Untitled - Future Pipe Industries

5.6: Pipes with locked joints
For some underground applications, pipes might be provided with a restrained mechanical gasketed joint. Typical applications
are pipes laid in deep slopes, or where thrust blocks can not be used, and for pipes used as well-casings. In this case,
special pipe and Reka couplings (or special Bell/Spigot joints), designed to resist the high longitudinal stresses, are provided.
One locking key (strip), or more, is inserted into the joint to restrain and lock the two-pipe sections jointed. The joint
assembly shall be done as per the following recommendations:
• The joint should be assembled in such a way that the position of the hole in the socket (coupling) allows the locking strip
to be inserted easily.
• Lubricate lightly the first 6-8” section of the locking key (strip).
• The beveled end of the locking key should be resting against the inside surface of the socket or coupling when inserting.
The insertion should be made using a plastic hammer or a piece of wood to tap the key until it resists against the first part of
the key. See figure 14 for typical joint configurations for rubber seal lock coupler and rubber seal locked joint (restrained bell
and spigot joint).
• The Contractor must insure that the locked joint is stretched after assembly and that both the spigot stop and coupling (Bell)
stop are in contact with the locking key.
• The maximum allowable joint deflection for “locked” socket joints is 1.5o for sizes up to 24” and 1o for larger sizes. It
is recommended not to reach these values during installation.
Figure 14: Typical locked joint configurations
Pipe may also be provided with plain-ends for laminated joints (butt-wrap).
5.7: Standard short pipe lengths & connections to concrete structures
Standard short pipe lengths are required to be installed to protect against differential settlement outside structures, such as:
• Outside rigid structures (i.e. water reservoirs, pumping station, valve chambers, manholes, etc.)
• To connect the pipes to a line fitting such as bends or tees inside thrust blocks.
Standard short lengths of pipes shall be planned ahead by the contractor. The recommended length (L) of standard short
pipe is:
•L=2to 3 feet for Pipe up to and including 12” in diameter.
• L = 3.5 – 7 feet for pipe larger than 12” in diameter.
Note: See figure 15 for typical details. Option (1) is the typical connection details to fittings inside thrust blocks and may
also be used for connections to manholes. Option (2) is typically used for connections to manholes.
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