Facility siting has come under increasing scrutiny in recent years, but it is an important aspect of process safety for plant personnel and their contractors and assets. Safety has long been a priority in operating a refinery or chemical processing facility. The reality of process units possessing high-pressure systems and often carrying hazardous materials creates significant risk by its very nature. There are a multitude of scenarios in the typical chemical processing plant that can lead to the loss of containment and subsequent toxic dispersion, fire or explosion. Working in this complex environment means providing gross mitigation strategies to prevent injuries or accidents from occurring. Building occupancy is an important consideration when ensuring the safety of plant workers, which has been one of the most widely overlooked aspects of plant safety until recently.
Inevitability of risk
As recently as the early 1990s, employees operated out of standard office trailers or tents that were positioned in close proximity to process units, in order to allow workers to be as close to the jobsite as possible, thereby maximizing productivity. Risks at this time were seen as unavoidable given the nature of normal plant operations. It is well known that the design of older facilities may not have initially considered or addressed facility siting risks and may have placed more emphasis on operability and the efficiency of operations. As a result, this approach has led to several accidents. Although there were many checks and balances already in place with regard to process safety, incidents began driving the need for further innovation that focused on providing assessment and protection in the face of growing concerns.
The U.S. Occupational Safety & Health Administration (OSHA) began investigating many of these incidents that were occurring within the industry. Based on its findings, OSHA 29 CFR 1910.119 Process Safety Management (PSM) was introduced in 1992 in an attempt to provide a balance between worker safety and the associated risks. PSM focuses on preventing the accidental release of hazardous chemicals or vapors. PSM has since evolved and expanded as new risks posed to employees were identified and addressed. With the shift in the governmental requirements came an equally beneficial response from the industry. The American Petroleum Institute (API) provided additional support to OSHA by introducing Recommended Practice (RP) 752 for permanent occupied buildings and RP 753 for temporary buildings. These recommendations complemented OSHA standards and further solidified the resolve of both government and industry to provide safety for plant employees. The final piece of this complex puzzle was accurately determining the level of risk in such a considerable environment. Facility siting was introduced as a means of assessing risk and providing an analysis of what level of protection is needed in occupied building requirements. Facility siting is the assessment and management of explosion, fire and toxic release hazards to occupants of buildings located in close proximity to process plants so that the proper steps to mitigate these risks can be taken.
The age of risk assessment
Facility siting studies (FSSs) were developed by various engineering firms as a means to assist the industry in evaluating potential hazards with regard to blast loads from accidental explosions, fires and toxic releases. Quantitative risk assessments (QRAs) are often performed as a follow-up to FSSs to determine the risks present at a facility as a result of the identified hazards. Through on-site evaluations, analysis of facilities and advanced software, reports are generated that provide a detailed assessment and mitigation options. Typical blast mitigation strategies include reducing the occupancy in and around high-risk areas, performing upgrades to strengthen existing buildings or relocating the building to an area less susceptible to damage. Additional strategies may include providing explosive or toxic gas detection, classified electrical components, pressurized vestibule entries, fresh air stacks and HVAC shutdown/recirculation.
FSSs and QRAs consider several aspects of a plant. Per the requirements in API 752, the maximum credible event must be considered for each hazard scenario. Blast loads are determined by considering the size and location of flammable clouds of hydrocarbon gas, as well as the congestion and confinement within the process unit. Fires and toxic clouds are modeled based on the process conditions and materials that are released. Finally, consequences and risks to occupied buildings are calculated based on the severity of hazards at each location and the type of building construction. Based on the results determined, mitigation strategies can be developed for specific situations.
Providing a solution
Moving all personnel far from the process units to an area of low blast loads presents its own set of challenges. Keeping productivity at an acceptable level while also providing security and safety for workers is a common issue with this approach, especially in larger facilities. Housing temporary contractors who work in various areas of a plant for varying lengths of time created the initial need, to which Hunter provides a highly effective solution. Hunter's blast-resistant modular buildings enable facility owners to maximize productivity and provide adequate safety measures for both temporary and permanent workers.
Since our founding, Hunter has strived to diligently serve the refining, petrochemical and specialty chemicals communities by enhancing productivity and occupational safety through the reliable manufacturing of superior-quality blast-resistant modular buildings. Blast-resistant modules (BRMs) have become a practical solution for industrial facilities to provide a cost-effective way to protect personnel or equipment. Hunter offers temporary or permanent structures for any application. Hunter's buildings are designed, engineered and manufactured from the ground up to meet the site- and safety-specific requirements of the customer as well as all current industry recommendations and requirements. Hunter's blast design has been validated by physical blast tests performed by third-party specialists. All Hunter blast calculations are performed by third-party professional structural blast engineers. This ensures each calculation is made with the utmost integrity. Furthermore, Hunter's BRMs are designed so all walls can withstand blast loading from any direction or orientation, as opposed to having only one or two stronger walls with weaker walls on the rear. This allows Hunter's BRMs to offer protection from potential explosions from any direction, unlike other BRM manufacturers.
Continuing the evolution of evaluation, change
Safety remains an ever-evolving topic in any industry, but it is always evolving in the complex world of refineries and chemical processing facilities especially. As risk mitigation strategies have grown and solutions presented have expanded, regulations have grown to address further concerns. Initially, after implementation of the OSHA regulations, the definition of an occupied space was subject to interpretation. Lunch tents, restrooms and other buildings, which were previously classified as unoccupied, began to fall under consideration for facility siting.
Even in cases where the facility undergoes consistent checks and improvements, an incident could happen at any time without warning. It is important to take all the necessary precautions to minimize the risk of explosion, ensuring that a proper facility siting study has been conducted. As we continue down the path toward ensuring the safety of everyone who works in and around refineries and chemical processing facilities, the hope is to protect people from hazards that may ensue from accidental releases. People feel confident Hunter's BRMs will protect their personnel or equipment in the event of an accidental explosion or incident. Hunter is ready and able to provide safe solutions regardless of the hazardous environment.
For more information, visit www. hunterbuildings.com or call (281) 452-9800.
