Im not familiar with Sect I, but based on sec IX; no.
Review QW-356. P-number is an essential variable.
Welding P91 when qualified on A105 is a HUGE difference. WHat filler has been used on P91? F-number is an essential under QW-356 too.
Also keep in mind that PWHT may be required by the code of construction (sec I). That also sets requirements to the qualified WPS.
For strictly material grade issues, a welder qualified on P1 materials is qualified to weld P‐No. 1 through P‐No. 15F, P‐No. 34, and P‐No. 41 through P‐No. 49. See ASME Section IX QW 423.1.
You are right. SectionIX. Disregard my previous comment "Section IX QW-423.1 refers to welder qualification test alternative base metal but not on production weld. Correct me if I am wrong then SectionIX.".
You're right! SectionIX, totally forgot about that. I think the question should be if the welder would be able to make a sound weld, if he's qualified on A105.
My rationale is based upon variable QW-403.18 [in QW-351] which states "A change from one P‐Number to any
other P‐Number or to a base metal not listed in Table QW/QB-422, except as permitted in QW-423, and in QW-420".
QW 423 states "Base metal used for welder qualification may be substituted for the metal specified in the WPS in
accordance with the following table..."
Section I defaults back to Section IX for WPS and Welder Performance qualification, period. You have base material and filler metal for performance qualification. The purpose of the welder performance qualification is to demonstrate the ability of a welder to produce a sound deposit. Based on the above, I see no nonconformance for the welder qualification provided the diameter and thickness ranges are correct.
Sorry guys, I was completely wrong on this one. I've forgotten that when welding P1 for a WPQ, one's allowed to weld more Pnumbers.
What I've never really understood is the freedom the code gives in this respect (or how this rule is actually used by some manufacturers in that they use one WPQ for a welder to weld more than just that specific material grade). Given the difficulties that come with P91 (at least, from what I've read about this grade and its applications over the years, not from actual experience), I find it hard to believe this is allowed by the code. But maybe that's just me.
XL83NL;
No sweat. I am not a member of Section IX but I do know a fair number of members. Basically, what it boils down to is this, a welder follows a detailed procedure for production welding. When it comes to performance qualification, the welder need only demonstrate that they possess a minimum proficiency for depositing a sound and quality weld. When it comes to welding Grade 91, what really matters is that the welder follows exactly the requirements on the WPS and uses their demonstrated ability to deposit the specified weld metal in a quality manner.
By the way, there are a number of Owners that require welders to qualify on P91 material with radiographic testing.
The employer can require welders to qualify on the materials to be joined if he so chooses. As metengr stated, ASME IX provides some assurance of a welder's "minimum proficiency" which may not be enough to assure sound welds in specific materials.
"When it comes to welding Grade 91, what really matters is that the welder follows exactly the requirements on the WPS. . "
Exactly; the problems on P91 come in when the preheat, interpass, or PWHT requirements are 'fudged' or totally disregarded by the welders. And these requirements are NOT easy to maintain without having a Heat-Treatment company provide them, vs. giving the welder a oxy-acetylene torch and temperature crayon.
