Acceptance test for tanks used for storage of hydrazine

A test has been developed based on the measurement over four days of the rates of pressure rise at 60 °C of tanks filled with hydrazine with the objective of assessing the acceptability of these tanks for long-term sealed storage at normal ambient temperature. Rates of hydrazine decomposition in a number of tanks were measured over the temperature range 30-80 °C in order to correlate rates of pressure rise measured during the acceptance test at 60 °C with those occurring at normal storage temperatures. Results from a large number of stainless steel production tanks filled with various batches of hydrazine are presented, indicating the considerable range of rates of pressure rise that can result from tanks that are nominally identical and filled with hydrazine, which meets normal specification requirements. Data from tests carried out after extended storage show there was some decrease in rates of pressure rise with time, thus indicating that the acceptance test carried out shortly after filling underestimates life and errs on the side of safety for this type of tank.