S9407-AB-HBK-010 Datasheet, PDF (26/276 Pages) Glenair, Inc. – HANDBOOK OF SHIPBOARD ELECTROMAGNETIC SHIELDING PRACTICES

S9407-AB-HBK-010, Rev. 2
Where a hybrid (a combination of rigid and flexible) conduit installation requires single-point
grounding, the flexible conduit end opposite the rigid conduit must be isolated from ground at both
ends of the cable run. The rigid conduit provides the single-point ground. Multiple grounds along the
rigid conduit portion of the run are acceptable.
2.4.3 Shock and Vibration Protection
The blast effect following the explosion of a bomb, torpedo, depth charge, etc., is devastating
and widespread. Moreover, such explosions are often followed by destructive waves of vibration.
Accordingly, piping and associated equipment installations should be designed to be shock and
vibration resistant. Brittle materials such as cast iron should not be used for fittings. Piping should not
run in direct contact with decks or bulkheads, but rather should be cushioned by rubber-padded pipe
hangers. The rigid conduit should be terminated with approximately 30 inches or less of the flexible
conduit described in section 3 to absorb shock and vibration at the point of entry to an equipment
enclosure, a bulkhead stuffing tube, or a hull fitting. Conduit fittings and methods described in this
handbook shall be used for coupling the rigid conduit to the flexible conduit, and for attaching the
flexible conduit to connectors, stuffing tubes, and hull fittings.
2.5 RIGID CONDUIT (PIPE) PREPARATION
2.5.1 Cutting Rigid Conduit
Pipe ends shall be cut square with a hacksaw or metal-cutting bandsaw. Burrs shall be
removed by reaming or filing.
2.5.2 Bending Rigid Conduit
Any acceptable pipe bending method that will not deform the inside diameter of the pipe may
be used.
2.5.3 Cleaning Rigid Conduit
After all machining, welding, and brazing operations are completed, the exterior and interior
surfaces of the pipe shall have all rust or visible corrosion products and flux removed, and shall be
thoroughly cleaned of grease, oil, and dirt by solvent wiping, vapor degreasing, caustic washing and
rinsing, or other effective methods.
2.5.4 Conduit (Pipe Threads)
This conduit (pipe) shall be threaded with NPSM threads (American Standard straight pipe
threads for mechanical joints). Straight pipe threads are required to mate with such mechanical
assemblies as the rigid conduit coupling illustrated in figure 2-2. Also, straight pipe threads are more
suited for mechanical assemblies since adjustments can be made between threaded parts and
secured by use of a locknut. NPSM thread sizes for various pipe sizes are listed in table 2-1.
2.5.5 Torque Requirements
A mechanically tight coupling on threaded steel pipe fittings normally requires a minimum
torque as shown in table 2-1. A locknut shall be used with threaded pipe and fittings when the
threaded joint is such that the minimum torque requirement cannot be achieved. The torque
requirements of joints that include threads of MS- and UG-type connectors and conduit fittings
described in this handbook shall be tightened to manufacturer's specifications. See S9300-AW-EDG-
010/EPISM for MS connector backshell torque values.
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