Almost any device, piece of equipment or machinery can cause injuries or damage to property if mishandled. One of the process safety hazards that can endanger human lives and damage property for millions of dollars are pressure hazards. Michael Speegle (2012) identifies two general categories of them: “rupture of pressurized vessels” and “dynamic pressure hazards” (p. 82). Their proper explanation and exemplification may help prevent accidents and save lives.
Rupture of Pressurized Vessels
Improperly handled or undermaintained vessels that hold liquefied gas substances or other pressurized content can trigger serious destructions. Hazardous consequences can follow if structural integrity of a pressurized container is broken. For example, it can happen if workers on a construction site drop a compressed oxygen tank on the ground. Due to the fall, the tank’s exterior casing may have a breach, through which the substance will escape with immense speed causing an explosion. According to Speegle (2012), an explosion of pressurized tanks can be extremely dangerous due to the metal parts pushed by the explosion in many different directions that can harm people and destroy equipment. Above that, an explosion creates a blast wave that can be even more destructive. Otherwise, the container might be damaged because of the metal casing defects or an increase in internal temperature or pressure.
Dynamic Pressure Hazards
Dangerous circumstances can also occur due to sudden or continuous release of pressurized substances. They can include a stream of gas bursting from a blown out pipe or valve. Such stream may severely burn or even cut a person standing in front of it. Another hazard may come from flexible pipelines or hoses used by firefighters. Such pipelines can cause severe traumas if they are left unattached or got loose from the improper grip. The danger of pressurized tanks failure builds up if the atmosphere of a working site contains flammable substances. Such situations are the prime concern, for instance, on oil platforms where there is a lot of high-pressure equipment in use and natural gas in the air.
Detection of Pressure Hazards
Detection of a vessel integrity disruption can be possible with the help of pressure and heat sensors that are normally installed on such equipment. In case of an explosion due to sudden ruptures, detection can rarely be possible because of the often-instant character of the blast. Hissing sound can in some cases also indicate a rupture and gas substance leakage.
Pressure Hazard Prevention
To prevent pressure-related hazardous events safety procedures are to be elaborated. Such procedures can include accident prevention manuals that contain a set of actions that each employee working with pressurized containers must do to eliminate a possibility of hazardous consequences. For instance, constant monitoring of the pressure equipment or wearing protective gear. In addition, in companies that work with pressure-hazardous machinery a periodical safety inspection is usually needed to check its condition. Should an emergency arise, each employee needs to follow a special protocol to mitigate the outcomes. Furthermore, each piece of machinery that contains or transmits pressurized substances must be constructed according to a special design code. This code usually implicates an installment of various safety mechanisms like relief valves. Working with flammable substances under pressure usually supposes a high degree of explosion protection for both employees and equipment.
All things considered, both rupture and dynamic pressure hazards pose a serious threat to health, life, and capital. Steam, natural gas, and other pressurized substances must be treated with caution at any time. Therefore, there is a need for constant monitoring, maintenance, and advancement of fail-safe technologies to prevent a disaster.
Mechanical Integrity in the Context of Process Safety Management
Process safety management (PSM) is a vital aspect of any organization code because it helps develop low-risk conditions even in hazardous environments provided all employees would comply. Ensuring all equipment works properly is one of the most critical conditions of safe work environment. Mechanical integrity (MI) that encompasses that idea is an essential component of PSM, a guarantee of a proper functioning and installment of equipment.
Human Factor Hazard
The human factor is one of the most common sources of dangerous situations that cause various leakages, explosions, power cutoffs, and mechanical integrity violations. Those who operate, maintain, and inspect hazardous machinery are subject to various imperfections leading to adverse outcomes. Among them are fatigue, lack of knowledge or training, inattention to detail, carelessness, and many others. Any of that may result in seemingly small error that, however, could have catastrophic consequences. For instance, tuning the gas pressure to a slightly different value from normal could become the reason of an explosion in a gas storage. A more common example would be a mechanic who did not properly tighten a bolt in a car wheel after changing a tire, which resulted in a car crash. In both cases, mechanical integrity of a gas tank or a car was violated because of the human actions. Human errors are typically minimized with the help of automatic equipment, strict code with sizable fines, multiple levels of quality control, various inspections, and hiring professionals with many years of experience.
Natural Hazards
Natural hazards can also harm mechanical integrity of the equipment and sometimes cause millions of dollars worth of damage. A relatively recent tragedy in Fukushima nuclear power plant can be a vivid example of such hazards. An earthquake and tsunami have damaged the reserve generators undermining the work of cooling systems, which resulted in the melting of reactor cores. From the PSM point of view, the plant had an automatic emergency shutdown system, which responded as it should have. However, it was not prepared for the second disaster in the form of a tsunami. According to official sources, necessary precautions have been taken to prevent such catastrophes from happening again.
Hazards of Pressure
Mechanical integrity may be quite sensitive to pressure changes. Explosions caused by excessive pressure can sometimes break and blow off even the thickest metal components. Metal pieces are torn apart and thrown in various directions causing grave injuries. The situation may become even worse if the substance from an exploded vessel is flammable. Various precautions are taken to ensure safety of the personnel and to preserve the mechanical integrity and stable operation of the equipment. Since many accidents happen due to human error, companies tend to install automatic fail-safe systems to monitor pressure-hazardous equipment. Different sensors inform operators of any changes in mechanical integrity, pressure, temperature and can even automatically take emergency actions.
All three types of hazards can significantly undermine or break mechanical integrity of the equipment. Since violation of MI leads to significant losses, companies take steps to prevent or mitigate their equipment from hazardous consequences. Both human and nature can be quite unpredictable, so process safety and mechanical integrity are constantly evolving.
References
Speegle, M. (2012). Safety, health, and environmental concepts for the process industry. New York, NY: Cengage Learning.