Thermowell Welding Procedure Specification (WPS) and Procedure Qualification Record (RQR)
A WPS is a document that describes how welding is to be carried out in production. They are recommended for all welding operations and many application codes and standards make them mandatory.
The purpose of the document is to guide welders to the accepted procedures so that repeatable and trusted welding techniques are used. A WPS is developed for each material alloy and for each welding type used.
A WPS is supported by a Procedure Qualification Record (PQR or WPQR). A PQR is a record of a test weld performed and tested (more rigorously) to ensure that the procedure will produce a good weld.
The variables required to be documented are typically such items as:
- Welding process used, size, type and classification of filler alloy.
- Type and thickness of base material welded.
- Type and polarity of welding current, amps and volts recorded.
- Travel speed during welding, welding position, type and dimensions of joint design.
- Preheating temperature, inter-pass temperature, post weld heat treatment details, and others.
In addition to the recording of all the welding variables used during the test, in order to qualify a welding procedure, details of the inspection and test results must also be recorded.
These records must show that the inspection and testing has proven that the weld samples have met or exceeded the specified standard requirement.