Is PWHT required for A333 Gr.6 Piping Weld joints? 3

[ak1965]

We need to weld A333 Gr-6 pipes for a modification.

Should we go for the PWHT of these weld joints. The Pipe wall thickness is 12.5 mm.

As per B31.3 Table 331.3.1, PWHT requirment does not specify separately for LTCS PWHT...it talks about chemical composition and thickness as the criteria.

Please opine......!

 

[SNORGY]

This is just my opinion:

If your WPS / PQR demonstrate hardness in the as-welded condition on the order of 215 BHN or lower (or around 225-230 Hv for microhardness) throughout the weldment and HAZ, and if you are not sour or are at least less than 70 kPa partial pressure H2S, I am inclined to not do PWHT.

Regards,

SNORGY.

 

[metengr]

At 12.5mm, I would not perform PWHT on this material (P-No. 1) per B31.3. PWHT for this material is required once the nominal thickness exceeds 20mm.

 

[stanweld]

Assuming that you have a welding procedure properly qualified (impact testing required?)without PWHT, you need not post weld heat treat the involved welds.

 

[ak1965]

Thanks to all....


Clause 4.2 of standard SA333/SA333M for HEAT TREATMENT states:-

"All seamless and welded pipes, other than grades 8 and 11, shall be treated to control their microstructure in accordance with one of the following methods".

In fact this clause prompted me to think about PWHT in A333 GR. 6 to have a impact strnght at low temperautres.

 

[vesselfab]

their microstructure controlled at mill

if you are a standard nom thickness less than 3/4"
I would not pwht at all

and you should not have to worry about hardess or impacts if you are using a weld procedure that is already qualified to these.

this material is normally no problem to get hardess below 200 bhn an impacts at -45*F