Near Miss on a Flange of a Heat Exchanger in a Refinery
An operator noted a loose tube sheet flange stud on a high temperature, high pressure heat exchanger in an hydrodealkylation unit.The stud was found to be cracked through. Analysis proved to be made of standard steel instead of the alloy type specified. Some of the other studs had started to crack.The studs had been replaced on the previous shutdown when the heat exchanger was opened up to clean the tube bundle.
Event Date
January 1, 1976
Record Quality Indicator
Region / Country
Event Initiating System
Classification of the Physical Effects
Nature of the Consequences
Cause Comments
Maintenance inadequate and incorrect material of construction crack
Facility Information
Application Type
Application
Specific Application Supply Chain Stage
Components Involved
shell and tube heat exchanger
Location Type
Location description
Industrial Area
Pre-event Summary
EXPLANATORY NOTE ON THE CHEMICAL PROCESS: Hydrodealkylation is a chemical reaction that often involves reacting an aromatic hydrocarbon, such as toluene, in the presence of hydrogen gas to form a simpler aromatic hydrocarbon devoid of functional groups. An example is the conversion of 1,2,4-trimethylbenzene to xylene. This chemical process usually occurs at high temperature, at high pressure, or in the presence of a catalyst. These are predominantly transition metals, such as chromium or molybdenum. [Source: Wikipedia, accessed December 2022]
Lessons Learned
Lessons Learned
Quality control of replacement parts used in maintenance is as important as for new equipment.
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)