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  #1  
Old 03-16-05, 04:04 PM
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Sulfuric acid tank

I work for a company that has a 5,000 gallon tank that has had sulfuric acid in it. The tank has started to leak and the company wants the tank removed. The tank has had soda ash put in it along with water to try and get the PH level back to seven. When the water and soda ash was put in the tank the chemical reaction ate some holes in the tank at the water line. There is some pretty nasty looking stuff lying around the bottom of the tank on the floor. The tank is in a location where it can not be removed in one piece. This tank is also inside where there is not too much room to get around it. It looks like this will be my job to cut apart this tank in pieces small enough so it can be removed. I am somewhat concerned about what kind of fumes that will be given off when this tank is being cut up. I am guessing but i think this tank is 3/8" thick. Does anyone have any suggestions about this or has anyone ever done this before? It does not look like a very nice job.
 

Last edited by Jerome; 03-16-05 at 04:09 PM. Reason: wrong title
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Old 03-16-05, 10:02 PM
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Maybe a bit more information

I am assuming 3/8" steel for the tank. Does/did it have a liner or other protective coating as well?

It's a close quarters situation. What secondary issues would arise if dismantling the tank a) exploded, b) caught fire or c) flung acid or soda ash on the surrounding structures?

Is it next to an outside wall of the building? What are the dimensions of the tank and what is it sitting on?

Never having attacked such a problem I would suggest:
1. Consider filling it with some type of non-flammable foam before cutting it.
2. Secure/support the tank walls such that they remain in place even after being cut free. Containment is the idea. Don't let it come apart until all the cutting is done.
3. How about a saw cut with water cooling and wastewater collection to minimize heat and sparks? Even better a pneumatic saw with a water mist over the area to continually wash the bad stuff out of the air.
 
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Old 03-17-05, 04:39 AM
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Doesn't sound like fun.

I hope that your employer can provide supplied air breathing equipment for those involved in the dismantling. You would be a fool to attempt this kind of project without it.

What is the specific nature of that "nasty stuff" on the floor? You will be in contact with it, so you had better get an MSDS on it.

Has there EVER been anything else in the tank that could leave a reisdue?

What happens if the tank is thicker?

How will the pieces be carted off? Something to ponder if there is limited access for people, much less equipment. The work may fit OSHA definitions for confined space.

What kind of piping is around the tank? What is in those pipes? What happens if those pipes get damaged by rough handling or welding slag?

I hope you have expeience in this kind of work, your life safety is at risk if you do not. You should be more concerned that your employer might be trying to save a buck by not having the proper protections in place for this dismantling, especially if it really is beyond the scope of current employees and equipment on site, and if it should be classified as a hazmat situation and contracted out.

Lots of luck.
 
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Old 03-17-05, 05:53 AM
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Jerome,

I agree that lots of planning has to go into this.
The msds sheets will have info on the individual hazardous components but someone experienced in working in this type of demolition should be doing it.

If you have any concerns whatsoever I would suggest you call a health and safety inspector, anonymously if necessary.
 
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Old 03-17-05, 07:37 AM
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Where is it going?

This project appears to be WAY beyond a plant maintenance operation. Somehow this container of nasty stuff must be safely removed. Then there are two other considerations:

Cut-up nasty tank produces disposal issues for the nasty pieces.

Residue surrounding the former location of the nasty tank must be removed. The building and its surrounding area must be brought back to a safe working condition.

The disposal issues could easily outweigh the demolition issues. Just because it's no longer on the property does not remove liability.
 
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Old 03-17-05, 12:59 PM
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I've used sulfer powder on ag fields and let me tell you just having a little in the air caused my eyes to water up so bad I couldn't see. Sulfer is very potent in minut quantitys. I would research this with your local government official hazerdous materials guys. Good luck.
 
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Old 03-17-05, 06:36 PM
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Sulfuric Acid Tank

Thanks guys, This tank is roughly six feet in diamenter and maybe twenty five feet long, could be a little longer. It is shaped like a presure vessel. It sits on two strap looking legs about five feet in from the ends. The nasty looking stuff that is on the floor around the tank is something that might look like the stuff that is built up on the cables on a neglected car battery. Only lots more of it. This tank has always held sulfuric acid until it started to leak,nothing else. They are thinking about washing the tank out and sending the soda ash and whatever else is in the tank down to our waste water treatment plant to dispose of anything that might be left in the tank. They were going to have a man go into the tank after one-half of end had been removed and have him scoop out the crud that is still in it. That would be a real nasty job. There is piping around the tank, it is not in the way of cutting this tank out. One of the pipes happens to be a sprinkler line. So if the tank blows up and kills us all at least the fire will be suppresed. The pieces will have to be cut small enough to be carried by a couple of men. There is also a moat around this tank about two feet high. to hamper the removal. A saw might work to cut this up but I feel it would take forever. I have thought about using our new plasma cutter instead of the torch. It will cut 3/4'' steel and still make sparks only not as many of them. I am still concerned about the vapors that will be given off when it is being cut up. Maybe if a fan or two are blowing at our backs any vapors will be blown away from us. I am not sure if we have a device that will detect explosive vapors, so that could be checked out before we start. We do have a device that will check a confined space to see if it is safe for you to be in the space. If it is not safe for you to be in the confined space does that mean it is explosive? Maybe if I stalled long enough the tank could be still there when I retire. If you guys have any more suggestions throw them at me. I have been cutting and welding since 1965 so I am not too green at it, I just have not had anything like this before. Thanks again guys
 
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Old 03-17-05, 07:15 PM
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Jerome,

I have only one thing to offer and that is call your health and safety official about this.

Someone could die!
 
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Old 03-18-05, 04:49 AM
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Fans blowing behind you may help, but the concentrations of hazardous material will be so high that a supplied air respirator is the only way to go. You will be breathing metallic fumes embedded with toxics, so if a fan is ok by you.....

A big fan will also spread the bad air throughout the plant.

The biggest concerns regarding confined space work are oxygen displacement or deprivation (in addition to an explosive atmosphere). Again, a fan might help, but in the end you are simply recirculating bad air. There is no way a fan will help the person that will go inside that tank, scraping crud after 1/2 of an end is removed (from your description). If that person doesn't come out after being overwhelmed by toxics, how fast can you get him? Will you make it out while dragging him out?

Some normally non-hazardous dusts and mists become hazardous in high concentrations. That is what you are dealing with here. I do not know if your situation will become hazardous in the explosive sense, but you had better find someone that does know.

At the very least, high concentrations of any acidic vapors will erode your breathing passages from the inside out. Might not kill you, but long term extreme damage is likely based on long term close exposure to high concentrations of sulfuric acid during dismantling, clean up and disposal. At the end of the job, without proper breathing equipment, you could have serious long term health and quality of life issues. Not hard to reason if your lungs, nasal passages and trachea are eaten away by acidic vapors. Your employer will probably fire you if your health problems prevent you from doing the job, so no more health benefits, leaving you holding the bag.

Kind of a raw deal for you because the boss saved so much money by providing those fans.

Update the will and read up on the long term disability insurance provided by your employer.
 
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Old 03-18-05, 09:46 AM
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Get outside bids

For this type of job, it would be worthwhile to AT LEAST get outside contractors to bid on the work. Minimum 3 bids, including sufficient detail to assure everyone that no corners are being cut.
Price out the work as it would cost internally as well.

This is all about money. When those bids arrive with budget-busting quotes, you will know what to do. If the bids come in only moderately more than the internal bid, you may learn how to do it more safely with internal labor.

The health and environmental hazards are sufficient to take a second look.
 
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Old 03-18-05, 07:15 PM
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Sulfuric Acid Tank

Today I voiced a concern about hydrogen gas being formed from the sulfuric acid. A sniffer was lowered into the tank to test the air. It's pretty hard to believe what the sniffer results were. No flameable vapors, 21 percent oxygen level, and no CO2 present. To test the sniffer I turned over a 5 gallon bucket and let it hang over the weld table about 6 inches, put the sniffer on top of the table inside the bucket. Took the acetylene torch and opened the acetylene valve and placed the torch inside the bucket, the sniffer went crazy. So at least the flameable vapor part of the sniffer works. You can smell acid fumes at about 10 feet away from this tank, so I am sure thoes fumes will not do you any good. One of their plans now is to install a drag out tube to the top of the tank to suck away the fumes while we are cutting this tank apart. There is still more discussion to be done on this job before it will be started. There has to be a couple of people deem this job safe before it can be started. I was told today that this tank did not leak, they had someone come in and do a ultra sound on the tank to see how thick the tank walls were. Their report was that the bottom one third was a lot thinner than the rest of the tank. So a new lined tank was installed outside and the old tank should be removed. The old tank took a turn for the worse when water was added to to the soda ash that was dumped in the tank. The tank must have had some acid in it ,or else there was enough residue in the tank to cause the reaction that ate the holes through the tank. Sulfuric acid alone is not too corrosive to steel, when you add water then you get a big corrosive reaction to steel. On the new tank there in something added that will take humidy out of the air that is in the tank. That will prevent this from happening again. There are more people than myself that will be involved in this job, they don't like it any more than I do, one person likes it a whole lot less and he is the main managers pet. I need to find out what the long term affect of breathing the sulfuric acid fumes will do to someone. It can't be any good. Thanks guys
 
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