Nope.

Never seen it but always heard about it. There may be certian situation in which this should be controlled however that code doesn't restrict it. I call it a wives tale. There are a few threads in some other forums I'll look up and refer

This is usually expressed as a concern over having a weld too close to the HAZ of another weld.

Having looked at many micro etch specimens (on P1 & P8 materials) that show the HAZ as a relatively narrow band, I am no longer concerned about the proximity.

It usually boils down to workmanship, resulting in the need to have two welds very close to each other (it doesn't look good). Alternatively, there are times when it just can't be avoided.

Charles Hall

Thanks for the replies. I've seen several customer requirements as of late that have referenced their requirements ("...no less than 10 times the wall thickness for fittings or 2 times the OD for girth welds" for example) but could not locate anything in the code.

No code requiremnet in this regard.

My advice would be 2 OD or 50 mm (2") minimum to allow for UT of the weld. The size of HAZ might not have anything to do with it.