SAFETY AND PROCEEDURES WELDING SAFETY AND PROCEEDURES

OXY-ACETYLENE PROCESSES Acetylene is an unstable gas produced by immersing calcium carbide in water It is dissolved in acetone and store under pressures of 250 psi Cylinders contain a honey comb structure Cylinders have 2 safety plugs to prevent cylinders from heating up and exploding

0xy-acetylene Acetylene regulators and hose connections are left hand thread Working pressure should never exceed 15 psi Acetylene becomes extremely unstable at pressures above 15psi

Oxygen Cylinders Oxygen is stored at 2000 psi Cylinders have a burst disc, to protect against pressures exceeding normal pressures Oxygen regulators and hose fittings are right hand thread

Regulators and Gauges Device used to reduce pressure at which gas is delivered Working pressure will increase when turned clockwise Regulators usually have 2 gauges Cylinder pressure gauge and working pressure gauge

Hoses and Fittings Hoses are usually color coded Green identifies the oxygen line Red identifies the fuel line Hoses should be routinely inspected and replaced if leaking never try and repair! Fittings couple hose to regulators and torch Fittings are machined out of brass and are self lubricating never lubricate fittings

Backfire Happen when fuel ignites within the torch tip-----produces a popping or squealing noise Occurs when torch nozzle overheats Must extinguish torch and clean tip

Flashback Takes place when the flame travels backward in the torch to the mixing chamber Caused by low pressure settings and leaking hoses When a backfire or flashback is suspected close the cylinder valves starting with the fuel valve Flashback arresters are normally fitted at the torch connections

Torches and Tips After working pressures are set, open fuel valve and ignite tip, set acetylene burn to a clean burn (no soot) Open oxygen and set flame to desired flame When extinguishing the torch close the fuel valve first the oxygen valve

Adjusting the Oxy-acetylene Flame At point of ignition the flame will be yellow and producing black smoke Increase acetylene pressure using the torch valve At the point the smoke disappears the working pressure can be assumed to be correct

Setting a Neutral Flame Next turn on torch oxygen valve, this will cause the flame to become less luminous and an inner blue cone surrounded by a white plume will form at the tip. The white colored plume indicates excessive acetylene As more oxygen is added the white plume disappears and a more define blue cone appears Ideal setting for most welding operations Flame temperature approx. 5900F (3260C)

Oxidizing Flame After setting a neutral flame, the oxygen supply is increased the blue cone becomes smaller and sharper Oxidizing flame indicates excessive oxygen For most welding operations an oxidizing flame should be avoided Flame temperature approx.6300 F (3500C)

Carburizing Flame Indicated by a white plume surrounding a blue cone Should also be avoided for most welding operations Flame temperature is approx. 5300F-5800 degrees F (2927C-3205C)