Over-Pressure Damage to a Storage Tank in a Refinery
The incident occurred during a temporary shutdown of the distillate hydro-treatement unit. The crude oil distillation units main column overhead product was pumped to a gasoline storage tank via the straight run gasoline rundown line. When restarting the distillate hydro-treatement unit, a valve in the start-up line to the high pressure separator branching off the crude oil distillation unit main column overhead product line was opened before the line to tank was closed.Hydrogen gas at a pressure of 30 bars consequently reached the tank, caused an overpressure and caused substantial damage. The tank shell was lifted upwards by approximately 110mm.No one was injured in the incident and there was no leakage of liquid product.
Event Date
July 11, 1989
Record Quality Indicator
Region / Country
Event Initiating System
Classification of the Physical Effects
Nature of the Consequences
Cause Comments
The immediate cause was an operation error, a wrong sequence of opening and closing of the valve connecting the storage tank to the high pressure section of the hydrocracker, with consequence entrance of hydrogen at 30 bars to the tank. The ICHEME report (see reference) does not mention the root cause, but the operation error seems to hints at inadequate operative instruction and risk assessment.
Facility Information
Application Type
Application
Specific Application Supply Chain Stage
Components Involved
Distillation tank, hydro-treater
Storage/Process Medium
Actual Pressure
30
Location Type
Location description
Industrial Area
Pre-event Summary
Failure of a tank roof. The incident occurred during a temporary shutdown of the distillate hydrotreater. HYDROTREATING aims at removing (approx. 90%) the liquid petroleum fractions contaminants such as nitrogen, sulfur, oxygen, and metals. The process brings compressed hydrogen to react with organic compounds to remove oxygen (deoxygenation) and other heteroatoms (nitrogen, sulfur, and chlorine).
Currency
Lessons Learned
Lessons Learned
According to the ICHEME report (see reference) the following lesson learned were drawn:1)Consider training of operators for routes by which storage tanks can erroneously receive unwanted pressure and ensure that facilities and/or procedures prohibit this as far as possible.2)The pressure of volatile hydrocarbons must always be considered as a possibility in any refinery storage tanks until shown to be otherwise. This is very important when considering dipping and sampling procedures (e.g., adequate relaxation time to dissipate static charge), and when giving clearance for tank entry and repair work.
Event Nature
Emergency Action
Unknown
Detonation
No
Deflagration
No
High Pressure Explosion
No
High Voltage Explosion
No
Source Category
References
References
Event description extracted from the UK database ICHEME in PDF
ICHEME database is no longer available for purchase, but data can be download as PDF for free.
https://www.icheme.org/knowledge/safety-centre/resources/accident-data/
(accessed October 2020)