Incorrect Relief Valve Set Point Leads to Explosion

First Name
Andy
Last Name
Piatt

Incident Synopsis
During a standard testing procedure, a 3,000 psig relief valve actuated at normal line pressure, releasing gaseous H2. The gaseous H2 combined with air, resulting in an explosion which damaged the test facility.

Cause
The relief valve was improperly set to open at line pressure, and the inspection was inadequate in that it didn't identify this error. Contributing cause was poor design of the venting system, which was installed in a horizontal position, causing inadequate venting and buildup of static electricity.

Ignition of Leaking Hydrogen from Pressure Transmitter Tubing

First Name
Andy
Last Name
Piatt

An instrument engineer at a hydrogen production facility was arresting the hydrogen leakage in tapping a pressure transmitter containing 131-bar hydrogen gas. The isolation valve was closed and the fittings near the pressure transmitter were loosened. The pressure dropped from 131 bar to 51 bar. The fitting was further loosened (though very little); the instrument tube slipped out of the ferrule and got pulled out of the fitting. With the sudden release of the 51-bar hydrogen, there was a loud pop (like a fire cracker) and the spark-proof tool was observed to have black spot on it.

Pressure Relief Valve Triggered on Metal Hydride Storage Tank

First Name
Andy
Last Name
Piatt

A metal hydride storage system was refilled using compressed hydrogen in a closed lab environment. The tank system is an in-house development and is optimized for high hydrogen storage density and use with an air-cooled fuel cell. The system is equipped with a pressure relief valve that opens gradually at 35 bar to protect the tank from overpressure conditions. The tank itself is designed to adsorb 400 g of hydrogen at a pressure less than 15 bar.

Unexpected Failure of Rupture Disk on Liquid Hydrogen Tank at Manufacturing Plant

First Name
Andy
Last Name
Piatt

A 9,000-gallon (34,069-liter) cryogenic liquid hydrogen storage vessel, installed outdoors at a manufacturing plant in an urban area, over-pressurized and released hydrogen into the atmosphere through a safety relief device (burst disk). When the burst disk released pressure, a loud bang was heard by neighbors and reported to the local police. The police investigated and heard the sound of gaseous hydrogen escaping from the vessel's vent stack, which rose approximately 15-20 feet (4.6-6.1 meters) in the air.

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.

Ignition of Pre-mixed Inventory by Venting

First Name
Andy
Last Name
Piatt

A steel tube with inner diameter of 6 mm and 10 m length was filled with radiolysis gas (stoichiometric H2-O2 mixture) at 70 bar for boiling water reactor simulations. Via a pneumatic valve, a venting line with similar cross-section and 2 m length, filled with atmospheric air, was connected.

For venting the tube, the valve was opened (fast) and an explosion occurred.

Hydrogen Explosion due to Failure of an Incorrectly Sized Spirometallic Gasket at a Refinery Hydrodesulfurization Plant

First Name
Andy
Last Name
Piatt

Overview: A hydrogen leak and explosion occurred due to the installation of an incorrectly sized gasket at the suction line of a hydrogen compressor in a refinery hydrodesulfurization plant. The incorrectly sized gasket was mounted during the startup of the plant in 2001 and had never being inspected nor replaced.

Hydrogen Explosion in Battery Compartment of Dinner Cruise Boat

First Name
Andy
Last Name
Piatt

First responders were dispatched to the waterfront area to investigate a possible explosion on an 85-foot dinner cruise boat that was moored there. Upon arrival, the incident commander noted that nothing out of the ordinary was visible on the exterior of the boat. A crew was sent to the interior of the boat to investigate. The boat was powered by diesel engines and there were no compressed gas cylinders on board.

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