On Dec. 3, 2004, a 50,000-pound steel pressure vessel violently exploded at the southwest Houston Marcus Oil and Chemical facility.
The pressure vessel contained flammable hydrocarbons such as hexane.
The pressure vessel was a horizontal tank 12 feet in diameter, 50 feet long, and operated at a pressure of approximately 67 psi.
Marcus Oil did NOT use a qualified welder or proper welding procedure to reseal the vessels and did NOT pressure-test the pressure vessel after the welding was completed.
The defective welds had decreased the strength of the vessels by more than 75%.
Metal fatigue further weakened the welds.
Texas is one of 11 states that have not adopted national safety standards for pressure vessels and is one of 17 states that do not require adherence to the National Board Inspection Code.
The code requires alterations to pressure vessels to be inspected, tested, certified, and stamped.
Lessons Learned
- It is important to provide documentation concerning the design, construction, or safe operating pressure of the vessels.
- It is important to recognize unregulated, uninspected, and improperly maintained pressure vessels and to follow safety codes, including installing relief devices on all pressure vessels and avoiding contaminating their nitrogen supply with air to prevent fires.