am convinced that this refurbishment work comes under repair. Thanks for ther prompt reply. regards,
 
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4/21/2010 9:00 AM
 
Krish123 Since they have provided end cap (internal inspection man hole cover type) for the 16" pig trap, original vessel designer had considered this as part of ASME Sec VIII Div 1 pressure vessel code conditions. Strictly this will not come under ASA B 31.3 due to this end cap. For repair, cutting at the reducer C Seam and repair to meet ASME Sec VIII Div 1 would be OK. Hope this helps C.V.Srinivasan Nishi Engineers Pvt Ltd India April 21,2010 E-mail: nishi@vsnl.com >Normally pig traps are fabricated under B31.3 or Sec VII >Div1/2. Our case it is Sec. VIII Div.1. In pig traps the end >closure is being used as a manway for internal check. In >this case we cut the barrerl at reducer section C-Seam weld >to carry out weld build-up at corrded location. I am >convinced that this refurbishment work comes under repair. >Thanks for ther prompt reply. > >regards,
 
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