All too often the conditions you cite are exactly the case.
"I personally think the pWPS is a great idea but unless it is written by someone with sufficient knowledge / experience it is generally of no use to the welder at all."
I agree and I say the same is true of the WPS used for production. Based on past posts, I believe you and I are in agreement that a WPS that is not founded on good data serves little purpose to the people that are most likely in need of good data; the welders.
Since I am basing my response on ASME Section IX, it should be noted that it is not a requirement to record the actual welding parameters used while welding the test assembly. If one does no more than the absolute minimum to comply with Section IX, only essential (and when notch toughness is invoked, the supplemental) variables must be recorded on the PQR. I find it difficult to write a WPS that will replicate the welds of the test assembly (PQR) if I do not record all the test data while the test assembly is welded. That is my way of saying that meeting the minimum requirements of the welding standard may not be sufficient to make an informed decision regarding the production welds.
Few welders are in a position to record the welding parameters by watching meters and stop watches while they are busy welding the test coupon. With that in mind, even though Section IX does not require a test witness be present to record such data, I must ask the question of how else is the test data to be collected? Without the test data, how is one to write a WPS with meaningful welding parameters for welders to use to make production welds? Few welders have any idea of what their actual travel speed is while depositing a weld, yet it is just one of several nonessential variable that should be controlled if consistent results are expected once production starts.
As for the PWPS, it is required when specified by the applicable welding standard and there are several that do list it as necessary. After all, the purpose of welding a test assembly is to qualify the WPS. The WPS used in production is a variant of the now qualified WPS assuming the conditions listed in the PWPS are proven to produce acceptable results.
I guess I look at it this way, the code or standard provides the user with the minimum requirements that must be met. It is up to the contractor to decide how and the means by which those requirements are met. If the operation is not terribly sophisticated and the welding fairly rudimentary, a casual approach will work. The analogy is changing the tire on the family car. The approach taken by the average backyard mechanic is to rummage around to find a suitable jack, grab a wrench or two, begin removing the lug nuts, and continue until the tire is changed. The process is simple and requires little fore thought. However, the process of changing a tire on a multimillion dollar aircraft is much more regimented and formalized. The cost of failure involves more than financial repercussions. A disaster will change the lives of hundreds of people.
When conducting training for engineers and inspectors that will be tasked with qualifying WPSs or possibly designing welds, I always recommend the newly minted engineer or inspector to spend time with the welders to decide on the best course of action. Those decisions are translated into the PWPS to make sure everyone understands what must be done. The more involved and complicated the weld, the more important that everyone know what must be done. It can be very frustrating to have a test weld made only to find out notch toughness is required, but no one recorded the heat input of each weld bead.
The PWPS is just another part of the planning process to decide what has to be done and how it will be done so all the code and contract requirements are met.
ASME specified the requirements that must be met, but not how those requirements are to be met. Is a PWPS needed? Maybe not if it is something that is done on a regular basis just as changing the tire on the family car does not require a set of written instruction.
When witnessing the welding of the test plate (again, there is nothing in Section IX that says I have to witness the actual welding), I verify everything is as specified by the PWPS. It serves as a checklist of what is to be welded and how it is to be welded. Is it the right material? Is it the right filler metal? Is it the correct shielding gas? Nope! Wrong gas. Why? Is there a reason the welder isn't using the gas that was specified?
The importance of following through with verifying all the proper materials, etc. were used many years ago. The contractor decided to switch the shielding gas to Argon. The WPSs had to be qualified for the new shielding gas. All the WPSs had to be submitted to the US Government for approval and their blessing. The WPS was qualified in my absence. Everyone assumed the welder used the correct gas. It was only after the WPS and supporting PQR was blessed by the government that we learned the welder used Helium. Ouch! That was a lesson that will not be repeated soon.
Are you qualifying a WPS for ASTM A53 schedule 40 6 inch pipe with E7010? You probably do not need a formal PWPS to meet ASME Section IX.
Do you need to be a welding engineer to write a PWPS? Heck no, anyone other than the CAWI can write a PWPS.
A very interesting thread but the recomended form supplied by ASME (QW-403) does leave room to list the WPS number that was used with the PQR. So it might not be manditory but it is recomended. We list the preliminary WPS which then becomes the permanent WPS when the PQR is registered but have never developed a satisfactory system to cross reference every related WPS and PQR. It is often confusing but ASME does not have a method so i have never had an auditor that could find fault with it either.
Reg
