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Life Or Death Options

Published: 04th Sep 2013 in OSA Magazine

A focus on the use of flame retardant PPE to guard against arc flash

Personal Protective Equipment (PPE) refers to any clothing such as gloves, goggles or any other equipment that is designed to protect the person wearing it from injury or illness. Health and safety professionals will tell you that PPE should only ever be used where there are risks to someone’s health and safety that cannot be controlled in other ways. In other words, PPE should be seen as a last resort.

The Asian Development Bank’s Asian Development Outlook 2013 estimated that regional economic growth in the Asia Pacific region will pick up to 6.6% in 2013 and reach 6.7% in 2014. 

As demand for home sourced income grows, Asia is becoming an important part of oil and gas exploration and drilling. As the oil and gas industry develops in the region, so too will the need for appropriate PPE to protect the workforce from some of the extremes it will face in such a hazardous industry.

This article focuses on protective clothing – specifically fire retardant clothing used in the electricity and oil and gas industries. It will take you on a journey from the first attempts at manufacturing flame retardant fabrics through to the innovations of today.

General protective clothing

Think of the hazards: temperature extremes, adverse weather, chemical or metal splash, spray from pressure leaks or spray guns, impact or penetration, contaminated dust, excessive wear or entanglement of own clothing. 

To protect against hazards such as these your options include conventional or disposable coveralls, boiler suits and specialist protective clothing; for example, chainmail aprons or high visibility clothing. The choice of protective materials includes flame retardant, anti-static, chainmail, chemically impermeable, and high visibility. Don’t forget other protection, like safety harnesses or life jackets. 

When looking for the right PPE the body needs to be considered as a whole, and the different hazards faced in the workplace also need to be identified – these can vary from job to job.

When it comes to choosing the right PPE suppliers can be approached for advice on the types available and its suitability for different tasks, but if you are still not convinced, you may want to approach a specialist. 

In the world of occupational health and safety, when it comes to PPE the hierarchy of controls needs to be considered. This is outlined in the bullets below:
1. Elimination – Redesign the job or substitute a substance so that the hazard is removed or eliminated; for example, duty holders must avoid working at height where they can.

2. Substitution – Replace the material or process with a less hazardous one. An example of this would be using a small mobile elevated work platform to access work at height instead of a step ladder. Care should be taken to ensure the alternative is safer than the original.

3. Engineering controls – Use work equipment or other measures to prevent falls where you cannot avoid working at height. Install or use additional machinery such as local exhaust ventilation to control risks from dust or fumes. Separate the hazard from operators by methods such as enclosing or guarding dangerous items of machinery/equipment. Give priority to measures which protect collectively over individual measures.

4. Administrative controls – These are all about identifying and implementing the procedures you need to work safely. This could include reducing the time workers are exposed to hazards by job rotation, prohibiting use of mobile phones in hazardous areas, increasing safety signage and performing risk assessments.

5. Personal protective clothing and equipment – Only after all the previous measures have been tried and found ineffective in controlling risks to a reasonably practicable level, must personal protective equipment be used. If chosen, PPE should be selected and fitted by the person who uses it. Workers must be trained in the function and limitation of each item of PPE.

Origins of flame retardant clothing

Flame retardant or fire resistant fabric is a common feature in clothing designed for the industrial sector. Firefighters are the most frequent wearers of flame retardant clothing, but other professions including electricians and oil and gas drillers make use of it too. 

The earliest attempts at making fabric fire resistant were in 1632 when it was suggested that fireproofing the textiles would reduce fire risks in theatres. The first materials used in this process were clay and plaster of Paris. Moving forward to the 18th Century, the inclusion of alum and ammonium phosphate added to methods of making fabrics fire retardant.

It was not until 1820 that French chemist Gay-Lussac tested the success and failings of making fabrics flame retardant. He concluded that there were two types of salts capable of resisting flame: the first, low melting and able to form a glassy layer over fabrics, and the second broke down into a non-flammable vapour when it was heated. By the early 20th Century this work was furthered, and chemists incorporated stannic oxide into fabrics to make them flame retardant.

In the electricity industry

Electric arcs pose some of the most serious safety hazards for electric power industry workers. Arc blast or flash hazards include extremely high temperatures over fractions of seconds, hot gases, and an intense pressure wave from the explosion. This results in molten metal particles both vaporising and dispersing into flying fragments. 

Arc-related injuries can range from minor to severe burns, blindness, hearing and memory loss from the pressure wave, broken bones, or death. When a worker is exposed to an arc, the clothing they wear plays a significant role in the severity of the potential injury and can even be the difference between life and death. 

Following the principles of all PPE, with protective clothing in these environments it is essential that:
• Workers are trained in the potential hazards of electric arcs and the flames they can produce by igniting other materials in the area

• Workers are prohibited from wearing clothing which, in the presence of an arc, can potentially increase the extent of injury; for example, if the clothing would ignite and continue to burn, or if it melts on the skin. Hence workers are generally prohibited from wearing clothing materials made entirely of, or blended with, synthetic materials such as acetate, nylon, polyester, or rayon 

There are some specifics that must be taken into account when working with electricity. Clothing made from 100 percent cotton or wool may be acceptable if its weight is appropriate for the flame and electric arc conditions to which a worker could be exposed. 

As heat levels increase, these materials will not melt, but they can ignite and continue to burn. The amount of heat required to ignite these materials depends on a number of factors including the weight, texture, weave, and colour of the material. 

Clothing does not comply with standards if it can ignite and continue to burn under the electric arc and flame exposure conditions found at the workplace. If flame retardant clothing is not selected, employers need to make a determination of whether or not the clothing worn by the worker is acceptable under the conditions to which he or she could be exposed – in other words you must justify your actions.

In the offshore industry

The largest risk to those working in oil and gas are ‘flash fires’. A flash fire is a fire that spreads rapidly through a diffuse fuel, such as dust, gas, or the vapours of an ignitable liquid.

The intensity of a flash fire depends on the size of the gas or vapour cloud. 

Hydrocarbon (oil and gas) flash fires generate temperatures of 1,000 to 1,900 degrees Fahrenheit. The duration of a flash fire can last up to five seconds. Inherent flash fire hazards are associated with oil and gas well drilling, servicing and production related operations. Additionally, the industry has a history of burn related injuries and fatalities due to flash fire hazards when engineering and administrative controls have failed. 

One of the challenges for the oil and gas industry is that nature dictates where the work happens. In terms of geographic location some workers may have to endure extremes of environmental temperatures. This huge fluctuation ensures that manufacturers have to be able to offer many different types of garments in differing weights and constructions, bringing forth the need to balance protection with comfort in order to work effectively. 

All of the fabrics currently available can be divided into one of two categories: ‘Inherent’ or ‘Treated’. Garments manufactured from Inherent fabrics are robust and will retain their flame resistant properties through washing and cleaning. The majority of Treated garments offered in the workplace are 100 percent cotton which has been treated with a chemical that extinguishes flames on the fabric within a second or two, although a limiting factor with this type of fabric is that the flame retardant treatment will deteriorate with washing. 

The oil and gas industry has worked hard to reduce the risk of flash fire incidents, but these efforts have not eliminated their occurrence completely. The use of flame resistant clothing greatly improves the chance of a worker surviving and regaining quality of life after a flash fire. It can significantly reduce both the extent and severity of burn injuries to the body.

The standards

It is imperative that the right standard of flame retardant protective clothing is selected. This process is not always as straightforward as it may appear.

Flame retardant clothing has to conform to international testing standards before it can be offered in any marketplace. Currently there are the European Standard BS EN ISO 11612, the USA Standard NFPA 2112 (5), and also standards in Canada, Australia and other areas of the world. These standards are not wildly different but you must ensure that you follow the codes your employer adheres to in the country you are working.

Where the distinction is not clear it is advisable that you work to the more stringent set of standards. 

In addition to the main standard of BS EN ISO 11612 there are additional standards, for fabrics and garments for workers exposed to heat and flame such as standards BS EN ISO 14116 and BS EN ISO 11611 for limited flame spread fabrics. For finished garments within the oil and gas industry, it is the BS EN ISO 11612 which is relevant. 

The standard makes clear that workers caught in typical short duration flash fires suffer in the worst case scenario nothing worse than second degree burns to the areas protected by the garment. 

A second degree burn is an injury from which the body can recover completely. The European standards differentiate as follows:

Flame retardant Standards
EN 11611
Tensile strength
Tear strength
Burst strength
Seam strength
Dimensional change
Requirements of leather
Limited flame spread
Molten droplets
Heat transfer (radiation)
Electrical resistance

EN 11612
Heat resistance
Limited flame spread (A)
Dimensional change
Tensile strength
Tear strength
Burst strength
Seam strength
Convective heat (B)
Radiant heat (C )
Molten aluminium splash (D)
Molten iron splash (E)
Contact heat (F)

EN 14116
Flame spread
Tensile strength
Tear strength
Seam strength 

Arc Standard
EN61482-2:2009 live working – protective clothing against the thermal hazards of an electric arc – Part 2.

Anti-static Standards
EN1149 protective clothing – electrostatic properties. Anti-static clothing suppresses static charge, thereby preventing sparks, which might cause a fire or explosion. 

EN1149- 5 is a part of a larger system, seen below.

EN 1149 consists of the following parts:
EN1149-1: Test methods for the measurement of surface resistance
EN1149-2: Test methods for the measurement of the electrical resistance through a material
(vertical resistance)
EN1149-3: Test methods for the measurement of charge decay EN1149-4: Garment test method (under development)
EN1149-5: Performance requirements

EN Standards can be confusing, so you need to know what to look for. The term fire retardant as applied to organic (i.e. containing carbon) materials, might be better being referred to as reducing the fire hazard, as all will burn under certain circumstances. First of all, if you need specialist work clothing or protective clothing for those at risk, you need to look very carefully at what you are buying and who you are buying it from. Flame retardant clothing is a niche market and you need to buy from someone who is competent and who manufactures to the correct standards.

You may see varying symbols and codes written on labels. Over time the standards have changed. This does not necessarily mean that the old standards are defunct; it simply means that the new standards will make clothing even safer.

The safety standard for fireproof protective clothing was EN531. This has now been replaced by EN ISO 11612 – Protective Clothing for Heat and Flame. Requirements not only test the fabric used to produce the clothing, they also test the complete manufactured garment. This is to stop an influx of sub-standard flameproof protective clothing flooding the market with faulty seams, or additional materials used that do not conform. If you are ever in doubt check with the manufacturer. 

Innovation and the future

Innovations in fire retardant fibre and fabric products are raising protection to new levels, while keeping users more comfortable and giving them a greater range of fit and mobility. 

New clothing options are being designed for a wider range of body types, including products designed specifically for women. In addition, companies that develop these products are going directly to the users to find out what new innovations and applications are needed. 

The Limiting Oxygen Index (LOI) measures the amount of oxygen required in the environment for a fabric to support combustion. Any material with a LOI less than 20.95 – the oxygen volume of air – will burn in air. Fibres have been developed with a LOI rating of 55, indicating a required oxygen level of nearly three times that of air to burn. 

When exposed to intense heat or flame these fibres blend, carbonise and then expand, eliminating any oxygen content within the fabric. After intense exposure to 250° C, one particular fibre on the market claims to possess 100 percent of its original strength. 

Workers who are exposed to intense heat may have the outerwear clothing to protect them, but they are still subjected to potential problems if their base layer garments don’t perform as well. Companies have also developed moisture-wicking garments such as T-shirts, boxers and long pants in three weight classes to assist those in the military, fire fighting, utility and industrial fields. 

Those who work around fires or in deserts can be subject to steam burns from intense heat when they wear a basic cotton T-shirt under their protective gear. Developments in base layer fabrics draw moisture away from the individual’s skin and dry automatically. The material is now also likely to contain antibacterial and anti-odour components. 

References

Joanne Robitaille, eHow Contributor http://www.ehow.com/about_7371432_history-flame_retardant-clothing.html

Workplace Safety Awareness
Council, OSHA
HSE, Leadership and Worker Involvement Toolkit www.HSE.gov.uk
Du Pont Global www.dupont.com
NFPA 2112, National Fire Protection Association Standard on Flame-Resistant Garments for Protection of Industrial Personnel Against Flash Fire, 2007 Edition
MI Nelson, HS Sidhu, RO Weber and GN Mercer, (Received November 29, 1998; revised February 2, 1999) A dynamical systems model of the limiting oxygen index test, Cambridge University Journal
CarbonX product technology - http://www.carbonx.com/science-innovation.php

Published: 04th Sep 2013 in OSA Magazine

Author


Jane White


Jane White BA(Hons), MSc, CMIOSH
Chartered Safety and Health Practitioner

Jane White is research and information services manager at the Institution of Occupational Safety and Health (IOSH), based in the UK.
IOSH is the chartered body for health and safety professionals. With 40,000 members in 85 countries, the Institution is the world’s biggest professional health and safety organisation.

IOSH has a branch in Singapore and Hong Kong, with close links to other safety organisations in mainland China who actively promote ‘good’ workplace safety within the region. For more information about the groups visit www.iosh.co.uk

ith a background in facilities management, Jane began her career in public sector health, safety and wellbeing almost 10 years ago.
Specialising in health and safety for the education sector, Jane has created a number of training packages, and worked on various risk strategies for schools.


Jane White

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