Rust-resistant sleeve for use in a branch hole of a water pipeline

Abstract

A rust-resistant cylindrical metal sleeve for preventing rust and corrosion from developing around the wall of a branch hole when the sleeve is rigidly fitted into a branch hole that is drilled through the wall of a metal conduit such as a water pipeline. The sleeve has a projecting portion on its outer circumference and an inner flange portion inwardly projecting at its lower end. The metal sleeve on its outer circumference is coated with a water-absorbing swelling rubber into which a synthetic resin rubber and a water-absorbing polymer are blended. Preferably, 100 parts by weight of styrene-butadiene rubber or ethylene-propylene-dienemetylene linkage rubber is blended with 10 to 40 parts by weight of the water-absorbing polymer. Since the water-absorbing swelling rubber increases its volume as it absorbs water, pressure in the rubber increases, preventing water ingress through between the metal sleeve and the wall of the branch hole.

Dependencies are inferred from the claim text.