By ROBERT ZUIDERVELD
In light of several highly publicized explosions and fires in the refining and fuel storage industriesthe result of vapor leaks followed by ignitionhow can you improve safety measures to prevent mobile equipment operating under hot work permits or within the fringes of the classified areas from creating another disaster? Heavily regulated by governments throughout the world, refineries and similar energy industries must ensure that any explosion risk is minimized. Within the United States, refineries must comply with the codes and regulations to use powered industrial equipment in explosion-hazardous areas. However, because of code interpretation and explosion-hazardous areas’ rating variances, equivalent regulations and worker protection levels have not been established. This means that today, many refineries’ workers still remain at risk.
To start a fire or an explosion, three constituents must come together: an oxidizer (air), a hazard (gas or vapor), and an ignition source. Although you cannot eliminate the oxidizer, it is possible to plan processes and protect equipment to limit, wherever possible, the chances of the hazard’s contacting an ignition source. However, when it comes to controlling mobile equipment, those responsible for site operations sometimes lack the experience, site discipline, and budget to enforce safe and acceptable control of mobile equipment movement.
To begin, make sure to use the equipment designed and certified to operate safely in those areas. If an area is classified as Class 1-, Division 1-, or Zone 1-certified, then use only equipment certified to EX Class 1, Division 1, or Zone 1 codes and regulations in those areas. For Division 2 or Zone 2 hazardous areas, test and certify equipment according to the codes and regulations applicable to equipment in those areas.
Insisting that only Division 1-, Zone 1-, Division 2-, or Zone 2-certified equipment be allowed to operate in the refinery is neither practical nor desirable. The same thing applies to personnel carriers, tractors, tankers, mobile compressors, and gen-sets not being permitted into formally classified areas without first being made fully explosionproof. In these situations, most refineries rely on hot work permits and risk management processes. Usually, those who issue work permits have the relevant experience and authority to manage the risk involved with the task at hand.
When you use diesel-powered equipment, it is common to insist that an engine over-speed air shutdown valve and an exhaust spark arrestor are installed. Provided these components are correctly fitted and serviced, they should alleviate some of the many ignition sources found on a forklift truck, crane, tanker, compressor, or gen-set.
Besides working under a hot work permit, the operator usually carries a handheld gas detector. But who or what procedure ensures that the gas detector has been specifically calibrated against the gases and vapors that could potentially be released into the operating area? Does the gas detector always remain with the equipment and its operator throughout the permit process, or does the operator stray away from the equipment? A handheld gas detector relies on an operator to “kill” the equipment before the equipment ignites the explosive atmosphere that has developed unexpectedly. Unfortunately, most accidents are caused by human failure or response time.
You could rely on fixed gas detection systems’ monitoring, but it is necessary to ensure that sufficient gas detector points cover all areas where mobile equipment is operating. If you do not, the hazard and ignition source may combine before you can take appropriate action.
Some companies ring fence the equipment and its ignition sources with dedicated gas detectors that may automatically shut down the gen-set or compressor when flammable gases or vapors are detected. However, if the equipment is mobile, such as a crane or van, the process becomes rather impractical. Also, how do you prevent equipment that has automatically shut down from being restarted before it is safe to do so?
Relying on engine over-speed valves, fixed gas detectors, and handheld gas detectors has been the traditional reactive protection methods of yesterday, but with today’s powered industrial equipment relying on sophisticated electronics, the use of over-speed valves and the limitations of relying on handheld gas detectors being held by workers is not the way to improve facility safety.
Using proactive gas detection technologies limits worker risks and allows the operator the flexibility he needs to perform his job safely and efficiently by ensuring the following:
- The operated equipment has its own integral gas detection system that will allow the equipment to function only when the immediate area surrounding the equipment is free of flammable gas or vapor.
- The equipment performs a forced automatic gas test to ensure it is calibrated correctly before the operation begins.
- The operated equipment has its own integral gas detection system that shuts down the equipment automatically when an unexpected increase in flammable gas or vapors is detected in the equipment’s surrounding area.
- If shutdown occurs, any restart is controlled by a person in charge of facility safety.
- The installation protection systems are simple to fit, use, and maintain and, most importantly, are designed to isolate most of the ignition sources from explosive atmospheres.
Even though this technology has been available, the safety culture and corporate mind-set need adjustment. With the right mind-set, some investments, minor equipment modifications, and fine-tuning of the site process and permit schemes, significant progress in equipment and employee safety can be made.
ROBERT ZUIDERVELD is the general manager of business development for Pyroban. He has an associate’s degree in economics and two bachelor’s degrees in marketing and public relations and business.