How to specify preheat on a WPS? 2

[ethan18]

A welder is making a test coupon for procedure qualification. The provisional WPS used for making the coupon specifies preheat of 150°C. Welder aims for 150°C, however – after a few passes the actually observed preheat rises to 200°C. Overall, preheat is observed to be in the range of 150°C – 200°C over the course of test coupon welding.

1. What temperature should be recorded on the PQR? 150°C? 200°C? Or, 150° to 200°C?

2. What minimum temperature can be specified on WPS? QW-406.1 says that ‘A decrease of more than 100°F (55°C) in the preheat temperature qualified’ attracts re-qualification. Can one specify preheat of ‘minimum 95°C’ on the production WPS then? (I am guessing this is not how QW-406.1 is intended to be used. If not, QW-406.1 needs rewording).

Similar questions exist for QW-406.3 too – for inter pass temperature.

 

[ethan18]

r6155, the latest one.

Shane, you make a good point. I subscribed to this thinking too for 9 out of my 10 years experience. Then i chanced upon the CASTi book, which it must be said - is a treasure trove. It is hard to ignore the reasoning of the gentleman, at least from the Sec IX standpoint. I too had a hard time wrapping my head around Mr Houle's thinking. It is understandably tough to let go of long held beliefs.

Like i said, i have filed an interpretation. If the reply comes in the favor of what Mr Houle's discussion, then i think you'd have no option but to revise your long held understanding, Shane.

But i agree with you - this is a good time to quit prolonging this discussion. With due respect.
Cheers
Ethan

 

[ethan18]

DekDee,i think you posted something and deleted it (i wonder why). Yeah, i own mewelding.com. I am a Sec IX enthusiast. Ever since i discovered Interpretations, i have been enamored by them.
It does look like Mr Houle's thinking needs further corroboration (or refusal) from ASME IX committee. Either way, the subject is quite interesting. Regards.

 

[DekDee]

Ethan,
After a few beers I posted the interpretation you have noted on your website which quite clearly shows the ASME IX committee have a totally different interpretation to you and Mr Houle.
They quite clearly state a 400 degree F minimum preheat noted on the PQR may be recorded as a 300 degree F minimum preheat on the WPS.
They also noted you cannot have a preheat range on PQR as noted by you and Mr Houle.
Sorry, too lazy to go back and find the interpretation again
After a bit of reflection I realised we had both agreed to end the back & forth so I deleted my post.

Please remember code committees are made up of individuals - Mr Houles 40 year service is definitely noteworthy but the concensus of all committee members is more important than the opinions of an individual member. (regardless of whether they have created a CASTI publication)
I have been on 2 x B31.3 committees for nearly 10 years now and I can guarantee you discussions regarding interpretations are robust.
If the interpretation noted above was issued it was because the majority of committee members agreed with the response.
Cheers,
Shane

 

[r6155]

During production, things should be easy to understand for the welder and the inspector. Not as complicated as in this forum.
Regards

 

[r6155]

I know several engineers who make nice specs on the desk, but have no experience on the shop floor.

Regards