ASME Code and Pressure Relief Devices

[JAGLA]

My Question is this:
Is there a rule or reference in The ASME code that states when an ASME stamped vessel (Such as a tank or heat exchanger) has to have a pressure relief device installed on it? No matter what is up or down stream of the vessel. I have a steam pressure reducing station with a pressure relief valve after the reducing valves. It then feeds a heat exchanger. A large heat exchanger, more than 25 cu ft in steam volume. There is a question of should there be a pressure relief valve on the exchanger. There is a pressure relief valve on the tube side of the exhanger. Thanks for any help.

JMP

 

[pleckner]

Reference ASME Section VIII, Div. 1, Paragraph UG-135 Installation.

The PSV does NOT have to be on the vessel itself. There are restrictions on the installation so you should read parapraph UG-135 and understand it. However, these restrictions only refer to things such as valving and line and fitting sizes. Again, in your particular circumstance, there is no reason you can't have the PSV on the line to the exchanger.

 

[davefitz]

While the Code specifies a relief valve shall be in communication with every pressure vessel, that does not by itself ensure protection against overpressure. Often we will see pressure vessels shipped with token "whistles" that may qualify as relief valves, but they often were not provided with any reference to the system's casualty flowrate.

The piping system's designer is responsible for ensuring the pressure vessels are adequately protected against overpressure as required by the relevant codes, after reviewing control valve casualty flows, fire overheat issues, chemical reactions, etc.

 

[deanc]

See Sec VIII Div1 Appendix M

 

[chaulklate]

Also refer to UG-125(g)(1) & (2).

 

[jte]

Good stuff above.

See also local jurisdictional requirements. Simply following VIII does not ensure that you aren't violating state or local law.

jt

 

[JAlton]

Also refer to NBIC Appendix G, Safety Relief Valves on Low Pressure Side of Steam Pressure Reducing Valves. The Safety Relief Valve downstrema of the Pressure Reducing Valve is there to Protect the Vessel (Shell Side) Should the Pressure Reducing Valve fail open. If the Safety Releif Valve is sized properly, it will prevent the failure of the Pressure Reducing Valve in the open position from allowing the upstream pressure to damage the Vessel. The size of the vessel is not the significant issue. The maximum flow through the Pressure Reducing Valve in the open position based on the upstream pressure & volume is the determining factor for the Safety Releif Valve capacity.

JAC