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The Storage of Gas Cylinders

August 8, 2018

INTRODUCTION

This document provides advice and guidance for the safe storage of gas cylinders. It gives guidance on the construction and management of gas cylinder stores and provides information on the hazards likely to be encountered.

It shall be used when sitting and constructing storage facilities or when reviewing the safety and suitability of existing storage facilities. It does not preclude the use of alternative designs, materials, and methods when they provide equivalent standards of safety.

The content of this publication is in line with advice from the Health and Safety Executive (HSE).

 

SCOPE

This document defines the principles of safe practice for the storage of gas cylinders and gas cylinder bundles and outlines the relevant legal requirements.

Cylinders are never fully empty unless a cylinder is new, de-valved, or following inspection and test where it has not yet been filled with a gas. Therefore, cylinders, containing a gas but regardless of the quantity of gas, shall all be treated in-line with this Code of Practice.

A gas cylinder(s) is deemed to be in storage when

  • It is not in use; or
  • It is not being transported.

 

Storage of full and empty LPG cylinders and cartridges. Where a mixture of LPG (>400 kg) and other gas cylinders are stored then the applicable sections of UKLPG CP 7 (60) and this Code should be applied.

Exclusions from this Code of Practice are:

 

(i) Cylinders in use i.e. connected to the user equipment, or permanently connected for use; for example, fire protection systems and specifically sited emergency response equipment, such as fire extinguishers and self-contained breathing apparatus.

(ii) Cylinders being processed for filling or for periodic inspection and test.

(iii) Medical cylinders in domiciliary use.

(iv) Gas cylinders during carriage by road, rail, air, and sea.

(v) Cylinders permanently manifolded together to form part of a bulk gaseous hydrogen installation.

(vi) Transportable vacuum insulated containers.

(vii) Containers (vessels) for cryogenic liquids.

(viii) Cylinders stored off-shore.

(ix) Aerosols.

 

GAS CYLINDER IDENTIFICATION

 

Gas Cylinders

 

 

 

 

The cylinder label shall always be used as the primary means of identifying the contents of gas cylinders. The label will identify the product name and the class of hazard (Diamond Hazard Label(s)). Some gas cylinders may have this information stenciled on the body of the cylinder.

Colour coding is a secondary method of identifying certain gases or the properties of others, however, colour coding is not mandatory for most gases but its use is supported by the majority of gas suppliers. Colour coding is typically applied to the shoulder, or curved part, at the top of the cylinder.

 

POTENTIAL HAZARDS

Gas cylinders present a number of different hazards:

  • Size, shape and weight – Manual handling, security.
  • Pressure hazards.

Size, shape, and weight

Gas cylinders are generally heavy and are relatively unstable due to the base diameter to height ratio. Large cylinders can weigh over 100 kg when full they are easily toppled over. Gas cylinders are awkward objects to move safely.

Pressure hazards

Cylinders contain gases stored under pressure and will have significant stored energy.

Any pressure above atmospheric released from a cylinder has the potential to cause injury to personnel or damage to plant or property.

Pressure can be released by:

  • Inadvertent operation of the outlet valve during handling.
  • Deliberate operation of the outlet valve.
  • Damage to the valve if cylinder topples or falls.
  • Application of heat, for example, fire.
  • Mechanical impact.
  • Leaking valve.
  • Operation of pressure relief devices.
  • Unauthorised modification of the cylinder assembly.
  • Failure of the cylinder wall, for example, from excessive internal and/or external corrosion (by reducing wall thickness).

 

 

CYLINDER STORE – CONSTRUCTION AND GENERAL PRINCIPLES

Gas Cylinders

Risk assessment

All gas cylinders contain gases under pressure and may present a risk of explosion if not safely handled and stored. Legislation requires that a site-specific risk assessment is required for each gas cylinder store, refer to The Management of Health and Safety at Work Regulations (6) and The Dangerous Substances and Explosive Atmospheres Regulations (DSEAR). Every storage situation must be considered on its merits and special circumstances may necessitate variations on the recommended requirements.

 

 

Legal and permit requirements

Consent from the local authority may need to be obtained to store quantities of dangerous substances over certain thresholds. The regulations contain thresholds for both named substances, such as oxygen and hydrogen, and for generic categories of substances (flammable, toxic). For example, the threshold for oxygen storage is 200 tonnes, for flammables 50 tonnes, but for hydrogen only 2 tonnes. In some cases, the percentage / partial faction of thresholds (for example, flammables and oxidants) are additive when determining if consent is required.

 

 

Location of the storage area

The majority of gas cylinders are designed so that they can be stored in the open air and, as such, they will not be adversely affected by inclement weather.

 

Storage areas should be located in an external area where there is good natural ventilation. Adjacent buildings, structures, and geographical features may adversely affect natural ventilation and their effect should be taken into account during the risk assessment. The store should not be located in low lying areas; where gases may accumulate.

 

Storage within a building is not recommended. Where storage indoors cannot be avoided please see below. Internal storage locations should be at ground level and in the following order of preference:

 

(i) A bespoke stand-alone dedicated, adequately naturally ventilated building.

(ii) A dedicated room sealed from the rest of the building, adequately naturally ventilated to the outside, only accessible from an external door(s).

(iii) A dedicated room, adjacent to an outside wall, inside a building, adequately naturally ventilated to the outside, sealed from other areas of normal occupancy.

(iv) A dedicated room, inside a building, with forced air ventilation, sealed from other areas of normal occupancy.

(v) In a building, as far as is practicable away from normal work locations.

The location of the store shall take account of the minimum recommended separation distances, refer to Section 5.4.1. Cylinder stores are to be located away from the site designated emergency exits and escape routes.

Gas cylinder storage areas should be segregated from other stores. The risk assessment shall take due regard of the potential hazards of the gases being stored and the risk from other hazardous processes or storage sites that may impact on a cylinder store. It shall also consider the potential for impact due to vehicle movements.

Storage locations should be sited at ground level. Where cylinders are stored at any other level this shall be specifically covered in the risk assessment. If the store is located at another level then consideration needs to be given to providing an area to allow vehicles to collect and deliver cylinders, cylinder movements between levels and the impact in the event of an incident, for example, gas leakage, fire, access for emergency services, proximity to people, etc.

The risk assessment shall take account of both underground and overground services. The location shall be chosen so that it is not directly beneath overhead power or other cables and where it will allow access for vehicles and other plant machinery without the risk of them coming into contact with power or other cables.

Each storage area and its boundaries shall be well defined. The footprint of the store shall allow space for the expected quantity of gas cylinders being stored as well as for the safe movement and handling of the gas cylinders, including access for mechanical handling equipment.

Appropriate access to the site will be required. This will include access for delivery vehicles and the emergency services.

The location of the storage area should consider the security of cylinders to avoid theft and to prevent tampering with the cylinders.

 

Storage area layout and separation distances

The physical dimensions of the storage area shall take into account the storage requirements, for example, grouping by hazard classification, full/empty or unserviceable cylinders and providing adequate space for access and egress, for safe manual handling operations and the use of mechanical handling equipment.

Means shall be provided to secure cylinders to prevent them from falling over, for example, pallets, chains, lashing, etc.

 

Minimum recommended separation distances

Appendix 2 shows the minimum recommended separation distances between cylinders, the store(s) and other features.

Where there are space restraints a permanent physical partition may be used to help achieve the required minimum recommended separation distances. The height of the partition should be relevant to the hazard, however, it should be not less than 2 meters high, unless for non-fire hazards a lower partition can be justified through risk assessment. The required minimum recommended separation distance can include the length of the sides of the partition, as shown in Figure 1. Such partitions should be imperforate and constructed of suitable materials, for example, solid masonry or concrete. Where protecting against fire hazards they should be constructed to achieve at least 30 minutes’ fire-resistance.

 

Where the wall separates vulnerable populations from the cylinders (not including inert gases), the fire resistance provided should be a minimum of 60 minutes.

 

Gas Cylinders

 

 

 

 

 

Figure 1: Use of a partition to achieve the minimum recommended separation distances

Within Figure 1 the minimum recommended separation distances may include the distance measured around the sides of the partition by determining the sum of A + B + C.

If flammable gas cylinders are stored against a building wall the area up to 2 m either side of the storage area and up to 9 m above ground should be imperforate and of a minimum of 30 minutes fire resisting construction.

When planning the gas cylinder storage facility, adequate handling space shall be allowed. The total amount of floor space required will depend on the quantity and the size of the cylinders, and the handling equipment to be used during their movement. Refer to Section 6 and Section 8.

 

Floor

The floor should be level and constructed from non-combustible, non-porous material. All floor surfaces shall be constructed so that they can be maintained in a clean manner.

Obstacles such as expansion joints, steps, and drainage systems, shall not impede cylinder handling operations.

The floor shall be of sufficient strength to support the weight of the gas cylinders/gas cylinder pallets, plus any mechanical handling aids employed on gas cylinder handling.

The floor should be laid to prevent the accumulation of water so that stored cylinders do not rest in standing water and risk being subjected to corrosion.

 

Roof

Cylinders are designed for outdoor storage, however, some applications require protected storage conditions for quality, hygiene and security reasons, for example, analytical and medical gases. Cylinders may also need additional protection from local environmental conditions.

Where required, the roofing shall be designed to prevent gas pockets from accumulating, for example, gaps between the wall and sloping roof, natural ventilation in the roof apex etc.

 

General security

All stores containing gas cylinders shall be secure and access shall be restricted to authorized personnel. This may be achieved by securing the site with a boundary fence with lockable gates or by securing individual stores. Dependant on the site security requirements both conditions may be required.

Suitable security arrangements shall take into account the classification of the gases and the quantities being stored. The security arrangements shall include appropriate physical and management security controls to prevent unauthorized access, theft, tampering, arson, vandalism and to effectively monitor the usage of gases, as well as any specific local considerations. Keys for each store shall be kept in a secure location and only issued to authorized persons; a log should be kept.

Where electronic security systems, for example, alarms, are installed comply with the electrical requirements on site.

The security perimeter shall meet the ventilation requirements and be not less than 1.8 meters high.

Where the gas cylinder store is enclosed, a suitable emergency exit(s) may be required dependant on the size and/or layout of the store.

All persons handling gas cylinders shall have appropriate training, as required.

Where high consequence dangerous goods, such as toxic gases, are stored on site a security plan shall be drawn up and implemented in compliance with the Health & Safety department.

 

Ventilation

Ventilation is required to ensure that any small leakage of gas is adequately dispersed and will prevent a hazardous atmosphere being created. An outdoor store with open or ventilated sides and is considered to provide adequate ventilation and is the preferred option.

Where a store may have restricted ventilation, due to, for example, adjacent buildings or a wall acting as a store boundary, it is necessary to ensure that there is through and thorough ventilation in all areas inside the store.

A semi-enclosed store may be considered ‘outdoors’ if it consists of up to three adjacent solid sides, with a roof, provided at least 25 % of the perimeter is constructed to ensure that ventilation is not impaired, for example, meshed cladding.

Where the configuration of the store restricts air flow, the installation of high and low-level vents should be considered to ensure a regular change of air. The design of a roof shall meet the ventilation requirements. Minimum recommended separation distances should be considered when locating vents.

A store with less than 25 % of the perimeter open is to be considered an indoor store.

Examples of store design are displayed below.

If a store is located against a building wall, then the risk assessment shall take account of the likelihood of escaped gas entering the building, and the method of entry, for example, an overhanging roof, cellars, windows, air intakes, etc.

 

Gas Cylinders

 Gas Cylinders

 

 

 

 

 

 

 

 

Access

The storage area should be located so that it is readily accessible for cylinder movements with manual handling distances kept to a minimum and clear access maintained at all times for deliveries and the emergency services.

Access to the delivery and storage area(s) is to be kept clear, with no parking allowed, except for the loading and unloading of cylinders. No vehicles are to be allowed within the minimum recommended separation distance.

Aisles should be provided to allow safe access to cylinders, to facilitate good housekeeping, stock control and for the ease of handling. They should be a minimum of 1 metre wide.

The layout of the storage area should allow for the safe movement of gas cylinder handling trolleys, forklift trucks, and any other powered vehicles. The layout shall take account of the separation of personnel and vehicles with appropriate traffic routes defined.

Where the gas cylinder store is enclosed suitable access and egress shall be provided. The risk assessment (refer to Section 5.1) shall determine the maximum travel distance to enable escape and therefore identify the number of exits required.

Where installed, all designated emergency exits shall open in the direction of escape and shall be fitted with panic furniture of a type not requiring a key, card, or code to open. They are to provide an unobstructed means of escape and in operation shall not obstruct any other escape route. These exits shall be properly identified by signage and maintained in a serviceable condition at all times. Ensure that emergency exits are secure and cannot be opened from the external side of the store (whilst still allowing emergency escape from the inside of the store).

 

Lighting

The area should have adequate lighting to assist in providing a safe work environment, to allow the identification of the cylinder contents, signage and where necessary to assist with security. Where artificial lighting is used it shall give suitable colour rendering to enable colour labelling to be easily recognised by persons with normal colour vision.

Where required, emergency lighting shall be to the requirements of BS 5266 (28).

 

Electrical equipment

Only electrical equipment that is necessary for the safe and practical operation of the gas cylinder store shall be installed. As a minimum, all electrical installations shall conform to BS 7671 (31), Requirements for electrical installations. IET wiring regulations. Where flammable or oxidising gases are stored the risk assessment (refer to Section 5.1) is to determine whether protected electrical equipment is required, if so refer to BS EN 60079, Part 14 (33), Explosive atmospheres. Electrical installations, design, selection, and erection.

 

Fire safety requirements

A responsible person shall carry out a Fire Safety Risk Assessment on all gas cylinder storage areas to determine the hazard and the risk associated with a fire originating from a gas cylinder and/or a fire impacting on a gas cylinder(s). The findings from which are to be incorporated into the Site Fire Safety Management Plan that is to be implemented and maintained. As necessary, advice should be sought from the Fire and Rescue Service. The risk control measures identified shall be incorporated into the construction of the gas cylinder store(s).

The location of each gas cylinder store shall be recorded within the site’s hazardous locations record. This record should include information on the products stored, their maximum quantities and their hazardous classification. This should be updated on a regular basis. This is to be made available to the emergency services in the event of an incident.

 

TRAINING

 

Gas Cylinders

 

 

 

 

 

 

 

 

All personnel who are required to handle and store gas cylinders shall receive suitable information and instruction regarding the hazards associated with gas cylinders and the gases being stored, and provided with the necessary skills and knowledge to carry out their job safely.

It is the duty of the employer to ensure their persons are adequately trained and to establish competency. It is recommended that a training programme is carried out under a formalised system where an acceptable level of competency has to be achieved. Records shall be kept of the training provided and the competence level achieved. The training programme shall make provision for periodic re-training.

 

Training should be reviewed and/or updated following:

 

  • A related accident or incident.
  • The receipt of gases which have not previously been used on site.
  • Change to guidance or information previously provided.
  • The appointment of new and/or transferred employees.

 

All persons engaged in the storage of gas cylinders shall have training commensurate with their responsibilities and should include, but not confined to the below subjects.

 

  • Identification of the cylinder and its contents.
  • Properties and hazards of gases, including pressure.
  • Cylinder and valve types.
  • Movement of cylinders, including local carriage.
  • Stock management.
  • Store management.
  • Actions to be taken in an emergency situation.

 

Specific training and certification requirements are required for persons handling fluorinated gases.

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