In 1981, workers at LANL were about to fill hydrogen (H2) cylinders from a large, H2-filled tube trailer. They used a manifold containing residual oxygen (O2), which was also connected to a tube trailer of O2 with only one valve separating these incompatible gases. When the mix ignited, the workers attempted to purge O2 from the manifold using low-pressure H2. The resultant fire destroyed the valve, allowing high-pressure O2 to flow into the low-pressure H2 tube. The subsequent large mix of O2 and H2 resulted in an explosion.
Because the energy required to ignite H2-O2 mixtures is so low and can even be created by friction, rushing sand particles in the tubing sparked an explosion. Pieces of the tube flew approximately 700 yards away. Two (2) workers were severely burned, and damage to equipment was extensive.
Causes
Investigators found that the fittings for the H2 and O2 delivery systems were similar, allowing the connection of incompatible gases to the same manifold. In addition, workers were not following procedures and did not understand the serious hazards of mixing H2 and O2.
Corrective Actions
Some of the changes made as a result of the explosion were:
- the gas facility’s management structure was changed.
- standard operating procedures were rewritten.
- worker training requirements were improved.
Source: Los Alamos National Laboratory, Pressure Safety Course