×
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

Checking for weld defects using low pressure pneumatic testing

Checking for weld defects using low pressure pneumatic testing

Checking for weld defects using low pressure pneumatic testing

(OP)
Hello,

For a 100 m^3 tank would a test pressure of 0.6 barg be sufficient to detect if there was a defect/ leak in any of the welds?

A small overpressure is required for safety concerns as the tank would have to be located in close proximity (>10m) to the workshop as that is where the compressor is.

How long would the tank have to be left for before a leak was detectable?

The MAWP for the tank is 1.96 bar. A lot of tests talk about test pressures of 1.1 x MAWP (2.156 bar), but I think that is to test the integrity of the tank rather than checking for defective welds.

Any feedback would be greatly appreciated!

Tom

RE: Checking for weld defects using low pressure pneumatic testing

If you did a fluid (soap film) "bubble test" on the outside you would see a nasty leak in minutes.

But a slow leak? Probably would nt be detectable at that low a pressure. The tank heating up/cooling off unevenly due to sunshine would overwhelm any such test.

Do a NDE dye penetrant test of the joint welds from BOTH sides. If no surface defects were found on either side of any weld joint or bolted joint, you probably have no through cracks that would yield gas leaking out.

RE: Checking for weld defects using low pressure pneumatic testing

Was the tank in-service and weld repaired?

RE: Checking for weld defects using low pressure pneumatic testing

Avoid pneumatic testing if at all possible due to the large release of energy if it fails. Pneumatic testing to check weld integrity begs the question- what happens if a weld fails? Once a failure point starts it may propogate and then it'll get real interesting.

Second the NDE dye pen tests suggested above.

Can you fill the tank up and do a standard hydrotest?

As a chem eng/metallurgist the first part of any answer I give starts with "It Depends"

RE: Checking for weld defects using low pressure pneumatic testing

I thing a DP and hydrotest will do the job for you.

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