Calculating and Accommodating Pipe Line Thermal Growth - Victaulic

26.02Movement Dueto Pressure ThrustOffsetPlan View(Zero Pressure)Offsets have to be capable of deflecting sufficiently to preventharmful bending moments which would be induced at the jointsof the offset. Note, if the pipes were to expand due to thermalchanges, then further growth of the pipes would also take placeat the ends.Angular deflection at butted or fully spaced joints is not possibleunless the ends of the pipes can shorten and grow as required.Unrestrained deflected joints will straighten up under the actionof axial pressure thrusts or other forces acting to pull pipesapart. If joints are to be maintained deflected, then lines must beanchored to restrain pressure thrusts and end pull forces,otherwise sufficient lateral force must be exerted to keep jointdeflected.FΘHangerLateralForcePlan View(Pressurized)Gross effect ofinadequate lateralrestraint on suspended system.(illustration exaggerated for clarity)Flexible couplings do not automatically provide for expansion orcontraction of piping. Always consider best setting for pipe endgaps. In anchored systems, gaps must be set to handlecombinations of expansion and contraction. In free floatingsystems, offsets of sufficient length must be used toaccommodate movement without over-deflecting joints.GFULLY APARTExpansion OnlyLateral forces (F) will always act on deflected joints due tointernal pressure. A fully deflected joint will no longer becapable of providing the full linear movement normally availableat the joint.Joints DeflectedNo Expansion/ContractionAvailableFULLY BUTTEDContraction OnlyPARTIALLY GAPPEDExpansion and ContractionForExpansionForDeflectionEnsure anchorage and support is adequate. Use anchors todirect movement away from or to protect critical changes indirection, branch connections and structure. Spacing and typesof supports should be considered in accommodatinganticipated pipe movements. (Refer to the Victaulic I-100Pocket Handbook or Section 26.01 of the General Catalog forsuggested hanger spacing.)The grooved piping method will not allow both maximum linearmovement and maximum angular movement simultaneously atthe same joint. If both are expected simultaneously, systemsshould be designed with sufficient joints to accommodate both,including allowance for recommended tolerances.For anchored systems, where pressure thrusts do not act tohold the joints in tension, or in systems where the joints havebeen intentionally deflected (e.g., curves), provide lateralrestraint to prevent movement of the pipes due to pressurethrusts acting at deflections. Lightweight hangers are notadequate in preventing sideways movement of pipes. It shouldbe anticipated that small deflections will occur in all straightlines and side thrusts will be exerted on the joints.= Anchor = Lateral ResistanceMovement in piping systems due to thermal changes can beaccommodated with the grooved piping method. Sufficientflexible joints must be available to accommodate anticipatedmovement, including Movement Tolerance. If anticipatedmovement will be greater than provided by the total number ofjoints in the system, additional expansion in the form of aVictaulic Style 150 Mover or Style 155 Expansion Joint shouldbe used (Refer to Section 09.04 or 09.05).Calculating and Accommodating Pipe Line Thermal Growth 5