How to decide the WPS requirements for a project?

Welding Procedure Specification(WPS) requirements for a project

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How to decide the WPS requirements for a project? 
How many WPS are to be made for a project?

Finalizing the number of welding procedure specification (WPS) is one of the difficult tasks for any QA/QC or welding engineer. The non-availability of a WPS will pop up at any time during a project phase and that is one of the nightmares of any welding engineer.

How to solve it? It is impossible to solve it by 100% but can be reduced by following small steps and some logic. Experience can add a further helping hand in this.

From Documents:

1. Go through the project documentation for understanding the welding requirements of the project. Note down those requirements. 

2. Search for the special requirements, if any,  laid down by the piping designer.

3. List the materials that are in the project. This can be obtained from project documents/contract documents. Note down all the materials that are mentioned in those documents in a paper or  MS Excel. 

4. From project documents /contract documents/ piping line list/ piping schedule, note down the minimum and maximum thickness  to be welded of a material. Write that thickness against each material in the MS Excel we have made for materials.

5. Decide which welding process is to be used for each material. This will vary according to thickness also. Detail the process against thickness and material in that MS Excel sheet. 

6. From the project specification/contract documents find the requirements for preheating,  post heat and PWHT.  Mention that against each material and thickness range. 

7. Write the welding consumables against each welding process and material. Special requirements such as NACE qualified,  Ferrite controlled if any also to be listed out.

8. Now we have listed all the requirements for the WPS/PQR.

9. Search for the availability of pre-qualified WPS,  WPS qualified by reputed clients or the third party if any. Discuss with the client whether those qualified PQR are acceptable which are qualified in the witness of the reputed client or the third party. 

10. If PQR is not available go for PQR qualification. 

11. Search for material and thickness which minimize your number of PQR qualification coupons.

From Experience:

1. SS to CS welding will be there in any of the refinery related projects. So PQR for that should be made available.

2. Alloy steel to SS maybe there particularly at instrumentation connections. 

Following these guidelines will help you to generate the WPS/PQR for a project.