Document MM0MRGKxYjyed218nBbE1Zppa

42--Flammable and Combustible Liquids nection, a bieak in the bottom of the tank, sludge, sediment, or sidewall scale, or wood structures soaked with the liquid The in terior framing of floating tank loofs can tiap quantities of liquids that will iclease vapois Therefoie, periodic tests with a combustible gas indicator should be made during the woik Burning or cutting mav lelease lead fumes from paint on eithei the inner or outei suiface of the tank or from some othei source An approved mask lor piotection against lead may be necessaiy, 01 it may be advisable to exhaust the fumes Wood suppoits inside the tank should be piotectcd 01 icmoved be fore hot woik is begun Some companies use low-voltage tiansformers to eliminate the dangei of electuc shock, especially when men aie lequned to woik in wet areas All poitable electrical equipment should be grounded Cold woik in a tank may piesent a dust problem, and approved dust lespnators and goggles should be svoin if tests defimtels show that wealing of a hose mask is not neces sary Gas tests should be made fiequentlv if the presence of gas is suspected The concen tration of gas 01 vapoi in a tank or vessel mav mciease as woik progiesses, especially if the inside of the tank is sciaped or heated during the opeiation Foiced ventilation mav lie lequued in many cases wheie repair woik is to lie done inside a tank Wheie fumes develop fiom welding 01 othei lepair work, mechanical an moveis should be used or the woikmen should weai fiesh air hose masks On a laige tank, a door sheet or sheets mav be removed foi ventilation after the tank has been made gas fiee The open ing also can be used to expedite lemoval of sediment and to mciease illumination If a tank has been closed foi some time, theie mav be a deficiency of owgen due to rusting (oxidation) of the metal of the tank In that case, no one should cntci the tank without a supplied au mask 01, foi a lelativelv brief stay, a self-contained or self-generating breathing apparatus Cleaning aboveground tanks Here m step-by-step form is a summary of a typical proceduie for cleaning tanks that have contained flammable or combustible liquids 1 Remove all souices of ignition (matches, open flames, smoking, gas engines, weld ing, exposed electrical wiling and equip ment) Irom the vicinity of the tank 2 Empty the tank by pumping, draining, and floating tank contents with water The water should be intioduced through fixed tank connections 3 Disconnect and blank all product, steam smotheimg, foam, and similai lines Do not lely on valves 4 Open all manholes and allow the tank to an thoroughly Ventilate or steam the tank foi the numliei of hours lequued by its size If steam is used, cool and ventilate afteiwaid 5 Have available the lequired peisonal pro tective equipment hesh an hose masks, approved flashlights, safety belts and life lines, mbbei boots and gloves 6 If light is needed, use onlv flashlights or electuc lanterns approved foi combustible atmospheies bv Umleiwnteis' Laboratones Inc 7 Test for vapor content with a combustible gas indicatoi Foi entenng the tank befoie it becomes vapoi-fiee, sseai a fiesh air hose mask, air supply tanks, and safety lielt and lifeline, if the tank atmospheie contains moie than the maximum accept able concent!ation of sapor Have ample help available outside foi the numbei of men inside S If a stoiage tank has contained leaded gasoline subsequent to its last thorough cleaning, follow instiuctions of suppheis of tetiaethsl lead 9 Bond steam lines and water wash nozzles to the tank 10 Wash sludge sediment, and scale from the tank through the diain oi lemove it with a pump Flush out well and oveiflosv the tank with w ater if necessarv 11 Make a gas test and, if the tank is found 1316