PWHT for CS equipment fully clad with SS316 in Amine Service
PWHT for CS equipment fully clad with SS316 in Amine Service
(OP)
API RP945 does not cover SS equipment/piping in amine service. Hence the question is whether PWHT is required for CS equipment/piping which is fully clad with SS316L and handling Rich amine service or would the velocity restrictions (less than 3 m/s or 10 f/s) suffice?
Maximum operating temperature ranges from 80-100°C and chloride is restricted below 50 ppm by use of wash water. Thanks.
Maximum operating temperature ranges from 80-100°C and chloride is restricted below 50 ppm by use of wash water. Thanks.





RE: PWHT for CS equipment fully clad with SS316 in Amine Service
RE: PWHT for CS equipment fully clad with SS316 in Amine Service
Any PWHT after overlay will sensitize the 316 and greatly reduce its corrosion resistance.
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P.E. Metallurgy, Plymouth Tube
RE: PWHT for CS equipment fully clad with SS316 in Amine Service
https://books.google.com/books?id=qTfNZZRO758C&...
Why bother to clad when you can perform PWHT of butt welds and eliminate the risk of SCC? Seems like a much simpler approach than going to the expense of adding a corrosion resistant overlay (CRO) to avoid PWHT.
If you need to use a CRO, I would suggest you deposit a butter layer of 309, PWHT and add two layers of 316 SS to achieve a CRO.
RE: PWHT for CS equipment fully clad with SS316 in Amine Service
RE: PWHT for CS equipment fully clad with SS316 in Amine Service
"If you don't have time to do the job right the first time, when are you going to find time to repair it?"
RE: PWHT for CS equipment fully clad with SS316 in Amine Service
EdStainless - We're probably going with Hot Roll Bonded SS 316L plates (3 mm) and then weld them together so PWHT cannot be done beforehand. Besides PWHT is inevitable if required by code so we're ensuring that IGC testing is done for corrosion resistance.
Metengr - I would agree on using CS with corrosion allowance in lean amine service with pwht. But what about rich amine containing high H2S (but below the pH2S limits of ISO 15156) & CO2 in vapor phase? The Client requirement is SS cladding and we as a Contractor are obliged to do it.
Regards,
Suraj Tinani
RE: PWHT for CS equipment fully clad with SS316 in Amine Service
Or you chose to not do it since it is not the wetted surface.
You have a lot of weld qualification to do to show that you can get full corrosion resistance on the inside.
You also will be doing some UT after fab to verify that you didn't get any disbond, right?
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P.E. Metallurgy, Plymouth Tube
RE: PWHT for CS equipment fully clad with SS316 in Amine Service
How have you made up your mind finally??
Considering high H2S and CO2 concentration in Rich amine service, 316 cladding will definitely be the cheapest selection since your chloride concenration in amine recovery is below 50 ppm. For using CS, the velocity of your rich amine service is above limit and not seems to be prudent in using that.
CoCoCa
RE: PWHT for CS equipment fully clad with SS316 in Amine Service
Has anyone looked at building this entirely out of a lean duplex alloy?
The strength is high, the walls would be much thinner, there would be less metal, faster welding, and no overlay or PWHT.
Just a thought.
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P.E. Metallurgy, Plymouth Tube
RE: PWHT for CS equipment fully clad with SS316 in Amine Service
Regards,
Suraj Tinani