Steam Injection Heater
Steam Injection Heater
(OP)
I am installing an EZHeater, which is a steam injection device, to generated tempered water. This is similar to a Pick heater, with which you may be familar. I will be using 250 psig steam, and the heater will be designed for 300 psig. The upstream steam is limited to under 300 psig. I considered installing a curtesy RV in the line, but this seems like a waste. Any thoughts would be welcome.
RE: Steam Injection Heater
Consider the possible need for a sound enclosure ...
MJCronin
Sr. Process Engineer
RE: Steam Injection Heater
You also state a (maximum?) pressure of 300 PSIG and that the upstream pressure is 'limited to under 300 PSIG' - but how much under? What is the maximum pressure that can be generated against all possible causes?
Per ISO-4126, only the term Safety Valve is used regardless of application or design.
RE: Steam Injection Heater
RE: Steam Injection Heater
Per ISO-4126, only the term Safety Valve is used regardless of application or design.
RE: Steam Injection Heater
If it's designed per ASME Sec VIII, why isn't relief protection required for this item? It's true that we can't ordinarily choose to forego relief protection for Sec VIII equipment - Sec VIII design/construction means that the item must be protected from overpressure according to the requirement in that code. However, the opening section in ASME Sec VIII (U-1 Scope) explains specific cases which are exempted from the scope of Sec VIII. Refer to U-1(c). The item we're discussing is one such case which can be exempted from Sec VIII scope (exempted from Sec VIII requirements). U-1(c)(2)(e) states that piping components (e.g strainers, mixers) which are generally recognized as a piping component or accessory, can be exempted. It's reasonable to say that this steam/water mixer fits that exemption. And, BTW, this is separate from UG-140. UG-140 only applies when omitting PRDs from vessels that are not exempted in U-1(c).
RE: Steam Injection Heater
don1980, a bag filter is basically a coarse strainer with a nylon sock (filter bag) in it. The standard single and double length basket filters are fabricated from 8" pipe; therefore it does not qualify for the 6" ID exemption, U-1(c)(2)(i). We view these bag filters as more "pipe-ular" than "vessel-ular", but this gets challenged once in a while. Does this specific case seem reasonable for exemption under U-1(c)(2)(e) to you?
Obturator, ditto?
A fact that is favorable for not having a PSV on these bag filters, is our products are white, sticky stuff that dries readily, thus any relief device will become plugged and useless in short order without a superhuman effort to keep it clean.
Good Luck,
Latexman
RE: Steam Injection Heater
RE: Steam Injection Heater
Per ISO-4126, only the term Safety Valve is used regardless of application or design.
RE: Steam Injection Heater
Oh, we almost always put the filter in the suction side of an AOD pump to limit the dP across the bag, because in some soft particle (low Tg) products the large particles can be extruded through the filter media at high dP.
Good Luck,
Latexman
RE: Steam Injection Heater
If a relief device is omitted from a bag filter, then I think you should apply UG140, and generate the documentation for that.
RE: Steam Injection Heater
Often the filter housings are provided and stamped with a UM stamp. To me, that seems a clear indication that the filter housings are NOT piping items. In that case, it is generally a good idea to prevent any over-pressure from occurring per UG-140, especially when considering, as you noted, neither a rupture disc nor relief valve work particularly well in such an application.
Bill3752,
If your steam pressure is truly limited by an upstream PSV, then you won't have to size for an over-pressure event. This may, or may not, mean you can eliminate any PSV on the heater - you likely will still have a "blocked inlet/outlet" thermal expansion case. It does mean, however, you can likely reduce the PSV size.
If you truly have no over-pressure case, I would not install a "courtesy" valve. It would be additional time, expense, and PMs. If you do not install a pressure relieving device, make darn sure you are thorough and document all scenarios evaluated.
RE: Steam Injection Heater
Good Luck,
Latexman