What is Group-Number in Welding & ASME?

What is Group-Number in ASME?

Group number is applicable when toughness requirements apply to materials. This is sub-grouping of the P-Number materials by the similarity of metallurgical properties except for impact requirements. However, per ASME Section IX,

These group numbers divide a P number into several group numbers for the purpose of Welding procedure qualification when impact testing is a requirement by the construction code such as ASME Section VIII.

Grouping number only applicable for welding qualification and not to brazing qualification. In brazing only material P Number is applicable.

ASME Materials group number

The below table shows the example of ASME Section IX Table QW/QB-422 where we can find the materials P-Number and Group Number.

As we can see in Table Qw-253, material Group Number is a Supplementary Essential Variable and therefore Group Number is related to toughness properties of materials.

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