WELD JOINT NUMBERING SYSTEM

WELD JOINT NUMBERING SYSTEM

FOR PROCESS PIPING

There is no hard and fast rule for the piping weld joint numbering system, but it should be done with good engineering practices to avoid confusions and errors.

At the beginning of every piping project, a joint numbering procedure is established in consultation with all stake holder's. 

1. The joint numbering is done in the process flow direction or else agreed between client/consultant and contractor.

2. Joint number will start from 1 and will continue that is 1,2,3,...…

3. If a joint is cut and rewelded (because of the error in fabrication attributable to contractor) a suffix of RW0 is given.

eg:If joint number with 8 is cut and rewelded then the new joint number for that joint will be 8RW0. If the joint is cut and rewelded for the second time it is numbered as 8RW1 and if further done 8RW2 and so on. (RW means Rectification Weld) 

4. If a joint is modified (due to revision in the drawing or of reasons not attributable to contractor) a suffix of M0 is given

eg:If joint number with 10 is modified then the new joint number for that joint will be 10M0. If the joint is modified for the second time it is numbered as 10M1 and if further done 10M2 and so on.

5. If a joint is repaired (because of defect in weld joint, identified by NDE) a suffix of R0 is given.

eg: If a joint number with 12 is repaired then the new joint number for that joint will be 12R0. If the joint is repaired for the second time it is numbered as 12R1 and if further done 12R2 and so on.

6. If suppose a new joint is added between two joints, suffix A is given with the least joint number. If further joints are added between those two joints, B, C ..etc are given in Capital Letters. It is to be remembered that suffix and R and M should not be used as these suffixes are used for repair and modification joints respectively.

Eg: Suppose one joint is added between 5 and 6, then the new joint number will be 5A. If two joints are added between 5 and 6 the the joint numbers will be 5A and 5B.

7. If a new joint is added between 5A and 5B then the new joint number will be 5A1, if further joints are added between 5A and 5B then joint numbers will be 5A1, 5A2... and so on.

These numbering system are for piping in process plants. The numbering system followed for pipe lines may not follow this rules.

8. In some cases shop and field joints are also to be identified in the numbering system itself. In such cases, Shop and field joints are separated giving prefixes  "S" and "F" respectively. 

Eg. Suppose joint 8 is a shop joint and Joint 9 is field joints. we can write it as S8 and F9 respectively. 

9. If a shop joint is modified in field then the new joint will be field joint. 

Eg.  S8 is modified then the new joint will be F8M0.

Last edited on: 12 Nov 2019

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