Preventing Fires

The Regulatory Reform (Fire Safety) Order 2005 requires that a Fire Risk Assessment is carried for all premises, to identify fire risks and to plan for emergencies.

Fire controls

Hot work, including cutting, welding, flame and arc processes, etc are a significant fire hazard. Hot debris, sparks, etc may travel a significant distance.

The following controls should be observed:

• work well away from other flammable materials; 
• work well away from combustible materials such as wood; 
• maintain good housekeeping, eliminating unnecessary materials, heat-sensitive items, debris and dusts, accumulated rubbish, etc; 
• avoid hot work on or near wooden items, e.g. roof joists, floorboards, etc unless adequate additional protection can be applied (e.g. covering with heat or flame resistant materials). Sparks falling through gaps in floorboards are a particular hazard; 
• if necessary, douse floor and walls with water before commencing work. Check thoroughly afterwards. 
• if sparks can come into contact with combustible (e.g. wooden) items, or enter wall cavities, special precautions should be taken. Heat and sparks can smoulder for long periods before igniting into a fire; 

• thoroughly check the work area for sparks and heat, smouldering material, etc, during and after work; 
• prevent anyone smoking or vaping, in the work area or anywhere nearby. This is critically important where flammable substances, oxygen and/or fuel gases are present. 
• develop an emergency plan, as determined by your Fire Risk Assessment, including detection provisions, evacuation routes, scope for traps, need for fire control equipment, instruction and training requirements, emergency comms, possible impact on others nearby, etc. 
• provide fire control equipment, where necessary (as determined by your Fire Risk Assessment), e.g. detection, alarm system, extinguishers, fire-blankets, water, etc noting that this provision is not a substitute for good fire control, and that special training and instruction will be needed for use of these items by you and/or your employees;
• Seek further advice and information if you need further guidance on any aspect of the work.

Detecting and Dealing With Flammable Gas Leaks and Fires

Flammable gas leaks can cause fires. If gas leaks, identify the gas and then take appropriate action.

Refer to BCGA Leaflet 6 for Cylinders in Fires. Minor ignited cylinder-valve leaks can sometimes be tackled where it is safe to do so and where people are competent. Assess the risk, often it is better to evacuate rather than attempt to tackle a fire. Dry-powder fire extinguishers or thoroughly doused textile (wetted rag) may extinguish a cylinder valve fire. Re-assess if the fire remains, and evacuate. If the fire is extinguished, immediately close the cylinder valve, wearing suitable PEE (e.g. leather gauntlets). If the fire has resulted in anything more than momentary heat being applied to a Dissolved Acetylene cylinder, cool the cylinder with water, evacuate the area and urgently contact the Fire and Rescue Service.

The information below concerns Dissolved Acetylene, LPG and Hydrogen.

Common Advice – all gases

• Hissing sound or unexplained loss of pressure or presence of vapour or visible equipment damage etc – may all suggest gas leakage;
• If safe, confirm leakage via a leak test, using a suitable leak-detection fluid (e.g. teepol solution);
• If it is safe to do so, extinguish all nearby sources of ignition (note: the switching of electrics may INCREASE the risk of ignition);
• Remove personnel from the vicinity (evacuate). If necessary, cordon the area to exclude people and ensure adequate warning is provided to those nearby or who may pass by;
• Check to ensure the supply valve is properly closed, using moderate force (hand tight);
• Ventilate the area and/or if safer to do so remove the cylinder or equipment to a well-ventilated outdoor area away from drains windows or air intakes, until any flammable atmosphere is thoroughly dispersed. Do not allow re-entry until the area is safe.
• Support and assistance is available via your local Fire and Rescue Service, from the BOC Customer Service Centre, or your BOC contact (telephone numbers are labelled on every cylinder), or via our website.

Dissolved Acetylene (DA)

Identifying features:

• Often a sweet, garlic-like smell.
• DA specific gravity is 0.9 (i.e. slightly ‘lighter’ than air, so will tend to accumulate at higher levels e.g. in roof spaces, upper floors, etc)

Hydrogen

Identifying features:

• Hydrogen is colourless and odourless, and burns with an almost invisible or pale flame which can be difficult to see except for the heat haze.
• Hydrogen’s specific gravity is 0.07 (i.e. much ‘lighter’ than air, so will tend to quickly disperse upwards, potentially accumulating at higher levels).

Working in Cold Conditions

In cold weather vessels and tankers can be damaged during deliveries due to their contents and how they are transported.

Cold gases

Any gas in a very cold state can cause cryogenic burns. When working with pipes carrying liquid or cold gases it is important to protect your hands by wearing suitable low temperature gloves, preferably made of leather. They should either be loose fitting to allow for quick removal or cuffed to prevent substances from entering the glove. Where possible all bare skin should be covered.

Tanker deliveries

Before a delivery:

• Make sure the area outside the compound and the access route is clear for the tanker to enter and turn.
• Check the level gauge on the vessel before filling begins.

During a delivery:

• Make sure that people do not smoke or use naked flames within five metres of tankers making oxygen deliveries.
• Avoid entering vapour clouds in the event of a spillage.

After a delivery:

• Check the level gauge to see that filling is complete.
• Agree the quantity on the delivery note with the tanker driver.
• Ensure the blanking cap has been replaced on the filling connection.
• After up to one or two hours, check there is no leakage or liquid from valves 12 and 13. Hand-tighten any valve that is leaking.

In the unlikely event of an emergency during delivery, where the driver cannot complete their duties, tanker discharge may be stopped by:

• Pressing the red STOP button located in the control panel at the rear of the tanker.
• Stopping the vehicle engine using the cut-off in the driver’s cab.

De-icing Equipment

Vessel pipe work and vaporisers may be prone to ice build-up during cold weather or sustained periods of high use.

If the ice builds up to an excessive degree, it could threaten structural stability. It may also obstruct or impair the operation of valves and gauges. The gas outlet temperature of the vaporiser could fall too, causing embrittlement of downstream equipment. Under these circumstances it is important to defrost the vaporiser.

Where processes are intermittent, there are alternate banks of vaporisers or equipment is in sunny, well-ventilated locations, defrosting can often occur naturally. However, in some circumstances you will need to manually de-ice the equipment and it is important to do it correctly. Never attempt to remove the ice mechanically.

Do:

• Use hot water or steam.
• Work from the top of the equipment downwards.
• Ensure the run-off is appropriately managed (e.g. adequately drained).
• Ensure you provide safe access arrangements when working on larger vaporisers. Specialist access equipment may be needed to reach the top of the unit, for example a Mobile Elevated Working Platform (MEWP) or scaffold tower.

Don‘t:

• Use cold water, especially where vaporisers are in use, as it can increase the volume of ice build-up.
• Use naked flames or de-icing compounds.
• Use metal hammers, picks and other mechanical items.
• Remove ice from the bottom of the vaporiser until the ice above it is cleared. If the ice from the bottom is removed first, ice may fall from the higher parts of the equipment, risking operator injury and damage to the equipment.

The frequency of de-icing will depend upon individual site circumstances. It could be each shift, daily, weekly, monthly or throughout periods of winter weather.

If you find your system requires regular de-icing, it is better to plan for this in advance on a scheduled basis before significant ice forms. It is far easier and safer to remove light ice build-up, so a daily equipment check is recommended. Check for ice build-up, visible or audible leaks and for mechanical damage, and take the appropriate action as necessary.

You can read the latest BCGA guidelines in their leaflet: Cryogenic Installations - Managing ice build-up (pdf)