B31.3/Sec IX Weld Procedure Impact Testing Exemption by Thickness 1

[croy]

Per B31.3, impact testing for a weld is not required if the maximum obtainable width across the notch is less than .098".(correct me if I'm wrong) Base materials and filler metal are good at the -50F temp. If I run a .096" thick PQR, naturally I cannot get a charpy of .098" width. This would qualify the WPS for a thickness range of .098 to .196. Obviously I COULD get a charpy specimen out of a .196 coupon. I have always thought that this range would be acceptable per Sec. IX and B31.3 without any impact testing even though the upper end of the qualified thickness range could be impact tested. Is this correct? Thanks.

 

[metengr]

No, review ASME Section IX for weld procedure qualification under impact testing. ASME Piping Standards reference you back to ASME B&PV Code, Section IX. You need to follow the requirements in Section IX for coupon geometry and base metal thickness range under impact testing.

 

[croy]

Metengr,

Could you please elaborate on your response? Thanks.

 

[weldtek]

croy,
I think you may be confusing the rules for fabrication with the rules for qualifying a weld procedure. Refer to Sec IX for your PQR.

 

[croy]

Since impact testing is not possible on such a small coupon, the WPS, per Section IX would actually be qualified from .0625 to 0.196. My point is, that since within this range there IS a thickness that a 2.5mm specimen could be machined from (let's say you need 1/8" thk. for purposes of discussion)the non-impact tested qualified range, due to B31.3 would only be .0625 to .125 (?), and then I would have to run a .125 coupon (and impact test)which would qualify me for .125 to .25 (?). I would have to do this in order to qualify the .0625 to .25 range per Section IX AND B31.3.(?) It does not seem reasonable that a WPS thickness range could be qualified without impact testing, simply because of coupon size on the low end, if the range contains a thickness that COULD be impact tested. Thanks!

 

[DVWE]

Why not weld up a coupon which you can impact test and be done with it?

Read QW-403.6 (if it applies) and review QW-451.

 

[weldtek]

Keep in mind that per Sec IX, when the test coupon is < .25" thick, the qualified thickness range is 1/2 T to 2 T, making it possible, in most cases, to run an impact tested PQR. That being said, qualify your PQR with impacts and take the exemption, if applicable, for production impacts.