Here is great question and received many answers in the linkedin.
QW-304.1 (b), if small diameter pipe required minimum length of 150 mm or not exceed four production test.
Yes, we also contact with AI that they replied this is not clear in the statement of required measurement the length determined inside or outside diameter. Quickly answer that should prepared 4 production welds for NPS 1/2" regardless thickness, 2 production welds for NPS 2".
That means they are assume the length may account inside diameter as a minimized risk of additional qualification in the production weld.
Mr. MD SHAHBAZ replied:
Minimum 150 mm length required as per QW-304.1 for performance qualification,
So, if 1/2" Sch 80 pipe then we have to consider OD of pipe (Refer TABLE QW-452.3).
As per schedule chart OD of 1/2" pipe=21.34mm
So,we have to calculate the whole length i.e circumference=π×OD of pipe
=67.0076 mm (this is for one test coupon)
Then 3 test coupon =201.0028 mm.
So, 3 test coupon is required for 1/2" pipe for Performance qualification.
Mr. Kashif Farhan Syed replied
For any test and qualification, minimum length required is 150mm irrespective of size and dia.
Therefore, in order to cover the 150mm length, 1/2" sch80, 21.34mm (OD), calculate the circumference (67mm). Hence 67mm for single coupon x 3= 201mm.
Hence, 3 test coupon required to cover for qualification as per QW 304.1.
Mr. MUHAMMAD AWAIS ALI BUTT replied
Reference QW-304.1( b)
Here mentioned for small Dia pipe where required minimum length cannot obtain from single piece you take additional small pipes to fulfil requirement but total number not to exceed 4 .
If schedule was not added then you need 4 No’s.
But for this case
Here if you go according to 1/2" Dia schedule 80 then you need 3 No’s here.
Mr. Jon Ferreira replied
Section IX does not define OD or ID, nor are there any interpretations that ask. The only way you can get a straight answer is to ask ASME as they are the only ones who can interpret the code.
Most people would use the OD as QW-304.1. (b) uses the word circumstance. Then three production welds would need to be RT’t to get at least 150 mm.
If there is any doubt, then shot four. Or use test coupons to certify the welder rather than using production joints. In my opinion, the use of production welds to qualify welders should be limited as the risk is high.