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ASME B31.3-2016
<br /> (b) Constant-support spring hangers provide a sub- (a) Integral reinforcement, complete encirclement
<br /> stantially uniform supporting force throughout the reinforcement, or intermediate pads of suitable alloy
<br /> range of travel. The use of this type of spring hanger is and design may be used to reduce contamination or
<br /> advantageous at locations subject to appreciable move- undesirable heat effects in alloy piping.
<br /> ment with thermal changes.Hangers of this type should (b) Intermediate pads, integral reinforcement, com-
<br /> be selected so that their travel range exceeds expected plete encirclement reinforcement,or other means of rein-
<br /> movements. forcement may be used to distribute stresses.
<br /> (c) Means shall be provided to prevent overstressing
<br /> spring hangers due to excessive deflections.It is recom- 321.4 Structural Connections
<br /> mended that all spring hangers be provided with posi- The load from piping and pipe supporting elements
<br /> tion indicators. (including restraints and braces)shall be suitably trans-
<br /> mitted to a pressure vessel,building,platform,support
<br /> 321.2.4 Counterweight Supports. Counterweights structure, foundation, or to other piping capable of
<br /> shall be provided with stops to limit travel. Weights bearing the load without deleterious effects. See
<br /> shall be positively secured. Chains, cables, hangers, Appendix F,para. F321.4.
<br /> rocker arms,or other devices used to attach the counter-
<br /> weight load to the piping shall be subject to the require-
<br /> ments of para. 321.2.2. PART 6
<br /> SYSTEMS
<br /> 321.2.5 Hydraulic Supports. An arrangement utiliz- 322 SPECIFIC PIPING SYSTEMS
<br /> ing a hydraulic cylinder may be used to give a constant
<br /> supporting force. Safety devices and stops shall be pro- 322.3 Instrument Piping
<br /> vided to support the load in case of hydraulic failure.
<br /> 322.3.1 Definition. Instrument piping within the
<br /> 321.3 Structural Attachments scope of this Code includes all piping and piping compo-
<br /> nents used to connect instruments to other piping or
<br /> External and internal attachments to piping shall be equipment, and control piping used to connect air or
<br /> designed so that they will not cause undue flattening of hydraulically operated control apparatus. It does not
<br /> the pipe,excessive localized bending stresses,or harmful include instruments, or permanently sealed fluid-filled
<br /> thermal gradients in the pipe wall. It is important that tubing systems furnished with instruments as tempera-
<br /> attachments be designed to minimize stress concentra- ture or pressure responsive devices.
<br /> tion, particularly in cyclic services.
<br /> 322.3.2 Requirements. Instrument piping shall
<br /> 321.3.1 Nonintegral Attachments. Nonintegral meet the applicable requirements of the Code and the
<br /> attachments, in which the reaction between the piping following:
<br /> and the attachment is by contact,include clamps,slings, (a) The design pressure and temperature for instru-
<br /> cradles, U-bolts, saddles, straps, and clevises. If the ment piping shall be determined in accordance with
<br /> weight of a vertical pipe is supported by a clamp,it is para. 301. If more severe conditions are experienced
<br /> recommended to prevent slippage that the clamp be during blowdown of the piping,they may be treated as
<br /> located below a flange,fitting, or support lugs welded occasional variations in accordance with para. 302.2.4.
<br /> to the pipe. (b) Consideration shall be given to the mechanical
<br /> 321.3.2 Integral Attachments. Integral attachments strength(including fatigue)of small instrument connec-
<br /> include plugs,ears,shoes,plates,trunnions,stanchions, tions to piping or apparatus (see para. 304.3.5).
<br /> structural shapes,and angle clips,cast on or welded to (c) Instrument piping containing fluids that are nor-
<br /> the piping. The material for integral attachments mally static and subject to freezing shall be protected
<br /> attached by welding shall be of good weldable quality by heat tracing or other heating methods,and insulation.
<br /> [See para. 321.1.4(e) for material requirements.] Pre- (d) If it will be necessary to blow down (or bleed)
<br /> heating,welding,and heat treatment requirements shall instrument piping containing toxic or flammable fluids,
<br /> be in accordance with Chapter V. Consideration shall consideration shall be given to safe disposal.
<br /> be given to the localized stresses induced in the piping 322.6 Pressure-Relieving Systems
<br /> component by welding the integral attachment,as well
<br /> as differential thermal displacement strains between the Pressure-relieving systems within the scope of this
<br /> Code shall conform to the following requirements. See
<br /> attachment and the component to which it is attached.
<br /> Welds shall be proportioned so that the shear stresses also Appendix F,para. F322.6.
<br /> meet the requirements of para.302.3.1(b).If the allowed 322.6.1 Stop Valves in Pressure Relief Piping. If
<br /> stress values differ between the piping component and one or more stop valves are installed between the piping
<br /> the attachment material, the lower of the two values being protected and its protective device or devices, or
<br /> shall be used. between the protective device or devices and the point
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