INADEQUATE REPAIR OF AN AMMONIA VESSEL KILLS 3

The 109D-C was one of three identical vessels at the facility that removed moisture and carbon monoxide from a synthesis gas used in the manufacture of ammonia. The 109D-C, which had been taken off line to replace its desiccant material, had been online for approximately 11 1/2 hours when the vessel exploded into flame. One employee was killed instantly in the explosion and 6 more suffered severe burns. Another employee, a crane operator, suffered from severe burns and was hospitalized for several weeks before he died. An ammonia operator, was standing on the catwalk above the 109D-C when it exploded. He also suffered severe burns and died several weeks later. Subsequent inspection of the vessel revealed a cracked weld. Apparently, an inadequate repair job had been made to the weld two days before the accident. 

Source:osha.gov 

INCIDENT DUE TO THERMAL EXPANSION OF AMMONIA

At approximately 7:10 a.m. on June 11, 2008, Operators at the C2 unit (Plant 2) in C building were injecting 60-psi steam at a temperature of approximately 400-degrees Fahrenheit into a precooler, heat exchanger Model Number E300-G, to purge the process of the latex products. Latex was on the tube side and ammonia was on the shell side. The steam was injected into the tubes heating the ammonia on the shell side. The precooler over pressured, rupturing the shell, releasing ammonia into the environment. Employee #1 was found dead beneath the debris in the area of the heat exchanger several hours after the explosion occurred. Five contracted employees were severely exposed to ammonia. Employees #2, #3, #4, and # 6 were hospitalized. Employee #5 received first aid and was released. 

Source:OSHA.gov

WORKING ON THE WRONG LINE INCIDENT

How do you address human factors of lookalikes when handing over lines/ equipment for maintenance?

 At approximately 9:00 a.m. on March 15, 2022, an employee disconnected nuts to a line for service and repair work. The employee was working to depressurize lines of ammonia for service work. The team had isolated, performed proper lockout/tagout, and bled the line assigned for work off. The employee began disconnecting nuts on the wrong line with pressure still on it. Pressurized ammonia began to leak from the pipe; the employee reacted to protect the plan and other personnel on-site, grabbed the nut, and manually screwed a few turns of the threads to stop the leaking. This action caused burns to the employee's hands that needed medical attention. The employee was not wearing his protective gloves because he was supposed to be working in the bled offline, which would have eliminated the hazard of glove use. 

Source:OSHA.gov

Hazards of pyrophoric materials

 Pyrophoric materials create fire and explosion hazard

There have been several explosions involving pyrophoric materials in storage tanks. It's important to take preventive measures when emptying tanks or vessels, or when opening equipment and piping for inspections and maintenance.

This bulletin explains how pyrophoric materials can form in tanks. It also describes how to prevent the explosions that can occur when pyrophoric iron sulfide is exposed to oxygen. Download and read the bulletin in this link

Fatal incident with a pyrophoric liquid - TEAL

At approximately 11:00 a.m. on May 11, 2003, Employee #1 was transferring a waste liquid from a 5 ft portable tank into an active incinerator. The waste liquid was a mixture of mineral oil and triethyl aluminum (TEAL). TEAL is pyrophoric and reacts spontaneously with air or moisture resulting in ignition. The liquid waste was moved by nitrogen pressure on the tank, through a flexible steel hose, into a rigid piping system for delivery into the incinerator. The delivery hose and piping had been pre-purged with nitrogen. The explosion and fire destroyed the flexible steel hose, splitting it both lengthwise and into approximately 6-in crosswise segments. Employee #1 was in close proximity to the ruptured hose and was engulfed in flames sustaining fatal burns. Employee #1's body was not retrievable until after the fire was extinguished. The portable tank was charred on the side where the steel hose was located, not undamaged on its opposite side. The rigid piping had char marks on the outer surfaces, but was not bent or deformed. The incinerator was unaffected by the explosion and fire which had occurred only 20 to 30 ft away. A coworker reported having had some operational difficulties while he was working on the waste transfer with Employee #1 that morning. The rigid piping system had clogged and was cleared by nitrogen pressure. The piping system had also developed hot spots, something that never occurred before. 

Source:osha.gov

Lessons to learn from this incident

"A terrible accident occurred at a process plant in Taiwan on May 18, 2001. The plant was destroyed by a series of explosions that resulted in the death of one man, 112 injuries and extensive damage. The accident was caused by the ignition of a leak of mixed flammable vapours from an out-of-control exothermic batch
reactor, which produced water-born acrylic resin. Most of the victims, who were employees of nearby factories, were cut by glass splinters and other debris that rained down over an area of radius 200 metres around the plant. This accident reveals that both the process plant and the neighbouring factories
did not handle safety information properly. This paper describes the accident, the discussions and the conclusions from the viewpoint of safety information management. The lessons learned from this accident include the importance of information management and the need for using a safety information management system throughout the plant life cycle. A research project at Loughborough University is investigating safety information management and its measurement and is developing a prototype tool for use in this area. This project is also described briefly in the paper".Read the paper in this link