SE = maximum allowable stress in material due to internal pressure
and joint efficiency at the design temperature, in psi (kPa).
The value of SE shall not exceed the value given in Appendix A
of the B 31.1 Code. For materials to be brazed, a joint
efficiency of 0.8 shall be used.
A = an additional thickness in inches (millimeters).
1. To compensate for material removed in threading, grooving,
2. To provide for mechanical strength of the pipe for extreme
conditions of misapplied external loads or for mechanical
3. To provide for corrosion and/or erosion.
(2) Additional Wall Thickness, Threaded Pipe. While the
thicknesses determined from Formula (4) or (4A) are theoretically ample for
both bursting pressure and material removed in threading, the following
minimum requirements are mandatory to furnish added mechanical strength.
(a) Where steel or stainless steel pipe is threaded the pipe
shall have a minimum ultimate tensile strength of 48,000 psi (330 MPA) and a
weight at least equal to Schedule 80 of ANSI B 36.10.
(b) Where threaded brass or copper pipe is used for the
services described in (2) (a) above, it shall have a wall thickness at least
equal to that specified above for steel pipe of corresponding size.
Minimum Wall Thickness, Straight Pipe Under External Pressure.
For determining wall thickness and stiffening requirements for straight pipe
under external pressure the procedures outlined in Para UG-28, UG-29, and
UG-30 of Section VIII, Division 1, of the ASME Boiler and Pressure Vessel
Code shall be followed.
(1) Corrosion or Erosion. When corrosion or erosion is expected,
an increase in wall thickness of the piping shall be provided over that
the designer shall be consistent with the expected life of the piping.
(2) Threading and Grooving. The calculated minimum thickness of
piping (or tubing) which is to be threaded shall be increased by an allowance
equal to thread depth; dimension h of ANSI B 2.1 or equivalent shall apply.
For machined surfaces or grooves, where the tolerance is not specified, the
tolerance shall be assumed to be 1/64 inch (0.40 mm) in addition to the
SYSTEM DETAILING AND FINAL FLOW ANALYSIS. For any category I, II, III,
or IV piping system, a detailed system layout, consisting of a complete
necessary. The preparation of a system layout is discussed in the following