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

INCIDENT DUE TO "WE DO NOT KNOW WHAT WE DO NOT KNOW"

 On April 10, 2020, at 12:46 a.m., a mixture of hydrogen and hydrocarbon gas was accidentally released within the Hydrocracker unit of a refinery/ The flammable gas formed a vapor cloud that ignited, resulting in an explosion and fire (Figure 1) that seriously injured one operator and caused approximately $5.15 million in property damage.
After a heavy rainstorm, the flow to the Hydrocracker unit’s flare began increasing. Operators found that although the unit’s cold separator was operating at normal working pressure, its emergency pressure-relief valve had malfunctioned and remained open, allowing flammable gas to flow into the flare system. Two managers at the refinery phoned the complex manager, who gave the onsite managers verbal approval to proceed with immediate actions to stop the flaring by reseating the safety device.
The company uses the term “reseating” when referring to its practice of trying to close and seal a malfunctioning emergency pressure-relief valve by incrementally closing the inlet (upstream) isolation valve to lower the inlet pressure to the safety device. If the emergency pressure-relief device successfully closes (reseats), its inlet valve is reopened, which returns the safety device to its protective condition.

Onsite managers used the refinery’s management of change process for isolating a safety device for approval for the operations team to perform the urgent reseating activity. One of the onsite managers—the operations supervisor—worked with two field operators to perform the reseating activity while the board operator monitored the system pressure from the control room. Operations personnel raised safety concerns related to accessing either of the two 6-inch inlet valves, resulting in a decision to close the 20-inch outlet valve on the downstream side between the emergency pressure-relief valve and the flare system instead of trying to close one of the inlet valves.

The hazard of closing the outlet valve instead of closing one of the inlet valves was not recognized. Although the two 6-inch inlet valves were designed for high-pressure conditions—2,470 pounds per square inch (psi), the 20-inch outlet valve to the flare system was rated for just 275 psi. Closing the 20-inch outlet valve would subject this valve to about 2,100 psi of pressure from the flammable vapor flowing from the cold separator, much greater than the valve’s 275 psi pressure rating.
When the operations team had the outlet valve about 90 percent closed , the valve failed—releasing a high-pressure mixture of hydrogen and hydrocarbon vapor into the surrounding air. The flammable gas formed a vapor cloud, which ignited resulting in the explosion and fire.

Source: CSB.gov

Become Natech Savvy - Aimee Russell highlights the issues you probably haven’t thought about when it comes to extreme weather risks and what you should do about them

HAVE you ever thought about the impact a natural hazard could have on your site? Have you identified which natural hazards are even credible? For upper tier Control of Major Accident Hazards (COMAH) establishments there is an expectation from regulators that duty holders are aware of external hazards, but what does that really mean? What about sites which do not fall under these regulations? Does that mean they shouldn’t be concerned with such hazards?

Read the article in this link 

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