Heat treatment requirement for cladded vessels 1

[Bmechz]

Dear All,

Kindly go through the below query and let me know your valuable feedback...

Recently we have a vessel with SA 516 Gr. 70 base material and SS 316L internal cladding for corrosion resistant.. The max thickness of shell and dished end is 10 mm only. Design code is ASME Sec VIII Div 1 Ed. 2013.

As per ASME Sec VIII div 1, UCL-34 (b), "Vessel or parts of vessels constructed of chromium stainless steel integral or weld metal overlay cladding and those lined with chromium stainless steel applied linings shall be post weld heat treated in all thicknesses except vessels that integrally clad or lined with TYPE 405 or 410S and welded with an austenitic electrode need not be post weld heat treated unless required by UCL 34(a)"

From the above clause from code we presumes that our above mentioned vessel shall be post weld heat treated, Kindly correct me if i am wrong...

Thanks & regards


Baijuz

 

[metengr]

PWHT is not required based on Table UCS-56. Why? see below

Note (e) for corrosion resistant weld metal overlay cladding or for welds attaching corrosion resistant applied lining (see UCL-34) provided preheat to a minimum temperature of 200°F (95°C) is maintained during application of the first layer when the thickness of the pressure part exceeds 11/4 in. (32 mm).

UCL-34
(a) Vessels or parts of vessels constructed of base material
with corrosion resistant integral or weld metal overlay
cladding or applied corrosion resistant lining material
shall be postweld heat treated when the base material is
required to be postweld heat treated.

 

[metengr]

Your reference to

(b) Vessels or parts of vessels constructed of chromium
stainless steel integral or weld metal overlay cladding and
those lined with chromium stainless steel applied linings
shall be postweld heat treated in all thicknesses, except
vessels that are integrally clad or lined with Type 405 or
Type 410S and welded with an austenitic electrode or
non‐air‐hardening nickel–chromium–iron electrode need
not be postweld heat treated unless required by (a) above.

Your reference to (b) is for martensitic stainless steel containing chromium, and not nickel.

 

[Bmechz]

Hi Metengr,

Thanks for your reply, but i have a doubt regarding the material..

As per UCL 34(b), they talks about the chromium stainless steel and they haven't used a word of martensitic stainless steel and as per my understanding Type 410 comes under martensitic stainless steel which is not required to be heat treated as per the above clause last line..

Thanks and regards..

Baijuz

 

[metengr]

Chromium stainless steel is martensitic stainless steel, the Type 405 and 410S are ferritic grades of stainless steel. Why are you even citing (b), when (a) in UCL-34 in the above paragraph is the appropriate reference for 304 or 316L, corrosion resistant cladding???????

 

[Bmechz]

Thanks for your reply...

Baijuz