Hydrogen leak incident

A hydrogen leak at the flange of a 6-inch synthesis turbocharger valve in an ammonia production plant ignited and exploded. Hydrogen detectors and the fire alarm alerted the control room, which immediately shut down the plant, and the fire was then extinguished rapidly. There were no injuries caused by the accident, since the operator heard a wheezing sound and was able to run away just before the explosion occurred. The leaking gas was composed of 70% hydrogen at a flow rate of 15,000 cubic meters per hour. Property damages in the turbocharger included electrical cabling, melted siding, and heavily damaged pipes. The ammonia plant was shut down for more than a month.Five days before the incident, a problem with the CO2 absorber column led operators to open the vent downstream of the column. In retrospect, this excessive venting was an operational error. It caused a reduction in the suction pressure of the ammonia synthesis turbocharger and the activation of the plant emergency stop. The relief valve on the line between the turbocharger and the methanation reactor was then exposed to high pressure, causing it to open without the operator noticing. Production resumed the next day, but abnormal consumption of syngas led the operator to conduct further investigations. He discovered that the valve was no longer leak-proof and was allowing the gas to escape through a 47-meter chimney. The plant was shut down again to replace the relief valve.When the plant was restarted, the methanation reaction was initiated at 10:00 PM, the synthesis turbocharger started operating at 1:30 AM, and the incident occurred at 3:14 AM on the flange of the newly installed 6-inch-diameter valve. The incident was caused by vibrations in the relief valve, resulting in the quick release of the flange screws, which were probably not tightened sufficiently. In addition, when the relief valve was replaced, it was probably under-calibrated.

Source:https://h2tools.org/lessons/hydrogen-leak-ignites-and-explodes-ammonia-production-plant

Cryogenic incident

 What Happened?

A researcher inserted metal racks into a liquid nitrogen tank when her right hand came into contact with the chemical; she sustained cold burns to her index, middle and ring fingers. The researcher reported the incident immediately to her PI, and went to the emergency room for medical attention. At the time of the incident the researcher was wearing appropriate PPE including a pair of latex gloves underneath the cryogenic gloves; however, the chemical had penetrated the gloves upon submersion.
What Was The Cause?

The cryogenic gloves worn by the researcher appeared to be intact. Cryogenic gloves are meant to handle cold items and protect to temperatures as low as -162°C (-260°F). However, they are not meant to be submerged into liquid nitrogen which has a temperature of −196 °C ( −321 °F). In addition, if the gloves were used for other purposes where they get wet, the problem can be compounded. Not all cryogenic gloves are water-resistant.
 

What Corrective Actions Were Taken?
• Review the correct use of cryogenic gloves and modify SOP for handling cryogenic chemicals
• Review modified SOP with lab members
 

How Can Incidents Like This Be Prevented?
• Make sure to use all equipment according to their specifications

 

Source: https://cls.ucla.edu/

High pressure water can kill

 At 5:45 p.m. on April 29, 2018, an employee was inspecting a leak beneath a valve. The employee was struck by high pressure water at 2,200 psi when the valve failed and came off, penetrating his upper torso. The employee was killed. 

Source:osha.gov

Hydraulic hose incident

 At 6:15 p.m. on November 20, 2017, an employee was working on a hydraulic leak on Filter Press #1 at the Pollution Control Plant. The employee was struck on the left side of his head by a high pressure hydraulic hose which was released from a tee fitting. The employee sustained trauma to the head when struck by the high pressure hydraulic hose fitting and was killed. 

Source:osha.gov

Hydrogen explosion

 At 9:23 a.m. on November 17, 2018, an employee was stabilizing magnesium metal. Magnesium is reacted with water to make magnesium oxide, which is a more stable compound. During this process hydrogen and oxygen are released. The hydrogen ignited and in the presence of oxygen and created a large explosion. The employee was killed. 

Source:osha.gov

Ammonia incident

 On January 10, 2020, Employees #1 and #2 were working from a scissor lift and dismantling an ammonia blast freezer in preparation for installing a new freezer. As they worked, ammonia was released. Employee #1 was killed by the chemical exposure. Employee #2 self-rescued, but was seriously injured. He was transported to the hospital and treated for severe burns and inhalation injuries. 

Source:osha.gov

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Hydrogen Sulphide accident

 At 11:00 a.m. on July 7, 2017, Employee #1was attempting to dislodge a 24 inch rubber plug from a 2foot diameter sewer pipe located inside a 24foot deep wet well. The workers were outside the well pulling on a 1/4-inch nylon rope that was attached to the 24-inch diameter plug. The plug was lodged inside a T-shaped PVC fitting from the force of the waste water emptying into the well. Without conducting any atmospheric testing of the work space, Employee #1 climbed down the ladder with a crowbar to dislodge the deflated 24inch diameter rubber plug, which was about 8 feet below the top of the well. He had difficulty releasing the plug with the crowbar and started to make his way up the ladder. He lost consciousness when he was about 2 feet from the top of the well and fell into the 24 foot deep well. Employee #2 descended down the ladder to provide emergency rescue, but lost consciousness and went underwater. The waste water level was about 3 feet deep at this point. Employee #3 climbed down the ladder to provide emergency rescue, but consciousness as well. All three workers were asphyxiated by hydrogen sulfide (H2S) gas. 

Source: osha.gov

Confined space incident

 At 12:30 p.m. on February 20, 2020, Employee #1, employed by a structural steel fabricator and erector company, was entering a tank to clean it. The tank had a combination of Ecocure II and methyl ethyl ketone (MEK) residues and had been purged with nitrogen. Employee #1 entered the permit required confined space that contained the residual chemicals and nitrogen to perform the cleaning operations. She was overcome by the oxygen deficient atmosphere. Employee #2, employed by a chemical distribution company, entered the tank to make a rescue attempt for Employee #1. He was also overcome from the oxygen deficient atmosphere. Both employees were killed by asphyxiation. 

Source:osha.gov

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Hazards of hydraulic accumulators

 https://www.machinerylubrication.com/Read/30331/hydraulic-accumulators-dangers

Fluid power incidents

 Fluid power incidents

Vacuum pump explosion in a lab

 Vacuum pump explosion in a lab

Learn from this incident

Employee #1 and several coworkers were working at a chemical plant that deals with nitric oxide. On the day of the accident, a major leak occurred in a stainless steel distillation column. The nitric oxide leaked into the facilities surrounding vacuum jacket and into the atmosphere through a pump, which controls a high quality vacuum inside the jacket to minimize transmission of heat toward the cryogenic distillation columns. A brown cloud quickly formed and the temperature and the pressure inside the distillation column and its surrounding vacuum jacket began to rise. The leak was detected and the vacuum pump was turned off to halt the leakage of nitric oxide into the atmosphere, allowing the pressure inside the column and vacuum jacket to stabilize around 130 psi. Although stabilized, the pressure was far above the normal pressure of less than or equal to atmospheric pressure (14.7 psi). Approximately 3 hours later, an explosion occurred. The operation and process were destroyed, and debris flew through the plant. Employee #1 suffered lacerations due to flying glass and was treated at a local hospital, where he received stitches and then released. A detailed investigation determined that the cause of the explosion was most likely due to something inside the vacuum jacket initiated the dissociation of nitric oxide, a reaction that is very rapid, exothermic, and self-propagating once started. 

Source:OSHA.gov

Accident due to a change implemented during an emergency

Reactor #1, part of the ABS polymerization process began to overheat as the viscosity increased and threatened to stop agitation. This would cause a runaway reaction and ultimately result in an explosion. A small leak had developed in the lower bushing of the agitator and the employer instructed an employee to tighten it with a wrench. The employer replaced the normal feed (a mixture of styrene monomer, ground rubber, and acrylonitrile) with pure styrene monomer, which has a much lower viscosity, to "flush" the process in the hope that this would stop the leak. The mixture began to spill through the lower agitator packing and at approximately 2:30 p.m., there occurred a major spill of styrene monomer (flammable) and acrylonitrile (flammable and carcinogenic). They evacuated the plant and called for outside assistance to stop the spill and initiate clean-up. 

Source: OSHA.gov

How fragile is your plant?

 How fragile is your plant?

Employee Killed By Inadvertently Drinking Acid Cleaning Fluid

At approximately 9:30 a.m. on October 3, 2002, an employee who worked for a company that provided vehicle maintenance such as car washes, detailing, fueling, and lube and oil servicing, inadvertently drank acid from a plastic spray bottle while he was on a rest break. The employee, feeling very ill after ingesting the contents of the quart bottle, asked his coworkers to transport him to the hospital. He was taken to San Antonio Community Hospital where he was pronounced dead at 11:49 a.m. from internal injuries. Laboratory analysis indicated that the acid solution in the plastic bottle contained hydrofluoric acid and phosphoric acid with a pH of less than one. 

Source:osha.gov

Employee dies in explosiove reaction

 At 12:00 p.m. on November 5, 2019, Employee #1 was making a small spot weld on a piece of metal. He was performing the weld on a drum of that contained flammable windshield washer fluid. There was an explosive reaction, and the cover of drum hit the employee's face. Liquid splashed on the employee and was ignited by the explosion. Employee #1's clothes caught on fire. He sustained body burns and was killed. 

Source:osha.gov

Be careful while excavating

 At 8:30 a.m. on August 1, 2020, Employees #1, #2, and #3, employed by a electrical services company in the telecommunications field, were working on a multi-employer construction project at the intersection of two streets. They were potholing to locate underground utility lines, with the aim to then bore in a new fiber optic line under the intersection. After finding what they thought was over-pour from the concrete curb, they used a Ring-o-matic Vacuum Excavator to excavate over top of the concrete. They then used a jackhammer on the concrete. The jackhammer bit made contact with a 12,470-volt underground electrical distribution line, and an electric arc explosion occurred. Employees #1 and #2 were killed by electrocution. Employee #3, who was knocked down by the force of the explosion, was transported to the hospital, where he was observed, determined to have no injuries, and released. 

Source:osha.gov

Employee injured by pressurised gas release

 At approximately 9:00 p.m. on August 8, 2006, Employees #1 and #2 attempted to clean out a heat exchanger. The heat exchanger was part of a natural gas piping system in the power generation facility of a wastewater treatment plant. The heat exchanger contained methane and natural gas, pressurized to approximately 300 pounds per square inch. Approximately 200 parts per million of hydrogen sulfide contaminant was present in the natural gas. The natural gas piping system contained two compressors, labeled Compressor A and Compressor B. The heat exchanger that Employees #1 and #2 were to clean out was connected to Compressor B. Compressor B was off and Compressor A was running. Employees #1 and #2 incorrectly assumed that since compressor B was not running, it had already been isolated from Compressor A by a closed valve. However, the valve between compressor A and B was in the "open" position. Employee #2 began removing a plug on the Compressor B heat exchanger, with a pneumatic impact gun, while Employee #1 was standing directly behind him. When the heat exchanger plug was removed, the pressurized natural gas came out of the 0.5-inch plug opening and blew Employees #2 and #1 back. The natural gas did not ignite. Employee #1 was rendered unconscious from the impact. Employee #2 initiated emergency shutdown of the natural gas system and notified other employees about the emergency. An ambulance was called, but neither employee was hospitalized. 

Source:osha.gov