Accidental Formation and Ignition of Hydrogen Due to Corrosion
At least one person was injured in an explosion at a theatre building. The investigation concluded that the accident has been caused by hydrogen entering the sprinkler room from the sprinkler piping, during maintenance of the building's sprinkler system. Together with indoor air, it formed a flammable mix of hydrogen gas and air. it is known that hydrogen forms in pipes due to corrosion of the pipe internal zinc coating by oxygen and water. The investigation could not identify the exact cause of the ignition.
Event Date
June 29, 2020
Record Quality Indicator
Region / Country
Event Initiating System
Classification of the Physical Effects
Nature of the Consequences
Causes (Select all applicable options):
Cause Comments
Hydrogen formed in pipes due to corrosion of the pipe internal zinc coating by oxygen and water. Ignition cause unknown.
Application Type
Application
Specific Application Supply Chain Stage
Components Involved
water pipes serving a sprinklers system
Storage/Process Medium
Location Type
Location description
Inhabited Area
Operational Condition
Pre-event Summary
Maintenance work was being carried out on the building facilities.
Lessons Learned
To avoid similar accidents, it is recommended that sprinkler systems should not use anymore zinc-lined pipes in the country. Systems already under construction may be completed as planned, but the possible formation of hydrogen in the system piping must be taken into account to ensure safety.Further recommendations from tukes (see references): Zinc-coated sprinkler pipes may form hydrogen gas, which can leak out during maintenance or other work on the sprinkler pipes, forming a flammable mix of hydrogen gas and air. This should be taken into account when assessing the danger of explosion and when required to draw up an explosion protection document. Sprinkler fitters must use a detector for hydrogen gas when emptying sprinkler pipes. A company that maintains sprinkler systems must device instructions for their employees that covers the ventilation of a facility, use of gas detectors, observation of pipe pressure, protective equipment and other equipment thought necessary. The sprinkler rooms ventilation should be ensured and boosted if needed when the sprinkler pipes are emptied or altered.
Emergency Action
Unknown
Release Type
Detonation
No
Deflagration
No
High Pressure Explosion
No
High Voltage Explosion
No
Source Category
References
tukes Finnish Safety and Chemicals Agency
https://tukes.fi/en/-/hydrogen-explosion-caused-the-helsinki-city-theat…
(accssed Dec 2022)