1. SAFETY AND PROCEEDURES
WELDING
SAFETY AND PROCEEDURES

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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)

12. 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)

13. 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)