Joint Efficiency acc to UW-12

[juancito]

Dear all,

Please help me with the proper interpretation of table UW-12 for class (1) weldments.
If a weldment is done only from one side, say with GTAW for the root and SMAW for completion, with comprobable full penetration, can E=1 be used in calculations?. Or this E=1 can only be used when welding is done from both sides only?.
Thanks and regards

 

[metengr]

If a weldment is done only from one side, say with GTAW for the root and SMAW for completion, with comprobable full penetration, can E=1 be used in calculations?.

Reply; No. My interpretation of joint description for Type No 1 weld joints in Table UW-12, implies that both sides of the weld joint would have the same weld quality. Double welding or back grinding the weld root to add weld metal, thus welding from both sides achieves this intent.

There are other Type No weld joints in Table UW-12 for single welded butt welds.

 

[prex]

A single welded butt joint with a GTAW first pass is normally recognized (based of course on a PQR) as a method of obtaining a type No.1 joint per UW-12.

prex

http://www.xcalcs.com

Online tools for structural design

 

[weldtek]

Two Sec VIII interpretations that you might find interesting are 86-10 & 92-158. Both indicate that single sided welds can be considered as Type 1 as long as they meet other Code requirements such as UW 35.

 

[metengr]

weldtek;
The reason I answered No to the original poster's reply is that simply using the GTAW process for the root pass of a single sided weld joint does not guarantee or demonstrate compliance with a Type 1 double-sided butt weld. The other Code requirements that need to be met are indeed critical, as you have mentioned. I have seen some good looking roots using the GTAW process and some that were borderline quality visually, that if I were an Inspector, I would not allow compliance to a Type 1 joint unless some local back grinding was performed to clean up the root.

 

[deanc]

Think the verbage in "joint description" needs to be read very carefuly.

Don't think it includes "dog nuts" and "hangers".

Another reason to do a good job as metengr pointed out.

I would say a full pen weld from one side could meet 100%---

IF------------

 

[weldtek]

metengr,
Point well taken.

 

[JoeTank]

In order to meet the requirements of UW-35 a visual inspection of the both faces of the joint must be possible. This would seem to eliminate the single welded joints with backing bars from consideration of E=1.0.

Steve Braune
Tank Industry Consultants

http://www.tankindustry.com

 

[weldtek]

Joints with permanent backing bars can never be considered type 1 with a JE of 1. See UW-12