Venting in double-welded slip-on flange 1

[nlgcode]

ASME B31.3-F308.2 state that "The need for venting the space between the welds in double-welded..."

Please help me in clarification it. Is this mean drill a hole for venting during welding? And after that is need weld to close it?

Thanks,
nlgcode

 

[moltenmetal]

Read the section. If you need to leak check the inner fillet, you need a means to do that. It's of no use if you plug it. Appendix F is precautionary, not mandatory.

The predrilled vent hole is also helpful to ensure that you don't blow out a bubble in the closing (back) fillet due to expansion of trapped gas in the space between the two fillets.