1. Introduction

Cylinders of compressed gas are used in connection with engineering maintenance work
and the storage of refrigerant gases.

2. Purpose

2.1 Accepted guidance on this subject is issued by the Health and Safety Executive and The British Compressed Gases Association (BGCA). These are extensive and must be referred to directly.

2.2 The purpose of this section is to ensure that those responsible for the use and handling of compressed gases in cylinders are familiar with the additional requirements of Greencore Group.

3. Storage

3.1 Storage areas must be well ventilated top and bottom. Cylinders stored in the open must be protected in cold weather from accumulation of ice and snow, and in hot weather from the direct rays of the sun.

3.2 Tarpaulins or any other cover must not be used in direct contact with the cylinders.

3.3 "No smoking" signs must be clearly displayed.

3.4 At all times the cylinders must be protected from rusting and corrosive conditions.

3.5 No artificial heat is to be allowed in stores where compressed gas cylinders are kept.

3.6 Lighting for stores containing acetylene or other combustible/flammable gas cylinders must either be of the approved flameproof type or must be outside the building, so that the interior is lit through fire resisting windows.

3.7 Electric switches must be of the approved flameproof type and sited outside the store room.

3.8 Storage areas must be of fire resisting material and so designed and situated, that in the event of a fire, the cylinders do not present a significant fire risk to the factory.

3.9 In the event of fire, cylinders must be easily removable.

3.10 Full and empty cylinders must be kept apart.

3.11 Full and empty cylinders must be clearly labelled to prevent confusion and mistakes.

3.12 Oxygen and combustible gases such as acetylene must not be stored together.

3.13 Acetylene cylinders work on the dissolved gas principal. They must always be stored and used in the upright position. They must be secured to prevent them being knocked over.

3.14 Do not prop any cylinders against a wall or bench but use a suitable cylinder stand.

3.15 Never use a cylinder as a roller, work support or jack.

3.16 When cylinders have been exposed to heat the cylinder wall is weakened, at the same time the gas content will increase in pressure and dangerous conditions may arise. Do not, therefore, allow cylinders to be exposed to heat.

3.17 Cylinders must be stored well away from stores, boilers, radiators and well away from combustible material and blowpipe flames.

3.18 Oil and grease will cause spontaneous combustion in the presence of high pressure oxygen and an explosion may result on contact.

3.19 Cylinders and fittings must be kept away from all sources of contamination, such as oil barrels, overhead shafting or drive belts.

3.20 Engineering staff must not smoke, wear clothes heavily contaminated with oil/grease, or have any exposed light in any place where compressed gases are stored.

3.21 Measures must be taken to prevent grit, dirt or any type of oil, grease and water from entering cylinder valves. They must be kept clear of all corrosive influences, e.g.. battery charging areas.

3.22 Should a cylinder become accidentally over heated or damaged, the suppliers must be notified immediately and the cylinder must be taken out of service.

4. Handling and use of cylinders

4.1 A study of compressed gas cylinders shows in the majority of cases the danger arising from the mishandling of cylinders falls under a number of well defined headings as follows:

i) Cylinders may be subjected to undue strain by blows or mechanical damage

ii) Pressure in the cylinder may be increased and the cylinder wall may be weakened by heat

iii) The gas in the cylinder may accidentally come into contact with some material with which it reacts violently, or even explosively

iv) The gas may escape from the cylinder valve or apparatus attached to it and form a hazard by becoming concentrated in a confined space.

v) Faulty apparatus may be attached to the cylinder, or after attachment may become damaged.

vi) Cylinders may drop or come into violent contact with others.

vii) Transported incorrectly or in a dangerous manner by road, rail or sea.

4.2 Cylinders must not be lifted with magnets and chains. A rope or nylon sling must be used to lift one cylinder.

4.3 Never lift more than one cylinder at a time and ensure the sling is properly adjusted to prevent slipping.

4.4 If more than one cylinder has to be lifted by a crane, a properly designed cradle with tested chain/wire suspension must be used.

4.5 Cylinders must not be allowed to come into contact with electrical apparatus or live electrical wires, since arcing will heat or damage the cylinders.

4.6 Cylinders must be kept away from sparks, flames, or slag from welding or cutting operations.

4.7 Personnel must not lubricate any valve or fitting, and must not use any jointing compound to prevent leaks.

4.8 Oxygen has no smell and whilst it does not burn, it supports and accelerates combustion. Ordinarily clothing and more flammable materials such as oil can be ignited, and will burn fiercely in oxygen or where the atmosphere has been enriched with oxygen.

NOTE
In a confined space a small amount of acetylene or oxygen may create a dangerous condition which will cause explosion or fire from a spark or naked light.

4.9 Take care to avoid leakage's. Always test with a 2% solution of Teepol in water (liquid soap), or a recognised brand of leak detection spray. Never check for leaks with a naked flame.

4.10 If an acetylene cylinder is heated accidentally or becomes hot due to excessive or severe back fire, usually from faulty accessories, it must be dealt with promptly as follows:

i) shut cylinder valve;

ii) detach regulator or other fittings;

iii) if possible, move the cylinder outside and away from the factory;

iv) immerse in, or apply waste copiously to cool;

v) open valve fully vent to atmosphere, keep applying water until the cylinder is fully empty.

4.11 Acetylene can form explosive compounds in contact with certain metals or alloys in particular;

• Copper
• Silver

4.12 Joint fittings or piping made of copper must on no account be used. Acetylene must never be allowed to come into contact with copper or any alloy containing more than 70% copper.

4.13 Keep cylinders and valves clean. Grit, dirt, oil, or dirty water must not be allowed to enter the cylinder valve sockets, otherwise it may be impossible to prevent equipment from leaking at the joints.

4.14 Clear out any loose dirt by "SNIFTING" some gas through, i.e.; by opening and closing the cylinder valve momentarily before attaching regulators or fittings. Remember to stand clear of the cylinder valves and turn head away before clearing outlet sockets.

4.15 Shut cylinder valves when work has to be stopped for more than a few minutes, or when the cylinder is empty.

NOTE:
When compressed gases are used in confined spaces - both ends of the hose must be broken to atmosphere when the equipment is left unattended for extended periods.

4.16 Use only the suppliers standard keys for operating cylinder valves.

4.17 Do not increase the leverage of keys or employ long leverage spanners or badly worn keys.

4.18 Do not attempt to get gas from cylinders with broken spindles, otherwise valves may be damaged and the cylinder rendered useless.

5. Valves & Regulators

5.1 The cylinder valve must always be opened slowly.

5.2 Cylinder valve spindles always have right handed threads, irrespective of whether the cylinder contains a fuel gas or a non-combustible gas.

5.3 The cylinder valve must be closed sufficiently to shut off the gas. Excessive force must not be used.

5.4 If regulator or cylinder valve becomes frozen, they may be thawed with hot water only, never by use of a flame.

5.5 Cylinders must never be transported with the regulators and hose attached, unless a proper trolley or carrier is used.

5.6 When transporting by trolley, the cylinder valve must be shut before the cylinder is moved.

5.7 Welding or cutting apparatus must not be used unless automatic pressure regulators are fitted to the oxygen and fuel gas cylinders.

5.8 Do not rely entirely on a needle valve, as this does not prevent a reverse flow of gas towards the cylinders.

5.9 The use of needle valves in place of a regulator, may cause the bursting of the house if the gases are cut off at the blowpipe, as the hose will be subject to cylinder pressure.

5.10 Before any regulator is put onto a full cylinder, the operator must always release the adjusting screw for regulating the pressure of output, otherwise there is a risk of damage to the regulator.

5.11 Threads on regulators and other auxiliary equipment must be the same as those on the cylinder valve outlets.

NOTE:

Right hand threads for oxygen and non-combustible gases

Left hand threads for acetylene and hydrogen.

5.12 Never force connections that do not fit. Where cylinders are connected to manifolds or headers, such manifolds must be of proper design and equipped with one or more pressure regulators, and flash back arrestors.

5.13 No attempt must be made to use equipment for gases other than that which is intended for it.

6. Gauges

6.1 No attempt must be made to use pressure gauges other than those recommended by the supplier.

7. Hoses

7.1 Only best quality hoses are to be used. Interior hose tends to harden, crack and leak. Cheap hoses have been known to fire when oxygen passes through it.

7.2 Hoses must be firmly attached to the blowpipe and other connections by approved clips (jubilee clips are not suitable).

7.3 Lengths of hose are supplied with the ends firmly attached to suitable ferrules having screwed unions suitable for connecting to standard regulator outlets and blowpipe inlets. These must be used in preference to any other hoses.

7.4 Frequent accidents occur due to leakage's or to the supply hoses becoming loose or blown off. Hoses and connections must be formally examined every 3 months. A record of inspections must be kept.

7.5 Lengths of hose must be joined by means of approved BCGA connecting fittings when more than the standard length is required. Do not use unnecessarily long lengths of hose.

8. Light up procedure for Oxy/fuel welding and cutting operators.

8.1 It is important that an adequate flow of fuel gas is issuing from the nozzle of the blowpipe or other apparatus before lighting up.

Personnel must follow this procedure:

i) set the regulators to the recommended working pressure;

ii) keep the blowpipe nozzle away for the source of ignition until the fuel gas is flowing freely from the nozzle. The use of a spark gun is recommended for lighting the blowpipe.

If the blowpipe flashes back on lighting up it is because:

a) the regulators are not set to the correct pressures; or

b) a light has been applied before the flow of fuel gas is properly established.

8.2 If the flame snaps out when the blowpipe is in use, it is because:

i) the regulator pressure and/or gas flow are incorrect, either too high or too low;

ii) the nozzle is obstructed or dirty;

iii) the nozzle is held too close to the work;

iv) the nozzle has become overheated causing pre ignition.

8.3 Completely shut both blowpipe valves, check regulator setting and cylinder pressures and re light in accordance with the guidance given above.

8.4 In the case of (iv) above, allow the blowpipe to cool.

8.5 The blowpipe must not be hung on the cylinder whilst lit.

9. Inspection calibration on maintenance

9.1 All Oxy fuel cutting or welding equipment must be inspected by a competent engineer on a regular basis. The British Oxygen Corporation now provides a swap exchange scheme for this purpose. The frequency of inspections must comply with BCGA guidelines.