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ASME B31.3-2016 pressure and weight, and of the stresses produced by pressure or as determined in accordance with occasional loads,such as wind or earthquake,shall not para. A304.1.3 for external pressure exceed the limits in the applicable part of para.A302.3.3. t,,, = minimum required thickness, including Wind and earthquake forces need not be considered as mechanical, corrosion, and erosion allowances acting concurrently. (b) Test. Stresses due to test conditions are not subject A304.1.2 Straight Nonmetallic Pipe Under Internal Pressure. The internal pressure design thickness, t, to the limitations in para. A302.3.3. It is not necessary to consider other occasional loads, such as wind and ing equations, using stress values listed in or derived shall be not less than that calculated by one of the follow- earthquake, as occurring concurrently with test loads. from the appropriate table in Appendix B: A302.4 Allowances (a) Thermoplastic Pipe [See Para. A302.3.2(a)] Paragraph 302.4 applies in its entirety. P� t = (Table B-1) (26a) 2S +P PART 2 (b) RTR (Laminated) Pipe [See Para. A302.3.2(b)] PRESSURE DESIGN OF PIPING COMPONENTS A303 GENERAL t = PD (Table 13-2) (26b)3 2S +P Paragraph 303 applies, except that references to Table A326.1 and para. A302.2.1 replace references to (c) RTR(Filament Wound)and RPM(Centrifugally Cast) Table 326.1 and para. 302.2.1. For nonmetallic compo- Pipe [See Para. A302.3.2(c)] nents, reference to para. A304 replaces reference to para. 304. t 2SF�P (Table B-3) (26c)3 A304 PRESSURE DESIGN OF PIPING A304.1.3 Straight Pipe Under External Pressure COMPONENTS (a) Nonmetallic Pipe. The external pressure design thickness, t, shall be qualified as required by A304.1 Straight Pipe para. A304.7.2. A304.1.1 General (b) Metallic Pipe Lined With Nonmetals (a) The required thickness of straight sections of pipe (1) The external pressure design thickness,t,for the base(outer)material shall be determined in accordance shall be determined by eq. (25). with para. 304.1.3. tm = t +c (25) (2) The external pressure design thickness, t, for the lining material shall be qualified as required by The minimum thickness T for the pipe selected, con- para. A304.7.2. sidering manufacturer's minus tolerance, shall be not less than t,,,. A304.2 Curved and Mitered Segments of Pipe (b) The following nomenclature is used in the equa- A304.2.1 Pipe Bends. The minimum required thick- tions for pressure design of straight pipe: ness, t,,,, of a bend, after bending, shall be determined c = the sum of mechanical allowances (thread or as for straight pipe in accordance with para. A304.1. groove depth) plus corrosion and erosion allowance.For threaded components,the nomi- A304.2.2 Elbows. Manufactured elbows not in nal thread depth(dimension h of ASME 131.20.1 accordance with para.A303 shall be qualified as required or equivalent) shall apply. For machined sur- by para. A304.7.2. faces or grooves where the tolerance is not spec- A304.2.3 Miter Bends. Miter bends shall be quali- ified, the tolerance shall be assumed to be fied as required by para. A304.7.2. 0.5 mm (0.02 in.) in addition to the specified depth of the cut. A304.3 Branch Connections D = outside diameter of pipe A304.3.1 General. A pipe having a branch connec- F = service (design) factor. See para. A302.3.2(c). tion is weakened by the opening that must be made in P = internal design gage pressure it and,unless the wall thickness of the pipe is sufficiently S = design stress from applicable Table in in excess of that required to sustain the pressure, it is Appendix B necessary to provide added reinforcement. The amount T = pipe wall thickness (measured or minimum in accordance with the purchase specification) 3 The internal design pressure thickness t shall not include any t = pressure design thickness, as calculated in thickness of the pipe wall reinforced with less than 20%by weight accordance with para. A304.1.2 for internal of reinforcing fibers.