Backing (Back up Bar)

Date 06-08-2012 20:51

All,
Where can I find this simple minded answer, Regarding steel backing, Would a back up bar be required to be as least as wide as your included angle at the top of joint? Or wide enough to assure complete fushion at the root opening? Thanks RS

By 803056

Date 06-09-2012 01:01

I would factor in whether the joint was to be radiographed or not. If RT was required, it would be advisable to have the backing wider than the opening of the groove and width of the completed weld. It would make interpreting the film much easier for the film interpreter. If the joint was not examined by RT or if it was to be checked using UT, I would make the backing bar wider than the root opening, perhaps 3/4 inch plus the width of the root opening as a guide.

Best regards - Al

By Shane Feder (****)

Date 06-09-2012 23:49

RS,
You don't mention if it is a qualification test or if it is a production weld.
Figures 4.21 and 4.22 give required thickness and width of backing bar (with RT and without RT).
I presume those measurements would be applicable to production welds as well,
Regards,
Shane