Weld on mate! A guide to flashback arrestor inspection and testing

Safe storage and handling is critical for keeping and transporting compressed gases. In particular, flashback is a very real danger when welding with oxy acetylene torches.

If you’re using welding equipment in your workplace, here’s what you need to know about national gas bottle storage requirements, as well as flashback arrestor regulations, inspection and testing.

Back to basics: What is flashback and when does it occur?

A flashback happens when a flame burns back into the torch’s blowpipe, and travels back along one of the gas lines into your gas cylinders. 

At best, flashback can burn the inside of your hose and cause damage over time. However, at its worst, flashback can cause explosions which injure people, damage property and release hazardous gases into the environment.

A flashback arrestor is a safety device that stops a flame from re-entering a gas cylinder or gas pipe, usually by cooling or extinguishing the flame.


How often should you inspect your welding equipment?

The Australian standards for gas cylinder storage require fuel gas systems to have flashback arrestors installed in compliance with AS4603. Flashback arrestor testing procedures require arrestors to be tested or replaced by a competent person at least once every 12 months, to ensure that the arrestor is still working correctly.

On top of this, every time a flashback happens, the flashback arrestor, gas hose, and any fittings should be removed, inspected by a competent person, and repaired or replaced if needed. 

This is because flashbacks can damage the arrestor and cause it to lose its effectiveness. If there are any other unusual sounds (such as hissing) or cracks, it’s important to report these too as your equipment could need an oxy acetylene leak test.


How to choose flashback arrestors

When it comes to choosing a flashback arrestor, there are a few key factors to keep in mind:

  • Connection size: different types of torches may require different connections, so it’s important to pay attention to this when choosing your flashback arrestor. Having the incorrect size could cause insufficient gas flow, and lead to hazards when using equipment, so be sure to check with the manufacturer or supplier before buying your arrestor.
  • Gas type: different arrestors and regulators are designed for different types of gases. If you’re using oxygen or air, the type of flashback arrestor you need will be different to if you’re using fuel gases such as acetylene, methane, hydrogen, or LPGs.
  • Flow rates: the pressure of the gas released into your torch will play a part in which flashback arrestor you need. Often there are two options – standard and high flow – so when you’re choosing your flashback arrestor, make sure to keep an eye on the maximum working pressure of the gas and match it to your torch.

Flashback arrestors are colour-coded, and should be marked with AS4603 (in compliance with the GHS labels for hazardous goods). They should also have the date and country where the arrestor was manufactured, the manufacturer’s mark, the model and batch number, and the name and direction of the gas.

It’s important to communicate with your manufacturer or supplier before purchasing arrestors for the first time. Tell them exactly how arrestors will be used, stored and transported, so they can give you tailored advice on selection, storage and maintenance.

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Placement of flashback arrestors

Arrestors need to be placed correctly to ensure they effectively protect you in the case of a flashback. In line with WorkSafe recommendations, flashback arrestors should be fitted at each gas line at the regulator outlet for hoses less than 3m long. For hoses longer than 3m, an additional flashback arrestor is needed at the torch end.

In addition to the arrestor, the regulator end of the hose should have a non-return valve and a temperature actuated cut-off valve, while the torch end also needs a non-return valve. Some arrestors have these all built in – be sure to check with the manufacturer to make sure you have everything you need.


Maintaining flashback arrestors

Oxy acetylene testing requirements for Australia require flashback arrestors to be tested after the manufacturing process. On an ongoing basis they should also be tested by a competent person – or replaced – annually. In the event of a flashback, the arrestors also need to be tested to see if any parts need to be repaired, replaced, or discarded.

When it comes to expiration dates, Work Health and Safety do not have any set guidelines, so it’s critical to check these dates with your manufacturer or supplier. Also check with your supplier for any additional storage or maintenance requirements.


Storing and transporting oxy acetylene

Storing and transporting compressed gases can be highly hazardous, so proper care must be taken to keep everyone safe. Firstly, every cylinder should be labelled in compliance with the GHS label requirements for hazardous goods. The storage cylinder should also be made of compatible materials, and a valve protection cap needs to be used until the cylinder is secured.

Compressed gases such as oxygen and acetylene should also be stored and transported in cool, dry, and well-ventilated areas, and kept out of direct sunlight. If you’re storing oxygen and acetylene cylinders next to each other, they will need to be stored in separate gas bottle cages. The cages will then need to be separated by at least 3 meters. If this distance of 3 meters cannot be achieved, you will then need to erect a non-flammable barrier that will segregate the oxygen gas cylinder cage from the acetylene cylinder cage. 

When transporting gas cylinders within buildings, the cylinders must only be transported in lifts, and properly secured to the lift handrail. No person should travel with the cylinder, and a sign should be placed in front of the lift to advise others that a cylinder is being transported.

If oxy acetylene is being transported using a vehicle, the cylinders can only be transported on an open back utility or a utility back canopy that’s separate from the main vehicle body.

Cylinders should ideally be transported standing up, and it’s important that they are always firmly secured. If they are transported lying down, then support devices should be used to keep the cylinders from rolling around. Don’t forget to check the settling time for the cylinder before use.

If you’re transporting gas cylinders to or around a worksite, STOREMASTA’s new Transportable Gas Bottle Trolley can make the process safer and more efficient. 

Fork channels, a crane lifting attachment, an adjustable handle and wheels ensure the trolley is highly mobile, as well as transportable by forklift, excavator or crane - making it an ideal transportation method for inaccessible and crowded locations.

Learn more about the Transportable Gas Bottle Trolley by clicking the image below.

transportable gas bottle trolley

Walter Ingles

Walter Ingles Compliance Specialist

Walter is STOREMASTA’s Dangerous Goods Storage Specialist. He helps organisations reduce risk and improve efficiencies in the storage and management of dangerous goods and hazardous chemicals.

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