Safety Evaluation.

The Northwest Regional Calibration Center (NRCC) operated this vessel for nearly twelve years (November, 1984 -- August, 1996). According to documents supplied by NRCC, the PTV was originally designed for a maximum pressure of 20 kpsi. As an added safety measure, NRCC voluntarily derated the vessel to a maximum working pressure of 10 kpsi. Following their lead, the UW adopted the same safety measure when it petitioned the Washington State Department of Labor and Industries (L&I) for Washington State Special Certification. The certification was granted subject to the following 5 conditions:

1. The PTV must pass a hydrostatic test, in accordance with a procedure approved by the L&I Chief Boiler Inspector, at 1.25 times the maximum operating pressure of 10 kpsi.
2. The PTV must pass a complete inspection, including a Liquid Dye Penetrant (PT) examination.
3. The PTV must have a code-acceptable PT and a hydrostatic test once per year. These tests are to be conducted 6 months apart from each other.
4. Perform documented training with the operators in accordance with the requirements of the Operating and Maintenance Procedures.
5. A mechanism must be developed for building-wide notification of PTV operations. The board suggested a public address (PA) announcement coupled with lights & signs indicating operations in progress. Also, access to the basement area must be restricted. This mechanism must be approved by the L&I Chief Boiler Inspector.

The damage associated with a hypothetical catastrophic failure of the PTV stems from the conversion of potential energy stored in the compressed water into kinetic energy. The kinetic energy possessed by flying objects, jets of water, or a transient outward propagating pressure disturbance (ie., a shock wave) are examples of potential safety hazards.