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gvdlans
Does anyone know how to size a Vacuum/Relief valve on a storage tank? I looked into API Standard 2000 (appendix C), but that only says that "The size of a vent valve is based on the venting device's tank connection". API RP 520/521 only deal about Pressure Relief Valves...
Diederik Zwart
Normally sizing of low-pressure relief and vacuum relief valves is done by the relief-valve vendor. The process engineer specifies the required relief load (based on API2000) and from this the vendor calculates and selects a relief valve. In my experience, when requested, vendors are willing to show you their calculation method (especially if you buy their valve). I don't think there is one generic sizing method, because each vendor has its own valves, with vendor-specific flow-factors (K-values).

If you do come across a generic sizing method, please post it, because I would be interested as well.

Regards,
Diederik Zwart
gvdlans
Thank you, Diederik (or may I say dank je wel?)

After I posted my question I did some more searches on the web, and came across a PDF file from Tyco valves containing flow curves for their vacuum/relief valves. See Tyco Brochure.

This illustrates your answer that sizing of the valves is normally done by the valve vendor...
Art Montemayor
Guys:

For my benefit, let's define what "sizing" means. I define the sizing of a vacuum/pressure relief on a storage tank as the exercise an owner's process engineer has to do to arrive at the capacity of the required tank relief devices sought. This requires, of course, that the process engineer carefully and accurately detail out all the possible, credible relief scenarios surrounding the tanks and their operation. The worst case is the relief design case.

The process engineer should also, in my opinion, decide if he will handle normal pressure relief and emergency pressure relief separately - not the instrument supplier.

The instrument supplier "sizes" (mechanically designs and rates) his instruments in accordance with the required relief capacity specified by the owner's process engineer. The owner and his process engineer are the responsible parties for the relief capacity installed on the storage tanks -- never, never the instrument supplier.

At the risk of being redundant, let me say it another way: In the USA (& in Europe) the government's regulatory agency holds the owner totally responsible for determining the correct relief capacity that will prevent an accident or incident. The owner is subject to being inspected and is held legally liable for producing up-dated and accurate calculations determining the true design case for each relief device. I believe that I am correct in all the prior statements I have made in this regard. I hope that we are in agreement on this issue, because it is a very, very important point.

I have designed and produced an Excel Workbook that leads you through the proper and documented calculations for pressure and vacuum relief of storage tanks. If anyone is interested, let me know by emailing me with your name, location and interest. I will gladly share this information with anyone that qualifies.

Art Montemayor
Spring, TX
Diederik Zwart
Art,

I totally agree: What I meant by the term 'sizing' in my previous post is (only) the mechanical sizing by the valve vendor based on the relief loads calculated by the process engineer. I can see that there could be some misunderstanding, so thanks for your comments.

I would like to receive your excel workbook, so I'll e-mail my address etc. to you.

Regards,
Diederik Zwart
MB
Art,
My name is Michael Berger.
I am chemical engineer and I am working in Geothermal Power Station Industry (Ormat Company).
I live in Israel.
I would like to receive your excel workbook.
My E-MAIL is mberger@ormat.com
Thanks in advance
Michael
gvdlans
Art and Diederik, thank you for your replies.

I also agree with post from Art Montemayor. With the word "sizing" in my question I meant the determination of the required orifice size inside the relief device, which is of course based on the required capacity determined in earlier steps.
pleckner
Allow me to add my two cents worth here.

We, the Process Engineer size them, period. And Art gave the correct definition of sizing. I am amazed that there are engineers out there that still think the vendor sizes rupture disks, relief valves and even relief piping and all they think they need to do is supply the flow rate and some fluid properties.

I also pretty much tell the vendor what I want even mechanically after discussing the applications with them. They are a great source for this but the owner is still responsible, not the vendor. I bring this up a number of times in my series on Rupture Disks, which, by the way you can find on this site (I got my plug in).
gvdlans
The discussion seems to go down to a matter of definitions. Question is whether sizing includes determination of relief requirements or not. When I look at API RP 520, I see that there are separate subsections called "Determination of Relief Requirements" and "Sizing For Gas or Vapor Relief, etc.". So there is some ground for seeing it as different steps. Anyway, as I already explained, this was what I meant in my question.

Who is responsible for the exercise is a different issue. I don't think there is any doubt that the process engineer is responsible.
Art Montemayor
Guido:

I consider this such an important subject in the area of process design that I tried to emphasize the following (which I may have failed to do):

1. As Phil Leckner has inferred, the process engineer does The Design. What I have always understood (and what I believe Phil is saying) is that regardless of what is "out-sourced", sub-contracted, or done by others in the total system design -- the Owner and his process engineer are the responsible parties of record. I think we all understand and accept this basic, legal principle; let's go into the subject a little further.

2. The basis of a Pressure/Vacuum relief design scenario is composed of several factors, but basically the underlying need is one of total safety. Those factors affecting or canceling out the system's safety are the responsibility of the Owner/process engineer - as stated above. Therefore, if a correctly defined and identified worse case scenario for a storage tank is submitted to a conservation vent vendor as a capacity specification, this does not mean that the selected (or vendor-proposed) vent valve is the decision of the vendor. It is the Owner's responsibility to ensure that he has selected a reliable vendor that will furnish the vent that will, indeed, fulfill the capacity (& pressure drop) requirements at the conditions identified as the hazard scenario. How the Owner goes about in making damn sure that he is dealing with a reliable and credible supplier should be of concern to him and especially his process engineer.

3. In this example, all tank vent suppliers will furnish you with their free software programs that calculate the "correct" vent model and size. What the process engineer should concern himself with (& what I think you are concerned with) is that the vendor calculations should be correct, that the correct model is selected and that the correct vent installation is done on the tank. What I mean by the "correct" installation is that you're not done with your job until every detail that could go wrong is nullified or erased. You essentially start the process by identifying the worse-case scenario capacity required. Then you entrust the supply to an outside contractor to design and fabricate the required vent. You check his calculations, method, logic, and proof of capacity and pressure drop. You accept delivery of his product at your plant and subsequently go forward and install the apparatus. You also, if you're smart, have to document the critical details of what was calculated, "sized", purchased, and installed. If you fail to ensure that the correct orifice, model, etc. is truly installed and left to operate and, by bad luck or error, the wrong item is installed -- you are guilty of failing to meet the law's requirement for safety. What legal action occurs between you and your supplier does not affect the fact that the law holds you/the Owner responsible for the installation. This is basic Caveat Emptor.

4. The above, I think, is the thrust of Phil's statement. It is not enough to "trust" a supplier (as I know you are concerned); you have to "trust" your own organization to basically identify the worse-case design scenario and logically and correctly proceed to resolve the problem. The Owner and management (as well as everyone else in the plant) depends on your correct assessment and logic decisions. Needless to say, this is why they pay you the "big bucks".

5. Additional areas for thought are the capacity constraints in the vent inlet nozzle and the discharge nozzle/piping/header(s). Any and everything that can affect the correct safety situation must be addressed. This is another, but related, area of concern that many engineers either discount as "minor" or as un-necessary. You will note in the workbook that I sent you that even the method of cleaning certain tanks - such as steaming out - is studied as part of the vacuum scenario. And the credible potential situation must be addressed and resolved - such as the correct vent nozzle size for vacuum relief during a steam-out + rain shower. Process blow-through and steam heating coil rupture are just more scenarios that might affect you. All of this is the Owner's responsibility through the process engineer.

I don't think responsibility is another issue in this case. It's at the bottom of every action and step that is taken towards the final, safe solution. That is why I can relate to your concern in making sure that you understand and dominate the calculations done by your sub-contractors. You will have to defend them, should you accept them tacitly or not. This is why I believe I fully understand Phil's statement of dominating the process design and mechanical solution. You must interject yourself in the total process - or at least be in total control of what is happening. Otherwise, somebody else's interpretation of the solution will be installed and operated without your knowledge.

An American president, Harry Truman I believe, once put a sign on his desk that stated "The buck stops here!" - meaning that he was not going to let responsibility pass him by. I think the same sign rightfully belongs on every process engineer's desk.

I have not tried to get into Phil's brain and read his thoughts - nor much less try to speak for him. But I think this subject is so important that I anticipate and welcome his valued comments in the event I have mis-interpreted anything or have spoken out of line.

Art Montemayor
Spring, TX
gvdlans
To Art and Phil,

First of all, thank you for your efforts!

You answers seem to suggest that there is any disagreement from my side. There is not: Process engineer is responsible for determination of relief requirement and size of the relief device, period. I never suggested anyting else, so we can stop that "discussion".

If anything, there is some confusion on the word "sizing", whether it includes determination of relief requirement or not. Again, both API RP 520/521 and API Standard 2000 leave room for interpretation that "sizing" is a different step from "determination of relief requirement". I do not see anyting wrong or unsafe in that. If anyone feels that "sizing" also means "relief requirement determination" that's fine with me.
pleckner
To "gvdlns"

I did not mean any direct criticsm to you when I stated,

"I am amazed that there are engineers out there that still think the vendor sizes rupture disks, relief valves and even relief piping and all they think they need to do is supply the flow rate and some fluid properties."

I meant this as a general observation in my experiences so I apologize if it came across anyother way.

And, to all who read this, I don't care how you want to interpret the word "sizing" or "Determination of Relief Requirements" or how many steps you want to break it down, the owner is responsible, not the vendor.

To "Art".

You did just fine!
amarjeet
Art,

I am a chemical engineer working in an Engineering company for Oil & Fas Projects.
I would like to receive your excel workbook.
My E-MAIL is amarjeetkaur@dsme.co.kr
Thanks in advance

Amarjeet
David Shah
Art,

I am also a Chemical Engineer who would like your workbook.

Please send it to shah.david@syncrude.com

Thanks a lot.

David
Joseph
Art,

I am a chemical engineer working in a resin manufacturing company.
I would like to receive your excel workbook.
My E-MAIL is joseph.omabetow@siigroup.com
Thanks in advance

joseph
escape
Art,

I am a chemical engineer in the ethanol industry, where bulk ethanol fixed roof storage tanks need to be protected with inline flame arrestors and pressure cum vacuum relief valves.

I would appreciate receiving your excel workbook.
My E-MAIL is skonchady@chemengg.com

Thank you,

S. Konchady
Paul S.
Art,

I read your offer and am interested in your Excel workbook. I am a ChE currently working in an Intermediates plant.

My e-mail address is pesten@solutia.com

Thanks,

Paul
rxnarang
Art,

The spread sheet! Me too! smile.gif Thanks rxnarang@bechtel.com
Guest
DearArt,

I am a chemical engineer and have gone through the discussion over this plateform. I am interested to know more about the topic. I am in india and working for a fine chemical group. i am interested to have a copy which would be help us in gaining more.
i request you please send me a copy of this one on given below address

anneepch@rediffmail.com

-Annee
Kiran Parihar
Art,

I am a chemical engineer from India and working in Oil & Gas industry. I would like to know more about sizing of relief / vent. Any references or good book would be useful.

I would appreciate receiving your excel workbook.
My E-MAIL is kirangparihar@rediffmail.com

Thank you,

Kiran Parihar
joshofindia
Mr. Art,

I would like to get your excel workbook. If possible please email me at
amit.joshi@cdicorp.com

Amit Joshi.
Carlos Sanchez
Mr. Montemayor

I would like to get your excel workbook. If possible please email me at
borracheroc@intecsauhde.com

Carlos Borrachero
Art Montemayor
Carlos:

It will be my pleasure to email a "serious drinking man" a copy of my workbook. Be looking in your inbox.

Saludos
Art Montemayor
trilok_sontakke
Dear Art

Me too waiting for your valued spreadsheet.

Thanks
Trilok
Guest
Mr. Montemayor

I would like to get your excel workbook. If possible please email me at
chemengg00@yahoo.co.uk

Lucio Miranda
Sameer
Dear Mr. Montemayor

I am a Process Engineer working for an EPC company. I would like to get your excel workbook.
If possible please email me at

ssharma@ykh.chiyoda.co.jp

Thanks a lot

Sameer Sharma
Trefor
Hi Art,

Could I get a copy of your much sort after work book
my email address is tsymonds@jllennard.com.au
Cheers
Trefor
Jayadev.Devulapally
Mr Montemayor

Read the valuable discussion on the subject.I am a chemical engineer and will appreciate receiving a copy of your Excel spread sheet.My email address is devuj273@telus.net
Regards
Jayadev
Kirsten McFadin
Mr. Montemayor,

I am a chemical engineer working with various chemical plants in the southeastern U.S. I would like to receive a copy of your Excel spreadsheet. My e-mail address is kmcfadin@atslab.com. Thank you.

Kirsten McFadin
Zack Adam
Hi Mr. Montemayor;

I am Zulkernain Adam From Malaysia. You can call me Zul

I'm currently working as a Process Engineer with Petronas Carigali Sdn. Bhd. (PCSB), base in Malaysia.

I would appreciate if you can email the valuabe excell spreadsht to me also at zulkernain70@gmail.com or zulkernain_matadam@petronas.com.my

Regards
Zul
'Diran Babalola
I am a new member in this forum. I also need this Excel sheet on relief valve sizing. You can email it to me on diran.babalola@tri-ocean.com
hgjdesai
dea art,
pl. mail me ur valued worksheet. hiru@desai@rediffmail.com
thks
Guest_ALI
Hi Mr. Montemayor
I am a Chemical Engineer from Pakistan. I am very much interested in your Excel Sheet.
My email is smarty_1984@hotmail.com
I will wait for you reply. Thanks in advance
Umesh Sharma
Hi Mr. Montemayor
I am a Environmental Engineer from India. I am very much interested in your Excel Sheet.
My email is sheelforum@indiatimes.com
I will wait for you reply. Thanks in advance
rolleyes.gif rolleyes.gif
Eric
I know this is an old topic, but noticed people still requesting the spreadsheet from this year.

I am working on an oil sands upgrader and would appreciate the spreadsheet for reference purposes.

Please email to eric.lam@ameccolt.com. However, the moderator can be picky about what emails get through to that email address. If you have troubles, please email it to emhlam@hotmail.com.

Thanks!
Vladimir Karanovic
[quote name='Art Montemayor' date='Mar 23 2004, 10:37 PM' post='1355']
Guys:

Dear Art,

I am a chemical engineer from the UK, and I am very intersetd to have your spreadsheet for pressure/vacuum valves sizing.

Look forward to hearing from you.

e-mail: karanco@lineone.net


Regards,

Vladimir
James Kieffer
Art,

I am the Process Dept. Mgr. for a small engineering company, Hunt-Guillot & Associates, in Ruston, LA. I have a couple of chemical engineers validating sizing of pressure and vacuum relief for several storage tanks for a chemical company. We are also validating rupture disks and relief valves on reactors and other production vessels.

I believe your Excel Workbook would be very helpful. Please e-mail a copy to jkieffer@hga-llc.com. I greatly appreciate your offer and comments.

Thanks,
James Kieffer
Ruston, LA
Prem
I'm working on sulfur storage tank and would appreciate your worksheet for reference.

email me at: premsarda@gmail.com.

Thanks
Joan-Manel Claveria
...
suresh reddy asi
Dear Art,

I am a Chemical Engineering graduate from Texas A&M kingsville.

I was not aware of control valves. I always go through your replies. now i got some idea about control valves sizing.

I like your way of answering a question, starting from basics, which a student could understand.

I would appreciate if you could send me Pressure/Vacuum relief valve sizing Excel sheet.

E-mail: s_asireddy@yahoo.com

Thanks a lot

sureshreddy asi.
Anand Rao
Dear Art,

I am a chemical engineer and working with BS&B Safety Systems. I do the sizing (mechanical that is) day in and day out as a part of my job. I am overwhelmed by the response to your excel sheet and would be interested to have a look at it too...

My mail id is apr1@sanmargroup.com

Can you please send a copy to me.

Many thanks & Regards

Anand Rao
Jay Howard
Art,

I am a process engineer at Fluor and have just been asked about calculating vacuum relief for use with a deaerator. A copy of your Excel workbook would be a great help I think.

Thanks in advance for your help and workbook.

jay.howard@fluor.com
Daniel Gomes
Hello Art,

I'm a process engineer working at a small company in Brazil, could you please send me a copy your spreadsheet? It would be most helpful.

Thanks!

Daniel.
Daniel Gomes
Hello Art,

I'm a process engineer working at a small company in Brazil, could you please send me a copy your spreadsheet? It would be most helpful.

my email dgomes@rtsengenharia.com.br

Thanks!

Daniel.
Guest_Babu_*
Hi I would like to obtain the excel spread sheet. My email address is babuchemy@yahoo.com
regards
Babu
South Australia
asim_umer
I am a chemical engineering and studying for Postgraduate. Kindlly send me EXCEL BOOK.

Best Regards
Asim Umer
asim_umer@uetian.com
Adriaan
For steam vessels there is a quite simple rule; relief valves have to be dimensioned in such a way that the pressure with the relief valve(s) open cannot exceed a certain limit (normal pressure + 10 % or something like that).

I would presume that to determine the relief valve(s) size (be it for pressure or vacuum) you would take the most extreme scenario (for vacuum a half full hot tank in a sudden ice storm would be pretty extreme <wink>) and calculate the capacity needed to keep the pressure within acceptable limits?
Hardik Patel
Hey Art Montemayor

I m a chemical engineer and working in engineering firm and my job duties are designing of pressure/ vacuum relief valve (PVSV) on LP tanks. I m designing PVSV for last 8 monts and i would like to get your excel sheet and i know it might be useful for me.

My email address is Hardik@schmart.com or Hardy_ptl@yahoo.com

i would appriciate if you send me your excel sheet to this email address.

Hardik Patel
sudip chakrabarti
Mr. Montemayor

I would like to get your excel workbook. i will higly appreciate if you can email me at
sudip.kumar@sg.prosafe.com
beejay
Hello Art,

I will truly appreciate receiving your excell workbook. Please send to bmomah@hotmail.com
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