LoC: Maintenance error

On April 26, 2018, an explosion and subsequent fire occurred at the Superior Refinery Company LLC refinery in Superior, Wisconsin (‘Husky Superior Refinery’). The incident occurred in the refinery’s Fluid Catalytic Cracking Unit (FCCU). In preparation for the shutdown, the refinery brought in hundreds of contractors and increased operations staffing. The contractors were performing many tasks such as electrical work, preparing for chemical cleaning, building scaffolding, and welding. As a result of the explosion, thirty-six people sought medical attention, including eleven refinery and contract workers who suffered OSHA recordable injuries. In addition, a large portion of Superior, Wisconsin was evacuated. The refinery was shutting down in preparation for a five-week turnaround when an explosion occurred, sending several people to area hospitals with injuries.

KEY ISSUES:
• PYROPHORIC IRON SULFIDE

Image credit: CSB

Shortly after 6pm, on 2 June 2011, an atmospheric storage tank within the amine regeneration unit at the Chevron Pembroke Refinery exploded. A fireball split the tank open and killed four workers: Robert Broome, Julie Jones, Dennis Riley and Andrew Jenkins. The sole survivor, Andrew Phillips, sustained severe burns and suffered life-changing injuries.

The force of the explosion ejected the five-tonne steel tank roof over 55 metres through the air. After narrowly missing a multi-fuel pipe track, the roof crashed onto a pressurised storage sphere containing extremely flammable butane. Good fortune prevented the airborne roof from puncturing the butane storage vessel, which would have led to an uncontrolled release of liquified petroleum gas (LPG).

The explosion was caused by the unintended ignition of a flammable atmosphere within the tank (17T302), during what should have been a routine cleaning operation conducted in preparation for maintenance.

KEY ISSUES:
• OPERATING PROCEDURES
• PERMIT SYSTEM
• CONTROL OF CONTRACTORS
• RISK ASSESSMENT
• COMPETENCE

Image Credit: HSE

An explosion at the Partridge-Raleigh oilfield in Raleigh, Mississippi. The incident occurred at about 8:30 a.m. on June 5, 2006, when Stringer’s Oilfield Services contract workers were installing pipe from two production tanks to a third. Welding sparks ignited flammable vapor escaping from an open-ended pipe about four feet from the contractors’ welding activity on tank 4. The explosion killed three workers who were standing on top of tanks 3 and 4. A fourth worker was seriously injured.

KEY ISSUES:
• HOT WORK CONTROL
• SAFE WORK PRACTICES AT OIL & GAS PRODUCTION WELLS

ROOT CAUSES:
1. A gas detector was not used to test for flammable vapor.
2. ‘Flashing’ tanks containing hydrocarbons with a lit oxy-acetylene torch to determine the presence of flammable vapor is unsafe and extremely dangerous.
3. The open pipe on the adjacent tank was not capped or otherwise isolated.
4. A makeshift work platform – a ladder placed between the tanks – was used.
5. All tanks were interconnected and some of the tanks contained flammable residue and crude oil.

Image credit: CSB

A contractor died after entering a confined space at Dow Chemical’s plant in Oyster Creek.

Source: A web-based collection and analysis of process safety incidents (https://www.sciencedirect.com/science/article/abs/pii/S0950423016302285)
Image Credit: Unidentified

On June 9, 2009, a major natural gas explosion heavily damaged the ConAgra Slim Jim meat processing factory in Garner, North Carolina, just south of Raleigh. Three workers were crushed to death when a large section of the building collapsed. The explosion critically burned four others and sent a total of 71 people to the hospital including three firefighters who were exposed to toxic anhydrous ammonia from the plant’s refrigeration system. Approximately 18,000 pounds of ammonia were released to the environment and 100,000 square feet of the plant were damaged. Due to the severity of the structural collapse, there was the potential for numerous additional deaths or serious injuries.

KEY ISSUES:
• DIRECTLY VENT PURGED GASES TO A SAFE LOCATION OUTDOORS, AWAY FROM PEOPLE AND IGNITION SOURCES.
• USE COMBUSTIBLE GAS DETECTORS TO MONITOR THE GAS CONCENTRATION DURING PURGING OPERATIONS.
• ENSURE PERSONNEL INVOLVED IN GAS PURGING OPERATIONS ARE FULLY TRAINED.

ROOT CAUSES:
1. Purging into equipment vicinity is common practice

Image credit: CSB

On 11 June 1987 a team of four contractors was cleaning a crude oil storage tank at the Dalmeny Oil Storage Terminal. The tank was of the floating roof type and the roof had been lowered due to the tank being empty. It was resting on a series of 219 support pillars. Three of the contractors worked inside the tank with one on duty outside along with a BP employee.

The tank had been emptied of its contents and three roof manhole covers opened to allow natural ventilation. However, the evolution of a vapour with the risk of forming an explosive atmosphere was not considered sufficient to merit either mechanical ventilation or rigorous monitoring of the vapour concentrations within the tank. As a precaution though, the workers were required to wear airline-breathing apparatus supplied by a compressor located outside the tank bund.

At 13:20 hours the outside man looked in and saw a ring of fire surrounding the three men. Two of the employees managed to escape the fire but the third man died from the effects of asphyxiation and burns. The fire escalated rapidly with flames and smoke coming out of the open man ways.

The cause of the accident was one of the contractors smoking inside the oil tank. It was apparently common practice for the workers to remove their breathing apparatus while inside the tank, with some workers choosing to smoke while the supervisor was not looking. On this occasion one of the men working in the tank had dropped a lit cigarette on to the floor where it had ignited the crude oil.

KEY ISSUES:
• MAINTENANCE PROCEDURES
• SITE SECURITY
• HAZARDOUS AREA CLASSIFICATION / FLAMEPROOFING
• TRAINING
• ISOLATION

Report: https://www.icheme.org/media/13700/the-fires-and-explosion-at-bp-oil-grangemouth-refinery-ltd.pdf

Image Credit: HSE

An explosion occurred when employees were attempting to isolate a leak on a condensate line between the natural gas liquid (NGL) plant and the refinery. Three crude units were damaged and two reformers were destroyed. The fire was extinguished approximately nine hours after the initial explosion. Five people were killed and 50 others were injured. The initial investigation into the loss indicated a lack of inspection and maintenance of the condensate line, which was not owned by the refinery. A lack of clear understanding of the ownership of the line is thought to have delayed the isolation of it.

[ Property Damage $412 Million. Estimated Current Value $718 Million ]

KEY ISSUES:
• Ownership and responsibility for equipment should be understood
• Third party interfaces must be managed
• Quality maintenance and inspection regimes are critical for plant integrity

Image credit: KNPC

A natural gas pipeline explosion and fire occurred at a gas booster station as a crew worked on a 4-inch gas line. The workers were replacing some gas lines, repairing a ruptured line.

Source: A web-based collection and analysis of process safety incidents (https://www.sciencedirect.com/science/article/abs/pii/S0950423016302285)
Image Credit: News Channel 10 Amarillo

An explosion occurred at a chemical plant. Before the explosion, some workers were welding the interior of waste water storage. The blast tore out the upper structure of the storage facility, which subsequently collapsed

Source: A web-based collection and analysis of process safety incidents (https://www.sciencedirect.com/science/article/abs/pii/S0950423016302285)
Image Credit: BBC

A release and ignition of gas condensate from a section of piping in the gas compression module of this platform set off a chain of fires and explosions, resulting in the almost total destruction of the facility. The condensate was released from the site of a pressure relief valve that had been removed for maintenance when this section of piping was inadvertently pressurized.

The severity of the accident was largely due to the contribution of oil and gas from ruptured pipelines connected to the platform and the disabling of nearly all emergency systems as a result of the initial explosion. The compression module had been retrofitted to the platform adjacent to the control room, which was rendered useless by the initial explosion.

In addition, the firewater pumps had been placed in to manual operation mode due to divers being in the water prior to the accident.

There were 226 people on the platform at the time of the accident; only 61 survived. Contributing to the loss of life was the location of the quarters, which was directly over the site of the initial release and resulting explosion and fire.

[ Property Damage $850 Million. Estimated Current Value $1963 Million ]

KEY ISSUES:
• MANAGEMENT OF CHANGE
• PERSONAL SAFETY OVER PROCESS SAFETY
• ISOLATION AND PERMITS FOR MAINTENANCE
• HANDOVER
• SAFETY CULTURE
• EMERGENCY RESPONSE

Image Credit: Press Association

This event occurred on a crude unit at this 360,000 bbl per day refinery. A furnace was undergoing maintenance when a worker performed a hot cut and material was released. Inadequate flushing and blinding and a work scope that did not meet normal industry practices appear to have been the likely causes.

[ Property Damage $100 Million. Estimated Current Value $199 Million ]

Image credit: Rosneft

On July 17, 2001, an explosion occurred at the Motiva Enterprises LLC Delaware City Refinery (DCR) in Delaware City, Delaware. Jeffrey Davis, a boilermaker with The Washington Group International, Inc. (WGI), the primary maintenance contractor at DCR, was killed; eight others were injured.

A crew of WGI contractors was repairing grating on a catwalk in a sulfuric acid (H2SO4) storage tank farm when a spark from their hot work ignited flammable vapors in one of the storage tanks. The tank separated from its floor, instantaneously releasing its contents. Other tanks in the tank farm also released their contents. A fire burned for approximately one-half hour; and H2SO4 reached the Delaware River, resulting in significant damage to aquatic life. .

KEY ISSUES:
• MECHANICAL INTEGRITY
• ENGINEERING MANAGEMENT
• MANAGEMENT OF CHANGE
• HOT WORK SYSTEMS

ROOT CAUSES:
1. Motiva did not have an adequate mechanical integrity management system to prevent and address safety and environmental hazards from the deterioration of H2SO4 storage tanks.
2. Motiva engineering management and MOC systems inadequately addressed conversion of the tanks from fresh to spent acid service.
3. The Motiva hot work program was inadequate.

Image Credit: CSB

A vapor-cloud explosion centered in the Cryogenic Unit No. 2 and two subsequent explosions in the Cryogenic Unit No. 1 occurred at this gas-processing complex. As a result of the explosions, the Cryogenic Unit No. 2 and liquid petroleum gas (LPG) product pumps in the Cryogenic Unit No. 1 were extensively damaged, the control rooms for both units were destroyed, and the remainder of the Cryogenic Unit No. 1 experienced minor damage.

Plant personnel noticed that one of the two LPG product pumps in the Cryogenic Unit No. 1 had a seal leak. Consequently, plant personnel decided to have the faulty seal replaced. In preparation for the maintenance work on the LPG product pump, the motor-operated valve (MOV) in the suction line and the isolation valve in the discharge line of this pump were manually closed. A spectacle blind was then inserted into the pump flange on the suction side of the pump. After the seal was replaced, plant personnel removed the blind and were in the process of tightening the flange bolts when LPG product began to leak from this flange. A vapor cloud formed and drifted into the Cryogenic Unit No. 2. It was ignited and resulted in the initial explosion. Following the explosions, it was determined that the MOV in the suction line of the pump was in the open position, which allowed the LPG product to reach the pump flange. The fire brigades successfully extinguished the fire following the explosions after approximately three hours, and protected the adjacent LPG spheres. If these spheres had failed due to BLEVE, the property plant damage would have been substantially greater. Although the explosions damaged the electric power in the plant and rendered the electric motor-driven fire water pumps non-operational, fire water was provided by two diesel engine driven fire water pumps. Because of this incident, the 2.13 billion-cubic-feet-per-year gas-processing capacity at this complex was shut down, disrupting one third of Mexico’s total gas-processing capacity.

[ Property Damage $137 Million. Estimated Current Value $260 Million ]

Image credit: PEMEX

Three workers were killed in an explosion at the Packaging Corporation of America (PCA) fiberboard manufacturing facility while they were welding on a temporary metal clamp to stabilize a damaged flange connection. The flange was located on top of an 80-foot tall storage tank that contained recycled water and fiber waste.

Facility personnel were unaware of the potential presence of flammable gas from the decomposition of the organic material in the tank, and combustible gas monitoring was not typically required or performed prior to starting work. At the time of the accident, three workers were on a catwalk above the tank; one began welding the flange into place when sparks from the welding ignited flammable vapors inside the tank. The resulting explosion ripped open the tank lid, knocking two of the workers to the ground 80 feet below. All three workers died of traumatic injuries. A fourth worker, who had been observing the work from a distance, survived with minor injuries.

KEY ISSUES:
• ANALYZE THE HAZARDS
• MONITOR THE ATMOSPHERE
• TEST THE AREA

ROOT CAUSES:
1. Anaerobic bacteria
2. Hot work

Image credit: CSB

On August 12, 2016, seven workers were injured – three critically – when a flash fire occurred during hot work activities at Sunoco Logistics Partners, a terminal facility in Nederland, Texas.

KEY ISSUES:
• HOT WORK

Image credit: CSB

While a worker was welding on top of a tank that contained one million gallons of sodium hydrosulfide a massive explosion occurred.

Source: A web-based collection and analysis of process safety incidents (https://www.sciencedirect.com/science/article/abs/pii/S0950423016302285)
Image Credit: Alicia Turner