Welding, brazing and cutting are essential processes in manufacturing industry. All these processes depend crucially on industrial gases.
BCGA is committed to ensuring SAFE use of industrial gases in these processes and produces several useful guidance documents, as detailed below, which operatives and their employers should be familiar with.
One of the principle hazards is the fume given off by welding and hot cutting processes which create varying mixtures of airborne gases and very fine particles that can cause a range of respiratory ill health effects if inhaled. Precautions should be taken to avoid its inhalation, not only by operatives doing the welding/brazing/cutting, but also by others nearby.
BCGA has engaged with the HSE and others via the Welding Fume Health Partnership to try to influence attitudes and behaviours with respect to welding fume, particularly in encouraging the use of appropriate local exhaust ventilation and Personal Protective Equipment.
BCGA has published a Safety Alert on the hazards of welding fume, BCGA TIS 24. The Welding Fume Health Partnership has produced a website www.badairday.info which explains in detail the safety concerns associated with welding fume and which encourages appropriate safe behaviour.
BCGA also supports the Chartered Society for Worker Health Protection (BOHS) and its Breathe Freely campaign to control exposure to hazardous substances, such as welding fume, and to prevent occupational lung disease in the construction industry. Lots more information is available on their website - www.breathefreely.org.uk
Fuel gases are mostly hydrocarbon based and each has its own unique properties. The choice of a fuel gas is based on its ability to burn in air or oxygen and will be dependent on the specific requirements of the job, as well as the location at which it is being used. There are several useful fuel gases of which acetylene and propane are the most common. Following a major review of legislation in 2014, acetylene was placed under The Acetylene Safety (England and Wales and Scotland) Regulations 2014. These regulations require that all mobile systems shall be fitted with a purpose designed regulator for acetylene, a flashback arrestor incorporating a non-return valve and a pressure and/or temperature sensitive cut-off valve.
Brazing requires that the work be heated to the correct temperature for the process to take place. There are several different methods for achieving this heating, but the use of an oxygen / fuel gas burner is the most common. Typically oxygen / propane or oxygen / acetylene are used, with the higher temperature of the oxygen / acetylene flame giving maximum flexibility. BCGA CP 7 defines how to design, operate and maintain portable and mobile systems for oxygen / fuel gas processes. Fixed installations, with cylinder manifolds supplying gas via distribution piping systems, are specified in BCGA CP 4 and, for acetylene, BCGA CP 6.
Cutting of metals is commonly carried out using oxygen / fuel gas equipment. The process consists of heating the work using the flame, and then using excess oxygen to burn the metal. Depending on the scale of the job either oxygen / propane or oxygen / acetylene systems can be used. As for brazing BCGA CP 7, BCGA CP 4 or BCGA CP 6 are the appropriate publications to refer to.
Welding can be either gas welding or electric arc welding. For gas welding of ferrous metals the flame temperature must be the highest possible to get the metal to melting point. Thus only oxygen / acetylene is suitable for this process. Modern electric arc welding requires the use of shielding gas to protect the weld from the atmosphere.
Sometimes this shielding gas is a single gas, very often argon, but the use of gas mixtures is increasingly common, with mixtures tailor-made according to the metal being welded. Where the shielding gas is provided from a single cylinder, local to the welding equipment, then BCGA GN 7 gives detailed recommendations. Fixed supply systems are, as before, defined in BCGA CP 4.
This area of gas use is well supported by published standards, most of which are either European (EN) or International (ISO). BCGA is very active within BSI in the development of these standards, via the Welding Committee WEE/18.
To help maintain gas equipment in good order, BCGA publish BCGA TIS 18 to assist in identifying the inspection and replacement date markings on certain items. BCGA TIS 19 sets out the BCGA policy for no longer supporting the refurbishment of components used with welding equipment.
At all workplaces where hazardous products are in use, such as welding gases, a formal risk assessment is required and, where necessary, reasonable steps are to be taken to prevent harm occurring. BCGA TIS 15 lays out a model risk assessment which includes a series of tabulated risk assessment sheets that address the main aspects of the storage, transportation and use of gas cylinders for oxygen / fuel applications.
Within BCGA, TSC3 is the Technical Sub-Committee that covers this topic. BCGA members interested in this subject should consult the minutes of TSC3 within the Meetings section of the Members area.
The following documents are available from the Publications section:
- BCGA CP4 - Industrial Gas Cylinder Manifolds and Gas Distribution Pipework (excluding acetylene).
- BCGA CP5 - The design and construction of manifolds using acetylene gas from 1.5 bar to 25 bar.
- BCGA CP6 - The safe distribution of acetylene in the pressure range 0 - 1.5 bar.
- BCGA CP7 - The Safe Use of Oxy-Fuel Gas Equipment (Individual Portable or Mobile Cylinder Supply).
- BCGA GN7 - The Safe Use of Individual Portable or mobile Cylinder Gas Supply Equipment.
- BCGA TIS 15 - Model Risk Assessment for the Storage and use of gas cylinders for oxy - fuel applications.
- BCGA TIS 15 - Model Risk Assessment for the Storage and use of gas cylinders for oxy- fuel applications Excel spreadsheet.
- BCGA TIS 18 - Gas equipment inspection / replacement date marking.
- BCGA TIS 19 - Refurbishment of components used with compressed gases for welding, cutting and related processes.
- BCGA TIS 24 - Welding Fumes - Safety Alert.
- BCGA TIS 29 - Oxy-fuel gas equipment. Selection and assembly
- BCGA TIS 32 - Acetylene or propane (for welding, cutting and allied processes).