With miles of piping and tubing used throughout most industrial plants, it is inevitable that leaks will occur, presenting increased costs and safety risks to staff. Implementing monitoring practices is crucial for identifying the level of risk to employees and operational efficiency. The US Department of Labor (DOL) found that in 2021, 551 fatalities were reported to be due to exposure to hazardous substances with 72 of these caused by inhalation of a harmful substance.
In the petrochemical industry, these hazardous substances often released are volatile organic compounds (VOCs), from a wide array of liquids often found in these settings
Bleeding of external pipes can create an environmental risk, causing regulatory headaches, losses of expensive gases and pressure drops affecting performance of the rest of the plant. Internal leaks, however, present the highest risk to employees — a minor leak of a toxic gas may require emergency evacuations that lead to a cease in production and hefty fines. In addition, indoor environments often exhibit air pollutant concentrations two to 10 times higher than the outdoor equivalents.
Common causes of leakage include corrosion of the piping, valves, seals, gaskets and other components, mechanical failures such as fatigue, vibration and movement, and thermal expansion and contraction. Equally, human error contributes to leak numbers through improper installation and incorrect parts selection.
Toxic gases can cause immediate death when inhaled but the effects of exposure from VOCs can also take years to develop, leaving workers vulnerable to illnesses such as cancer, respiratory disorders and kidney and liver damage. These illnesses present in sufferers as reduced productivity, lethargy, increased inactivity and therefore more frequent absences and compensation claims.[1]
Detection
The Occupational Safety and Health Administration (OSHA) issues citations and penalties if businesses violate permissible exposure limits (PEL). PELs are legal limits designed to control employee exposure to hazardous substances, averaged over an eight-hour period to prevent health risks. An estimated 90% of OSHA’s approximate 500 PELs have not been updated since the 1960s so it is recommended that employers take note of recent recommendations and advice from industrial hygiene experts.[2]
Consequently, OSHA may issue citations under the general duty clause of the Occupational Safety and Health Act (OSH Act) if exposure limits exceed industry-wide standards and pose a threat to employee health. The clause requires employers to keep its workforce free from hazards that may cause death or harm to employees.[3]
For gases and vapors, each toxic compound has an individual PEL so it is imperative to refer to OSHA’s Annotated Tables and refer to industry expert advice relative to the VOCs present in the plant.[4]
Personal sampling pumps
Industrial hygiene methods are geared towards measuring personal exposure using personal air sampling pumps because the tried-and-tested method can quantify personal exposure and ensure compliance with regulatory limits. Regular monitoring activities of gases that do not pose an immediate risk to life are essential as these airborne hazards still present the risk of longer latency illnesses, which are detrimental to worker health.
Pipes can be inspected using handheld devices and portable gas detectors to check for gas leaks in specific areas or confined spaces.
However, personal sampling pumps are the best way to accurately gauge the level of exposure to individual workers and comply with regulations. Attached to the wearer, these pumps draw the air in the wearer’s immediate breathing zone through a sampling media such as a sorbent tube at a controlled flow rate.
Once a sorbent tube has been set up with the pump, calibrating the device with representative sampling media determines the flow rate that will pass through the pump. The entire sample train — including the combination of pump, flexible tube, and air sampling device — should be calibrated to ensure accuracy of flow rate both before and after each day to ensure there is no deviation.
It is vital to check that your pump meets the latest international standard for air sampling pumps. Compliance to ISO 13137 ensures accurate flow performance amongst other performance criteria, ensuring accurate sampling and removing the need for repeat measurements.
Once the gas is drawn through the pump, the sorbent tube is sealed and sent to a laboratory for analysis. The gas undergoes desorption from the sorbent material and is quantified through gas chromatography or mass spectrometry.
The concentration of VOCs or gases in the air is determined by comparing the laboratory results with the volume of air sampled, which is calculated based on the flow rate and sampling duration. Regularly undertaking this type of sampling allows for employers to protect the long-term health of workers, minimizing regulatory and financial penalties.
One consideration for purchasing managers is the flammability of the gas or gases present, some VOCs can be extremely flammable, so the need for an intrinsically safety (IS) pump is likely, and the rating required can vary per site so this should be checked to ensure the pump is suitable.
Conclusion
Gas leaks can cause loss of life, long-term incurable health problems and costly losses to a plant’s operation. A comprehensive and well-implemented monitoring system will save workers’ lives, ensure regulatory compliance and protect the bottom line from unnecessary loss.
Using the correct components in the sample train for the VOCs and other gases present, calibrated properly, that conform to the latest industry standards, is the most practical and effective method to understand the level of exposure workers experience in a plant.
When creating a monitoring system, it is important for employers to consider the competence of the occupational hygienist when conducting personal air sampling. If unsure, it is always recommended to employ the services of an external consultant.
