Inspection Detail

Inspection: 306368671 - Kerr Mcgee Rocky Mountain Corp.

Inspection Information - Office: Denver Area Office

Investigation Summary

On March 31, 2003, Employee #1, a roustabout; Employee #2, a welder; and Employee #3 and #4, also roustabouts; were installing an additional tank for crude oil as part of group of steel tanks (tank battery). The existing tanks of the tank battery were used to separate waste water (salt water) from residual crude oil in the salt water. Employee #2 was installing anchor brackets at several locations around the circumference of the base of this additional oil tank. The attachment had been completed for one of four anchor brackets that needed to be installed. Welding was nearly completed on the second anchor bracket when suddenly an explosion occurred, which launched the tank approximately 15 feet vertically. At the time of the explosion, Employee #2 and Employees #1 and #3 were immediately adjacent to the tank. Employee #4 was outside the containment berm for the tank battery. Employee #1, positioned adjacent to the tank, suffered fatal injuries and died at the scene. Employee #2 and #3, positioned adjacent to the tank, were hospitalized with serious injuries. Employee #4, positioned outside the containment berm, was hospitalized, treated and released. Prior to welding on the anchor brackets, this additional steel tank had been connected to several pipelines that were already installed and connected to the three existing crude oil tanks in the tank battery. One of these pipelines was a ventilation pipe that was connected to top of the three existing crude oil tanks. The ventilation pipe had been installed to carry flammable vapors from the headspaces of the existing crude oil tanks to relieve pressure buildup in the tanks. The tank battery, at this salt water disposal facility, was comprised of seven steel tanks as follows: three salt water tanks, three crude oil tanks and a smaller sump drainage tank. All of these tanks were located inside a concrete containment berm with a concrete pad entirely covering the floor of the containment area. The tank, that exploded while being welded on, was to become the fourth crude oil tank in the tank battery. The three larger water tanks, labeled Number 1, Number 2 and Number 3, were each approximately 30 feet high and 15 feet in diameter with a reported capacity of 1,000 barrels (42,000 gallons) each. The three smaller crude oil tanks, labeled Number 4, Number 5 and Number 6, were approximately 15 feet high and 12 feet in diameter with a reported capacity of 300 barrels (12,600 gallons) each. The fourth crude oil tank, being installed, was also approximately 15 feet high and 12 feet in diameter with a reported capacity of 300 barrels (12,600 gallons). The entire facility (Salt Water Disposal Number 1) included: the tank battery within a containment berm, two pump stations for unloading tanker trucks with salt water containing 1- 2 residual crude oil, a separate pump and filter building for final treatment of salt water, and a deep well for returning salt water underground. The facility provided final separation of the remaining residual crude oil from the waste water that was produced when oil or gas was recovered from nearby production wells. This waste water was labeled salt water because it contained natural minerals and salts carried from underground. Although most of the crude oil was separated from the salt water at the sites of oil or gas wells, the salt water contained variable quantities of residual crude oil.

Keywords: WELDER, EXPLOSION, TANK