There are two welding standard that could be applicable. You should be using one of them as the basis of qualifying the procedures and the welders. They will also provide some guidance for the WPS, most likely by referring you to another welding standard. The applicable piping standard will list the acceptance criteria for the VT regarding the weld profile, etc.

ASME has a code that is an extension of B31.3 and AWS has a separate welding standard for similar sanitary applications. The customer should provide you with some direction as to which standard is applicable (it isn’t B31.3).

The ASME code (for pharmaceuticals) requires the bulk of the welding to be performed with orbital welding equipment and complete internal visuals if I remember correctly.

One project that involved pharmaceutical piping to the ASME requirements was a learning experience for one of my long time clients. My recommendation to my client was that they were not capable of producing welds to the level of quality required by their contract. My client was a plumbing contractor who took the job on the premise that the job was “just pipe.” The job was far from being just another pipe job. They didn't have the proper equipment or the proper training needed to fabricate and install the pipe to the level of cleanliness and to the stringent acceptance criteria required. The cost of performing the required inspections was about 50% of what they quoted the entire job. However they didn't include money for the type of inspections which included videotaping the internal remote VT.

It was fortunate that the owner didn’t understand the requirements of the applicable welding standards. The construction manager stated at the job meeting there was nothing special about the piping and that any mechanical contractor should be able to meet the job requirements. I asked him if he ever read the code that covers the piping requirements. He indicated he had not, so I reviewed the requirements that applied with those present at the meeting.

“You got to be sh…ing me!” was his response when I finished.

My client told the owner that he was in no way prepared to meet the requirements because he was told it was “just pipe.” The actual welding standard was never referenced in the “Request for Quotation.” It was a total surprise to him that the requirements include the need to use orbital welding equipment, videotaping all internal inspections (what was an internal inspection?), a “clean room” environment to fabricate and assemble, etc.

The owner offered to release him from the contract and my client jumped at the opportunity. It was the intelligent thing to do and probably saved his plumbing company from financial ruin.

Best regards - Al

Take a look at UA procedure 45 it may be closer to what you need and if your contractor belongs to the NCPWB they may already have a WPS that is exactly what you need, in the long run it may be more cost effective to join the NCPWB.

Dairy industry may seem to be a simple application but it's not.
Pressures are low and temperature doesn't go over 140 ºC, but there's another stringent requirement: surface finish.
I've asked Alfa Laval, a very well known manufacturer of milk handling and treating equipment (plate heat exchangers, centrifuges, pumps etc.) and their specifications are quite rigorous regarding surface finish: maximum Ra is 0.8 micrometers. Ra means "roughness average" (you convert to RMS, used in the USA). If the equipment has that surface finish, the piping should obviously have the same.
Why such a stringent finish? Because microorganisms would lodge into the metal roughness if it was larger. Once the microorganisms get in contact with milk, fermentation will start, and fermentation is to be definetely prevented.
Take this condition into consideration when preparing your quotation.
Giovanni S. Crisi
Sao Paulo - Brazil