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The West Texas Tragedy Reminds Us The Importance of Blast Resistant Shelters

Just two hours away from my home here in Texas, rescue teams were picking through the devastation in the small Texas town of West, after a massive explosion at a fertilizer company flattened the surrounding neighborhood. Initial estimates put the death toll at between five and 15, with at least 160 injured. Among the missing were three to four volunteer firefighters who were responding to a blaze at the facility when the explosion happened on Wednesday night.

Waco police Sergeant William Patrick Swanton said in a morning press conference that the emergency response was still in its search and rescue phase, but that eventually it would have to become one of recovery. “They are still getting injured folks out and they are evacuating people from their homes,” he said. “They have not gotten to the point of no return where they don’t think that there’s anybody still alive.”

The blast, which could be heard 45 miles away and shook the ground with a force equivalent to a magnitude 2.1 earthquake, happened just before 8pm on Wednesday, leveling up to 80 homes in the blocks around the facility. As a mushroom cloud climbed into the sky, more than 1,000 people in the town of around 2,800 were left without power. An apartment complex was ripped to shreds, a middle school was reportedly in flames, and 133 people, many of them injured, were evacuated from a nursing home. “I’ve never seen anything like this,” said McLennan County Sheriff Parnell McNamara. “It looks like a war zone.”

Emergency services said ammonia may have caused the fireball at West Fertilizer Inc, which reportedly had 20 tons of anhydrous ammonia on site. The site was being treated as a crime scene, officials said, though in the immediate aftermath there was no indication of the blast being anything other than an industrial accident.

It is no secret that many of the process technologies within our industry carry their own set of challenges and risks. Inherent in hydrocarbon processing is the continual concern for worker and operations protection in the event of explosion and fire. The ongoing history of refining is replete with accounts of disasters arising from simple and complex causes. Pipe corrosion was determined to be the prime cause of a May 2009 explosion and fire at the ethylene unit of Sunoco’s Marcus Hook refinery, located in Delaware. Superheated feed stock leaked out of a rusty pipe and ignited, causing a vapor cloud explosion (VCE). Even though the refining industry has experienced advances in process and safety technologies, risk of a blast event still comes with the  territory, underscoring the need for greater emphasis on worker and equipment safety.

The design, development and deployment of blast resistant structures to protect workers, power and process controls has been ongoing within hydrocarbon processing (HP) and chemical manufacturing. In more recent years the demand for these types of buildings has resulted in the creation of a relatively new industry that can provide benefits physically and financially to petrochemical companies and other chemical processing plants.

Although blast resistant shelters are being used at land-based chemical processing plants, their origins can be traced to the use of externally reinforced, steel intermodal shipping containers in offshore safety applications. Freight containers have been in plentiful supply since their inception, and their structural strength makes them natural candidates for personnel protection from low-level blasts. Converted containers are resistant to blast loads in the 1.0 to 2.0-psi range. However, much higher loads are experienced at refinery blast events, given distance and other variables affecting the force of a VCE, necessitating the use of stronger structures. This need led to the fabrication of the first, custom-designed blast resistant modules and the industry has been evolving ever since. The response of industry to the need for ensuring personnel and plant safety reached a high degree of intensity after March 23, 2005. On that day a series of explosions ripped through BP’s Texas City, TX refinery during the restarting of process equipment at the refinery’s isomerization unit, killing fifteen workers and injuring 180 others. A tremendous loss of manpower and equipment was suffered and as a result, the unit did not come back online for another two years.

Since this incident, demand has increased significantly for blast resistant, steel-fabricated buildings providing protection at HP facilities. Industry guidelines have been established to facilitate the design, construction and optimal location of blast resistant modules for personnel protection, as well as blast resistant electrical equipment centers (BRECs) for protection of the critical electrical process functions of the facilities they serve. The addressing of safety concerns at petrochemical and other hazardous manufacturing facilities began largely in the 1990s, resulting in publication of the Occupational Safety & Health Administration’s (OSHA) Process Safety Management (PSM) standards. In response to the OSHA publication, a joint effort was initiated by the American Petroleum Institute (API) and the Chemical Manufacturers Association (CMA) to establish a set of guidelines directly addressing OSHA’s concerns in the published PSM standards. This response is contained in API Recommended Practice 752, Management of Hazards Associated with Location of Process Plant Buildings.

Following the conclusions reached in the wake of events at Texas City, OSHA initiated a series of National Emphasis Program (NEP) Audits at U.S. refineries, during which OSHA inspectors began issuing citations to companies for failure to adequately protect essential or critical equipment at their facilities. This has added momentum to an already growing movement on the part of petrochemical firms to provide strong, ductile, affordable protective shelters. Advances in the design, testing and manufacture of such structures have served to further ensure market viability for them.

The primary function of blast resistant shelters has been to protect personnel at facilities at risk for accidental explosions. On the other hand, risk managers, engineers and owners of companies also realize that the risk of exposure to overpressure or blast wave extends to the critical and essential power and control systems of their facilities as well. Outside of protecting personnel during a blast event at a refinery, nothing is more critical than sustaining the proper function of process-related automatic shutoff valves and other critical power equipment, as well as water pumps for fire protection.

The manufacturing industry for blast resistant modules (BRMs) offers a wide range of sizes and blast ratings, conforming to IBC design and construction practices. BRMs are most often used as a substitute for unrated construction trailers but may be configured into multiple sections. Multi-sectional systems may be large single story buildings or stacked to create a multi-story configuration. Examples include offices, cafeterias, and even sleeping quarters.

In the past, all control was done from field shelters. A control system upgrade has enabled the site to move to a new control facility. The field shelters will still be used by field operators for important functions such as maintenance coordination, issuing work permits, sampling, new employee training, but are poorly designed for these functions. The main controls are transferred to the new control room, but maintenance and backup control view is available in the field shelter and is used for diagnosing, testing, and training. With the removal of the console operator it is important to re-design the room for the field operator functionality. These renovations may include hardening the building.

UCDS has in-depth experience in designing control rooms and modifying existing field shelters. Our process is compliant with the ISO 11064 Ergonomic Design Standard for Control Buildings. We interview management, supervision and a significant group of the operators to understand functional requirements, what works well in the existing environment, and identification and correction of problems with the existing design. Some customers prefer to walk away from their existing building and move the field operators into a Modular Blast Resistant Building. Our process helps facilitate this move and provides a detailed design for the Modular Building manufacturer. We help identify if you can rationalize many field shelters into a smaller number of more centralized field shelters. One site went from 16 field shelters to 3 new field shelters, utilizing modular buildings, located in strategic locations.

The first step in the process is identifying the required number and location of field shelters required. This is accomplished by reviewing process safety information, site plans, and API RP752 reports and then discussing renovation, remodel, or alternative solutions with plant personnel. Once the number field shelters has been established, we spend time capturing requirements from managers, supervisors, operators along with other secondary users of the building such as maintenance, planners, and laboratory staff. UCDS will ensure rooms are designed for functional requirements and good collaboration and communication, whilst addressing traffic flow through the building and minimizing disturbances. The building will also address issues such as responding to emergency situations and how operators use equipment like respirators and specialized PPE. We develop design alternatives and solicit feedback from the users. We then integrate this feedback into a final design and generate a budget estimate. To modify an existing building to code and to develop an estimate an architect will need to be involved. This estimate may require local planning permission, upgrading buildings to today’s building codes, and developing construction drawings. As the Client goes through the iterative process of finalizing the building design, User Centered Design Services will be available for consultation as required.

Our hearts and prayers go out to the victims of this horrible incident. May we learn from this event and do all that we can to protect each other today and tomorrow.