You are correct that the joint preperation is a non-essential variable. This means that you can change the joint preperation from that used in the PQR, without having to re-qualify your procedure.

Non-essential does however not mean "not important". Your joint preperation needs to be appropriate for the situation. Usually appropriate means that it must give you the required access to ensure proper joint integrity. Personally I see no problem with matching up a V prep with a J prep, as long as you have a sound weld at the end of the day.

If you are going to radiograph the weld, this should also serve to give you some assurance that it is sound. If appropriate, you may even try ultrasonic testing it.

Hope this helps

Regards
Niekie Jooste

I agree completely with Niekie3 in his explanation of the nonessential variables but you also mentioned “there is some difficulty with the welder”. There are only a couple of things I can think of that would give the welder any problem and both have to do with the geometry of the J-bevel itself.
1. If the radius used during the machining was small and the subsequent angle was less then 30º. Both of these conditions would make the J-bevel resemble a true single-bevel joint. Historically speaking, this geometry can cause a welder some problem especially if he’s used to a vee-groove. If the J-bevel is of the geometry I’ve described, beware of possible slag inclusions and/or IF (incomplete fusion) along its face. In order for the welder to be successful he has to deliberately direct his arc (roll his wrist) to that side of the joint (J-bevel side) where as with the single-bevel side, the arc returns to a more natural state and is directed at its face.
2. If the root face of the J-bevel is thicker then the opposite root face could be perceived as a problem, but here again, you have a resemblance to a single-bevel joint. This is still a weldable geometry if attention is properly given or you can re-dress the thicker root face.

Other then these two conditions, I don’t know what the welder’s problem could possibly be that would sway the Owner in disallowing the joint.

The joint could be a little "tight". A single J that was designed to be part of a U groove may not have a large enough radius or groove angle to allow good access to the root. Also the configuration may cause a little uneasyness to a welder that "walks over" his wire only as opposed to keyholing.

Because of the difference in heat transfer from each piece, the welder may be concerned about breaking down(fusing) the walls.

Without specific dimensions I can do no more than speculate. Most valves and fittings that are ordered can have specific ends provided.

Do you think the purchasing agent can weld it? I feel confident that if the welder had ordered it, it would be more suitable.

In many cases its the welders job to make up for the shortcomings of planners, estimators, fitters, power plants etc.. Very seldom do others "bail us out".

As far as the code goes, the specific WPS you have would have to be written to incorporate the joint type since it would be a change from what you have listed unless your wps indicates a general description of "joints in accordance with design documents" etc..

A non-essential variable is a variable that is dcocumented on the WPS and if the range of actual welding conditions fall outside the range on the WPS, the WPS must be revised to incorporate the new range.(this my definition as it applies to WPS writing. Sec IX has the definition in the code)

As with most welds, the configuration is weldable, or with at least as much effort as is required to find out what "Ordering information" means in all those catalogs.

No offense intended towards anyone with some of my statements. Ive just always wanted to say some of that stuff and here was a good place.

Good Day

Gerald Austin
Iuka, Mississippi.

Need to know what the dissimilar metals are and what the application is. Some unusual joint configurations are recommended for Cr/Mo steels welded to Stainless steels using nickel filler materials in an effort to mitigate carbon migration. Just because someone hasn't seen it before, doesn't mean it's not a good idea.