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Posted By Todd Hallam
Our company has to carry out some hot works to remove steel work 2 mtrs from a gas/oil silo. My advice was to isolate the works via industrial fire blanket (help in locating that please!. Anyones thoughts? Of course permits, emergency procedures etc will be in place.
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Posted By garyh
Be very cautious!! Are you certain that hot work is the only way? Can you wait until the unit is shut down / empty etc?
I would advise ensuring that if possible no transfers to and from the unit take place during the work; think about vapours from vents etc. Competent person(s) to plan and manage this job. Have secure isolations and a robust SSOW, written RA etc.
Check the atmosphere before / during work.
Have standby man and emergency plan.
Fire blankets can be obtained from well known suppliers - try the company which supplies your fire extinguishers etc?
Overall - don't underestimate the potential here; this can be done, but you need to be thorough.
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Posted By jom
Todd.
Have you seen the US Chemical Safety Board's latest safety DVD? Has a couple of tracks on fatal accidents arising from hot work on tanks. Being "empty" doesn't seem to guarantee no chance of explosion.
I wonder if, after confined spaces fatalities, hot work on tanks or drums accounts for more deaths in the chemical industries than any other kind of accident. Anyone know?
John.
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Posted By Crim
Todd, my advice is don't!
2 metres is far too close and unless you can guarantee the tank/s are completely purged of flammable vapours you are at risk of an ignition which could result in an explosion.
There must be a cold cut method available as an alternative?
Other advice is to contact your insurers to see what they say and also the local fire safety dept.
If in doubt just don't!
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Posted By artisdeeian
Hi Todd.
I agree with these guys, your risk assessment would have already picked up on the risk of fire/explosion, the Hazard effects, who would be affected should such a catastrofy occur, i.e is the silo near buildings, houses etc, members of the public. there are too many negatives with this one. I agree you would have to consider emptying and purging the silo, making sure it is well and truely vented. Or again cold cutting process. I would certainly not be rushed through with this one. Advice is there from the local authorities, my 'Advice' if in doubt ASK!
Ian.
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Posted By jom
What actually falls into the category of cold work?
Bolt cutters, hydraulic cutters, hacksaws?
Can every job be done without flames or sparks?
John.
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Posted By Ghaam
What type of cutting where you intending.
also have you have the area assessed for explosive atmospheres and has a the area been give a zone classification.
Are vent stacks install and where are they in relation to the desired work area are there any tank connetions again where are they located (should be more than 4m from the hot work area)
this work can be done safely. You could consult with the energy institute who have produced many excellent publications for carrying out this type of work
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Posted By Crim
Jam, you are on the right track. Cold cutting would involve saws, hydraulic cutters etc. Even angle grinders should be classed as Hot as they create sparks.
In a potentially flammable environment any electrical tools should be double insulated so a to prevent sparking within the casing from getting out.
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Posted By Garry Homer
Double insulated electrical tools should not be used in an explosive atmosphere. This class 2 rating is for preventing electrical shock it does not imply it has any gas or liquid rating.
There is nothing to stop gasses being ignited via the necessary cooling vents in the case of any drill etc.
Garry
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Posted By Robert.
Why not just simply contact the local petroleum officer
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Posted By Phil
you could always cold cut the steel using high pressure water as we did on a contract recently. Quite expensive though!
A cheaper way would be to empty the tanks, degas them and fill them with nitrogen or other inert gas. Hot works wouldnt be a problem then.
Phil
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Posted By jom
Interesting how, in trying to avoid on hazard, new ones are introduced.
Hydraulic tools involve high pressure oil - that's a hazard.
High pressure water blasts can be nasty.
Nitrogen blanketting? I know of one petroleum engineer who said that, of all the hazards in a refinery, nitrogen scared him the most.
John.
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Posted By Crim
Garry Homer,
Thanks for correcting me.
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Posted By Phil
Jom,
I wasnt refering to nitrogen blanketing, merely filling the vessel with nitrogen at atmospheric pressure so that no combustion can exist. I hear what he is saying though.
I think its inevitable that by introducing control measures to reduce risks we introduce new ones. I suppose if the new risk is easier to manage and less onerous than the original risk,we are on our way
Phil
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Posted By jom
Phil,
Would it be possible to achieve a non-explosive atmosphere by using a water spray rather than nitrogen?
What about that fine water mist that is described as a "pseudo gas"? It is been touted as a firefighting tool.
John.
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Posted By Jay Joshi
The information you have provided is inadequate.
It is extremely difficult to provide comments on such matters without having full details of the situation as there is no doubt that as a minimum, a permit to work is essential.
In the heading you state fuel tank, but refer to it as a gas/oil "silo".
You also state that you are want to carry out hot work near the tank, but NOT on the tank or its associated piping
A silo generally stores solids.
The first factor is what is the flammability and explosivity of the contents of the tank and the nearby area. It does make a huge difference if it is an "oil" or an explosive/highly flammable gas. (oil vapours can form explosive atmospheres if heated!)
As others have stated, if it is already a "zoned" area, then there will be prescriptive limitations due to the zoning parameters, if you want to carry out the work when other nearby vessels/equpiment are filled. On the other hand there can be other options if it is not a zoned area.
Secondly, what is the containment of the equipment and the level of positive isolation of the Silo/tamk you can achieve.The preference should always be to empty out and purge. However, if the vessel can be positively isolated by means of blanks so that you can ensure that there will be no leakage from the vessel AND carry out an explosivity test of the atmosphere to confirm its status as non explosive, you may be able to do the hot work and as long as you do not heat up the actual tank(this could be acheived by localised cooling) and prevent the sparks from straying into other areas .
It appears that you should get advice from a competent person who has all the details otherwise we are simply commenting on the basis of extremely limited information.
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