Hazards: Corrosive

On February 12, 2014, a mechanical integrity failure released sulfuric acid in the alkylation unit, which burned two Tesoro Martinez refinery employees. Approximately 84,000 pounds of sulfuric acid were released during the incident.

On March 10, 2014, sulfuric acid sprayed and burned two contract workers while they removed piping in the same alkylation unit. The CSB found that this second incident shared similar causation with a 1999 incident at the same refinery, then called the Avon refinery, owned by the Tosco Corporation, that resulted in four fatalities. Similarities between the two incidents suggest that the Tesoro Martinez refinery did not effectively continue to implement or communicate important safety lessons from the 1999 Tosco incident.

KEY ISSUES:
• PROCESS SAFETY CULTURE
• PROCESS SAFETY INDICATORS

ROOT CAUSES:
1. The safety culture at the Tesoro Martinez refinery created conditions conducive to the occurrence and recurrence of process safety incidents that caused worker injuries at the refinery over several years.
2. Prior sulfuric acid exposure incidents at the Tesoro Martinez refinery could have properly been considered leading indicators of an impending serious chemical accident and then triggered preventive inspections and review of the refinery’s safety systems and equipment.

Image & AcciMap Credit: CSB

Image credit: CSB

A high-pressure steam (3.7 MPa) discharge occurred during a maintenance process, resulting in three field workers burned to death.

Proximate causes:
• Lack of work rules/policies/ standards/procedures (wrong procedures for inspections);
• Inadequate work rules plan (lack of the pre-start safety review before inspection).

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

An explosion occurred when 6 personnel were working on the repair of a catalyst tower

Proximate causes:
• Lack of work rules/policies/ standards/procedures (wrong procedures for inspections);
• Inadequate work rules plan (lack of the pre-start safety review before inspection).

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

An April 11, 2003, vessel explosion at the D.D. Williamson & Co., Inc. (DDW), plant in Louisville, Kentucky, killed one operator. The explosion damaged the western end of the facility and released 26,000 pounds of aqua ammonia (29.4 percent ammonia solution in water), forcing the evacuation of as many as 26 residents and requiring 1,500 people to shelter-in-place.

DDW used the vessel in the manufacture of food-grade caramel coloring. It functioned as a feed tank for a spray dryer that produced powdered colorants. The feed tank, which was heated with steam and pressurized with air, was operated manually. To ensure that the filling, heating, and material transfer processes stayed within operating limits, operators relied on their experience and on readouts from local temperature and pressure indicators.

The feed tank most likely failed as a result of overheating the caramel color liquid, which generated excessive pressure. .

KEY ISSUES:
• OVERPRESSURE PROTECTION
• HAZARD EVALUATION SYSTEMS
• LAYERS OF PROTECTION
• OPERATING PROCEDURES & TRAINING

ROOT CAUSES:
1. D.D. Williamson did not have effective programs in place to determine if equipment and processes met basic process and plant engineering requirements.
2. D.D. Williamson did not have adequate hazard analysis systems to identify feed tank hazards, nor did it effectively use contractors and consultants to evaluate and respond to associated risks.
3. D.D. Williamson did not have adequate operating procedures or adequate training programs to ensure that operators were aware of the risks of allowing the spray dryer feed tanks to overheat and knew how to respond appropriately.

Image Credit: CSB

A fire occurred in a company producing ammonia, and other chemical products. The facility was severely damaged in the catastrophic fire.

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

On April 25, 2002, a chemical waste-mixing incident occurred at Kaltech Industries Group, Inc., a sign manufacturer located in the Chelsea district of New York City. At least 36 people were injured, including members of the public and six firefighters. Kaltech employees were consolidating hazardous waste from smaller containers into two larger drums when the explosion and fire occurred.

The Kaltech facility was located in a mixed-occupancy building in a densely populated urban area. Because the highly confined workspace in the basement offered limited pathways for the explosion to vent, there was extensive damage to the 10-story building. Street traffic was restricted for several days, and building tenants faced significant business interruptions.

KEY ISSUES:
• HAZARD COMMUNICATION
• HAZARDOUS WASTE HANDLING
• MUNICIPAL OVERSIGHT

ROOT CAUSES:
1. Kaltech did not develop or maintain a chemical hazard communication program in accordance with established OSHA standards.
2. Kaltech did not manage its hazardous waste in accordance with established EPA regulations.

Image Credit: CSB

Bulk Terminals was a storage tank farm with 78 tanks ranging in size up to 4900 m3. At about 12:30 hours on Friday 26 April 1974 a dull thud was heard and fumes were seen rising from the bund surrounding a 3300 m3 tank of silicon tetrachloride. It was discovered that a pressure relief valve on a 6-inch line leading to the tank had been inadvertently closed. The pressure in the system was sufficient to burst a flexible coupling in the line, shifting the piping system and cracking a 3-inch line on the tank wall. Liquid silicon tetrachloride escaped forming an irritant cloud containing hydrogen chloride gas.

The terminal management waited for the owners of the chemical to take emergency action and the fire service did not respond, as there was no fire. The EPA sent lime trucks to neutralise the chemical, but these were refused entry to the site. By 15:00 hours the cloud was 400 m wide, 300-450 m high and 1600 m long.

At 04:10 hours on Saturday 27 April, foam was added to blanket the liquid in the bund but this failed. At 09:00 hours fuel oil was added along with eight truck loads of lime. The vaporisation reduced dramatically and operations began to transfer the liquid from the damaged tank. At 08:00 hours on Sunday 28th April, it began to rain. Power lines were corroded by the hydrochloric acid in the rain, and four pumps became inoperable due to corrosion before a general power failure stopped all pumping.

The materials added into it had reduced the capacity of the bund, and a further pit had to be dug to take the overflow in the event of a full tank failure. It was attempted to seal the leak on the tank using quick drying cement. The first attempt failed and it wasn’t until 23:30 hours on Monday 29 April that the leak was sealed. It took until 3 May to empty the tank and until 15 May before emissions had reduced to tolerable levels. One person was killed, 160 hospitalised and 16,000 people were evacuated during this incident.

KEY ISSUES:
• RELIEF SYSTEMS / VENT SYSTEMS
• DESIGN CODES – PIPEWORK
• EMERGENCY RESPONSE / SPILL CONTROL
• SECONDARY CONTAINMENT

Image Credit: Chicago Fire Dept

An explosion, caused by sodium metal reacting with water, occurred in a chemical plant in Mohekou Bengbu City Industrial Park. The fire was put off in 1 h.

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

Ammonia release at recycling center workers was evacuated. Shelter in place was issued in nearby areas.

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

On May 24, 2017, an explosion occurred at the Midland Resource Recovery (MRR) facility in Philippi, West Virginia, killing two workers and severely injuring another worker. The founder and president of MRR was one of the victims. The CSB initiated an investigation of the incident and deployed an investigative team on May 28, 2017. While the CSB was investigating this incident, the MRR facility experienced a second explosion, on June 20, 2017. This explosion fatally injured a contractor employed by Specialized Professional Services, Inc. (SPSI). MRR had hired SPSI to perform investigation and mitigation work at its Philippi facility following the May 24, 2017, explosion.

The CSB determined that the probable cause of these incidents was reactive, unstable chemicals that exploded when workers tried to drain the uncharacterized, chemically treated liquid from natural gas odorizer equipment. The CSB investigation found that MRR lacked an effective safety management system to identify and control hazards from reactive chemicals. Among other things, MRR had no formal hazard identification process in place to analyze or characterize what chemicals were inside the odorizer vessels (and in what quantity) before decommissioning and chemically treating this equipment with sodium hypochlorite. The company also lacked effective safeguards to prevent unexpected or uncontrolled chemical reactions.

Following these catastrophic incidents, MRR asserts that it has stopped using reactive chemicals, including sodium hypochlorite, and the company now uses a proprietary process to remove the mercaptan smell from decommissioned odorization equipment.

KEY ISSUES:
• INEFFECTIVE MANAGEMENT OF REACTIVE CHEMICAL HAZARDS
• LACK OF A PROCESS SAFETY MANAGEMENT SYSTEM
• PERSISTING GAPS IN FEDERAL SAFETY REGULATIONS FOR REACTIVE CHEMICAL HAZARDS

ROOT CAUSES:
1. The company did not conduct a formal evaluation of the reactive chemistry, perform a hazard analysis, and ensure that sufficient safeguards are in place to prevent reactive chemical incidents.
2. The company did have a thorough and complete understanding of their reactive chemistry under design conditions and under all foreseeable abnormal conditions.

Image credit: CSB

On June 10, 2008, Goodyear operators closed an isolation valve between the heat exchanger shell (ammonia cooling side) and a relief valve to replace a burst rupture disk under the relief valve that provided over-pressure protection. Maintenance workers replaced the rupture disk on that day; however, the closed isolation valve was not reopened.

On the morning of June 11, an operator closed a block valve isolating the ammonia pressure control valve from the heat exchanger. The operator then connected a steam line to the process line to clean the piping. The steam flowed through the heat exchanger tubes, heated the liquid ammonia in the exchanger shell, and increased the pressure in the shell. The closed isolation and block valves prevented the increasing ammonia pressure from safely venting through either the ammonia pressure control valve or the rupture disk and relief valve. The pressure in the heat exchanger shell continued climbing until it violently ruptured at about 7:30 a.m.

The catastrophic rupture threw debris that struck and killed a Goodyear employee walking through the area. The rupture also released ammonia, exposing five nearby workers to the chemical. One additional worker was injured while exiting the area.

KEY ISSUES:
• EMERGENCY RESPONSE & ACCOUNTABILITY
• MAINTENANCE COMPLETION
• PRESSURE VESSEL OVER-PRESSURE PROTECTION

ROOT CAUSES:
1. Although maintenance workers had replaced the rupture disk by about 4:30 p.m. on June 10, the primary over-pressure protection for the heat exchanger remained isolated until the heat exchanger ruptured at about 7:30 a.m. on June 11.

Image credit: CSB

Three killed when feeding additives bnaphthalene sulfonate to a reaction pool at a chemical fertilizer company.

Proximate causes:
• Failure in following procedure (Improper operation)

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

On the morning of Sunday 27 June 1982 two explosions occurred at the premises of Staveley Chemicals Limited. The source of the explosions was a pit containing drums of sulphur trioxide and of oleum. The drums of sulphur trioxide had been returned from customers more than 10 years previously and had then been stored in the open. Over the following years minor leaks developed through corrosion, and sulphur trioxide vapour began to escape as a visible fume. In November 1981 the company decided to overcome the problem by surrounding the drums with an absorbent solid. A pit was dug out on some open land within the works site, the drums placed within the pit, then covered over with a proprietary absorbent material and topped with crushed blast furnace slag. No special provision was made for drainage of the pit, nor to prevent ingress of ground water or rain. Drums of oleum were included together with the drums of sulphur trioxide in the pit.

The first explosion occurred at 10:45 hours on June 27th. Two drums were blown out of the site, over a public highway, to fall into open ground outside the works boundary and about 300 metres from the containment pit. Fortunately no injury to persons or damage to property was caused by these events. Further, but less intense explosions continued until the following day. A cloud of white acid mist billowed up from the site.

The Fire Brigade could not use water hoses because of the possibility of causing a violent reaction with any escaping oleum or liquid sulphur trioxide within the containment pit. It was decided that the best immediate course of action would be to put anhydrous sodium sulphate powder into the open pit in order to absorb liquid and suppress fuming. Several bags of this powder were thrown in and by 12:00 hours the mist emission was lessening. However, a second explosion occurred at 12:30 hours with a large release of acid mist but without ejecting any drums. There was a third explosion at about 14.30 hours. Tarpaulins were put over the pit to prevent the ingress of rain. The last explosion was at about 03:00 hours, the following morning. This explosion was minor compared with those on the previous day.

On Monday 28 June, a heavy steel grid was placed over the pit to reduce the risk of further drums being ejected. Temperature measurements were made in the pit, and found to be as high as 90°C in places. Subsequently the drums were all taken out of the pit and put on to open ground nearby. There were 32 sound drums remaining, and 25 corroded and empty or nearly empty.

KEY ISSUES:
• DRUM / CYLINDER HANDLING

Image Credit: YouTube (Hollingwood Lad)

An explosion and fire was caused by the failure of ammonia synthesis equipment

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