×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Dimensional tolerances of weld joints

Dimensional tolerances of weld joints

Dimensional tolerances of weld joints

(OP)
I have specifications that require welder testing to ASME sect.IX and welding by API 650. On this job, a 1/16" root opening for a fillet weld is called out but our trial fit is showing an average of 3/16" root opening. Not being as familiar with API 650 as AWS D1.6, I am questioning where joint dimension tolerances are addressed. I have been informed that it will refer you back to D1.6 but I have not found that statement either.

Thank you.

RE: Dimensional tolerances of weld joints

Per 9.2.1.1 of API 650, your welding tolerances must be in accordance with ASME Section IX and your Weld Procedure Specification (WPS) for tank welds and attachment to tank components. For welds on other assemblies, but not their attachment to the tank, it is permissible to comply with AWS D1.1, AWS D1.6, or ASME Section IX and your Weld Procedure Specification (WPS).

RE: Dimensional tolerances of weld joints

(OP)
Based on what 9.2.1.1 says, our 3/16" gap for the fillet weld (not attached to the tank) is acceptable per D1.6. API 650 and ASME sect. IX seem a little foggy when tolerances of joint design are questioned. Surprisingly, I noticed that sect. IX allows for no range in root opening for the GMAW/FCAW process, allowing only what the WPS would say I suppose.

Thank you for your assistance.

RE: Dimensional tolerances of weld joints

Section IX does not address the issue. Joint design is a non-essential variable. The 1/16" gap is specified to mitigate cracking due to weld shrinkage and assure root penetration. Your 3/16" gap may well lead to poor root penetration (bridged root) which could well lead to failure in service, depending on the loads experienced.

RE: Dimensional tolerances of weld joints

holdpt,
Where does the 1/16" root opening for fillet welds come from ?
The idea of a fillet weld is to have 0 root gap - codes usually stipulate a maximum root opening for the reasons given by weldstan.
Cheers,
DD

RE: Dimensional tolerances of weld joints

1/16 inch root openings are acceptable per several structural welding codes/standards. Generally, when the root opening exceeds 1/16 inch, the weld size is increased by the root opening to compensate for the "loss" of effective throat caused by the presence of the root opening.

Best regards - Al

RE: Dimensional tolerances of weld joints

Hi Al,
No problem with that - my comment was based on this statement - " On this job, a 1/16" root opening for a fillet weld is called out".
Why would you call for a root opening on a fillet weld ?
I realise socket welds have a gap to allow for weld expansion but structural fillet welds are normally clamped together prior to welding.
Cheers,
DD

RE: Dimensional tolerances of weld joints

I use a 1/16 inch root opening when large multipass fillets are required. It provides a "release" mechanism for the residual stresses to reduce the probability of a root crack. I use "crush wires" that "crush" flat (reducing the root opening) as the weld cools and contracts in the transverse direction. By doing so, the transverse residual stress is accommodated and the root crack prevented.

Best regards - Al

RE: Dimensional tolerances of weld joints

(OP)
DekDee,
This is a door to a vessel. The re-pad going around the neck, left side and right side with FW in center, calls for 1/16" gap with a 3/8" fillet FW. Basically, the ID of the re-pad is 1/8 larger than the OD of the door neck. Rolling and breaking 1-1/4" 317L and 3/4" 317L made hitting this on the mark very difficult.
I do like the idea behind GTAW's use of a 1/16" gap on multipass fillets.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources