Overview
A solution of potassium carbonate was being drawn off to an inventory tank for a turnaround/shutdown maintenance activity at a refinery's hydrogen production unit. On the day of the incident, the solution level in the tower wasn't checked as it should have been, which resulted in hydrogen gas flowing back into the tank until the increased pressure caused the tank to explode. The direct cause of the incident was the workers neglecting to check the solution level in the tower. It is not known whether the potential for backflow of hydrogen gas into the inventory tank was understood beforehand or not.

Incident Synopsis
An explosion occurred due to unexpected backflow of hydrogen gas while a solution of potassium carbonate was being drawn off to an view more

A laboratory technician died and three others were injured when hydrogen gas being used in experiments leaked and ignited a flash fire.

The incident occurred in a 5,700-square-foot, single-story building of unprotected non-combustible construction. The building was not equipped with automatic gas detection or fire suppression systems.

Employees in the laboratory were conducting high-pressure, high-temperature experiments with animal and vegetable oils in a catalytic cracker under a gas blanket. They were using a liquefied petroleum gas burner to supply heat in the process.

Investigators believe that a large volume of hydrogen leaked into the room through a pump seal or a pipe union, spread throughout the laboratory, and ignited after coming into contact with the view more

An employee at a soap manufacturing plant died in a flash fire outside the facility's hydrogenation building. Responding personnel encountered a fire at the base of the plant's hydrogen storage towers, and they found the victim, who was burned over 90 percent of his body, some 50 feet away.

Officials determined that a pipe connection failed and that hydrogen, pressurized at 1,800 psi, ignited when it was released into the atmosphere, killing the plant operator.

According to reports, the pipe connection failure stemmed from pressures higher than design tolerance, which in turn were the result of over tightening that occurred during routine maintenance replacement. The new bolts were stronger than those they replaced, and the threads of the nuts had been partially view more

Overview
During operation of a succinic acid plant, hydrogen leaked from a mounting joint on a safety valve at the upper part of a reactor, which generated a hydrogen flame. Prior to the incident, the safety valve was removed and reattached during an inspection at a turnaround shutdown. An incorrectly sized, smaller gasket was installed on the joint, and the tightening force on the bolts was inadequate. Therefore, a gap was generated as time went by and un-reacted hydrogen leaked.

Background
In the case of many leak tests after construction, a leak is checked by a soap test after pressurizing piping and facilities for the test. (A soap test is conducted by pouring soap suds at the place to be checked (mainly a joint part) after pressurizing. If bubbles are found, view more

Overview
A hydrogen leak and fire occurred due to the installation of an incorrectly sized gasket at a solvent manufacturing plant. A worn gasket was accidentally replaced with a new gasket that was smaller than the standard one, and the system could not withstand the operational pressure of the hydrogen, causing the hydrogen to leak and ignite a small fire. Furthermore, a nearby gasket was damaged by the fire, causing a larger quantity of hydrogen to leak, and the fire spread. As nitrogen was substituted for the combustible hydrogen gas in the piping at an early stage of the fire, damage was limited to the immediate area. If the hydrogen had not been quickly purged from the system, the fire damage would have been greater. It is assumed that gasket management at a turnaround view more

An explosion occurred in an electrolysis system in a commercial facility. Electrolysis of a potassium hydroxide solution is used to produce hydrogen for a hydrogenation processes. The circular electrolysis cells are 1.5 m in diameter and 25 mm thick. Design current for the electrolyzer is 6,000 amps at 1.78 volts. Operating temperature and pressure is 70-90 °C and 435 psig. Hydrogen and oxygen product gases are separated from the electrolyte in separating drums. The system had been operating at the plant for 13 years prior to the explosion. Operating experiences had been generally favorable except for the need to periodically flush the system with water to remove sludge formations.

According to the investigative report, sludge deposits in the electrolyte passages started the view more

A rupture occurred in a 24-inch gas line in a reformer. The pipe contained hydrogen and carbon monoxide at a pressure of about 400 psi and a temperature of 930 °C. The ruptured section of pipe had a high-temperature alloy steel outer wall, a refractory liner, and a stainless steel inner liner. The refractory lining had been repaired several times before (including three months prior to the incident) because of localized deterioration and hot spots. The repair procedure consisted of cutting a section of pipe, re-pouring the refractory liner, and patch-welding the outer wall.

The first rupture occurred when the 42-inch-long welded section of the pipe suddenly blew out. On-site employees heard a rumble and observed a flame above the ruptured pipe. Before the torch fire at the view more