×
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

Pneumatic Leak Test (when the design temperature is greater than the test temperature)
5

Pneumatic Leak Test (when the design temperature is greater than the test temperature)

Pneumatic Leak Test (when the design temperature is greater than the test temperature)

(OP)
During my work last week, I was asked about the possibility to change the hydrostatic leak test for pneumatic leak test.
The line condition is:
Fluid: Steam
Temperature: 650°F
Design Pressure: 275 Psig

At first the test was specified in accor with ASME B31.3 Hydrostatic leak test
[b]345.4.2 Test Pressure
PT = 1.5 PRr

result: PT= 1.8P

If I want to change for pneumatic test, the ASME recommend in para.345.5.4 shall not exceed the lesser of (a) 1.33 times the design pressure.

If I change for pneumatic leak test, I will not get to represent the effect of temperature. This way I wont put my system in real conditions during the test.

So my question is:
In work conditions that I have high design temperature, I shouldn't do the pneumatic leak test?

Thank's in advance

RE: Pneumatic Leak Test (when the design temperature is greater than the test temperature)

2
You wrote:
"So my question is: In work conditions that I have high design temperature, I shouldn't do the pneumatic leak test?"

My answer is NO!!!

prognosis: Lead or Lag

RE: Pneumatic Leak Test (when the design temperature is greater than the test temperature)

(OP)
Pennpiper

Thank's for answer. I kept the hydrostatic due to security. But in cases where hydrostatic is not possible, how we do?

RE: Pneumatic Leak Test (when the design temperature is greater than the test temperature)

Define why hydrotesting is not possible.

prognosis: Lead or Lag

RE: Pneumatic Leak Test (when the design temperature is greater than the test temperature)

2
One of the common questions MBA managers use to "test" the young, inexperienced engineering staff is the old pneumatic test question.

Please do not fall into this trap......

You should keep in mind that ALL PIPING INSTALLERS WOULD MUCH RATHER PNEUMATICALLY TEST THAN HYDROSTATICLY TEST ! !PNEUMATIC TESTING IS QUICKER, MORE SIMPLE AND CHEAPER FOR THE INSTALLER.

This is especially true if the PIPING INSTALLER HAS YOUR BOSS, THE MBA....ON HIS SIDE ASSIGNING ALL RESPONSIBILITY TO YOU ! !

Google "pneumatic testing" piping, vessels and "accidents"....... read the many articles, heed the advice

....use the image searches also !

This issue has been brought up many times on these fora...... have you searched for other threads on this topic ?

RE: Pneumatic Leak Test (when the design temperature is greater than the test temperature)

(OP)
Hello, MJCronin.
Thank's for your answer.
I hadn't searched for other threads on this topics. Is my first time on forum.
I will look for the same topics. Agree with you the boss always prefers the pneumatic test independent of the case, with us assigning all responsibility.

Pennpiper.
You're right, always is possible use hydrostatic test. The piping installer said me that the circuit of test is too big for use hydrostatic and will be more complicate do the test.

I kept the hydrostatic.
thank guys

RE: Pneumatic Leak Test (when the design temperature is greater than the test temperature)

Hydrostatic testing is always safer and should be done first if there are not good reasons to preclude it. Good reasons would include a process or associated equipment which is so water- or other nonhazardous liquid-sensitive that a liquid-filled test cannot be done without damage. A steam system would, in my opinion, very rarely qualify.

Hydrostatic testing is sometimes followed by gas leakage testing, where the hydrostatic test greatly reduces the risk of failure under the lower pressure pneumatic leak test.

We do routinely pneumatically test systems which are of very limited product of pressure times volume (the product being stored energy which might be released during a failure), and of a physical configuration that makes filling with water (and complete emptying afterward) very difficult. Complete filling is necessary to make a hydrostatic test safe AND sensitive.

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