For example, load due to tank settlement is not cyclic. The secondary loads are often cyclic but not always. Load due to thermal movement of equipmentĪ pipe may experience expansion or contraction once it is subjected to temperatures higher or lower respectively as compared to temperature at which it was assembled.Also, a pipe may vibrate due to vibrations in the rotating equipment it is attached to. Similarly, pipe connected to a vessel is pulled upwards because the vessel nozzle moves up due to vessel expansion. For example, the pipe connected to a storage tank may be under load if the tank nozzle to which it is connected moves down due to tank settlement. Just as the primary loads have their origin in some force, secondary loads are caused by displacement of some kind. The reaction force due to steady state flow following the opening of safety relief valve in an open discharge installation can be calculated in accordance with ASME B31.1 Appendix II and applied on the piping model as static equivalent force. Safety valve Discharge: Reaction forces from relief valve discharge is considered as an occasional load.Though the flow is transient, for the purpose of piping stress analysis, only the unbalanced force along the pipe segment tending to induce piping vibration is calculated and applied on the piping model as static equivalent force. Steam hammer: Steam hammer, the pressure surge generated by transient flow of super-heated or saturated steam in a steam-line due to sudden stop valve closures is considered as an occasional load.Water hammer commonly occurs when a valve closes suddenly at an end of a pipeline system, and a pressure wave propagates in the pipe. Water hammer: Water hammer (or more generally, fluid hammer) is a pressure surge or wave caused when a fluid (usually a liquid but sometimes also a gas) in motion is forced to stop or change direction suddenly (momentum change).It happens at contact surfaces of a structure either with the ground, or with adjacent structures, or with gravity waves from tsunami. Seismic load: Seismic load is one of the basic concepts of earthquake engineering which means application of an earthquake-generated agitation to a structure.Fw = Pw x S x A, where Fw = The total wind force, Pw = The equivalent wind pressure, S = Wind shape factor, A = Pipe exposed area. Wind pressure for various elevations will be used to calculate wind force using the following formula. Wind force is modeled as a uniform load acting upon the projected length of the pipe perpendicular to the direction of the wind. Wind load: Piping which are located outdoors and thus exposed to wind will be designed to withstand the maximum wind velocity expected during the plant operating life.The weight of risers (vertical sections of pipe) can be supported by riser clamps. fluid weight) and concentrated weight load (e.g. Pipe bending is caused mainly due to two reasons: distributed weight load (e.g. In horizontal pipes, these loads cause bending, and the bending moment is related to normal and shear stresses. This type of loads act throughout the life cycle of pipe. Dead weight: It is the self weight of pipe including fluid, weight of fittings & other inline components (say valve, insulation etc.).If outer diameter is used for calculating approximate metal cross-section as Pressure well as pipe cross-section, the axial stress can often be approximated as follows : S =Pd /(4t) The internal pressure exerts an axial force equal to pressure times the internal cross section of the pipe.

The pressure also induces stresses in the radial direction, but these are often neglected. Internal or external pressure induces stresses in the axial as well as circumferential ( Hoop Stress) directions. A pipe such as a jacketed pipe core or tubes in a Shell & Tube ex-changer etc. Internal/External Pressure: A pipe used for transporting fluid would be under internal pressure load.These are typically steady or sustained types of loads such as internal fluid pressure, external pressure, gravitational forces acting on the pipe such as weight of pipe and fluid, forces due to relief or blow down, pressure waves generated due to water/steam hammer effects.

Brackets to secure pipes