×
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

Welding on a live pipe

Welding on a live pipe

Welding on a live pipe

(OP)
Hi,
Has anyone got any good reference material in relation to how to assess if it is safe / or able to weld a collar onto a live water line? Am looking at welding a 20mm collar onto a 300NB water line, materials are: Collar = A516 Gr 60, pipe is A106 Gr B. Pressure in line is 6600KPag, with demin water flowing through it at

I'm interested in finding the basic process how this is assessed and the details involved. Are there any rule of thumb guidelines etc

Dave

RE: Welding on a live pipe

Do a search for "in service welding".
Not easy, but definitely possible (if there is sufficient wall thickness on your pipe).

RE: Welding on a live pipe

What is the diameter and wall thickness of the pipe - especially at the weld location?

RE: Welding on a live pipe

Be careful --- if you superheat the water - you can easily get a "steam" explosion. Did that to myself working on a 1/2'' water line that I thought was dry!!

RE: Welding on a live pipe

See ASME PCC-2, Article 2.10 "In-Service Welding Onto Carbon Steel Pressure Components or Pipelines". There are a large number of considerations, including Welder Performance Qualification...

RE: Welding on a live pipe

Just a few comments:
1) Determine minimum thickness of pipe required for pressure containment of water - Internal pressure hoop stress calc
2) Add 0.1 inches for weld penetration factor and 0.04 inches safety factor to the minimum thickness calculated in step 1.
3) Take UT thickness measurements at the weld area to make sure actual thickness of pipe is greater than required thickness calculated in step 2.
4) Check welding procedures to ensure temperature of pipe with water flowing through it is not too low for welding.
5) Establish flow of water through the pipe prior to welding. There are min and max recommended rates for liquid flow during welding.
6) A qualified welder needs to do the work to reduce chances of burn through.
7) Have a contigency plan in place in case the welder does burn through the pipe.

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