LoC: Deficiency

The fire on the vacuum distillation unit (VDU) weakened the main vacuum distillation column supports, allowing it to collapse onto the heat exchange train. The VDU was shutdown completely and the refinery was left running but at a much reduced capacity. An investigation identified that the fire was caused by a leak from a branch on the column that was fabricated from an incorrect material.

[ Property Damage $143 Million. Estimated Current Value $191 Million ]

Image credit: ORLEN

On November 12, 2008, a 2-million-gallon liquid fertilizer tank (designated as Tank 201 by the owner) catastrophically failed at the Allied Terminals, Inc. (Allied) facility in Chesapeake, Virginia, seriously injuring two workers and partially flooding an adjacent residential neighborhood.

On the day of the incident, Allied was filling Tank 201 with liquid fertilizer to check for leaks prior to painting the tank. During the filling, a welder and his helper sealed leaking rivets on the tank.

At a fill level about 3.5 inches below the calculated maximum liquid level, the tank split apart vertically, beginning at a defective weld located midway up the tank. Within seconds, the liquid fertilizer overtopped the secondary containment, partially flooding the site and adjacent neighborhood. The collapsing tank wall injured the welder and his helper, who were working on the tank. Employees of a neighboring business responded and extricated them. At least 200,000 gallons of the liquid fertilizer were not recovered; some entered the southern branch of the Elizabeth River.

KEY ISSUES:
• LIQUID FERTILIZER STORAGE TANK STANDARDS
• TANK MODIFICATION FOR CHANGE-IN-SERVICE
• TANK INSPECTION

ROOT CAUSES:
1. Allied did not ensure that welds on the plates to replace the vertical riveted joints met generally accepted industry quality standards for tank fabrication.
2. Allied had not performed post-welding inspection (spot radiography) required for the calculated maximum liquid level for the tank.
3. Allied had no safety procedures or policies for work on or around tanks that were being filled for the first time following major modifications and directed contractors to seal leaking rivets while Tank 201 was being filled to the calculated maximum liquid level for the first time.

Image credit: CSB

An explosion and fire that occurred in a polyethylene wax processing facility operated by Marcus Oil and Chemical on the southwest side of Houston, Texas. On Friday, December 3, 2004, at about 5:50 pm, employees heard a loud “pop” then saw light from a fire reflecting off a shiny tanker truck parked near the process equipment. About 45 seconds later, a violent explosion occurred and a fire fueled by molten wax erupted near the main warehouse. The warehouse and nearby equipment were quickly involved in the fire.

The Houston Fire Department arrived approximately five minutes after the explosion. Firefighters extinguished the three-alarm blaze by midnight, approximately seven hours after the explosion.

Three firefighters were slightly injured while fighting the fire, and local residents sustained minor injuries from flying glass. The explosion shattered windows in buildings and vehicles and caused structural damage as far as one-quarter mile away. Significant interior damage resulted when suspended ceilings and light fixtures were blown down in the onsite buildings, nearby businesses, and a church. Tank 7, a 12-foot diameter, 50-foot long, 50,000-pound pressure vessel was propelled 150 feet where it impacted a warehouse belonging to another business..

KEY ISSUES:
• PRESSURE VESSEL REPAIRS & ALTERATIONS
• NITROGEN INERTING SYSTEM DESIGN & OPERATION

ROOT CAUSES:
1. Poor welding severely weakened Tank 7 and led to its catastrophic failure.
2. The connection between the nitrogen and the compressed air systems increased the oxygen concentration in the inerting gas to an unsafe level.
3. Pressure vessels had operating pressures in excess of 100 psig, yet none was equipped with a pressure relief device.

Image Credit: CSB

On December 7, 2009, at approximately 2:30 pm, State Special Vessel No. 2, under an operating pressure of 29,000 psig, suddenly and violently ruptured, 120 days into a 150-day operating cycle. A white cloud of steam and debris rapidly expanded outward from the facility, traveled onto the interstate, and dissipated within seconds.

The sudden release of superheated liquid caused an eight-foot tall by four-foot wide vessel fragment, weighing approximately 8,600 pounds, to travel through two concrete walls and finally land about 435 feet from the NDK building. The fragment skipped across a neighboring facility parking lot and slammed into the wall of an adjacent business office. The force of the impact pushed the wall inward causing furniture to shift and ceiling tiles to fall. One person working near the wall was injured.

The thrust from the escaping liquid caused the base of the vessel to violently shear away from its foundation and blew pieces of structural steel out of the building into the parking lot of a nearby rest stop gas station, known as the Illinois Tollway (I-90) Oasis. One piece of structural steel struck and killed a truck driver at the rest stop. After shearing from its base and throwing shrapnel out of the facility, the vessel swung from the building and landed on the ground outside.

KEY ISSUES:
• PRESSURE VESSEL DESIGN & MATERIAL SELECTION REQUIREMENTS
• LEARNING FROM PREVIOUS INCIDENTS
• INSPECTIONS

ROOT CAUSES:
1. Stress corrosion cracking.
2. Testing & inspection deficiencies.

Image credit: CSB

The Space Shuttle Challenger disaster was a fatal incident in the United States space program that occurred on Tuesday, January 28, 1986, when the Space Shuttle Challenger (OV-099) broke apart 73 seconds into its flight, killing all seven crew members aboard. The crew consisted of five NASA astronauts, one payload specialist, and a civilian schoolteacher. The mission carried the designation STS-51-L and was the tenth flight for the Challenger orbiter.

The spacecraft disintegrated over the Atlantic Ocean, off the coast of Cape Canaveral, Florida, at 11:39 a.m. EST (16:39 UTC). The disintegration of the vehicle began after a joint in its right solid rocket booster (SRB) failed at liftoff. The failure was caused by the failure of O-ring seals used in the joint that were not designed to handle the unusually cold conditions that existed at this launch. The seals’ failure caused a breach in the SRB joint, allowing pressurized burning gas from within the solid rocket motor to reach the outside and impinge upon the adjacent SRB aft field joint attachment hardware and external fuel tank. This led to the separation of the right-hand SRB’s aft field joint attachment and the structural failure of the external tank. Aerodynamic forces broke up the orbiter.

Image Credit: NASA