×
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

WELD PROXIMITY

WELD PROXIMITY

WELD PROXIMITY

(OP)
What is the minimum distance for any weld
proximity? To avoid HAZ (Heat affected zone), how much
minimum distance should be kept between the two
welds? As part of good engineering practice, we
usually keep a gap of 50mm between the two welds. In
UW section of ASME Section VIII Div 1, it is mentioned
somewhere that we can keep a distance of about 12.7mm
(1/2 inch) between the two welds. What is the opinion
of people on this forum?

RE: WELD PROXIMITY

PEHasan,
         12.7mm between two welds does not seem correct. Think about it if the parent material were 30mm thick then this is too close. I beleive it depends on the material thickness. We generally work on 40mm between the toes of the welds. I think this is noted in BS2633 the code for welding of pipes Class 1.

RE: WELD PROXIMITY

I believe the 1/2" distance you mention from ASME Section VIII, Div 1 is from UW-14 (d), and pertains to an opening in a solid plate placed next to a shell weld. These rules are specific to maximum hole size and plate thickness.

Your question really pertains to overlapping heat affected zones. For pressure vessels, it is always good design to locate welded openings and appurtances away from existing shell welds. However, I see nothing wrong if a designer has to overlap welds. You have shell and seam girth weld overlap and nozzles that penetrate thru vessel shell welds on a regular basis.

For piping systems, I have seen this problem on more than one occasion. Pup pieces that are installed adjacent to shop or original field welds. In this case, I would use engineering judgment and keep a minimum distance of 1" between weld toes of adjacent butt welds. The piping codes do not address this type of situation.

RE: WELD PROXIMITY

Interacting stress fields could also be a reason for separating welds.  If I remember correctly, 5 * t used to feature in the old BS 5500 or other British standard.

Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdo/

RE: WELD PROXIMITY

(OP)
Thank you guys for your responses.

The other information that I can recall from my mind is that the minimum distance for any weld proximity shall be smaller of the following: -
- 5 times the thickness of thinnest member being welded
- 50 mm

Regards,

PEHasan

RE: WELD PROXIMITY

if you use controlled preheat and then post weld heat treat the welds, then this should not be a concern.

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