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SS 347 or SS 316L FOR VALVE BODY
- Thread starter quiinces
- Start date
Your pipe spec is SS347 for some reason. Maybe the offset maximum design temperature is higher or in the past / design phase, possibility of inter-granular corrosion was found/estimated. Or else
That you need to understand the philosophy first.
Once you accept the SS316L, the next replacement more likely to be SS316L also (in the next 3-5 years) and deviates further from the design selection.
Refer to ASME 16.34 table 2-2.2, both material belong to different regime. Even though the value is almost similar, this is not apple-to-apple. More to apple to peach.
There is also a major risk that shall PWHT required for the dissimilar metal weld will soften the SS347 (your existing Pipe spec I presume) material to a yield and tensile strength below code minimum requirements.
If the risk has been assessed. The operating temperature is below its Maximum design temperature and controlled. Minimal inter-granular corrosion possibility, less critical parts of your plants, etc. then the decision is yours.
Regards,
MR
All valves will last for years, except the ones that were poorly manufactured; are still wrongly operated and or were wrongly selected
That you need to understand the philosophy first.
Once you accept the SS316L, the next replacement more likely to be SS316L also (in the next 3-5 years) and deviates further from the design selection.
Refer to ASME 16.34 table 2-2.2, both material belong to different regime. Even though the value is almost similar, this is not apple-to-apple. More to apple to peach.
There is also a major risk that shall PWHT required for the dissimilar metal weld will soften the SS347 (your existing Pipe spec I presume) material to a yield and tensile strength below code minimum requirements.
If the risk has been assessed. The operating temperature is below its Maximum design temperature and controlled. Minimal inter-granular corrosion possibility, less critical parts of your plants, etc. then the decision is yours.
Regards,
MR
All valves will last for years, except the ones that were poorly manufactured; are still wrongly operated and or were wrongly selected
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