What are the common knowledge of preventing welding flashback?

Prevent welding flashback

Oxyacetylene torch has been used for cutting, welding, brazing, and heating of metals for many years. The devices used today are safe, but every year hundreds of employees are injured or killed due to improper use. Wrong ignition/shutdown sequence, overheating caused by the nozzle being too close to the workpiece, etc. Knowledge and preventive measures can prevent fires and violent explosions.

Gas Pressure

One reason for fires and explosions is the high pressure of acetylene. Improper ratio of fuel gas to gas pressure or severe pressure fluctuations can cause acetylene to become unstable and undergo explosive decomposition when the pressure exceeds 15 pounds. This is also the main reason for using other fuel gases such as MAPP, propylene, propane, and natural gas, which can be safely used at higher operating pressures.

Burn Back

If your oxygen cylinder is low or empty, there may be gas backflow. Due to its high pressure, fuel gas can flow upwards along the oxygen pipeline and mix with the gas in hoses, regulators, and cylinders. If you do not clean the pipeline when igniting the blowtorch, it may cause it to burn back, and the hose, regulator, or cylinder may explode.

Backfire

If tempering occurs, the same situation may also occur under high oxygen pressure and low gas pressure, usually due to the cutting gun being too close to the workplace. This will result in insufficient cutting flame gas, causing the flame to be drawn into the nozzle. Usually you will hear a “popping” sound, which then turns into a whistle.

Flashback

When flashback occurs in the mixing chamber, unless the oxygen valve is closed, the flame from the nozzle may ignite the gas inside the hose, leading to flashback. Flashback refers to an explosion that occurs through a blowtorch, hose, regulator, and enters the cylinder. The consequences may range from hose rupture to severe explosions of regulators and cylinders.

Help prevent flashbacks, fires and explosions:

1. If using acetylene, keep the pressure below 15 pounds.

2.Purge your hoses before lighting the torch.

3.Never light your torch with a mixture of fuel and oxygen. After purging the lines, light the torch with only the fuel gas valve open.

4.Check valves should be installed on both torch inlets and operating properly. Check valves can stop the reverse flow of gases, but will not prevent flashbacks.

5.To prevent flashbacks, flashback arrestors must be installed on the outlets of both regulators, and/or torch inlets.

If you have any further questions about tempering in welding, you can contact DERKIA for free and answer at any time. DERKIA invites you to attend regular welding industry exchange lectures.

https://www.derkia.com/product-category/backfire-preventer-parts/

DERKIA BUSINESS