@ Christine74, thanks for sharing these cases. I am not sure if the Owner will concur with the approach of not doing a pressure test after the repair.
Also, I would like to know if a ASME VIII Div.2 vessel shop hydrotested at about 5000 psig,approved and stamped by the shop manufacturer's AI can...
I would like to know if a ASME VIII Div.2 vessel shop hydrotested at about 5000 psig and approved by the AI outside the US can be subjected to a rehydrotest in the field as part of the associated piping system circuit. The field piping joints are directly buttwelded onto the vessel nozzles and...
We have a major repair to be undertaken under NBIC to reweld the dished end to the shell of a ASME div.2 stamped HX in the field. The joints to be repair welded in the field are 6" and 3" in thickness. The HX has a design of 3000 psig. The original code of construction required a shell side and...
I would like to know if there are any restrictions in the ASME codes or industry practices to not use lubricants containing copper in ammonia piping systems or service facilities. Is there a potential for any corrosion or cracking due to usage of copper containing lubricants at flange joints?
The 3" thick dish material, ASTM A387 Gr.11 Cl.2 MTR calls for normalizing with a soak time of minimum 71 minutes. The dished end was hotformed and then normalized for 189 minutes per the shop HT charts shared. Any insights into if this is acceptable.
@R6155, this will be reworked to NBIC R stamp. The bottom dish and the groove weld will be replaced in its entirety. We are in the process of getting a new dished end from the OEM but the important aspect is with limited access from the inside and with a single bevel weld at this 3" joint...
@GD2, the vessel was hydrotested at the shop facility in the horizontal position per the ASME Data reports received. There was a shop shell side and tube side hydro done in conjunction without exceeding the maximum differential pressure as suggested by the OEM designer and signed off by the shop...
The weld was RT before and after PWHT with no relevant indication and hence accepted. The ellipsoidal head material is ASTM A387 Gr.11 and 3 " thick while the tubesheet is ASTM A336 Gr.F11 and 9" thick. Joint design is attached...
@EdStainless..the crack starts in the weld centerline from its initiation point and went circumferentially for abt 5 feet along the weld before it propagated diagonally into the dish head for about 3 feet.
We encountered a weld failure between an ellipsoidal head and the tubesheet material in the field even before the equipment had been started up. The head in the new HX equipment was over 3 inch thick and had gone through all necessary preheat, NDE, PWHT, hydros etc in an overseas shop with no...
@ SJmellurgist , Don56..thanks for your responses. For this P11 thickness of 120 mm, roughly 5 inch does hotforming have an advantage over coldforming?? Having crown snd petal design is adding more welding, Can welding be minimized by just having one weld seam?
Our supplier intends to fabricate a P11 dish head with dimensions of 3000 mm ID dia and 120mm thick using crown and petal design. The vessel is in ammonia service.The supplier plans to use four petals that will be manufactured by coldforming without any postforming heat treatment, weld them up...
Thanks for your replies @ MJCronin and Moltenmetal.in some of my previous jobs we did have stringent requirements by the design engineers. I will take it up with engineering team at my new job to address this requirement. Thanks for your help again.
We are to construct an ammonia plant piping to B31.3. Are there any specific code requirements for 100% NDT and PWHT to ensure there us no stress corrosion cracking issues. Is ammonia classified as A category M fluid service? Thanks.
