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Expansion joint and flanged joint

Short answer

Expansion joints absorb thermal movement via a spigot sliding in a stuffing box sealed by packing and a gland; used on long exposed lines, bridges, near pumps. Flanged joints use bolted flanges with a gasket to connect pipes, valves, or fittings, allowing easy dismantling but no angular movement.

Briefly describe the purpose and use of the expansion joint and the flanged joint with sketch.

Expansion joint

An expansion joint is a special joint which permits the pipe to expand and contract freely due to temperature changes, without causing leaks or stress.

  • Use: on long straight lines of exposed CI/steel pipe, on bridges, and near pumps and valves.
  • Construction: the spigot end slides inside a socket (stuffing box); a rubber or lead packing is compressed by a gland and bolts.
   pipe ====[ socket | packing | gland ]==== pipe
                          ^bolts
        spigot slides in and out (10-20 mm)

Flanged joint

In a flanged joint, flanges (circular plates with bolt holes) are cast, welded or screwed on the ends of the two pipes. A rubber, rubber-fabric or lead gasket is placed between the faces, and bolts and nuts are tightened evenly.

   pipe ===|F|gasket|F|=== pipe
           | |  ||  | |    F = flange, bolts hold
           bolts through the holes
  • Use: to join valves, pumps, meters and other fittings; for pipes in pump houses, treatment plants and exposed lines; wherever the pipe may have to be taken apart and rejoined.
  • It is strong, watertight and easy to dismantle, but costly and it cannot take any bending or movement.

✓ Answer checked by Claude Opus 5.5 (high effort)

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