"IGNITION SOURCES ARE FREE"

 On October 6, 2021, an accidental release of crude oil and produced water occurred during vacuum truck loading operations at  a facility. An unknown amount of flammable vapors from the released fluids ignited, resulting in a flash fire that seriously injured the vacuum truck driver.
An emulsion layer periodically developed at the oil and water interface within the heater treater at the facility and grew thicker over time. The presence of the emulsion layer impaired the heater treater’s efficiency. To address this problem, the company periodically removed the emulsion layer by transferring fluids from the heater treater to a vacuum truck.
The company's investigation identified the sequence of events as follows:
1. The contractor vacuum truck driver discussed the planned work with an operator, and the operator approved the truck driver to start the loading operation;
2. The vacuum truck driver connected a three-inch hose between the truck and the heater treater;
3. The driver opened valves on each end (the truck inlet valve and the process valve);
4. After these valves were opened, produced water and crude oil flowed from the pressurized heater treater into the vacuum truck (the truck’s vacuum pump was not operating);
5. When the vacuum truck driver detected crude oil, he closed the process valve on the heater treater to stop additional fluid from entering the hose; and
6. The vacuum truck driver disconnected the hose from the heater treater, and the contents flowed out of the truck and into the atmosphere through the open hose. The released fluid contained flammable hydrocarbon vapor that ignited, creating a flash fire that seriously injured the driver.
The company’s investigation concluded that the fired heater treater components may have been the ignition source. The heater treater burner was inadvertently left online during the vacuum truck loading operation. The company's investigation team did not eliminate static electricity as the potential ignition source because the hose components were non-conductive, and the truck was not electrically bonded or grounded.
The company's investigation identified additional causal factors, including:
A. The procedures, training, and administrative controls did not effectively control the hazards associated with draining an emulsion layer from its heater treaters;
B. No safety or hazard analysis was performed to identify or control potential hazards before performing this work;
C. There was no pre-determined location to electrically ground or bond the vacuum truck; and
D. Using system process pressure from the vessel to transfer the fluid to the vacuum truck rather than using the truck’s vacuum pump to pull the fluid into the truck contributed to the incident.

Siurce:CSB.gov

BEWARE OF MOVING EQUIPMENT IN PLANTS......

On June 14, 2021, at approximately 6:50 a.m., an accidental release of mineral oil occurred at a facility  that led to the permanent closure of the facility
Leading up to the incident, a contractor was hired to replace insulation on its heating oil piping system. To reach a portion of this piping, the contractor used a scissor lift.
As the contractor began raising the scissor lift near the work location, the top guardrail of the lift impacted a section of a ½-inch piping assembly that included a valve. This threaded piping was connected to a four-inch pipe containing mineral oil, which was part of a hot oil system that provided heating for other process equipment.
After the guardrail impacted the piping, a leak formed at the ½-inch threaded connection to the four-inch piping. The hot mineral oil, which was over 500 degrees Fahrenheit, was released as an aerosol. The mineral oil formed a white cloud and created the electrostatic conditions that most likely ignited the mineral oil.

Upon seeing the white cloud, workers responded to the release. The workers tried to contain the spill by placing absorbent barriers around mineral oil on the floor. Additionally, the workers shut off the oil heating system. The workers also lowered the pressure of the hot oil system, but the leak could not be remotely isolated from a safe location. As a result, the mineral oil ignited, and the fire grew and destroyed the facility.
The CSB estimated that less than 100 pounds of mineral oil was released between the start of the release and the time of ignition.
Probable Cause
Based on the company's investigation, the CSB determined that the probable cause of the mineral oil release was piping damage that resulted from force applied by the scissor lift. The flammable mineral oil was most likely ignited by static electricity. The hot oil system did not allow for the remote isolation of the damaged piping. Had they been able to stop the flow of mineral oil through remote isolation from a safe location, the incident could have been less severe.

Source:CSB.gov

CONFIRM CYLINDERS ARE EMPTY BEFORE DISCONNECTING!

On December 3, 2020, at approximately 2:30 p.m., an accidental release of toxic chlorine gas occurred at a facility in Point Comfort, Texas, and seriously injured one employee 

At the time of the incident, four employees were involved in replacing an empty chlorine container with a full 2,000-pound (one-ton) container at the facility’s Ethylene Glycol unit. Chlorine gas was used as a biocide in its cooling water treatment system.
As a employee disconnected the supposedly empty chlorine container from the process equipment, chlorine gas escaped because, unknown to the workers, the container still held 1,250 pounds of chlorine (62.5 % of its original inventory). Because the chlorine container was understood to be empty, the  employee was not wearing respiratory protection. After three failed attempts to stop the release, an emergency responder was able to close the chlorine container’s vapor valve and stop the release after 50 minutes.

The employee who disconnected the chlorine container was life-flighted to the hospital after showing respiratory difficulties from exposure to chlorine. Formosa reported that approximately 10 pounds of chlorine gas were released.

The investigation team recommended installing a scale for each container to address the false indication of an empty ton container of chlorine in the future. Knowing the weight of the chlorine container could help plant workers confirm that a container is empty or alert them that the container is not empty. In addition, the company strengthened its operating procedures to clarify that respiratory protection is needed when changing a chlorine container.

Probable Cause
Based on the company's investigation, the CSB determined that the probable cause of the accidental chlorine release was disconnecting process equipment from the chlorine container while the system was pressurized with chlorine. The lack of instrumentation or other equipment to allow the operators to confirm the amount of chlorine in the container contributed to the incident. Another factor contributing to the incident was the use of chlorine in the cooling water treatment program. Had the company used a safer alternative, such as bleach, this incident could have been prevented.

Source:CSB.gov

LINE OPENING INCIDENT

 On July 24, 2020, at 1:20 p.m., an accidental release of approximately 100 milliliters of silicon tetrachloride seriously injured two contract workers at a facility in Tennessee.

At the time of the event, contract workers were disassembling a 2-inch flange to remove a blind (a solid metal plate used for isolating equipment) before reinstalling a section of piping that had been taken out and cleaned. This type of equipment opening is commonly called a “line opening” or “performing a line break.”
The contract workers performing the line opening wore personal protective equipment (“PPE”), including full-face respirators, chemical gloves, and fall protection. The contractor’s pre-job safety analysis form did not require using chemical suits or rubber boots because the piping system had been taken apart the previous day for the cleaning activity. This additional protective equipment was required by the safe work permit, authorizing the contractor to perform the line opening work. As the workers disconnected the flanged connection bolts, they were splashed with corrosive liquid silicon tetrachloride that had leaked past an isolation valve and pressurized the piping, seriously injuring the two contract workers with chemical burns.
 

Based on the factual investigative information the CSB obtained from the company and OSHA, the CSB determined that the probable cause of the accidental silicon tetrachloride release was the failure to effectively isolate, flush, and drain the piping system before turning it over to the contract workers for disassembly. Not using PPE that could protect the workers from being splashed with corrosive silicon tetrachloride contributed to the severity of the incident.

Source: CSB.gov

TEMPORARY CHANGES MAY LOOK SIMPLE BUT ARE DANGEROUS!

 On April 11, 2020, at 11:25 p.m., a spent caustic release occurred at a facility in Louisiana. One operator was seriously injured by skin exposure to the corrosive liquid.

At the time of the incident, the operator was implementing a temporary procedure to remove liquid from a chemical hose connected to fill a portable storage tank (“frac tank”) that the company was using to store spent caustic. Once the frac tank was full, air was used to clear the chemical hose before moving the hose to an empty frac tank.
When the operator opened the valve at the frac tank, pressurized fluid in the chemical hose flowed into the tank, erupting spent caustic from the unsecured top hatch (manway) and splashing the corrosive liquid onto the operator. The operator's personal protective equipment (PPE) did not protect from caustic liquid exposure. It took the operator about two minutes to reach the closest plant safety shower to rinse off the corrosive liquid because there was no safety shower near the frac tank, despite the site requirement for a safety shower within 25 feet of the tank. The operator then went to the control room and reported the incident. Emergency responders transported the operator to a hospital, where she was admitted for treatment of chemical burns.

It was  estimated that approximately 20 gallons of spent caustic were released. The spent caustic was comprised of water, sodium hydroxide, sodium sulfide, sodium carbonate, and pyrolysis gasoline.

Source:CSB.gov