Supplementary coupon of PQR

[arvindshakya]

Dear All,
I am having a PQR with PWHT performed on 33.32mm pipe A106 Gr.B (Without impact), can I make a additional test coupon of lower thickness say 12.70 mm with keeping all the essential variable same as earlier PQR. And on basis of these PQR and its supplementary coupon, WPS may get the total thickness range of 5.0mm to 66.64mm (With Impact).

 

[Genetix]

As per QW-403.6, the minimum base metal thickness qualified is the thickness of Test Coupon T or 5/8" (16mm) whichever is less. In your case 12.70mm test coupon thickness shall be the minimum base metal thickness qualified. WPS may get total base metal thickness range of 12.7mm to 66.64mm with impact.

 

[david339933]

Do your supp. coupon on 5mm and you will be good for the thickness you require. Remember time at temp is an ess. variable for impacts.

 

[arvindshakya]

But in impact required WPS, thickness range will be T/2 to T+1/4".
So, I am confused and i am unable to get any reference which can give higher thickness with impact toughness (as per main PQR with the help of supplementary PQR).

 

[DekDee]

How can you expect to be qualified to 66.64 mm with impacts when your test coupon is 33.32 mm without impacts ?

 

[david339933]

You did not specify B31 code....so I incorrectly assumed Sec. IX. You will need multiple impact specimens.

 

[arvindshakya]

You are right Mr. DekDee, but my confusion is whether 12.7mm impact coupon can support 33.32mm not impact coupon. If yes, what will be the qualification range of material thickness with impact.

 

[DekDee]

As David has noted you will require multiple coupons (impact tested) to achieve the range you require.

In answer to your question a 12.7 mm impact tested coupon will qualify you to 25.4 mm max for ASME IX (impact or not impact tested) and for B31.3 it will qualify you to 25.4 mm (not impact tested) and 19.05 mm (impact tested).
Forget about ASME IX thickness ranges for a moment as B31.3 ranges take precedence.
Using the formula T/2 to T + 6.35 mm you should be able to work out how many coupons you require.
Cheers,
DD