UFC 4-390-01
23 July 2003
of the system or line of which they form a part. Piping subject
to external pressure should be designed for the maximum
differential pressure that can exist in either direction during
operating, shutdown or test conditions; otherwise suitable over
pressure protection should be provided.
Maximum Operating Pressure (MOP) is the highest pressure that can
exist in a system or subsystem under normal operating conditions.
All piping components must undergo a hydrostatic strength test
based on the MOP, with no external leakage or permanent
distortion permitted. Additional information concerning testing
requirements can be found in Appendix C.
B.8.1 Piping. Consideration should be given to material type,
wall thickness, minimum bend radius, back-wall thinning allowance
and inner radius wrinkling when specifying the method of piping
system fabrication.
B.8.1.1 Structural Considerations. The applicant should
consider the structural adequacy and fatigue life of the piping
system for all anticipated in-service conditions. Some in-
service conditions include the following:
a)
Weight of pipe fittings, valves and other components
including cleaning or testing fluids
b)
Internal or external pressure, both static and cyclic
c)
Restraint of hangers and supports
d)
Thermal expansion and contraction
e)
Shock, impact, vibration and water hammer
f)
Mechanical loads caused by operation of the system
g)
Effects of the corrosion
Piping which, if ruptured, would depressurize the unmanned
pressure test facility should be protected against damage.
Suitable routing, shielding, etc., may accomplish this. Piping
connections should be designed and arranged so that it is
physically impossible to inadvertently connect a system of one
pressure or service to a system of a different pressure or
service. If gas reservoirs, such as cylinders, are included in a
system, a readily-accessible valve should be provided to stop gas
flow from the reservoir.
B.8.1.2 Pipe Hangers. Arrangement and design of pipe hangers
should be carefully considered as a basic element of the piping
design. Piping support spacing should be IAW Table B.1 and ASME
B31.1, Power Piping.
Piping and tubing should be supported as close to bends as
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