×
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

ASME B31.3 Monitoring pressure upset conditions

ASME B31.3 Monitoring pressure upset conditions

ASME B31.3 Monitoring pressure upset conditions

(OP)
Our Process deparment has asked a question regarding allowance for increased pressure.

In ASME B31.3 para. 302.2.4 it is described allowance for increased pressure rating (33% or 20%).
Increased pressure is allowed if the duration is within limits described by the Code.

Process is asking whether it is necessary to monitor these occasional events?
Does the code describe any logging/monitoring of pressure and duration?

I have looked in the Code for it but cannot find description of such demand.

Do you have any comment on this?

RE: ASME B31.3 Monitoring pressure upset conditions

You'r question is a little vauge, and i dont have a b31.3 book in front of me. However, I can say that normally when looking at working pressures in a line, you have to take into consideration what the material data sheets say the pipe can hold, what your maximum allowable working conditions are, what the design pressures are, working temps, design temps, Max temps, material types. Normally in a working boiler as long as you dont start violating any of your maxes or come close to the 80% marks you dont have to document anything because all those factors should be pre calculated into boiler.  Provided this is a once in a while deal. If your cosntanly hitting your 30% marks, you might look at redisigning your line, and moving the code boundery. If your violating your maxes, you should not only document it, but notify the AI imediatly.
Worse case senerio go to the b31.1 book in the 102.x.x + look at what they say there, then figure out the diffrences between the b31.1 and b31.3 you probably wont find much detail in the 31.3 section due to it being less critical piping, normaly open air vents and drains, which shouldnt see a whole lot of exstreams.  

RE: ASME B31.3 Monitoring pressure upset conditions

not in my field of expertise, but there were some pipeline failures recently related to short term overpressure events ( "water hammer") aggravated by apparent pipe damage by excavating equipment ( Olympic pipeline failure 2000). I believe there were new federal rules issued that go beyond ASME code rules for pipelines.

Normally overpressure is limited by the use of relief valves, but some pipeline systems allow alternate overpressure protection by use of pressure switches and fast acting stop valves ( must close within 1 sec) plus multiple independent press red valves in series, etc , etc. In an extraordinary event ( fire) some overpressure is allowed, but generally below the proof testing pressure used during hydrotest.

I think the pressure monitoring and recording  may be required for systems that are routed in the public domain( fuel pipelines), and these rules are separate from ASME.

RE: ASME B31.3 Monitoring pressure upset conditions

Tarkjell, one of our clients is doing exactly what you describe and have done this on a number of projects, but only on piping, not on vessels as far as I know. Reference is made to the same section of ASME B31.3 code

They do monitor and record an overpressure event to proof to the local AI or boilers branch that they are in compliance with the code. A PLC records the time duration and pressure when the design pressure of the pipe is exceeded. The system is shutdown when the pressure reaches the 33% overpressure mark.

High pressures only experienced in the first phase of the project and cost savings are the main reasons behind this option. From a personal standpoint of view I do not recommend designing a system so close to the upper limits, but code allows it.
 
I strongly recommend you check your local AI on this subject and see what they have to say. I second the viewpoints from Aurrous

RE: ASME B31.3 Monitoring pressure upset conditions

I truly hate it when process engineers read that section of the code.  I have had this request made a number of times, and I have only allowed the use of it once.  In this case, recording devices were installed to monitor pressure and temperature.  In any event, the refinery had to have a lot bigger problems than this section of pipe overpressuring for this upset condition to be reached.

That said, it may be an economical approach to follow when doing revamps to an existing system.

Please note that usually the process guys and the owners only seem to read Para 302.2.4(f) and do not read the rest of the conditions (a-i) that must be met before these excursions can be permitted.  Once they see the amount of work involved in applying this paragraph, most of the time a relief valve is installed.

Anyways, the requirement to record conditions will fall with your local inspector.  And if the local inspector did not require it, I would.  If a system has a relief valve set at 33% higher than the flange rating of the system, what would prevent the owner from operating continuously at 30% over the flange rating????

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