High-Temperature Heat Exchanger Flange Leak Leads to Hydrogen Fire

First Name
Andy
Last Name
Piatt

Overview
During start-up operation of a high-temperature, high-pressure plant using hydrogen, hydrogen gas leaked from the flange of a heat exchanger and a fire occurred. The leakage occurred for two reasons:

Insufficient tightening torque control was carried out during hot-bolting and an unbalanced force was generated across the bolts.
A temperature rise was induced across the heat exchanger as a result of a revamping activity, during a turnaround shutdown.

Mounting Joint on a Safety Valve Developed a Hydrogen Gas Leak and Fire

First Name
Andy
Last Name
Piatt

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.

Gas Chromatograph Piping Leak Explodes in Instrument Room

First Name
Andy
Last Name
Piatt

An explosion occurred at a chemical plant in an analysis room containing various analyzer instruments, including a gas chromatograph supplied with hydrogen. A contract operator was performing work to install a new vent line to a benzene analyzer that was part of a group of CO2 analyzers, but separate and unrelated to the gas chromatograph. During the process of this work, a plant supervisor accompanying the contract operator doing the work had an indication of flammable gas present on a portable detector.

Liquid Hydrogen Tank Boiling Liquid Expanding Vapor Explosion (BLEVE) due to Water-Plugged Vent Stack

First Name
Andy
Last Name
Piatt

A rupture disc blew on a 20,000-gallon liquid hydrogen tank, causing the vent stack to exhaust cold gaseous hydrogen. Emergency responders were called to the scene. To stabilize the tank, the remaining hydrogen was removed from the tank except for a small volume in the heel of the tank that could not be removed manually. The tank vacuum was lost. Firemen sprayed the tank with water and directed a stream onto the fire exiting the vent stack.

Hydrogen Explosion in a Styrene Plant

First Name
Andy
Last Name
Piatt

A hydrogen explosion and fire occurred in the benzene unit of a styrene plant in a large petrochemical complex. The unit was being restarted following a scheduled maintenance shutdown. The explosion followed the release of about 30 kilograms of 700-psig hydrogen gas from a burst flange into a compressor shed. Two men were killed and two others were injured. If it had not been a holiday, the death toll and injuries would probably have been much worse.

Hydrogen Fire in Hydrochloric Acid Leaching Solution

First Name
Andy
Last Name
Piatt

Spent platinum catalyst is recovered from corrugated stainless steel by chemical stripping and recovery. The process is completed by placing the material in lined tanks filled with hydrochloric acid (HCl). Approximately 500 pounds of corrugated stainless steel with platinum coating was inserted into a HCl leaching bath. Prior to starting the process, the supervisor tested the material for reactivity for a period of one hour, and the material showed very little reactivity. Operators began setting up three 500-gallon tanks, each containing the corrugated material.

Ignition of Syngas Leak from Ammonia Production Plant

First Name
Andy
Last Name
Piatt

During restart of an ammonia production plant, syngas (50% hydrogen mixed with methane, ammonia, and nitrogen) leaking from a flange directly downstream of the synthesis reactor ignited. The plant had been shut down for about 90 minutes due to a technical problem. Alerted by the plant fire alarm, the operator activated the emergency shutdown, which isolated and depressurized the synthesis loop. Steam was sprayed onto the leak site to dampen the fire, which was brought under control 55 minutes later.

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