It is hard to imagine that a little over 150 years ago, the discovery of oil was often met with disappointment. Initial finds were the result of digging to find water or brine, a source of salt, they were unhappy when they struck oil.
In 1854 the kerosene lamp was invented and created the first large-scale demand for petroleum. Kerosene was originally made from coal oil, found to burn cleanly enough to compete with whale oil as an indoor lighting fuel.
In 1859, at Titusville, Penn., Col. Edwin Drake drilled through rock and claiming the first successful crude oil well. This was commonly known as the birth of the modern petroleum industry which sparked the international search for an industrial use for petroleum.
An Extremely Hazardous Industry
Forward to more recent times and in 2019 and it is estimated total world oil production in 2019 averaged 80.6 million barrels per day. As extraction, service and storage of oil and gas have advanced so have the protection of these assets and those responsible for their operation. This brings added risk of a potentially explosive atmosphere where a mixture of air, gas, vapour, mist, or dust combine in a way that can ignite under certain operating conditions. The Oil and Gas industry is no doubt one of the most hazardous industries in the world. The presence of gas and vapours may be constant and the potential for explosion is far greater than most sectors.
You only need to look at the World Offshore Accident Database to realise how hazardous the Oil and Gas sector can be. The WOAD (World Offshore Accident Database) reports accident data for diverse offshore facility types. It has been curated since 1975 by DNV GL.
As we evolve so does the equipment for use in these environments. By reducing the risk in any of these areas and providing robust and safe components then it will lead to safer working environments for everyone.
Hazardous area circuits and enclosures play a critical role in these challenging environments. From low voltage circuits to explosion-proof enclosures the range of products is extensive. The system may only need to perform once, however, when it does it needs to be up to the task.
Hazardous Area Classification and Control of Ignition Sources
In such cases, it is common for three types of hazardous area applications to be considered.
Intrinsically safe: (IS) Intrinsically safe circuits are designed to operate at really low currents. This means, in the event of a component failing there is not enough load in the circuit to create a spark and in turn a potential explosion. The application of this method is, obviously, limited to low power circuits. It is not possible to start an engine or to illuminate a plant using intrinsic safety equipment.
Increased safety: (Ex e) This protection method applies measures to prevent the formation of arcs, sparks or temperatures which can ignite the explosive mixture, therefore guaranteeing a high safety coefficient. This is normally achieved by isolating or protecting two elements carrying current from arcing or coming in to contact with each other.
Explosion-proof: (Ex d) Explosion-proof products are the most used and designed with extreme precision. These products must show they can prevent a spark reaching any explosive environment. This process is achieved by either containing the explosion within a housing or showing capabilities to quench the flame before entering an explosive environment.
This method can be applied to all low-voltage equipment such as lighting fixtures, panel boards, switches, command, control and signalling units, transformers, low and high-voltage motors and, generally, all equipment which can cause sparks or over-temperature during normal operation.
Rigorous Standards for ATEX Equipment Manufacturers
The locations or zones these products are certified is also quite detailed. They will be marked with conditions of use, temperature classes and specific gases or liquids each certified product has successfully been tested. Each product will carry a mark or logo showing which certified body carried out the testing.
Upon successful completion of testing, a full product approval licence will be awarded. This licence will be issued by a registered approval body and list the exact scope of their product. These certificates must be studied carefully to ensure the description of the product on the licence matches the application you require.
Every manufacturer or supplier of hazardous area product must be able to show the complete traceability of their product. Each item will be given a batch number, test record and supported with Declarations of Conformance when required. The supplier of the products is giving absolute confidence that in the event of an explosion, fire or leak their product will perform each time. They will also need to demonstrate process control where they can consistently maintain tolerances or specifications that play a detrimental role in achieving their product approval certificate.
Inspection and verification play a substantial role to ensure the test report or declaration issued by the supplier is not just a piece of paper. Control of records and documentation is monitored closely, and evidence must be shown that records of any product supplied into hazardous locations have been kept for 10 years after the life cycle of the product.
To achieve a hazardous area product approval, the manufacturer or supplier must hold appropriate Quality Management System Approval. Their facility will be audited at least annually and show evidence of how their controls and process ensure product conformity. They will need to show evidence of a robust product recall procedure in the event of a non-conforming product entering the marketplace.
Every drawing associated with a hazardous area product would be endorsed by the approval body. The manufacturer must show how these drawings are controlled. They must show how these drawings are communicated to any supplier that provides critical elements into the product. Each drawing must show where critical dimensions can be found and any flame paths specific to the product.
The amount of resources placed for monitoring and controlling these procedures is high but ensures a consistent conforming product every single time. As expected, the price of these precision components will be slightly more than those not controlled or monitored. However, the peace of mind in the oil and gas sector far outweighs any cost considerations.
One example that is particularly overlooked is cable and glands systems. These are the heartbeat of applications used within the Oil and gas industry. Not only will the cables need to be capable of surviving the harshest of conditions but their termination system must prove it’s capable of playing its part to greatly reduce the risk of creating a spark or preventing one from entering the explosive atmosphere. The risk of a leaking gland system or underperforming cable could prove to make the headlines for all the wrong reasons.
In many cases, the cables will require some form of fire protection, the highest rated fire performance cable on the market today is a fire-resistant cable.
The purpose of a fire-resistant cable is to continue to supply critical circuits with power when exposed to extreme fire conditions. This is achieved by protecting the vital conductors feeding the circuit. To meet the criteria of a true fire scenario you would expect as a minimum:
- A raging fire including the risk of flashover.
- Falling debris and movement of walls or floors
- Water exposure either from a sprinkler system or fire hose
Applications where a fire-resistant cable would be specified may include emergency lighting, emergency shutoff systems, sprinkler systems, extraction systems, smoke dampers and shutters, emergency generators, pressurisation fans, emergency voice communications and fire alarm panels, smoke detection systems.
Depending on its construction the manufacturer achieves the protection of the solid or stranded conductors with insulation such as magnesium oxide (MgO), MICA tapes or polymers. The insulation is then protected with an outer sheath which is commonly either a copper, steel wire armoured or a fire-resistant polymeric sheath.
To meet the requirements of a fire-resistant cable the construction must meet their own British Standard related to the manufacturing process and the British Standard appropriate to their type of fire-resistant cable.
All types of fire-resistant cable will be approved to a British Standard but as the recent Grenfell enquiry found do these products perform in a true fire scenario. Two quite different products, different constructions, different diameters, and fire performance materials. Even different types of conductors can all still fall under the same umbrella and “meet the Standard” Not only should these cables perform during a fire they are also used in hazardous areas, but you also need to be certain a cable, a gland and its associated seals will all perform together when needed.
One type of fire-resistant cable that is different from any other in its class is Mineral Insulated Cables or MICC cables. Commonly known as fire survival cables the unique construction gives protection during a fire up to the melting point of copper at over 1080C.
Whilst many know of mineral cables’ reputation for its fire performance, its advantages in most oil and gas applications is often overlooked.
Constantly Evolving for Improved Cable Safety and Certification
Wrexham Mineral Cables are the UK’s only manufacturer of Mineral Insulated Cables. Having held hazardous area ATEX approvals since 1991 they are extremely proud of their exceptional safety record within the Oil and Gas sector. They estimate to have supplied over 50 million cable glands and over 180 million metres of mineral insulated cable to date and have recorded no in field failures. In 2018 the company achieved IEC Ex approval which demonstrates their further capabilities to supply consistent, high-quality products from the UK’s only manufacturer of mineral insulated cables. WMC take their Standards and Approvals very seriously and are extremely proud to be where the brand is today. The cable gland system offered by WMC comes
with a full 30-year system warranty and manufactured only in the UK.
Steve Williams, Commercial manager of Wrexham Mineral Cables: I have never come across a cable system like mineral insulated cables. When you consider every single cable size has its own unique gland system it is hard to think of any other type of fire performance or hazardous area cable system like this in the field. The advantages of a fully ATEX approved mineral insulated cable system is something that WMC have looked at sharing in detail. The element of risk, additional costs and poor installation techniques are something that has been overlooked. A true fire scenario test is crucial and WMC gave recommendations to the Grenfell enquiry on ways to improve Fire Performance testing. We aim to share our recommendations, observations, and findings in future publications which we hope will raise awareness when choosing safety-critical products, particularly in the Oil and Gas industry.
For more information, go to www.wrexhammineralcables.com
About the Author
Steve Williams is Commercial Manager, Wrexham Mineral Cables Ltd.
