Heat treatment for lethal service for stainless steel drum

[jtseng123]

Dear all,

I have an acid gas knock drum 5' dia x 12' T/T vertical, which our process classifies as lethal service. It is 316/316L SS construction.
Per code lethal service requires PWHT. My question is, shall I ask for solution anneal after fabrication ?

(I have vendors either will provide solution anneal on base metal only, or no bid because of the concern of deformation or does not have enough water storage for quenching the entire vessel.)

 

[metengr]

The Code does not require PWHT for austenitic stainless steel vessels in lethal service, see below for Section VIII, Div 1, UW-2 (a);

(a) When vessels are to contain lethal substances,
either liquid or gaseous, all butt welded joints shall be
fully radiographed, except under the provisions of (2)
and (3) below, and UW-11(a)(4). ERW pipe or tube is
not permitted to be used as a shell or nozzle in lethal service
applications. When fabricated of carbon or low alloy
steel, such vessels shall be postweld heat treated.

 

[StoneCold]

As a side note. Most acids attack stainless. So stainless and Acid gas service seems like the wrong choice. But this is obviously a generality and you did not say what acid it was.

Regards
StoneCold

 

[jtseng123]

metengr, thanks a lot.
Stonecold, our material selection was originated from chemical engineering group. I believe they must have looked into it. I will double check.

 

[racookpe1978]

What pressure and temperature did they analyze the stainless steel to react with (to withstand actually)?

 

[jtseng123]

7 psig /120F operating
50 psig/274F design