Require? solution annealing for fabricated 316L stainless steel pipe

[yonglwe]

Hi All,
I'm buying some 316LStainless steelplates to fabricate into pipes barrels then cut to suitable spool length and welded to form the discharge portion ( including tees and mitre bend) of a two large pumps system each pump handling 400000 cubic meter per hour of municipal treated effluent( total 8 pumps) , pipe dia. from 1400 to 2200mm and thickness from 10 to 12mm. Fabrication to form pipe spools will be by rolling either into longitudinal weld or spiral weld by machine with stainless steel rollers to avoid contamination. My question are as regard to the need for solution annealing
1)Would the rolling process of pipe forming cause sufficiently rigorous work hardening thus required some forms of heat treatment such as process annealing Or even Solution annealing
2)Or is it because of the longitudinal Or Spiral weldings to form pipe barrel cause distortion in the HAZ which then required solution annealing to dissolve carbon particle/precipitate in the HAZ,
3)If both activities in 1 & 2 are the cause for solution annealing, then which one is the main cause.
Solution annealing above is defined as "heat to and soak for 30 minutes at 1040C, then air quenched in 5 minutes to 450C, then cool to ambient in 25~30 minutes".

Thanks you & look forward to your help.

Jyaces

 

[Latexman]

Jyances,

Sorry, I don't know the answer to your question, but my company requires all vessels made of SS to be solution annealled after fabrication due to past bad experiences with external chloride cracking from the environment, mainly on the gulf coast of the US, but it was a global standard.


Good luck,
Latexman

 

[kenvlach]

Speaking as a metallurgist not familiar with all applicable codes:
1) The solution anneal is to prevent weld zone corrosion by homogenizing the composition and microstructure.
2) Manufacturers anneal all pipe.
3) Re quenching and cooling rates – the faster, the better, as long as distortion does not occur. Of course, follow any code or approved PWHT.
4) A protective atmosphere is desirable during the solution anneal.

 

[yonglwe]

Hi All,
A correction is in order:
Solution annealing above is defined as "heat to and soak for 5 minutes at 1040C, then air quenched in 5 minutes to 450C, then cool to ambient in 25~30 minutes".

Thanks you & look forward to your help.

Jyaces