a. Minimum Wall Thickness, Straight Pipe Under Internal Pressure.
(1) The minimum wall thickness of pipe or tubing shall not be less
than:
PDo
tm = ---------- + A
(4)
2SE + 0.8P
Pd + 2SEA = 0.8PA
(4A)
tm = ------------------
2 (SE - 0.6P)
Design Pressure shall not exceed:
2SE (tm - A)
(5)
P = ---------------------
Do - 0.8 (tm - A)
2SE (tm - A)
(5A)
P = ---------------------------
d - 0.8 (tm - A) + 2 tm
where
tm = minimum required wall thickness, inches (millimeters)
(a) If pipe is ordered by its nominal wall thickness, the
manufacturing tolerance on wall thickness must be taken into account. After
the minimum pipe wall thickness, tm, is determined, this minimum thickness
shall be increased by an amount sufficient to provide the manufacturing
tolerance allowed in the applicable pipe specification. The next heavier
commercial wall thickness shall then be selected from thickness schedules
such as contained in ANSI B 36.10 or from manufacturers' schedules for other
than standard thickness.
(b) To compensate for thinning in bends refer to paragraph 3
of Section 4.
P = internal design pressure, psi (kPa) gauge
Note:
When computing the design pressure for a pipe of a
definite minimum wall thickness by formula (5) or (5A)
the value of P obtained by these Formulas may be rounded
out to the next higher unit of 10.
Do = outside diameter of pipe in inches (millimeters). For design
calculations, the outside diameter of pipe as given in tables
of standards and specifications shall be used in obtaining the
value of tm.
d = inside diameter of pipe inches (millimeters). For design
calculations, the inside diameter of pipe is the maximum
possible value allowable under the purchase specification.
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