Fires in buildings under construction caused by hot work

HOT WORK: FIRES AND INJURIES IN THE CONSTRUCTION SECTOR AND HOW TO REDUCE THE RISK

What is hot work?

Hot work refers to any task that requires using open flames or applying heat or friction which may generate sparks or heat.

More specifically, it is defined by the British Standards Institution (BSI) in BS 9999 as: “Any procedure that might involve or have the potential to generate sufficient heat, sparks or flame to cause a fire.” Examples of hot work includes welding, flame cutting, soldering, brazing, grinding and the use of other equipment incorporating a flame.

Hot work poses a particular threat within the construction sector as the cause of multiple fires in buildings.

For example, according to figures from the Scottish Fire & Rescue Service, who we contacted with a Freedom Information Request, there were 180 fires in the construction industry in 2018/19, a staggering 143 (79 per cent) of which were the result of hot work.

Fifty-one fires during this period were caused by welding or cutting equipment, 22 by manufacturing equipment and 23 by kilns or other services. These fires resulted in 21 casualties.

The most common examples of hot work and those that can pose significant risks without proper safety precautions are for example:

  • Brazing and soldering
  • Gas/electric welding cutting apparatus
  • Grinding wheels and cutting discs
  • Thawing pipes
  • Open flames, blow lamps and blow torches
  • Bitumen and tar boilers
  • Hot air blowers and lead heaters.

A variety of industries, construction in particular, may require hot work to be carried out in their premises as part of routine work activities. It is also frequently carried out as part of contractual work, which is common in construction. However, no matter who does it, they must know what kind of hazards hot work presents and how to prevent it from causing harm.

The fire hazards posed by hot work

Flying sparks are the principal risk posed by hot work and they can easily get trapped in cracks, pipes, gaps, holes and other small opening, where they could potentially smoulder and cause a fire to break out.

The debris and residue which hot work creates, such as flammable swarf, molten metals, slag, cinder and filings, are often combustible.

Hot work can cause pipes to substantially heat up and easily transfer, through the process of conduction, to another flammable surface and cause a fire.

Failure to remove flammable materials or substances from a surface before commencing work means that they could easily become hot and cause a fire.

In certain environments, there may be potentially explosive vapours or gases in the air which are highly combustible and could ignite if exposed to hot work. In a similar vein, hot work could generate fumes which, in turn, create an explosive atmosphere.

The consequences of these hazards can be severe and costly for any business. Injuries can result in workers taking time off work, while a serious fire could damage a building irreparably. Both of these could even lead to legal consequences under certain circumstances. Therefore, it is crucial to understand how to implement appropriate safety controls.

Injuries caused by hot work

There are direct personnel hazards to those involved in the task or those working nearby.
Hot work may cause injuries, such as:

  • Skin burns, eye burns and electric shock
  • Overexposure to welding or flame cutting fumes
  • Personnel working in the area or passing by can be also injured from sparks. Especially if the area is not properly isolated, access is restricted or there is no additional protection such as fire blanket.

Control measures to minimise the risk of hot work fires

Due to the high risk nature of hot work, the BS 9999 and the Health & Safety Executive (HSE) outline various safety procedures which organisations must adhere to. Their aim is to protect workers from dangerous aspects of hot work and to prevent fires from breaking out.

Measures to make hot work safer

BS 9999 states that “hot work should only be undertaken if no satisfactory alternative method is feasible.” Therefore, it is important to consider every possible alternative for completing a task before deciding to proceed with hot work.

For example, instead of welding, determine whether bolting is a suitable solution. In a similar vein, avoid torch cutting by using a handheld hydraulic shears instead.

In some situations, hot work is unavoidable. If this is the case, a permit must be created before the work starts. A permit is crucial as it sets out the safety measures which everyone must follow to minimise the risks associated with the work.

Creating a Hot Work Permit

Due to the level of risk posed by hot work, preparing a hot work permit is mandatory. According to BS 9999 “a hot work permit procedure, which may be part of an overarching safe system of work/hot work permit procedure, should be followed before any hot work is allowed in or near a building. This is to ensure that correct actions are taken before hot work commences, during the operation and afterwards.”

To fulfil this requirement, people need to know how to create a hot work permit.

Sections include:

  • Details of the work. What type of hot work needs carrying out?
  • Hazards and risks. What are the associated risks of the hot work?
  • Precautions and procedures. What steps will be put in place and apply before and during the work?
  • Personal protective equipment. Do people need to wear protective goggles, face masks and gloves?
  • Reference to isolation certificates. Does any nearby equipment need isolating before work can start?
  • Authorisation and acceptance. This includes those involved in creating, implementing, and following the permit.
  • Training and competence. Do people need any training before they can carry out the hot work?
  • Handover procedures. If the people doing the work swap shifts, what procedure will the workplace follow to ensure they change over safely?
  • Hand back and cancellation procedures. Once the work is completed or needs cancelling, who is in charge of managing this?

Understanding the tasks and knowing precisely who is involved makes a permit fairly straightforward to prepare. A competent person who is not directly involved in the hot work must prepare and authorise the plan but the input and commitment from everyone taking part is essential.

Housekeeping

One of the most crucial ways to prevent fire hazards posed by hot work is by clearing the area before starting. This involves removing flammable and combustible materials and liquids within a five-metre radius of the work. If overhead hot work needs carrying out, then site managers may need to extend this radius.

It is also vital to ensure that the atmosphere does not contain flammable or explosive vapours, gas or dust. If there could be an issue, gas or vapour monitoring should be carried out.

Protecting areas

Hot work often produces sparks that can easily get into holes or gaps in floors, walls, and ceilings or smoulder on combustible materials. Therefore, take the time to cover these areas with suitable flameproof sheeting, purpose-made blankets, drapes or screens before commencing work. Combustible floors can also be covered with damp sand to prevent ignition.

Where unable to fully clear the area of combustible materials, use appropriate flameproof covers on them but make sure to cover them completely and monitor the area closely.

Designated areas

It is vital that hot work takes place in an area designed specifically for it, but some areas will understandably not be specifically built to withstand it. For example, if a contractor needs to carry out welding work on a pipe in a staff room kitchen, this is not an area of the building specifically designed to minimise hot work risks.

However, it is perfectly possible to assess an area and prepare it for hot work, such as by applying protective covers as discussed above. This applies equally to five-minute jobs just as much as it does to a task that takes longer.

Fire safety systems

Those carrying out and supervising hot work must understand the fire safety procedures that are in place.

In particular, they should be aware of:

  • Whether the area has a sprinkler system and whether or not it is active.
  • How to activate the alarm, where to evacuate during an emergency and how to contact assistance or the fire authorities.
  • How to prevent false alarms. Do certain detectors need temporarily deactivating? If so, these must be reactivated as soon as the work finishes.
  • Which fire extinguishers are necessary. At the very least, the person in charge of supervising should receive fire extinguisher training. Furthermore, the site should have at least two appropriate extinguishers available, based on the type of hot work being carried out.

Finishing the work

Once hot work activities cease, workers must properly deal with the materials used.
For example, people are required to:

  • Fully extinguish LPG blow lamps and torches and allow them to cool after use. Remember to also let them cool down before changing cylinders and to fully remove the gas cylinders upon completion of the work.
  • Properly switch off, unplug and cool down electrically-powered hot air blowers before returning them to storage.
  • Submerge stub ends of welding rods in water before safely and appropriately removing and disposing of them from the site.
  • Clear up the area if the hot work produced flammable materials, such as metal filings.

Supervision

Appropriate supervision of hot work is beneficial for monitoring safe working practices, but is primarily necessary for checking the environment afterwards. A fire watch must remain within the area for at least an hour after the work finishes to ensure a fire does not start. This is crucial, as it is difficult to see a spark that has gone down a hole until it starts smouldering.
A fire watch can be anyone who is responsible and aware of the risks, such as a supervisor or someone who was involved in the work. They must have received fire extinguisher training and should monitor the main area where the work occurred, as well as any adjacent rooms and the floors immediately below and above it. Doing so ensures they are prepared to immediately suppress any smouldering or fires and prevent an emergency.

Legislation and guidance

There are at least three main pieces of legislation and two guidance documents which apply to any hot work carried out as part of construction activities:

1. Regulatory Reform (Fire Safety) Order 2005 (England and Wales), while Scotland has different legislation called The Scotland Fire Act 2005 and the Fire Safety (Scotland) Regulations 2006. This requires that a suitable and sufficient Fire Risk Assessment (FRA) is carried out at the site location in question.

Where hot work is carried out, this also requires a Permit to Work (PTW) system be implemented alongside a specific Hot Work Permit (HWP). The HWP is an appendix to the FRA and it makes the use of an HWP a legal requirement.

2. The Health and Safety at Work Act 1974, which provides the framework for a safe system of work.

3. The Construction (Design and Management) Regulations 2015, which aim to improve health and safety in the industry by helping people to sensibly plan their work so the risks involved are managed from start to finish.

4. HSG 168, which is a health and safety document from the HSE to manage fire risk in construction activities. It is worth noting that it is the expectation of the HSE, as the enforcing authority for fire safety issues in construction activities, that any hot works carried out on or near a building require an HWP.

5. A Joint Code of Practice, which is produced by the FPA and RICS for jobs costing more than £2.5 million, but can be applied to smaller jobs. It shares a lot of crossover material with HSG 168.

Here at CE Safety we provide Hot Work Passport Specialist Fire Training to expertly address these points, all in one place. It was introduced in response to requests from the construction industry for courses that can be used to indicate a level of competence in fire safety for both hot work operatives and project managers who, as part of their role, may issue HWPs.
The course offers advice around legislative requirements, contractor duties, risk assessments, fire prevention measures, hot work cutting equipment, creating permits, emergency procedures involving gas cylinders and storage of fuel gases.

The course ultimately provides a comprehensive guide to keep risks to a safe minimum and complete the hot work without any issues, such as the threat of fire or injury.