METHOD FOR FORMING GAP BETWEEN INNER AND OUTER PIPES OF FIRE RESISTANT DOUBLE-LAYERED PIPE JOINT

Japanese Patent JP2933251

B2

PURPOSE: To prevent an incombustible outer pipe from cracking by the expansion of a synthetic resin pipe due to the pressure of fluid flowing in the interior of the pipe joint by a method wherein the outer peripheral surface of the synthetic resin pipe joint, which is expanded by applying pressure to its interior, is covered with the incombustible material, of which the outer pipe consists, and, after that, the internal pressure is released so as to produce gap between the joint and the outer pipe.
CONSTITUTION: Inorganic incombustible mortars 2a are fed with an extruder or the like through the gap between a connecting pipe 8 and a guide core 9 to a space formed between the outside part 1b of polyvinyl chloride pipe and the inner surface 7a of a mold. The interior 1a of the polyvinyl chloride pipe and the space formed between the outside part 1b and the mold 7a are sealed by sealing material 10 so as to fully expand the polyvinyl chloride pipe 1 by applying pressure through a hole 5a provided in advance on an adapter 5. The application of the pressure may well be performed either after the covering of the outer peripheral surface of the pipe 1 with the mortars 2a or before the curing of the mortars. Further, the timing of pressure release may also well be before the curing of the mortars 2a. By releasing the pressure, the polyvinyl chloride pipe 1 shrinks, resulting in producing gap between the pipe 1 and the mortars 2a.

MEGURO KUNIO

JP12270492A

August 09, 1999

April 16, 1992

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ASANO SUREETO KK

B28B21/38; B29D23/00; F16L41/02; (IPC1-7): B28B21/38; B29D23/00; F16L41/02

JP5824696A
JP5627321A

Hitoshi Nakano (1 outside)

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