Placement of RVs on Piping - fire case
Placement of RVs on Piping - fire case
(OP)
I am evaluating several dozen relief valves that are protecting piping. Per earlier posts I surmise that I must provide for fire protection of the piping per ASME. That being said, the actual location is of interest.
For example, several of the valves protect piping at railcar loading stations. The material is feed through elevated piping (~15 feet), which then drops down to nearly ground level. The valves are currently in the horizontal run of piping at the loading area.
Is there a code which dictates that the valves should be placed in the elevated piping? Or am I allowed to keep the valves in their current, lower, area?
For example, several of the valves protect piping at railcar loading stations. The material is feed through elevated piping (~15 feet), which then drops down to nearly ground level. The valves are currently in the horizontal run of piping at the loading area.
Is there a code which dictates that the valves should be placed in the elevated piping? Or am I allowed to keep the valves in their current, lower, area?





RE: Placement of RVs on Piping - fire case
That said, there are always special cases in which piping needs to be protected from overpressure due to fire, but those are the exceptions.
Speaking globally, the only mandatory requirement for fire protection is a US requirement (OSHA 1910.106) that applies to storage tanks (operating pressure < 15 psig) which contain liquids with a flash point of 200F or less. Otherwise, the user is responsible for assessing the all potential causes for overpressure, and using good risk management judgment in determining which scenario(s) to consider for the final sizing. For guidance, refer to API 521.
RE: Placement of RVs on Piping - fire case
Your comments indicate that one would use a less conservative approach for piping vs. equipment. Can you point me towards a specific code that I might apply? I certainly don't want to be overly conservative when it comes to the piping.
Thanks again for the feedback.
RE: Placement of RVs on Piping - fire case
Safety valves on piping are needed when there's a risk of overpressure from causes such as valve failure/misalignment. Piping in liquid services also need to be protected from thermal expansion, but in most cases that done by inherently safe design or by administrative procedures. There are certain liquid services (ex:cold services, heat-tracing) that justify a relief valve. There might be some large liquid line that justify a fire sized safety valve, but that is very uncommon.
There's certainly a risk of fire at a loading station for flammable liquids, and if that occurs the load lines need to be shut off so they don't feed the fire. I would focus attention on that rather than on installing fire-sized safety valves on the piping.
RE: Placement of RVs on Piping - fire case
are installed to protect hoses - not pipe.
RE: Placement of RVs on Piping - fire case
RE: Placement of RVs on Piping - fire case
The root questions are (1) Is RV protection required for a fire, and (2) for a straight thermal case, is a certified valve required? I have attached a couple of highlighted pages from B31.3 for reference. Section 301.2.2 pretty much indicates that RV protection is needed; however, a fire case is not listed in (b).
Section 322.6.3 states that the valves must be designed per Section VIII. However, note that UG-129 - U-136 are not included; these sections pertain to valve capacity certification and stamping.
On a separate note, API 520 mentions that vessels and piping are covered.
Bottom line on the fire issue is that I have left myself quite confused. And I am not sure if a certified valve is required, especially for thermal protection.
RE: Placement of RVs on Piping - fire case
Section 322.6.3(a) states "Pressure relieving devices required by 301.2.2 shall be in accordance with BPV Code, Section VIII, UG-125(c), UG-126 through UG-128, and UG-132 through UG-136, exluding UG-135(e) and UG-136(c).
Hope this helps.