Welding equipment: Selection matters

 

Whether it is for oxy-fuel gas welding and cutting applications, including MIG/MAG and TIG processes, purging, pressurising or laboratory applications, flashback arrestors and regulators particularly require careful research before they are chosen.

When using gas welding and cutting equipment, the major potential hazard is fire. This can be caused by a number of factors and can lead to the creation of other workplace hazards. The risk of fire, or explosion, due to the release of fuel gases, is the greatest danger to safety in the operating environment. The cause can be loose or badly connected fittings, as well as an excessive amount of time between turning the gas on and igniting it at the blowpipe – that is to say, inadequate purging. Operator failure to actually turn the equipment off once the job is completed is also all too often a cause of fire.

Fire can also be spread due to oxygen enrichment if too much of it is released during the cutting operation. This situation is exacerbated if there is inadequate ventilation. High pressure oxygen also presents an explosion risk if it comes into contact with oil or grease and therefore no gas equipment should be lubricated in any way.

The consequences of flashback, backfire and sustained backfires can be devastating and correct working practices (purging of hoses, right choice of cutting nozzle, correct working pressures) are essential. However, sometimes the cause of flashback and backfire is beyond the control of the operator and it is therefore vital that to diminish the risk of fire, the highest performance flashback arrestors and non-return valves are fitted at the outset.

Flashback arrestors are available for service with all common gas types for welding, cutting & heating applications. They are essential safety devices which provide the maximum protection for the operator and his equipment in the event of a flashback. A flashback can be caused by a variety of conditions such as sustained backfire, incorrect hose purging or simply the wrong gas pressure. Most are attributable to operator errors. 

When a flashback occurs the flame front and pressure wave retreat into the blowpipe and hose at a very high speed. This can cause detonation within the system. It is essential that the regulator, and more particularly the cylinder, are protected from the effect of a flashback – with a suitable arrestor. 

In today's economic climate, it is of course very tempting to consider the price factor alone when investing in gas equipment, in order to make immediate up-front savings. However, that approach in the longer term, can lead to financial and human costs that can far outweigh any short term savings.

In the gas welding and cutting products market, there is a wide range of brands and products from which to select. As with many industrial products it is clear that in the UK inferior imported goods – often from the Far East – are readily available. Unfortunately, these products are often not manufactured to the standards that we should expect or accept. They are frequently manufactured using lower quality materials and not subject to the rigorous quality control checks that such safety related products demand.

Often, quality checks within their manufacturing plants can be overlooked and may also not be monitored. Third party manufacturing is also common which means even less control over the production process. As a result of all these factors, the operational safety of such products can be compromised.

Established brands, on the other hand, are likely to have been produced in the manufacturer's own factory. Quality control is normally central to the production regime. For example, the new ESAB single and multi-stage Elite regulator range is made in the company's factory in South Carolina. 

Conformance to the international manufacturing standard – BS EN ISO 2503 – is an essential pre-requisite for any regulator and if the product has additional third party accreditations, this is a further benefit. These can include, for example, national accreditations such as that of the South African Bureau of Standards (SABS) to their quality standard, SANS 2503.

The 'big three' quality management systems are ISO 9001:2008, ISO 14001:2004 & OHSAS 18001:2007, and checks should be made to ensure product compliance. With the Elite range of welding and cutting products, ESAB complies with all three.

Considering the tough shopfloor environments where gas welding and cutting typically takes place, the quality of manufacture of any product is extremely important. With gas regulators, the toughness and durability of the product are absolutely essential and there should be no compromise in the material used for the regulator body. A high strength, solid brass stock regulator body should is the ideal choice with the operating data permanently engraved. 

In the event of a regulator burnout (RBO), a protection feature within the device to contain the fire and provide protection from any potentially fatal consequences should be high on the list of features. New, recognised brands are now incorporating this feature in some versions. 

Aside from safety, economy in operation is a key factor. It is easy just to consider the upfront costs of the gas welding and cutting processes while overlooking the price of the shielding gas itself which, unlike welding wire and the regulator itself, is invisible. Gas welding operations can achieve up to 50% savings on shielding gas usage with a new gas regulator that ensures the gas flow is very strictly regulated. Payback on this investment like this can be achieved in just a few months, and thereafter the savings can boost gas welding profitability.

Other safety related issues to bear in mind include the fact that fire and hot materials provide a burning risk and therefore the use of proper gloves is essential. Remember too that removing components whilst they are still under pressure could cause them to be propelled with force. Badly fitting hoses could also, under pressure, flail dangerously in the vicinity of operatives.

Indeed, in terms of physical personal protection for the welder, there are risks to all parts of the human body if incorrect procedures are not properly followed. General physical damage and back strain can result from falling gas cylinders or attempting to move them incorrectly. Even general untidiness – bad house-keeping – in the workshop creates a risk of tripping and sustaining injury.

Think carefully too about eyes, ears and respiration. Intense glare and ultra-violet radiation from the welding or cutting process can be prevented through the use of goggles manufactured to EN 175. The lense must always be appropriate for the strength of the operation being attempted in accordance with EN 166/169. The lense will protect from both glare and stray sparks. For those who wear normal glasses, goggles are also available – some have a secondary clear glass lens for protection when the filter lens is removed to see the workpiece.

Heat and radiation can be a problem when heating or cutting thick or heavy sections of material. In these circumstances, normal gloves and overalls may not be sufficient and special insulated clothing may be required. Furthermore, local fume extraction equipment placed down wind of the operation will help both with radiation and fume problems caused by heating lead or zinc coatings as well as galvanized material. It is common practice to use a personalised fresh air unit for these operations today.

In summary, the correct specification of safety related equipment and PPE, as well as the promotion of general safety when gas welding and cutting, is imperative. Operatives must be provided with the best available equipment and head to toe protection that not only provides the correct level of protection for the job in hand, but is also sourced from the best possible source.