Backing Thickness

[atomicman]

AWS D1.1 Section 5.10.3 gives "recommended" minimum nominal thickness of backing bars, provided the backing shall be of sufficient thickness to prevent melt-through. For SMAW, that recommendation is 3/16-inch.

If melt-through is prevented, is a thinner backing plate allowed? I see for commercial weld rings for pipe these are 1/8-inch - the note in 5.10.3 says this is OK provided there is no evidence of melting on exposed interior surfaces.

I'm just trying to clarify in my mind the mandatory code items vs. recommended.

 

[unclesyd]

Here is one of the prime suppliers of weld backing rings. There is a lot of information here on paper and by contacting.

http://www.robvon.com/

We use your approach and went with the thinnest the welder could handle. Just remember the backing ring is not a crutch. The consumable insert is worst as it has been my experience that the majority of welders don't approach using either properly.