I intend to do more post today because in this Sunday I want to take a long rest in my home, that's why Piping & Fabrication gave so much article and pictures for this Piping Systems and enjoy it everyone!
Expansion joints are used in piping systems to absorb thermal expansion where the use of expansion loops is undesirable or impractical. Expansion joints are available in slip, ball, metal bellows, and rubber bellows configurations.
Slip-type expansion joints (Fig. A2.12a) have a sleeve that telescopes into the body. Leakage is controlled by packing located between the sleeve and the body. Leakage is minimal and can be near zero in many applications. A completely leakfree seal cannot be ensured; thus these expansion joints are ruled out where zero leakage is required. The packing is subject to wear due to cyclic movement of the sleeve when connected piping expands and contracts. Thus, these joints require periodic maintenance, either to compress the packing by tightening a packing gland or to replace or replenish the packing. Replacement of the packing rings is necessary when leakage develops in a joint that has an adjustable packing gland which has been tightened to its limit. Some designs provide for packing replenishment rather than replacement. These are usually called gun-packed or ram-packed slip joints. Since the packing can wear away, some packing material may be picked up in the line fluid. This rules out the use of slip joints in systems, where such contamination of fluid cannot be tolerated.
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| FIGURE A2.12 (a) Slip-type expansion joint. (Yarway Co.) (b) Typical ball expansion joint |
Slip-type expansion joints are particularly suited for lines having straight-line (axial) movements of large magnitude.
