I'm not aware of any OSHA requirements for two seals, but that could be the case...
I think that they may both be viable alternatives, and the question for my decision would be based in part also on the need to recal/certify/repair/replace the TE/TT without taking the process completely offline...
I would check with a valve vendor but I don't know that any of them would consider that 'acceptable' since the 15% dP may likely cause the PSV to chatter...I don't know that I'd use a conventioonal valve in that application.
Another vote for what zdas said. It's a complete PITA to get a lot of that info, and as an owner you'd think we'd have a lot more leverage on receiving it than an EPC firm may. It usually takes a lot of kicking and screaming on my part to get them to even think about site-specific scenarios...
I typically use 10-15%, depending on the size and quantity of piping. If it's an existing installation, I try to get a reasonable estimate of pipe from the vessel to the first isolation valve (fire case assumes that the vessel is blocked in).
Determine the max flow through your reducing valve based on the high side pressure (check with the vendor and get the full flow/fail wide open Cv values).
It's (still) there. Reading it right now. Check the A08...
UG-140 is the formalization of Code Case 2211 into the PV code. You don't get to just 'say' that you've got OP protection by design; there are a number of requirements you need to go through before you can claim it: process/system...
API 520/521 and ASME code technically wouldn't apply because you are working with piping rather than vessels. However, I've worked at places where similar situations can (and have) occurred. One thing to point out is that you aren't really talking about thermal expansion from a blocked in...
Is the 1,040 psi the MAWP or an operating pressure? Secttion I requires at least one valve to be set at the MAWP of the boiler and any subsequent valves to be set no higher than 3% of MAWP.
Depends on the system. UG-127(d) [part of A08] allows open flow paths or vents to be used as the sole pressure relieving device, or alternatively, the system may meet the requirements of UG-140 Overpressure Protection by Design (also part of the 2008 Addendum).
Yep. I'd either add a 'spillback' or recirc valve, or an interlock to shut down the pump [shut off would probably be my preferred option-why waste the pump energy if you don't have any 'real' work for it to do. There may be other process considerations, but that's what I'd work towards.]
For the actual sizing calcs you would need to re-validate the calculations based on the new relieving pressure, and then determine whether or not the orifice is adequate. For actual resetting (presuming the actual valve size is correct) then a VR or licensed valve shop would be able to reset...
Yeah, I agrree with Latexman. Nothing like that appears in Crane either; I would go back to the vendor and ask for some tech help. If these are the guys that supplied the PCV, and that's what they used to size the valve, then the source may not matter as much. If the valve came from another...
Sorry guys, missed the responses on this one...
CJK-to clarify, I'm not saying design for the actual fire temperature, but rather, the relieving conditions of the vaporizing liquid in the vessel during a fire case.
As far as increasing the risk...OK, so if you have someone that is going to...
I agree with greenche. I will typically include equipment above a solid elevated floor as a conservative measure, just because I know how well we (read don't)ensure that the strainers and caps on the floor drains are truly clean and free-draining. Also, I'll typically use 34,500 for the heat...
Ditto on the 50 foot for API "high hazard process areas." The only API 520/521 flame height I'm aware of is 25 ft above a surface that could conceivably contain a pool of flammable material (thus supporting a pool fire).
Bill,
If you are a subscriber at Che.com [or receive Chemical Engineering...
Are you looking for a pressure indicator [PI] (like a field gauge) or a transmitter [PT} (wired back to an indicator)?
We handle a lot of methanol, and honestly we don't do anything "special" with our gauges, whether it be a PT or a PI. Just check the materials of construction & temperature...
Sorry sheiko; forgot that you aren't in the US when I wrote that.
From my perspective (and everybody feel free to correct me) "directive" is used more in the EU, and I'm not sure exactly what it pertains to-whether it be law, recommended practice, etc.
In the US, technical bodies such as the...
My understanding (from discussions with API committee members) is that you are "allowed" to use either. The steam equation is a little more conservative-I tend to use it when I have a water storage tank or similar that would be vaporizing liquid. The API training class slide I have has the...
My thoughts:
1) "Is it a PV?" may largely be a jurisdictional issue. we have a number of vessels that we operate below 15 psi. For our particular jurisdiction, the operating condition determines the answer to "Is it a PV?" So, event though the vessels are designed and manufactured to ASME...
