Page number 52
70 Expansion joint selection HINGED Gn LFP Source: Freely adapted from EJMA Two-hinged expansion joint In deploying hinged expansion joints for the most effective use, it should be noted that in order to function properly the hinges do not need to be colinear. The illustration shows a two-hinged expansion joint system. In this case, the expansion joints will absorb only the differential vertical growth between the vessel and pipe riser. Any horizontal movement due to piping expansion, vibration and wind loads will be absorbed by the bending system of the vertical pipe leg. A planar guide may be installed near the top of the vessel to protect the hinged expansion joints from wind loads at right angles to the plane of the piping. The fix point shown at the bottom of the riser is a fix point only, since the pressure load is absorbed by the expansion joint hinges. This fix point must be capable of withstanding the forces created by the bending of the riser. Depending on the dimensions and weight of the pipe system, sufficient support may be obtained from the process vessel and from the fix point. If additional supports are required, spring type supports should be used. The vertical piping may be cold pull to reduce bending stresses, utilising the hinges to withstand the cold spring force. www.belman.com B022016-1 – Subject to alterations and eventual misprints
Page number 53
EXPANSION JOINT SELECTION 71 Expansion joint selection HINGED PG Equipment DIA IA Source: Freely adapted from EJMA Hinged expansion joint system A hinged expansion joint system may while the equipment serves as a fix be used effectively in applications point at the opposite end. The involving movement other than the displacements of the equipment are pure thermal growth of piping. The added to those of the piping to figure illustrates an application evaluate the movements of the combining the thermal expansion of a expansion joints. Planar guide piping system with the single plane clearances in the plane of the piping movements of an item of connected must be adequate to allow for the equipment. As long as all movements equipment movement as well as the are restricted to a single plane, the piping rotations. behaviour of the expansion joint The compact size and structural system is quite similar to that of the rigidity are the advantages of this system shown in the figure. A fix point expansion joint type. Through the use is required at one end of the piping, of these individual units, it is frequently possible to compensate for the thermal expansion of irregular and complex piping configurations, which might preclude the use of other types of expansion joints. Due to the ability of the hinge structure to transmit loads, piping systems containing hinged expansion joints impose minimal forces on the fix points. Such systems can be supported at virtually any point, without interfering with the free movement of the system. B022016-1 – Subject to alterations and eventual misprints www.belman.com
