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ASME B31.3-2016
<br /> (f) excessive interference with thermal expansion and (e) Attachments welded or bonded to the piping shall
<br /> contraction in piping which is otherwise adequately be of a material compatible with the piping and service.
<br /> flexible For other requirements, see para. 321.3.2.
<br /> (g) unintentional disengagement of piping from its 321.1.5 Threads. Screw threads shall conform to
<br /> supports ASME B1.1 unless other threads are required for adjust-
<br /> (h) excessive piping sag in piping requiring drain- ment under heavy loads.Turnbuckles and adjusting nuts
<br /> age slope shall have the full length of internal threads engaged.
<br /> (i) excessive distortion or sag of piping(e.g.,thermo- Any threaded adjustment shall be provided with a lock-
<br /> plastics) subject to creep under conditions of repeated nut, unless locked by other means.
<br /> thermal cycling
<br /> W excessive heat flow,exposing supporting elements 321.2 Fixtures
<br /> to temperature extremes outside their design limits
<br /> 321.2.1 Anchors and Guides
<br /> 321.1.2 Analysis. In general, the location and (a) A supporting element used as an anchor shall be
<br /> design of pipe supporting elements may be based on designed to maintain an essentially fixed position.
<br /> simple calculations and engineering judgment. How- (b) To protect terminal equipment or other (weaker)
<br /> ever, when a more refined analysis is required and a portions of the system,restraints (such as anchors and
<br /> piping analysis,which may include support stiffness,is guides) shall be provided where necessary to control
<br /> made,the stresses,moments,and reactions determined movement or to direct expansion into those portions of
<br /> thereby shall be used in the design of supporting the system that are designed to absorb them.The design,
<br /> elements. arrangement,and location of restraints shall ensure that
<br /> 321.1.3 Stresses for Pipe Supporting Elements. expansion joint movements occur in the directions for
<br /> Allowable stresses for materials used for pipe support- which the joint is designed. In addition to the other
<br /> ing elements,except springs,shall be in accordance with
<br /> p pp thermal forces and moments, the effects of friction in
<br /> para. 302.3.1. Longitudinal weld joint factors, Ei, how- other supports of the system shall be considered in the
<br /> ever, need not be applied to the allowable stresses for design of such anchors and guides.
<br /> welded piping components that are to be used for pipe (c) Piping layout,anchors,restraints,guides,and sup-
<br /> supporting elements. ports for all types of expansion joints shall be designed
<br /> in accordance with para. X301.2 of Appendix X.
<br /> 321.1.4 Materials 321.2.2 Inextensible Supports Other Than Anchors
<br /> (a) Permanent supports and restraints shall be of and Guides 9
<br /> material suitable for the service conditions. If steel is (a) Supporting elements shall be designed to permit
<br /> cold-formed to a centerline radius less than twice its the free movement of piping caused by thermal expan-
<br /> thickness, it shall be annealed or normalized after sion and contraction.
<br /> forming. (b) Hangers include pipe and beam clamps, clips,
<br /> (b) Gray, ductile,and malleable iron may be used for brackets, rods, straps, chains, and other devices. They
<br /> rollers,roller bases,anchor bases,and other supporting shall be proportioned for all required loads. Safe loads
<br /> elements subject chiefly to compressive loading. Gray for threaded parts shall be based on the root area of the
<br /> iron is not recommended if the piping may be subject threads.
<br /> to impact-type loading resulting from pulsation or vibra- (c) Sliding Supports. Sliding supports (or shoes) and
<br /> tion. Ductile and malleable iron may be used for pipe brackets shall be designed to resist the forces due to
<br /> and beam clamps, hanger flanges, clips, brackets, and friction in addition to the loads imposed by bearing.
<br /> swivel rings. The dimensions of the support shall provide for the
<br /> (c) Steel of an unknown specification may be used for expected movement of the supported piping.
<br /> pipe supporting elements that are not welded directly
<br /> to pressure-containing piping components.(Compatible 321.2.3 Resilient Supports 9
<br /> intermediate materials of known specification may be (a) Spring supports shall be designed to exert a sup-
<br /> welded directly to such components.) Basic allowable porting force, at the point of attachment to the pipe,
<br /> stress in tension or compression shall not exceed 82 MPa equal to the load as determined by weight balance calcu-
<br /> (12 ksi)and the support temperature shall be within the lations. They shall be provided with means to prevent
<br /> range of —29°C to 3430C (-20°F to 6500F). For stress misalignment, buckling, or eccentric loading of the
<br /> values in shear and bearing, see para. 302.3.1(b). springs,and to prevent unintentional disengagement of
<br /> (d) Wood or other materials may be used for pipe the load.
<br /> supporting elements,provided the supporting element
<br /> is properly designed,considering temperature,strength, 9 Various types of inextensible(solid)and resilient supports are
<br /> and durability. illustrated in MSS SP-58.
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