Meantime,, workers who were on the rig when it exploded are claiming that BP substituted sea water for a heavy fluid (?) used in drilling and that substitution caused the explosion. The sea water could not contain the pressure rise. They also claim there were dangerous pressure levels and a malfunction of the cutoff valve shortly before the explosion.

I am paraphrasing and do not have the technical terminology. More fingerpointing or the source of the explosion?
SINS