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Jon, just to add some detail to what you said:
1. Rated Depths only result from tests for the record in the presence of a
Surveyor.
2. The Rated Depth cannot exceed the Design Depth for the simple reason
that the Surveyor isn't going to test beyond what the builder has designated as
the Design Depth. And the reason for that is that the Design Depth had to
be previously approved by the hull passing the Hydrostatic Test
which is where the 1.25 factor comes into play (see
Paragraph 3.1 below). The other components of the sub have to pass various
tests during the course of construction as well before the sub is even
eligible for the rating tests.
Rated Depth:
The depth in meters or feet of water (seawater or fresh water) equivalent to the pressure for which the underwater unit has been operationally tested in the presence of the Surveyor, measured to the lowest part of the unit. The rated depth may not exceed the design depth. Test Dive (2007):
A test dive to the design depth is to be conducted in the presence of the Surveyor. All penetrations and all joints accessible from within are to be inspected visually at a depth of approximately 30.5 m (100 ft) before proceeding to greater depths. All components, such as hull valves, whose operation is subjected to submergence pressure and which are required for safe operation, are to be operationally tested at this depth, if practicable. A log of the inspection of all hatches, viewports, mechanical and electrical penetrators, and valves is to be maintained. The submergence is then to be increased in increments of approximately 20 percent of the design depth until design depth is reached. At each 20 percent increment constant depth is to be maintained and accessible welds and other closures are to be inspected, and valves checked. Unsatisfactory operations of a valve or unsatisfactory leak rate may be cause to abort the test. The test dive may be a single dive, as described, or a series of dives to accomplish the same purpose. The test dive is also to demonstrate satisfactory performance of life support systems, air conditioning systems (if installed), propulsion systems, electrical systems, and items required for safe operations. Where the depth of water available is less than the design depth, both the
rated depth (depth reached during test dive) and the design depth will be
indicated in the Record. The rated depth may subsequently be increased by
performing a test dive to a greater depth, not exceeding the design depth, in
the presence of the Surveyor.
3.1 Hydrostatic Test
After out-of-roundness measurements have been taken, all externally-pressurized pressure hulls are to be externally hydrostatically proof tested in the presence of the Surveyor to a pressure equivalent to a depth of 1.25 times the design depth for two cycles. I hope that ties at least some of the loose ends together.
Jim
In a message dated 12/11/2010 12:58:17 P.M. Central Standard Time,
jonw@psubs.org writes:
Alan, |