(4) Threaded joints which are to be seal welded shall be made up
without any thread compound. The threads shall be entirely covered by the
seal weld. Seal welding shall be done by qualified welders.
(5) Backing off to permit alignment of pipe threaded joints shall
not be permitted.
(6) Where pipe threads are to be used between stainless steel
components, there should be a hardness difference between the two components
of at least 5 Rockwell C.
(7) When straight thread O-ring sealed fittings are used in
locations that may subject the fitting to a torque that would tend to unscrew
it, provision shall be made to prevent inadvertent loosening of the fitting.
(8) A suitable thread compound shall be used in making up threaded
joints in aluminum pipe to prevent seizing which might cause leakage and
perhaps prevent disassembly. Aluminum pipe in the annealed temper should not
be threaded.
Section 5.
DESIGN GUIDANCE
1.
DESIGN GUIDANCE.
This section contains design guidance on the following
steps:
a.
Preliminary flow analysis.
b.
Design for pressure.
c.
System detailing and final flow analysis.
d.
Structural analysis.
e.
Noise considerations.
2.
PRELIMINARY FLUID-FLOW ANALYSIS. To conduct a preliminary fluid-flow
analysis, the piping designer should consider two aspects of fluid flow in
hyperbaric chamber piping systems: flow capacity and gas-flow-generated
noise. Design guidance for estimating the flow capacity of piping systems
can be relatively specific. Design guidance in regard to flow noise is less
well defined.
a.
Flow Capacity Estimates. The flow requirements for each fluid
system are best specified before starting the piping design in order that
complex calculations are not duplicated. The piping designer may be required
to seek assistance beyond his own area of responsibility to accomplish this.
The designer will need the following information to conduct a complete fluid
flow capacity analysis: maximum required flow rate; fluid characteristics;
approximate distance over which the fluid is to be transported; source
pressure,
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