Tubing Procedure versus WPQR

Date 11-14-2011 11:24

Hi rshanks

Took me a while to understand they question. I think I have deciphered it!

In essence the issue is that the one table (4.2) deals with WPS ranges, while the other table (4.11) deals with welder (performance) ranges. As with many welding codes, some of the essential variables' ranges are different for these two situations, so I see no problem with the code requirements or tables. Just remember that when qualifying a WPS you are trying to proove the physical ability of the procedure to deliver acceptable results, while when qualifying a welder you are testing the welder's skill. These are two different things.

Regards
Niekie

By rshanks (**)

Date 11-14-2011 14:23

So therefore, when will note E come into play versus a procdure?

By ozniek

Date 11-15-2011 10:37

Hi rshanks

Note e from table 4.11 relates only to welder qualification, so it is never considdered when looking at procedure qualification ranges.

Regards
Niekie

By rshanks (**)

Date 11-15-2011 16:27

Yes , I understand this but don't we qualify welders and welding operators from a written weld procedure, Know the procedure it's self is going to list the ranges, so when would Note E, from Table 4.11 ever come into play?

By CLH1978 (**)

Date 11-15-2011 21:32

Hi rshanks. Note e would come into play when writting or applying a wps to be used for welder qualifications. Depending on the range of material dimensions in specific joint wps's, more than one welder qualification maybe necessary to perform the welding.

By ozniek

Date 11-16-2011 11:50

Hi rshanks

I think there is a bit of a communication gap here. Probably caused by an assumption that we are working with that has not been communicated. I will try to answer your question, but may say things you already know in the process, just to try and get to the bottom of the mis-communication.

The first point to be made is that note e in table 4.11 is invoked only when referred to it by the table. In this case, when the welder qualification test piece diameters are >100mm. I will include the relevant section of the table below. Note e is not used at any other time.

Let us run through a possible scenario: A WPS (Call it WPS 1) is qualified on a 300mm diam pipe. From table 4.2, this allows pipes to be welded >=300mm diameter. (I will include a section of this table also.) A welder (Assume he did not weld the WPS 1 test piece.) uses this WPS to weld a welder qualification test piece of 300mm diameter. From table 4.11, note e, the welder is qualified to weld diameters of >150mm. Note that the welder's range qualified on diameter is wider than the WPS's range of diameters.

Let us say that for a later job, another WPS (Call it WPS 2) is qualified on a pipe of diameter 200mm. According to table 4.2, this allows pipes to be welded >=100mm. On this later job, the fabricator requires the welder to weld pipes of 150mm diameter, using WPS 2. Assuming that it was not this welder that welded the WPS 2 test piece, he is still qualified to perform this weld without further testing. (As long as he is welding within the other essential variables qualified in his welder qualification test piece.) Some people believe that the welder may only weld production welds that are welded to the same WPS that the welder followed during his qualification, but this is not correct. WPS is not an essential variable. (See Table 4.12 - I will add this also!)

I hope this example explains how note e in Table 4.11 actually makes sense.

Regards
Niekie