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?
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
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
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
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
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????