The Dangers of Hot Works in HazMat Environments

September 14, 2017

Introduction: Hot Works

After a recent incident, the HSA has issued a safety alert, a person who carried out hot works on empty hazardous waste containers was killed due to residue being present in the container. The operator had been using an oxy/propane torch to cut up the tank. It exploded with such force that one end of the tank flew over a fence and into the premises next door. This tragedy has accelerated the need for ensuring best practices for carrying out hot works in zoned areas where hazardous materials are stored.

The aim of this article is to portray the importance of employing best practice when carrying out hot works in an environment where hazardous materials are present.

Statistics on hot works

Read more about fire risks at Health & Safety Association here.

Materials Which Can Cause Fire & Explosion:

Flammable liquids and vapours such as petrol, diesel, fuel oil, paints, solvents, glue lacquer and cleaning agents all can leave residue in the container in which they are stored.

Hot work can be defined as a process that involves welding, soldering, brazing, cutting, grinding, drilling and burning or melting metals or other substances such as glass. Use of open flame in the furnace or sparks or such ignition tools are considered hot work procedures. These types of work are fire hazards when flammable material is present or not. Hot work procedures require a hot work permit from the safety department of the factory or the establishment before the workers begin, (safeopedia).

Hot Work Permit:

In accordance with University of Limerick guidelines emphasis and responsibility lies with the employer when obtaining a hot work permit. Employers should ensure that the area in the immediate vicinity of the hot work is fully secure.

In particular, you should ensure that:

  • Before starting hot work, an area within at least 10m of the hot work process is cleared of all loose combustible material and if work is to take place on one side of a wall or partition the opposite side is examined to ensure no combustible material will be ignited by conducted heat.
  • Where combustible materials cannot be removed from the area, they are completely protected by non-combustible screens or blankets.  Flammable liquids must always be removed from the area. It is crucial the hazardous materials are stored in the appropriate manner and in the designated stores to remove the threat of combustion. This is where our new software Chemstore Connect allows for the seamless management of hazardous materials on site.
  • Combustible floors are covered with overlapping sheets of non-combustible material.
  • That the floor is swept clean of combustible materials.
  • That all wall and floor openings, and all gaps in walls and floors through which sparks could pass are covered with sheets of non-combustible material. This is where Chemstore ensures all our fire rated walls are designed and certified from one to four hours depending on the legislation associated with the chemical in question on site.
  • Good ventilation is provided in all areas where hot work is being carried out.
  • Where work is above floor level, that non-combustible material is suspended beneath the work to collect sparks.
hot works safety permit

Measures Can Be Taken to Reduce Hot Work Risks

Risk Assessment

Before carrying out this procedure a risk assessment must be carried out. Employers are legally required to access the risks in the workplace and  must carry out an assessment of the risks. Safe options should be considered such as should containers be replaced rather than being repaired or using cold cutting or cold repair techniques. If hot works are necessary, the risks should be avoided by using a specialist company or reduced by using methods such as gas-freeing, cleaning or inerting.  A common pain for Environmental Health & Safety Officers is the inability to create a risk assessment report. Chemstore has designed a software called Chempli which offers our clients access to a seamless software platform where a risk assessment report can be created while on-site by using a handheld device such as a tablet.


All hot work supervisors and operators must receive hot work training. The training must include the safe practices for hot work, required personal protection equipment and fire extinguishing use. Drums, barrels, tanks or other containers should not be exposed to hot works unless absolutely necessary and the person involved has had adequate training in the risks involved and the precautions to be taken. Best practices as per the ISO 9001:2015 is to efficiently manage the required training for each employee for risks eg. manual handling. The HR & Training module which can be used on Chempli enables the user to identify staff training requirements through the use of an online training matrix


The preparation of a tank should be considered as a part of the risk assessment. The appropriate control measures need to be identified and addressed.


It is a requirement that tanks must be isolated from other equipment. This can be done by removing pipe sections. If possible disconnect small tanks and then transfer them to a safe environment.


Emptying the tank or drum should be emptied by pumping or draining the liquid into a designated container. The residue should then be disposed of in accordance with the environmental requirements.

hot works


Cleaning will be necessary in most cases. There are numerous ways to do so:

  • Washing or jetting using water or detergent solutions
  • Steam cleaning
  • Solvent washing/jetting


Vapours and other volatile material can be removed by blowing air through the tank a method known as gas-freeing. The vapour concentration should be monitored using a gas detector. Gas-freeing on its own is rarely adequate as most containers will still contain residues. A gas detector may not detect these residues and may still be flammable when coming in contact with hot works.


Attempting to inspect the inside of a storage container can be an extremely difficult process. Mirrors and torches can be used but any light that is used must be flameproof.


Another way to reduce the risk is to fill the storage container with water or an inert gas such as nitrogen. This can be useful although the tank must be cleaned as much as possible beforehand, (

Chemstore Compliance Chempli

Over the last eighteen months, Chemstore has been developing a new and innovative software which we are now proud to introduce Chemstore Compliance. This software is designed to aid Environmental Health & Safety Officers in the management and control of their organisation’s hazardous materials; improving compliance, lowering costs and reducing risk. This user-friendly software is equipped with a suite of modules. The six modules offered include a Document Library, Inventory Management, Risk Management, Site Map, HR & Training and an Inspection & Maintenance module. These modules are designed to provide an organisation with a cost-effective management system, control and workflow functionality.

Each Chemstore unit is allocated a QR Code which can be scanned remotely through mobile devices. This then allows the user to access all information associated with the Chemstore unit on Chempli instantly.

To speak with a Chemstore sales engineer you can get in touch here.

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