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Oxyfuel gas welding and cutting safety

oxyfuel gas welding and cutting safety

Gas cutting is a combustion process. It is used to cut steel and other metals of different thickness. The work is carried out using a torch through which oxygen and a fuel gas (acetylene, propane or mains gas) are passed.

oxyfuel gas welding and cutting safety

Characteristics of Gases :

* Oxygen  has no smell, but whilst not inflammable itself, promotes and accentuates rapid combustion, Hence it can be highly dangerous, particularly in confined spaces, where it may not dissipate quickly, because the addition of only a small amount of oxygen to the normal atmosphere can create a violent fire risk from any stray spark or cutting flame.

 Acetylene is highly inflammable and with air forms an explosive mixture which can be set off any spark, flame or heat in the vicinity. It is therefore essential that all joints, especially on the gas cylinder are tight, that the hoses themselves are in good condition and all valves are turned off on completion of work.

Storage of oxygen and fuel gas cylinders :

 Gas cylinders shall be kept away from sources of heat.
 Cylinders shall be stored in a well-ventilated and dry location, away from highly combustible materials.

*  Cylinders containing oxygen and combustible gases, such as acetylene and hydrogen should not be stored in the same room.
 Oxygen Gas Cylinder shall be kept with a safe distance of 6.1 meters from combustible gas cylinders
* Gas Cylinders shall always be stored upright and secured with chain to prevent from falling down.
 Cylinders stored in the open shall be screened against the continuous direct rays of the sun.
* Empty cylinders should be stored away from the full cylinders

* Empty cylinders shall have their valves closed.
Other safety measures :

 Inspect cylinders for leaks, Report any leaks or damage to your supervisor immediately
 Do not roll or drop cylinders
 Transport cylinders using trolley and secured with chain to prevent from falling down.
* Sufficient fire extinguisher and fire buckets shall be kept at the storage shed & work area

Gas cutting operation :

 Protective clothing and eye protection shall be worn.
 Blowpipe shall be shut off when not in use.
 Lighted blowpipe shall not be left on a bench or the floor as the force of the flame may cause it to move.

* Work - piece shall be clamped and not held by hand

 Hoses shall be kept away from the working area to prevent contact with flames, heat, sparks or hot spatter.

Gas cutting operation :

It is a special gas safety device to stop the flame or reverse flow of gas backup into the equipment or supply line and it prevents the user and equipment from damage or explosions.

Flashback arresters shall be provided at both ends of the hoses (cylinder end and torch end) to prevent back flow of gas towards cylinders.

Back fire while cutting :

Backfire occurs when the flame burns back into the blowpipe often with a sharp bang. This may happen when the blowpipe is held too close to the work-piece, or if the nozzle is blocked or partly blocked. The flame may go out or it may re-ignite at the nozzle.

Flashback while cutting :

Flashbacks are commonly caused by a reverse flow of oxygen into the fuel gas hose or fuel into the oxygen hose, producing an explosive mixture in the hose. The flame can burn back through the blowpipe, into the hose and may even reach the pressure regulator and the cylinder. The consequences of a flashback are potentially very serious. They can result in damage or destruction of equipment, and could even cause the cylinder to explode. This could end in serious injury to personnel and severe damage to property.

If Backfire / Flashback occur :

 Cylinder valves of both fuel gas and oxygen shall be closed immediately.
 The flame should go out when the fuel gas is shut off. In case of emergency the area shall be evacuated and emergency fire services shall be called.

* The blowpipe shall be cooled with water , if necessary

* The equipment shall be checked for  damage of faults, particularly the nozzle.

* Below pipe, hoses, regulators, flashback arresters, and other components may have been damaged. The damaged ones shall be replaced before reuse.

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