ASME BPVC SECTION IX WELDING_TRAINING - PART 5

In the process of PQR preparation we should know about,

1. Material to be welded with its P number (http://hareeshkv.blogspot.com/2013/05/asme-bpvc-section-ix-welding-training.html)

2. Filler wire or electrode to be used and its F number (Thttp://hareeshkv.blogspot.com/2015/04/asme-bpvc-section-ix-welding-part-2.html)

3. The thickness of base material that is to be used for the PQR process.

The third one will be discussed here.

The table (QW 451.1, ASME SEC IX, ED:2010, Page:144) below shows that the thickness of test coupon used for the procedure qualification and the range qualified by it.

Please note that there is a maximum and minimum range of thickness of weld metal and base metal that will be qualified as per the table.

Please see that up to 38mm of base material thickness of test coupon, the range of base material qualified is double the thickness of base material thickness used for test coupon for PQR.

Example: 1
If our job (in the project) ranges in between 5 to 20mm thickness, we will go for a test coupon of 10mm thickness for the base material.

By qualifying a test coupon of 10mm base material thickness, we can weld job ranging from 1.5 to 20mm thickness as per second row in the table QW-451.1.

Example: 2
If our job ranges in between 3 to 40mm thickness, we will go for a test coupon of 20mm thickness for the base material.

By qualifying a test coupon of 20mm base material thickness, we can weld job ranging from 5 to 20mm thickness as per fourth row in the table QW-451.1.

So in this case to qualify the range from 3mm to 5mm we need to do another test coupon having thickness less than or equal to 10mm as per second row in the table QW-451.1.

We have discussed about the thickness of base material qualified, now we will see the case of qualified weld metal thickness.

Please see that up to 38mm of base material thickness of test coupon, the range of weld material qualified is double the thickness of the deposited weld material thickness used in the test coupon for PQR.

Suppose in a 10mm test coupon, if we weld 5mm with GTAW welding process and the next 5mm with SMAW welding process, as per the code, the qualified range of 20mm of the base material coupon can be welded with 10mm of GTAW welding process and the other 10mm with SMAW welding process.

This way we can select the test coupon thickness for PQR based on the range of base material thickness (and based on the weld metal thickness) that will be qualified by the qualification of the test coupon and the range of base material thickness is assessed by the thickness of the work pieces/job that are to be welded in the project.