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ASME B31.3-2016
<br /> the wall thickness shall be increased to prevent over- the maximum value allowable under the pur-
<br /> stress, damage, collapse, or buckling due to superim- chase specification.
<br /> posed loads from supports, ice formation, backfill, E = quality factor from Table A-1A or Table A-113
<br /> transportation,handling, or other loads enumerated in P = internal design gage pressure
<br /> para. 301. S = stress value for material from Table A-1 or
<br /> (b) Where increasing the thickness would excessively Table A-IM
<br /> increase local stresses or the risk of brittle fracture, or T = pipe wall thickness (measured or minimum in
<br /> is otherwise impracticable,the impact of applied loads accordance with the purchase specification)
<br /> may be mitigated through additional supports,braces, t = pressure design thickness, as calculated in
<br /> or other means without requiring an increased wall accordance with para. 304.1.2 for internal pres-
<br /> thickness. Particular consideration should be given to sure or as determined in accordance with
<br /> the mechanical strength of small pipe connections to para. 304.1.3 for external pressure
<br /> piping or equipment.
<br /> tm = minimum required thickness, including
<br /> mechanical,corrosion,and erosion allowances
<br /> PART 2 W = weld joint strength reduction factor in accor-
<br /> PRESSURE DESIGN OF PIPING COMPONENTS dance with para. 302.3.5(e)
<br /> 303 GENERAL Y = coefficient from Table 304.1.1,valid for t<D16
<br /> and for materials shown. The value of Y may
<br /> Components manufactured in accordance with stan- be interpolated for intermediate temperatures.
<br /> dards listed in Table 326.1 shall be considered suitable For t >— D/6,
<br /> for use at pressure—temperature ratings in accordance
<br /> with para. 302.2.1 or para. 302.2.2, as applicable. The _ d+2c
<br /> rules in para. 304 are intended for pressure design of Y — D +d+2c
<br /> components not covered in Table 326.1,but may be used
<br /> for a special or more-rigorous design of such compo- 304.1.2 Straight Pipe Under Internal Pressure
<br /> nents,or to satisfy requirements of para.302.2.2.Designs (a) For t<D16,the internal pressure design thickness
<br /> shall be checked for adequacy of mechanical strength for straight pipe shall be not less than that calculated
<br /> as described in para. 302.5. in accordance with either eq. (3a) or eq. (3b)
<br /> _ PD
<br /> 304 PRESSURE DESIGN OF COMPONENTS t — 2(SEW+PY) (3a)
<br /> 304.1 Straight Pipe
<br /> (16) 304.1.1 General t _ P(d +2c)
<br /> 2[SEW—P(1 —Y)] (3b)
<br /> (a) The required thickness of straight sections of pipe
<br /> shall be determined in accordance with eq. (2) (b) For t >_ D16 or for P/SE > 0.385, calculation of
<br /> tm = t+c (2) pressure design thickness for straight pipe requires spe-
<br /> cial consideration of factors such as theory of failure,
<br /> The minimum thickness,T,for the pipe selected,con- effects of fatigue, and thermal stress.
<br /> sidering manufacturer's minus tolerance, shall be not 304.1.3 Straight Pipe Under External Pressure. To (16)
<br /> less than t,,,. determine wall thickness and stiffening requirements
<br /> (b) The following nomenclature is used in the equa- for straight pipe under external pressure,the procedure
<br /> tions for pressure design of straight pipe: outlined in the BPV Code,Section VIII,Division 1,UG-28
<br /> c = sum of the mechanical allowances (thread or through UG-30 shall be followed, using as the design
<br /> groove depth) plus corrosion and erosion length, L, the running centerline length between any
<br /> allowances. For threaded components, the two sections stiffened in accordance with UG-29.As an
<br /> nominal thread depth (dimension h of exception,for pipe with Dolt < 10, the value of S to be
<br /> ASME 131.20.1, or equivalent) shall apply. For used in determining Pat shall be the lesser of the follow-
<br /> machined surfaces or grooves where the toler- ing values for pipe material at design temperature:
<br /> ance is not specified, the tolerance shall be
<br /> assumed to be 0.5 mm (0.02 in.)in addition to (a) 1.5 times the stress value from Table A-1 or
<br /> the specified depth of the cut. Table A-1M of this Code, or
<br /> D = outside diameter of pipe as listed in tables of (b) 0.9 times the yield strength tabulated in Section II,
<br /> standards or specifications or as measured Part D, Table Y-1 for materials listed therein
<br /> d = inside diameter of pipe. For pressure design (The symbol Do in Section VIII is equivalent to D in this
<br /> calculation, the inside diameter of the pipe is Code.)
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