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Hazardous Gas Defences

Published: 03rd Mar 2014 in OSA Magazine

Emerging as a geographical leader in production capacity for petroleum and petroleum product manufacturing, the petrochemical industry is one of the most prominent and growing industries in the Asia-Pacific region. The petrochemical industry is strategically important to the global economy, creating final products like plastics, soaps, detergents, solvents, paints, drugs, fertiliser, pesticides, explosives, synthetic textile fibres and rubber, flooring and insulating materials, and more.
The process by which these products are made is hazardous in nature, as petroleum related activities and sites, including refineries, chemical manufacturing plants, shipping terminals, and bulk storage facilities, have always been vulnerable to the danger of gas leaks.

Gas leaks, which come from the collections of well defined, usually pure chemical compounds that are found in petrochemical products, have the ability to cause serious harm if released, creating a critical need to monitor and control the potential release of hazardous materials into the atmosphere.

Emergencies that involve the release of hazardous materials are vastly complex, as are the potential social, political, financial, and ecological impacts that can turn such emergencies into disasters. 

These hazards can be mitigated with the proper implementation and use of gas detection systems to monitor the process activity of a petrochemical or related facility.

Gas detection regulation

Given the inherent risks of working with petrochemicals, as well as the number of people employed within the industry, monitoring the potential release of hazardous materials – more specifically, gas leaks – is essential to create a safer work environment. According to the Institute of Instrumentation Control and Automation based in Australia, compliance with increasingly tough safety regulations is a major factor to incorporate safety systems and toxic gas detectors for the oil and gas, refining, petrochemical, and mining industries. Additionally, it is projected that the worldwide market for toxic and combustible gas detectors will continue to grow within this year according to a new ARC Advisory Group study.

Workplace safety and health conditions are very different between countries, economic sectors, and social groups. There are currently no finite standards for gas detection practises in the Asia-Pacific region for the petrochemical industry. The International Labour Organization is working with 34 countries in this region to develop general workplace safety and health standards. For the purpose of this article, the standards and best practises of the United States, United Kingdom, and Australia are the primary references.

The need for gas detection

Gas detection systems measure samples taken from a known volume of air to determine whether or not a contaminant has been captured. Contaminants may result from leaks in piping that vent toxic byproducts of a manufacturing, biological, or chemical process from material stored within a confined space, or from toxic gases expelled during a maintenance operation. Modern systems are able to detect several toxic or combustible gases. When detectors measure a gas concentration which exceeds a preset, safe level, a series of audible and visible signs are activated, such as alarms and flashing lights.

Contaminants discovered by gas detection systems can pose serious health threats to workers. Contaminants can cause explosions and fires, exacerbate asthma, cause heart attacks, and harm circulatory, respiratory, nervous, and other vital life systems. They can also be linked to cancer, developmental disorders, and even premature death. Additionally, in Australia, records of air monitoring for airborne contaminants must be kept for a minimum of 30 years, and must be available to workers who are exposed, in case a record needs to be referenced for a future health issue.

Hazardous gases in the workplace can lead to three main risk situations that should be considered when monitoring gas activities at a petrochemical plant:

• Fire risk

There is considerable potential for fire to spread in a petrochemical or gas processing facility. Although not all concentrations of flammable gas or vapour in the air will burn, a hazardous gas leak can easily lead to an explosion or fire in petrochemical work environments. An ignition source, typically a spark, flame, or hot surface mixed with oxygen and a toxic gas, could cause a chemical reaction that results in a fire or explosion. The power of the explosion depends on the gas and its concentration in the atmosphere. For ignition to take place, the concentration of gas in the air must be at such a level where it will react chemically with the oxygen.

The effects of fire caused by a toxic gas release can be devastating, as demonstrated in 2005 at the United Kingdom’s Buncefield Oil Storage Terminal where a series of blasts eventually engulfed 20 large storage tanks, leaving more than 40 people injured. Investigations into the disaster found that the explosions and subsequent fire resulted from a faulty automatic alarm system that failed to detect a petroleum leak. The leak caused a visible vapour cloud to form, which was soon ignited by a spark. This most likely came from a fire alarm activated by an employee, causing the series of explosions.

Other related fire and blast incidents include the 2010 explosion at a PetroChina oil storage depot in Dalian’s Xingang port, which caused China’s worst ever oil spill, sending 1,500 metric tonnes of oil into the Yellow Sea, and the 2009 Cataño oil refinery fire in Bayamón, Puerto Rico, which resulted from faulty equipment failing to alert an overflowing tank before the fuel vapours ignited, causing an explosion. Such accidents demonstrate the crucial need for gas detection systems, as well as effective fire and blast protection, and emphasise the value of a detailed risk evaluation to help limit the consequences of these kinds of disaster.

• Toxic gas risk

Under many circumstances, the gases and vapours released from petrochemical processing activities can have harmful effects on exposed workers. Sources of chemical exposure can include inhalation, absorption through the skin, and ingestion. The amount, type, and length of time a worker is exposed will determine if he or she is at risk. Once a toxic substance has contacted the body, it may have immediate effects or long term repercussions, such as the onset of cancer or other illnesses, many years after the first exposure.

Without the use of specialised gas meters and detection systems, some toxic gases may not be detectable until damage has already been done. For example, one of the most prevalent toxic gas hazards in the petrochemical industry is hydrogen sulphide. A highly flammable substance, hydrogen sulphide is naturally present in crude petroleum and is used in processing many different types of products.

Hydrogen sulphide may be present around pumps, valves and pipe fittings. It is heavier than air, which can cause it to collect in confined spaces like tunnels or utility vaults. High concentrations of hydrogen sulphide can cause paralysis of the olfactory system, rendering the victim unable to smell the gas. As a result, the victim can unwittingly suffer an exposure that can lead to disorientation, respiratory failure, loss of consciousness, and even death.

• Asphyxiant (oxygen deficiency) hazard

Air is made up of several different gases along with oxygen, including asphyxiant gas. Asphyxiant gas in low or moderate concentrations is a nontoxic or minimally toxic gas that reduces air’s normal oxygen concentration. Asphyxiant gas is normally not hazardous, but can become hazardous when elevated concentrations displace the normal oxygen concentration.

When the oxygen level dips below 19.5% concentration by volume, the air is considered oxygen deficient. Oxygen concentrations by volume that fall below 16% are considered unsafe for humans, and breathing oxygen-depleted air can lead to death by suffocation. Because asphyxiant gases are relatively inert and odourless, their presence in high concentration may not be noticed until the effects of elevated blood carbon dioxide are recognised by the body.

Types of gas detection systems

A typical gas detection system is used to mitigate further escalation of gas leak hazards by automating a high integrity safety and control solution. Gas detection monitors are designed to alert workers to toxic gases and other oxygen-deficient and combustible atmospheres that may exist in work environments, such as permit-required confined spaces, manholes, and other enclosed spaces.

Additionally, such systems can aid in facilitating a faster recovery time from emergency situations, allowing a facility to resume full production in a shorter timeframe. According to the UK’s Health and Safety Executive (HSE), an independent regulator for work-related health, safety, and illness, there are two main types of gas detectors: fixed and portable.

Fixed – A fixed detector is permanently installed in a chosen location to provide continuous monitoring of the facility and equipment. Used to give early warnings of flammable gas and vapour leaks, or for monitoring concentrations of such gases and vapours, fixed detectors are particularly useful where there is the possibility of a leak into an enclosed or partially enclosed space where flammable gases could accumulate.

Portable – A portable detector usually refers to a small, handheld device, also known as a point detector, which measures the concentration of gas at a sampling point. These instruments are used to test an atmosphere in a confined space, for tracing leaks, or to give an early warning of the presence of flammable gas or vapour in a hazardous area.

Some portable detectors are not intended to be hand-carried but are still considered transportable and can be readily moved from one place to another. This allows for a detector to monitor an area while a fixed gas detector is undergoing maintenance.

Proper calibration

To be effective, gas detection instruments must be properly calibrated. Over time, conditions such as temperature, humidity, age, and gas exposure will affect the ability and accuracy of the detector. Proper maintenance and calibration of these instruments is necessary to ensure a higher precision of gas analyses throughout the facility and both are essential to protect workers and employers from unseen workplace hazards.

In the United States, the Occupational Safety and Health Association (OSHA) recommends developing standard procedures for calibrating and using gas detection systems that include documentation to verify proper and regular maintenance and calibration of the instruments.

Where to implement gas detectors

Even though toxic gas hazards are generally well understood by operators, technicians, and safety personnel in the petrochemical industry, it is essential to have continuous training and refreshment of knowledge to avoid potential incidents that can be linked to complacency or misguided actions.

Relevant safety standards vary by region and are defined and specified by law; identified in workplace regulations and instructions; in rules and regulations of trade or employers’ liability insurance associations; and in the standards of property insurers. Above all, the highest priority of a safety standard is the protection of life and health through hazard prevention and established procedures that support the quickest possible reaction times in the event of an emergency.

In Australia and New Zealand, gas detectors are used as a means of reducing the risk whenever there is the possibility of a risk to life or property from the accumulation of a combustible gas-air mixture. There are numerous activities and settings surrounding petrochemical plants where there is risk to life or property from a potential toxic gas leak, requiring gas detection systems.

Confined spaces – Found throughout petrochemical facilities, confined spaces in this industry generally consist of storage tanks, which have restricted means of entry and exit, and are not intended for continuous human occupancy. Most storage tanks have the potential to become hazardous work environments, resulting from the presence of hazardous gases, vapours, fumes, cleaning chemicals, dusts, improper or insufficient lockout-tagout, or excessive heat or cold.

Before a worker can enter a confined space, continuous checks of the air within the confined space must be conducted in order to make sure the air is safe for entry. To test and monitor a confined space, gas detectors should be used that are capable of monitoring the multiple potential risks of a confined space, such as these hazards specified by OSHA: inadequate oxygen, flammable gases, and potentially toxic air that may result from activities in or around the space.

Pipelines – Pipelines are an integral part of petrochemical operations. Since the 1920s, pipelines have been used to transport petroleum products, sometimes across entire regions. The transportation of hazardous materials increases the opportunity for an accidental release, fire or explosion. Because of the nature of their function and the environments where they are used, a breakdown in the safe operations and functionality of a pipeline or valve, such as leakage of natural gas or hazardous liquids, could have serious consequences. Pipeline safety policies and procedures are focused on minimising worker exposure to the substances in the pipeline.

Before beginning a job task on or near a pipeline that may require a tool that could be a source of ignition, such as any type of electrical equipment or working with an open flame, use a portable gas detector to test air quality around all valves. Even trace amounts of natural gas or other types of hazardous gases can ignite, causing a fire or explosion. Workers should not rely on their sense of smell as not all gases have an odour.

Valves – Along with pipelines, the use of valves in petrochemical activities is widespread. Operating safely with valves begins with a risk assessment or job safety analysis for the task you will be performing to identify any and all potential hazards and ways to minimise your risk exposure. Any time a worker may be at risk of an accidental release of stored energy, lockout-tagout procedures must be followed, which will hinder the accidental release of hazardous materials. To decrease this risk further, consider using a portable gas detector if available to check the air around valves for leaks.

It is also important to pay attention to the physical location of the valve, as that can contribute to additional potential hazards. For example, valves located outdoors in cold climates can freeze and crack, causing a release of fluids and/or gas. Lines susceptible to freezing should have drain or drip valves with catchment containers at low points along lines to reduce problems created by freezing.

Valves in pipeline operations are often located in underground pits or vaults. These may be classified as permit-required confined spaces, in which case an entry permit must be obtained along with the required air monitoring and attendant responsibilities. The accidental release of stored energy can place co-workers downstream at risk when operating valves.

Gas detection saves lives

A stable environment can turn hazardous in the blink of an eye if not properly maintained or monitored. Because of the multiple processing activities that take place in petrochemical facilities, it is inevitable that the occasional release of hazardous gases will occur.

This threat of chemical contamination and the potential effects of such contamination have created a critical concern for the environment and the health of surrounding populations in the Asia-Pacific region. To counter these potential disasters, having the proper gas detection systems put in place is the most useful line of defence to monitor any and all occasions for the potential risk and release of toxic substances.

Published: 03rd Mar 2014 in OSA Magazine


Katherine McCarthy

Katherine McCarthy is the communications coordinator for Summit Training Source, Inc. Katherine researches, writes and manages Summit’s blog, as well as numerous white papers, articles, and marketing collateral. Katherine holds a Bachelor of Science degree in Business Administration from Grand Valley State University and can be reached at Katherinem@safetyontheweb.com or SafetyTraining1 on Twitter.

Summit Training Source has been an environmental, health and safety training innovator for more than 31 years. With more than 600 environmental, health and safety training titles in multiple formats, including online, DVD, streaming video, and OSHA accepted 10 and 30 hour, Summit provides proven content that delivers the business results expected in today’s competitive global environment.

Summit’s programmes are effective, offering a true return on investment to more than 40,000 clients worldwide. Our continued mission is to provide the highest quality training programmes available, meet industry needs, and comply with all regulatory guidelines to enhance the future productivity, growth, and bottom line results for all of our customers.

Katherine McCarthy


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