RUNAWAY REACTION DUE TO LOSS OF UTILITIES

 At 10:46 pm during a thunderstorm, an electrical outage interrupted polystyrene (PS) production at a Seveso-classified site. A safety disc broke and styrene was released. To minimise the effects of micro-outages (due to thunderstorms) on PS output quality, the site operator typically switched shop power supply onto the 4 electric generating sets of the facility’s Peak Day Withdrawal (PDW) unit. This manoeuvre was performed at 10:20 pm, with 3 sets still available. At 10:43, the thunderstorm knocked out the 1st set. Since the 2 remaining sets were no longer sufficient, the unit entered into safety mode at 10:46, closing all utilities. An employee tried to restart the PDW unit; the on-call electrical maintenance operator was called at 10:53 pm. By 11:05 pm, pressure on the 1st synthesis reactor had begun to rise. As per emergency procedures, gyro monitors started up at 11:15 to remove eventual vapours at the reactor line vent. The site was connected to the grid at 11:18 but the units were only allowed to resume operations a short time later. At 11:20, the disc on the 1st reactor burst at 5.8 bar, spraying a liquid mix containing 10 tonnes of PS and 3 tonnes of styrene.The runaway reactor was caused by the loss of utility service. The control room operator opened the vent too late, given all the actions required to put the 3 polystyrene lines into safe mode, in accordance with procedures.

Source: Aria ACCIDENT ANALYSIS OF INDUSTRIAL AUTOMATION

AUTOMATION INCIDENTS IN PROCESS SAFETY

 "The factory of the future will have only two employees, a man and a dog. The man will be there to feed the dog. The dog will be there to keep the man from touching the equipment.» Warren G. Bennis, North American consultant,1996"

HCL LEAKS FROM FURNACE FOR 10 MINUTES In a chemical plant, 0.6 tons of hydrogen chloride (HCl) escaped during a 10-minute period from all furnaces and vents within the potassium sulphate workshop while cleaning the HCl circuits. An employee living adjacent to the site notified the guard house of the presence of a cloud originating from the plant. The emergency sprinkling system connected to the washer was turned on to stop these emissions. Poor calibration of one of the two devices used to measure gas pressure at the furnace outlet (not directly related to the ongoing works), causing the control valve on the gas evacuation circuit to close, was responsible for this incident: since gases were no longer being drawn, they escaped from the furnaces. The lack of an alarm on this control parameter slowed personnel response, and the absence of any means for comparing the 2 pressure measurements prevented the detection of sensor drift. To reduce the probability of repeat occurrence, an alarm was installed to detect deviations between the 2 pressure readings; also, a procedure laying out the most sensitive steps, in particular those requiring a supervisor's presence, was issued.

Source: Aria ACCIDENT ANALYSIS OF INDUSTRIAL AUTOMATION

AI in process safety

 https://www.iiot-world.com/smart-manufacturing/process-manufacturing/ai-in-process-safety-industrial-safety/

Combustible Dust: An Explosion Hazard

 

Any combustible material can burn rapidly when in a finely divided form. If such a dust is suspended in air in the right concentration, under certain conditions, it can become explosible. Even materials that do not burn in larger pieces (such as aluminum or iron), given the proper conditions, can be explosible in dust form.

The force from such an explosion can cause employee deaths, injuries, and destruction of entire buildings. For example, 3 workers were killed in a 2010 titanium dust explosion in West Virginia, and 14 workers were killed in a 2008 sugar dust explosion in Georgia. The U.S. Chemical Safety and Hazard Investigation Board (CSB) identified 281 combustible dust incidents between 1980 and 2005 that led to the deaths of 119 workers, injured 718, and extensively damaged numerous industrial facilities.

A wide variety of materials that can be explosible in dust form exist in many industries. Examples of these materials include: food (e.g., candy, sugar, spice, starch, flour, feed), grain, tobacco, plastics, wood, paper, pulp, rubber, pesticides, pharmaceuticals, dyes, coal, metals (e.g., aluminum, chromium, iron, magnesium, and zinc). These materials are used in a wide range of industries and processes, such as agriculture, chemical manufacturing, pharmaceutical production, furniture, textiles, fossil fuel power generation, recycling operations, and metal working and processing which includes additive manufacturing and 3D printing.

Source: https://www.osha.gov/combustible-dust 

LOOK ALIKES CAUSE AN INCIDENT

On May 20, 2025, at approximately 8:15 a.m., approximately 8,000 pounds of toxic chlorine were released, seriously injuring one employee at a facility in  Texas . The community was ordered to shelter in place, and estimated that the incident resulted in approximately $23 million in property damage.

On the day of the incident, it was planned to replace a rupture disc (RD-217N) in the chlorine liquefication unit. This safety device protected the E-209A heat exchanger 

 

The company gave two contract maintenance workers the work package and a permit to replace the RD-217N rupture disc. At approximately 8:10 a.m., one of the maintenance workers began disassembling the RD-217N rupture disc holder using a battery-powered impact wrench. In addition to the standard protective equipment, the maintenance worker wore an air-supplying respirator with a 30-minute air bottle. At 8:15 a.m., liquid chlorine at a pressure of 100 pounds per square inch began releasing from the partially disassembled RD-217N rupture disc holder. The maintenance workers evacuated from the area. Alarm horns in the unit were activated after chlorine gas detectors identified the release. Local officials issued a shelter-in-place order for the cities. At 9:03 a.m., emergency responders closed Valve 1 to stop the release.
During the response to the incident, one emergency responder’s 30-minute air supply depleted. He switched to a cartridge-style escape respirator to exit the area, but the respirator likely became saturated with chlorine, causing him to inhale the toxic vapor. Other emergency responders then transported him to a hospital, where he was admitted for treatment.
The company's investigation found that although the work planning documents showed that RD-217N was to be replaced, its operations team had mistakenly isolated, cleared, and tagged a different but nearly identical piping system—heat exchanger E-209B—to replace a different rupture disc, RD-217S. As a result, the operations team did not isolate, clear, or tag the E-209A heat exchanger and the piping associated with RD-217N. This equipment was operating when it issued the contract workers a permit to replace the RD-217N rupture disc. The unit operator who issued the permit and the maintenance workers did not perform a field walk-through of the job. In addition, the contract workers did not review or sign the equipment isolation plan or the tag that identified the rupture disc holder to be opened. Seeking to do so should have revealed that RD-217N was in operation and had not been prepared for replacement.
Probable Cause
Based on the company's investigation, the CSB determined that the probable cause of the chlorine release was the mistaken disassembly of a rupture disc holder in an operating chlorine system. A breakdown in the equipment opening and control of work programs contributed to the incident, including the absence of a pre-job site walkthrough that should have allowed plant operators and the maintenance crew to verify the rupture disc had been prepared for replacement.

Source:CSB.gov