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Managing the risk of gas migration

The petroleum process industry represents a significant contribution to the global economy and is regarded as one of the largest energy industries. It is an extremely high-risk industry, with its downstream sector causing no less of a concern in regards to its Health and Safety and environmental risk. Throughout the refining process a variety of chemicals are produced such as; petrol, kerosene, jet fuel, diesel oil, heating oil, fuel oils, lubricants and liquid petroleum gas (LPG). These chemicals obviously need to be carefully handled and stored, more so when these products touch the consumer sector within petrol forecourts.

Although the industry has made significant improvements with the construction of petrol forecourts and the underground storage of fuel on these sites, my role sees further challenges in areas needed to help prevent gas migration and minimise the risk of injury or even an explosion.

During my many years of experience within this sector and specifically the water and gastight sealing of underground cable ducts and building entries, I have become aware of the importance of implementing the right process at each stage of the project to ensure any risks are minimised. Many incidents take place resulting in asphyxiation, injuries or loss of life from flammable substances accidentally catching fire or exploding and incidents leading to gas migration in the industry currently remain higher than they should. Taking a more robust approach to identify potential areas of risk and developing strategies to mitigate issues will help the industry become more consistent in operational excellence.

Supporting Improvements
Employers not only have a moral duty to protect their employees but are also required by General Health and Safety Legislation to provide their workers with protection in line with the details described by the Dangerous Substances and Explosives Atmosphere Regulations 2002 (DSEAR/ATEX). This also includes members of the public who are also deemed to be at risk.

The Health and Safety Executive (HSE) will enforce the regulations in Industrial premises, with the regulations being enacted upon under the Health and Safety at work regulations 1974. Local authorities, Fire Brigades and Petroleum Licensing Authorities will also be closely involved in ensuring compliance.

In my experience, dealing with these issues, the introductions of strict regulations and written specification documents have significantly increased standards. I have seen many examples both good and bad in attempting to prevent the migration of hazardous substances. Some of the bad include the use of inappropriate materials and methods of sealing; newspapers and plastic bags have been notoriously used as “bungs” in penetrations during an attempt to create an effective cable duct seal.

Some of the other recent issues I have seen on site include:- 

  • Too many cables running through a cable duct - Over populated ducts can prevent the adequate separation of cables which is essential when ensuring a gas tight seal.
  • Cables not separated within a cable duct – This will lead to leak paths running through the void when cables are bunched together. Even three cables within a duct can cause this issue (see fig1.)
  • Inappropriate sealing materials used to seal a duct – These can degrade over a relatively short period of time, especially when in contact with volatile organic content (VOC’s)

We can see the improvements in specifications when we look at, for instance, the current APEA (Association for Petroleum and Explosives Administration) specification, which provide detailed guidelines and specifically describing the requirements within the sealing material installation, i.e. “Where sealing compound is used to seal a duct, the inner wall of the duct and the cable sheath(s) should first be cleaned to ensure that the sealant adheres to the surfaces. Suitable spacers should then be inserted to space the cables apart to ensure that the compound is able to completely fill the spaces around the cables and also to minimize penetration of compound further into the duct” other specifications indicate how long a product is age tested for i.e. “ the sealing material should be age tested to 20+ years”  or how much cable capacity is allowed within a duct to help with cable separation (which is one of the key requirements in trying to seal penetrations) i.e. “All ducting shall have no more than 30% cable capacity within them to enable a sealing system to be installed”. This level of direction is a great step forward from previous specifications, which simply referred to “all ducts should be sealed”.

Since 2010 the ‘EI Technical guidance for filling stations’, also known as the ‘Blue Book’ is the established technical guidance on providing information about storage and dispensing of petroleum products used as fuels for motor vehicles (including petrol, diesel and autogas). This information is aimed at minimising the risks from fire, explosion, to health and to the environment.

Products that comply with regulations such as DSEAR/ATEX and the “Blue Book” provide peace of mind for clients to include within the project at specification stage. All this said any sealing solution is only as good as its installation. One of my main aims within this industry is to educate contractors and end users of their responsibility and to help them understand how important achieving a compliant seal can be in reducing the risk and potential danger associated with gas migration. At the end of the day people’s lives could be put at risk.

Who’s Responsible?
For gas migration safety to improve, the industry must acknowledge the risk and effects of using non-compliant sealing products. Enforcement by the regulator HSE under the DSEA R and ATEX regulations can only go so far. Many industry workers are unaware if gas safety detectors in their workplace function correctly. In a gas migration incident employees could remain unaware they have been exposed and put at risk as many of the gases released are odourless and colourless. The Control of Hazardous Substances to Health (COSHH) includes regulation: “7:1; that the employer should ensure exposure is prevented or if this is not possible, adequately controlled.”

If you are involved in the provision of a fire protection package, at any level, then you share liability for its usefulness, operation and provision of information under Building Regulation 16B that tells the user of the building about the fire prevention measures provided in the building. Otherwise the user cannot make an effective risk assessment under the Regulatory Reform (Fire Safety) Order 2005. Where a system also provides fire protection and prevents gas migration into hazardous areas, it is now a legal obligation for the specifier, owner or main contractor to ensure a contractor can prove competency for the materials used, or the works to be carried out.

All cable and pipe penetrations or building entries should be sealed according to the degree of fire resistance (if any) for both integrity and insulation, and any water tight and gas tight integrity must be reinstated to the same level required for the boundary before the penetration was made. In addition for bund walls and plinths any penetration seal must continue to provide protection from any leakage of transformer oil. 

Under pressure
The raising of standards and introduction of specification also helps to create a level playing-field within the commercial aspects of sealing. We live in a highly commercial world and in my experience, historically, profit and the competition of business hasn't helped with regards to sealing and safety. When the profit-safety equation is thrown into the commercial world, without specification & regulation profit usually wins. This can lead to substandard sealing materials being used as contractors look at savings and ways to be competitive on price and achieve success with tenders. Unfortunately in some cases this cost cutting has the potential to put assets at risk and also endanger the health and safety of any people on site. It's now commonly acknowledged across a number of industries that builders expanding foam is not compliant when trying to create a gas tight seal, but before regulations, specifications and guidelines were introduced it was a common practice to squirt foam into a penetration in the vain hope it would create a seal. 

As things move forward and business, associations and authority's start to find a balance, specification and regulation makes it much easier in my drive to educate and help resolve on-going problems and difficulties associated with all aspects of sealing on a variety of different projects.  

It’s good to see installation contractors now taking a bigger interest in the different types of sealing products that are out in the marketplace with companies, not just looking to see if a product meets specification but also looking at criteria such as ease of installation or if a contractor has the responsibility of maintenance work on a site after the build, how easy or difficult it is to re-enter a sealing system to add, remove or replace a cable or pipe. 

This in turn drives the education process forward, something that I am proactively involved with at CSD Sealing Systems, supported by the company providing instructional installation videos on its website and also getting involved with numerous industry toolbox presentations. In the past it was sometimes perceived negatively if you offered help, often presuming you were intimating that a contactor were incompetent if you had to help show them how to seal, nowadays company’s are much more willing to participate in toolbox talks and training sessions to support their employees training and development as well as quality control and continuous improvement processes.

I have recently had some extremely productive toolbox events with a number of Fire Officers discussing various different aspects of sealing, especially the difference of sealing against gas and liquid migration which comes under the banner of fire prevention rather than the sealing against fire which is fire containment! These toolbox talks are a great way to pass and share information between us and as I mentioned before, the better educated we are the better standards will become.

The cost and time it takes to implement risk prevention processes and strategies will be insignificant when compared with the actual and reputational costs facing companies who have responded to a crisis situation.     

Further information
For further information surrounding DSEAR, gas detection and the prevention of gas migration in the workplace please read the useful information provided by the Health and Safety Executive on their website at