In order to allow the telescope movement of inner pipe, expansion joint is installed within a firmly mounted outer sleeve of pipe in order to accommodate the contraction ad expansion in the piping system. These are available in nominal piping sizes with maximum travel lengths. These joints are also used as repair coupling.
* One should not weld the mating flanges with the expansion joints. There can be possibility of heat damage or spark.
* There should be proper support for the pipelines so that expansion joint should not carry pipe load.
* In the upstream and downstream, the anchors are placed at both ends of thermally contracting and expanding pipe length. These joints will not function and fall down unless the full thrust anchors are provided in place.
* One needs to check with the manufacturer that the pipe fitting can take the joints thrust, when the mechanical pipe fitting is installed in the joint line. If not, then anchoring for pipe is required on either side and two joints are installed rather than one. The arch area and thrust on the anchor in the pipeline area is multiplied by water pressure. The thrust of the pipe wall is only the area of the arch that is multiplied by water pressure.
* The control units should be used if it is not possible to anchor the pipeline in the above manner. There will no anchor on or both sides of the joint once the control unit is installed. Then the joint will open up the control rod lock out position and will remain in that position. The joint will not act to take up axial motion, rather it will provide make up for angular, misalignment and transverse motions.
* The cable assemblies should be substituted for rigid control rods, where the traverse forces are to be kept to a least. With the value of spherical seats on control seats, the force required to move the piping laterally very high, when control rods are used.
* Before installation of the joints, all the pipes are lined up in an accurate manner. The units will adjust them with the specified limits to misaligned flanges. Thus, it becomes difficult to force the joints to a position before they are rigidly bolted to the flanges.
These joints should not be piled one over another. After a period, the weight will be reduced to face-to-face length. Thus storing in shelves can prevent the reduction of weight. It is important to store the joints where they cannot sustain any sort of damage. These joints should be inspected for soundness and these joints require no maintenance. The detection of the leakage allows ample time for the replacement of flange tightening if it is required. If there is a deterioration of cover, from cleaning, then a coating of hypathelon paint is used to reduce the deterioration. It is good idea to check whether are joints are overly compressed, moving well, elongated or not after installation. Joints should be checked that whether they are operating outside of the rated movements.
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