Weld Tie-In

Date 08-23-2011 11:31

I'm not sure if I have the terminology right, but this is more or less what my company's weld acceptance criteria is:
"When joining into a weld crater left by a previous weld, 70% (minimum) of the previous crater shall be overlapped."

Aside from being totally subjective, what do others use as a minimum of overlapping the crater? I'm trying to come up with a better measuring stick. Any comments would be appreciated.

Tyrone

By js55

Date 08-23-2011 11:41

It will always be subjective because there is no mechanical criteria for acceptability based upon the 'overlap'. If the un-overlapped area is 'higher' than the base metal surface it is essentially acceptable.

By jwright650 (*****)

Date 08-23-2011 11:55

The crater just needs to be full....so whatever overlapping it takes to make that happen.

By TimGary (****)

Date 08-23-2011 14:38

Our criteria uses a minimum of 85%.

By Tyrone

Date 08-23-2011 14:48

TimGary,
Do you have a problem with the subjectiveness of 85%? How do you know how much of the crater is filled since you can only see the unfilled portion?

By TimGary (****)

Date 08-23-2011 18:22

Yes and no.
I train the welders to back step welds, for cosmetic, smooth tie ins that don't leave behind underfilled craters.
Those who choose to listen to wisdom don't have a problem.
Those who are hard headed get exposed to the subjectiveness of eyeballing 85% of crater size.
Where we have the most problem with tie-ins is around corners of square tubing.
Getting the full weld profile around the corner can be tricky, especially in flare bevel groove joints.

Tim

By Tyrone

Date 08-23-2011 18:38

Tim,
Welders are trained the same here. Fill it all up. Once in Production, the 70% rule takes hold.
I see groove welds being harder to tackle since it's all theoretical. Can't destroy the product going out the door.

Tyrone

By Blaster (***)

Date 08-23-2011 17:25

WABO Standard 27-13 for section on visual acceptance criteria for structural steel qualification:

27-13.8.1.1.3 "All craters are filled to the full cross section of the weld."

By Tyrone

Date 08-23-2011 18:40

Blaster,
Does that mean on fillet welds, the entire crater has to be filled since they are mainly concave? On groove welds, we can't measure the cross section of the actual throat.
Tyrone

By Tyrone

Date 08-23-2011 14:18

js55 - You are absolutely correct. If the un-overlapped area is "higher", then it is mechanically acceptable. You can therefore possibly have none of the crater filled and still be good. Structurally it may cause stress risers and cosmetically it looks like crap.

jwright650 - Changing the requirement for full fill was my first thought, but lots of people are telling me that snags are going to skyrocket. We might just have to bite the bullet for the short term untill everyone learns to fill 100%.

I was wondering what other industries (pressure vessel, nuclear, defense, etc) use as a requirement.