Investigation of the Self Destruction of a Liquid Nitrogen Container at South Pole Station, Antarctica

Abstract

A 2200 liter liquid nitrogen container suffered a spontaneous self inflicted accident which resulted in separation of the carbon steel outer shell into two parts at the joint between the forward dished head and the cylindrical body. The cylindrical shell, rear head, and skid mounting were displaced about six meters from their original location without damage to other equipment or personnel. The inner vessel remained connected to the forward head by four unbroken lines and did not move appreciably from its former location. However, the stainless steel liquid fill and withdrawal line was separated completely at its connection to the pass through the forward head. The rupture disc which protected the outer shell from overpressure in the vacuum space was not ruptured. There was no indication that the inner vessel pressure relief valve had operated. It was not damaged, remained connected to the forward head, and was later shown to operate successfully at its rated pressure.

Analysis of the accident concluded that it was initiated by a brittle failure of the liquid fill and discharge line at a pressure estimated to be less than four bars, well below its rated safe operating pressure of seven bars.