Non-ASME relief valve on code-stamped vessel 4

[barnesed]

Section VIII, U-1 states:

"the following classes of vessels are not included in the scope of this Division..."

"(h) vessels having an internal or external operating pressure (see 3-2) not exceeding 15 psi (103 kPa) with no limitation on size [see UG-28(f)]"

For a code stamped vessel with a design pressure of 50 psig and an operating pressure < 5 psig, can a non-code, properly sized (for all scenarios) relief valve set at < 15 psig be used?

Or, because it is a code stamped vessel, must a coded relief valve (which would have a set pressure > 15 psig) be used?

 

[pleckner]

I've always interpreted this part of ASME as saying that if I stamp it, it then falls within scope. Thus, I need a certified relief device. I have most of the interpretations and have seen no mention that woiuld invalidate my interpretation. So, unless your local municipality allows otherwise, you will need to install a coded valve.

If this is a gas/vapor PSV, then it would be beneficial to have the set pressure as high as possible so that it will be as small as possible (and cheaper).

 

[Ashereng]

I interpret the requirement also similarly.

If the pressure vessel is stamped, then it is subject to the code under which it is stamped.

In you case, your vessel is designed to 50 psi, obviously above 15 psi, therefore, you need a coded relief valve.

In general, for me, the operating pressure is immaterial in my mind. What is important is the rated pressure of the vessel. This way, I am sure to protect the vessel regardless of how it is used.

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[JimCasey]

Well there IS the consideration that you can't buy a code-stamped valve set for less than 15 psig. ...Because the code does not apply at less than 15 psi, as you pointed out.

Suggestion: Buy your low-pressure relief valve, and set a code-stamped 50 psi rupture disc on the pressure vessel. You're protected from your expected pressure. You're protected from operpressures great enough to harm the vessel, AND you're pretected from ( ecch ) lawyers.

 

[gene2007]

I asked the ASME B&PV Code Committee a similar question a few years ago. My question was as follows:

Re: ASME Section VIII Division I Boiler and Pressure Vessel Code Paragraph U1(c)2(h). Can a vessel that could be excluded from the scope of the Division because it operates at pressures less than 15 psig, but bears the Code Ustamp only because of owner requirements, be protected from overpressure with low-pressure relief devices other than those bearing either the UD or UV stamp such as spring-loaded or weighted-pallet type devices, or, an “open-to-atmosphere” vessel nozzle?

The ASME Code Committee response was as follows:
“Our understanding of the question in your inquiry and our reply is as follows:
Question: for a pressure vessel excluded from the Scope of Section VIII, Division I by the requirements in U-1(c)(2)(h), but that is constructed to the requirements of the Code including the application of the U Code symbol stamp, is it mandatory that such a pressure vessel be protected from overpressure by a UV or UD Code stamped safety relief device?

Reply: Yes."

So, you see from the Code interpretation, that once you place the ASME stamp on the vessel, you must follow all of the rules, including outfitting the vessel with an ASME Code certified relief device.

 

[pleckner]

For reference, I believe @gene2007's question and the committee's answer is in the Interpretations, VIII-1-98-112, Issued March 22,2000.

 

[moltenmetal]

Wow: that interpretation makes absolutely no sense. I'm shocked that ASME would take such a point of view. That's one ASME interpretation that I will recommend that vendors take exception to!

Design pressure, relief pressure and operating pressure are distinct from one another. It is by virtue of the relief pressure, NOT the design pressure, that a vessel is distinguished from a non-vessel! And "vessels", regardless of their design pressure, which are relieved below 15 psig by a means of relief device sized properly for the applicable relief cases, are no longer "pressure vessels" in Code terms.

 

[pleckner]

@moltenmetal, just what exactly would you recommend vendors take exception to? Are you recommending that the vendor disreagard the customer's request to stamp a vessel for a higher pressure than what it is to be used at?

The only thing we are saying is that, left by itself, if the vessel would normally not fall within ASME Section VIII, Div. 1 scope but you have the vessel STAMPED at a design pressure greater than 15 psig anyways (for whatever reason you might have), it must then be provided with an ASME certified relief device.

 

[dcasto]

Seems that as owner operator you could ignor the stamp and just do as you wish with the vessel. You could always go back and use the vessel as you see fit later as long as you are the owner. As for putting a non code valve, it can't cost that much more than a code valve. Then if the maintenance on the relief valve is a issure, only test and inspect it every 5 or more years, again not that much money.

All the things I say here are predicated that the vessel is in private ownership and not located where the general public has access.

 

[Ashereng]

The ASME stamp on a vessel represents to everyone that the vessel follows the ASME code - all of the code. If engineers start recommending to follow one portion of the code, but not another, then the code really isn't a code anymore - like Captain Jack Sparrow said, "More like a guideline." If an ASME stamped vessel is used, then ASME code it is.

Nothing in ASME prevents you from using a non-stamped vessel. Perhaps this is a better solution to the OP?


While it is true that an owner can ignore ASME, and do as they wish, I think the question is why would you, as an engineer, recommend that they ignore portions of the ASME code? I think it is more prudent to say either follow the ASME code because it appplies, or do not follow the ASME code because it does not apply.



"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[pleckner]

Wait a minute. @dcasto, what you wrote implies (and @Ashereng appears to be agreeing) that if a vessel falls within ASME Section VIII, Div. 1 scope the owner does not have to have it Stamped if they so choose not to? I'm hoping that what I read above has just been worded incorrectly or is just a generality; or is this in Texas, which is only one of two U.S. states that stil doesn't "get it".

I can't believe any engineer with any conscience can favor an owner ignoring ASME code and do as they wish. This is exactly the type of thinking (and corporate culture) that got BP into the heap of trouble it is now in!!

And yes, I saw the disclaimer by @dcasto, "All the things I say here are predicated that the vessel is in private ownership and not located where the general public has access."

Sure, you can build non-coded vessels and use them; not an issue (the original OP is about building what would normally be a non-coded vessel but changing it into a coded vessel by having it Stamped). But blatently disregarding code requirements because you choose to? This is just reckless and very dangerous thinking.

 

[pipehead]

So, how did anyone surive at all before any code or standard, I mean we should all be dead eh? Codes fill in for so any non engineer has access to engineering. Anyoneone can get a pressure vessel today cheaper and easier because of standards or codes. I'll defend Texas as a state that must have the most pressure vessels than most countries and I don't read about people dieing there daily because they are not with the program.

I look at people who protect codes as if they the only thing in the world as protectionists. Should all vessel engineers only use COADE software and all others be outlawed, how about no software? I got on the enlighted list of people that understand what standards are really for when working with some Russian engineers. I thought that they had third world low life standards. The engineer pointed out that their piping standards created a more conservative wall thickness than the US and that it allowed greater flexibilty than what we use. What they really lacked was a standard door or light switch (all doors were custom made and there where 8 different sizes of light switches in every house). Standards make for easier access, interchangability and should be lower costs, but NOT ALWAYS a safer product.

As for BP, their last accident had nothing to do with vessels. Personally, I'll use the ASME standards where I am not familir with that portion of engineering (as my Texas PE requires me to and it the Right thing to do), but I'll defend anyone that desires to use any standard they wish to use.

 

[pleckner]

ASME is NOT a standard but LAW in all but two U.S. states (I still wonder what is taking those guys so long to get with the program?). I don't believe ASME is even classified as a standard in Texas; they leave that up to the API documents. Standards are there to help engineers interpret and apply the Codes (LAW) in a consistant fashion.

Before the Boiler and Pressure Codes, many people did not survive in many industries, that is why these Codes were developed in the first place. I ask you @pipehead, why OSHA? We didn't all die before they got involved either. If your father or grandfather survived, it was your fortunate luck. Other people weren't so lucky. Even one fatality due to NOT adopting the Codes is one too many.

The BP catastrophy was more due to a corporate culture than to the actual mechanism (and by the way, the fractionator involved is, or was, a vessel). Had the corporate culture been more in tune with process safety, the catastrophy would not have happened. Accidents can and do happen but it is the approach one takes and the way of thinking about process safety that can prevent many "unpreventable" accidents.

So even though the OP was about a vessel, this whole discussion almost boils down to a way of thinking, a "culture" if you will in terms of how to approach process safety.

 

[moltenmetal]

I apologize: where I said "vendors" in my post I meant "owners".

I guess I can understand why ASME would take the position that they do: you either take the entirety of their code or you take none of it. You can't continue to call it a code-stamped vessel suitable for registration as such if you choose not to use a code-stamped relief device to protect it.

When a "vessel" is to be used for a service which permits it to be relieved at a pressure below 15 psig, what I recommend is what ASME recommends- to take NONE of their code because it simply need not be applied. That the vessel in question was originally designed and fabricated in accordance with ASME VIII does not prohibit its later use as an atmospheric storage tank, a tank with a pad pressure of 5 psig relieved with a non-ASME relief device at 14.9 psig, or as a garbage can if you cut off one of its heads.

 

[Armen75]

Does this mean that there are 2 options ?

OPTION 1 :
De-rate the tank and remove the ASME stamping and putting in a non-code relief valve set at < 15 psig

OPTION 2 :
Keep the tank's ASME coding and putting in a certified relief valve.
the question here would be,considering operation at 5 psig : what would the setting on the RV be, minimum at 15 psig or at the vessel design of 50 psig ?

 

[dcasto]

Visit this site and tell us again that ASME is an absolute law

http://www.codeprep.com/ed_nbic_vs_api.htm

 

[moltenmetal]

Armen75: you would be required, in order to stay out of ASME's domain, to set your relief valve at less than 15 psig, irrespective of the design pressure of your "vessel". Setting the relief valve at 50 psig renders the "vessel" a pressure vessel as defined by ASME.

 

[Ashereng]

pleckner,

Yes. An engineer may deviate from ASME codes, if in his/her expert opinion, a diviation is warranted. Deviations are not to be taken lightly, but they are allowed. Afterall, that is why we have licensed engineers - to determine what the best solution is.

By the way, I believe ASME is a standard/code/recommended practices/etc. The various laws in the 50 states reference ASME code/standard/recommended practices/etc. ASME is not a judicial branch of the US government last I checked.

Also, in many other jurisdictions, say Saudi Araia, ASME is also referenced. To say that ASME is a law in Saudi Arabia would be incorrect. To say that ASME is also referenced by Saudi law would be more correct.

Back to the OP. If your vessel is ASME stamped, then you should follow ASME - this reduces confusion, and increases consistency; which is also worthwhile.



"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[pleckner]

ASME is only absolute law if the municipality says it is. That's why there are still rouge states out there. They don't want to adopt ASME. Nothing stops a municipality from changing what ASME says and make that law instead.

@dcasto, I didn't see anything in that report on the site you reference that changes anything I've said.

From the OP, I don't see anything that tells us this vessel is "real" but it sounds more like a request for information.

If the vessel is already stamped, then just supply a code certified valve and be done with it as suggested by @dcasto in his first post.

 

[barnesed]

Wow! I have to say that I didn’t expect the response so far to my original question. I thank you all for taking the time to read the question and respond! It has been very enlightening.

I’ve been an Instrumentation/Automation Engineer now for over 30 years now and was originally schooled back then by some very knowledgeable, dedicated engineers who took safety very seriously. My belief has always been to use a coded relief device on a code stamped vessel, period. In all that time, I have never been asked to put a non-code relief device, even one set below 15 psig, on a coded vessel. So when this situation came about, I was surprised, yet curious. I like to think I am open to alternative points of view.

In this case, a customer has existing, small portable tanks (5 to 50 gal.) that are all code stamped between 95 and 128 psig. The customer wants these to pressure transfer the contents into another vessel using N2 via a regulator set <5 psig and expected that a small, cheap relief valve set <10 psig would be sufficient. The basis was that the application was excluded from the Scope of Section VIII, Division I by the requirements in U-1(c)(2)(h). I disagreed and stated that a coded relief device was required, but I was open to alternative views, thus my post on the forum. I believe that the Interpretations, VIII-1-98-112, Issued March 22, 2000 in response to gene2007’s question validates my response and that is what I was looking for. I can understand the argument that if a properly sized (for all scenarios) relief device set at 10 psig is provided, the vessel would be protected, however, I feel I would be doing a disservice and would be exposed to litigation if there was ever a problem, especially with prior knowledge of the Interpretations.

I’m still waiting for additional details from the customer, but aside from regulator failure, there are fire scenarios to consider as these vessels apparently can contain various solvents. I had expected to have a coded relief device set at the stamped pressures and would be willing to add the cheap relief set at 10 psig for the regulator if insisted. I’ll reserve final judgment after all details are known.