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Storing Flammables


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#1 Guest_fred_*

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Posted 10 March 2004 - 08:02 AM

Dear Sirs/Ladies

Am looking at designing atmospheric storage tank for flammable solvents. So far have liquid overflow into bund, (discharge has liquid seal), process vent to condenser to knock out VOCs, and an emergency vent/vac device. Please can someone comment on the venting/overflows required, and suggest a strategy for flame arrestors - if needed.

Thank you.

#2 Art Montemayor

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Posted 10 March 2004 - 11:41 AM

Fred:

You have a serious situation that shouldn't be tolerated.

I have prepared Excel Workbooks that guide you in the calculations and documentation of pressure/vacuum relief for API storage tanks and similar vessels. I designed this method for the purpose of following the prescribed procedure in OSHA' PSM ruling. If you have interest in learning how to design and protect your tank system, let me know and I'll share all this information with you. You should not have to re-invent the wheel. This technology has been around for some time and works. All you have to do is ask the people that have done it - as you have, in this case - and you will find the answers.

You can contact me through this Forum.

#3 Guest_Fred_*

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Posted 11 March 2004 - 11:41 AM

Mr Montemayor

Thank you for your comments. I am an engineer at a small firm trying to learn and find best practice as you mentioned. So far I have looked through a few books and some of the Protectoseal information available on the web. Alas I haven't seen any "ideal" installations that I can replicate - as put in place by top companies. I can be contacted at fred123711@hotmail.com

#4 Guest_fred_*

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Posted 15 March 2004 - 07:07 PM

Although it must be safer to nitrogen blanket storage tanks containing solvents, I have seen solvent tanks both with N2 blanketing, and those which vent solely to atmosphere. To complicate things further, I have also seen solvent based processes where the process vessels are blanketed, and those which again have no such blanketing. I am fairly confident that vessels are not designed to withstand pressure increase from fire/explosion in the case with no blanketing.

How can this be, and what allows (perhaps not he best word) for the case of no blanketing.

#5 Art Montemayor

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Posted 15 March 2004 - 08:03 PM

fred:

It is scientific and engineering fact: it is much safer to use Nitrogen Blanketing on flammable Solvent Storage tanks.

In my experience, there are only three (3) reasons why an owner would not employ Nitrogen Blanketing on flammable solvent Storage tanks:

1) The owner is cheap, or selfish and un-caring about the safety and welfare of the employees;

2) The existing storage tanks are too old, cheaply fabricated, or simply not capable of withstanding the 5+" of Water Column pressure needed to apply an effective Nitrogen blanket; or,

3) The owner is ignorant of what maximum pressure his tanks are capable of safely working under, of what is going on, of the losses of his solvent, of the jeopardies and hazards to his investment , and of the danger to his employees. For whatever reason, ignorance keeps the tanks or vessels venting to the atmosphere without any engineered blanket system. In fact, the ignorance may spread all the way to the neighbors and/or the local governing bodies and regulatory environmental agencies.

I have found two sure and certain ways to ensure that Nitrogen blanketing is done on flammable solvent tanks:

1) Educate the owner of the insurance costs and implications in not blanketing; also included here are the vent losses and operating hazards introduced.

2) Educate the local regulatory agencies of the flammable venting going on. This is drastic action - but if we are talking about the safety and welfare of human personnel, I have done it in the past.

I seriously believe that as professional engineers we all have a legal, ethical and, more importantly, a MORAL obligation to protect those people who we train and depend on for working under us. No one on this earth can be paid enough money to place his life and health in jeopardy everyday in order to earn a living. Some solvents like Methanol, Acetone, THF, and others that are carcinogens are serious business and shouldn't be taken lightly as merely a waste of money going out to atmosphere. The explosion, fire, and health hazards introduced by these compounds are our responsibility as plant leaders and if we don't do something about it, no one else will.

Art Montemayor
Spring, TX




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