Corrosion protective band for underground pipe joints with metal parts

Abstract

A system of protecting pipes with bell and spigot joints (having metal parts) from corrosion be by fitting between the spigot and bell at least one dry band of open celled material (preferably reticulated polyurethane foam) having a hydratable cement (preferably Portland cement) impregnated therein and engaging the band between the bell and the spigot. On wetting of the band, the cement is hydrated to form a water impervious hard sealant in the joint which releases alkalinity to protect the metal.

Description

This is a continuation-in-part application with respect to copending U.S. patent application Ser. No. 359,967 filed May 14, 1973 , polymer fibers or open celled polymers; may be used to make bands 19, 21. Usable polymers include vinyl, butadiene, styrene, urethane polymers, and the like. Foamed polyurethane is preferred. In one embodiment, the reticulated polyurethane foam used in the gasket is about 1 by 2 inches in cross section and has about 45 pores per square inch of surface. This polyurethane foam is seen in FIG. 4 and its cross-section carries about 5.5 ounces of Portland cement per linear foot. The foam can hold larger amounts of Portland cement, but such additional amounts of Portland cement do not increase effectiveness of the method of the present invention. The foam band may be surrounded by a water-soluble water-permeable member 22 as shown in FIG. 5 to reduce cement loss during shipping and placing, yet allowing water to pass through it for hydrating the Portland cement.

While cements other than Portland cement may be used, Portland cement is believed to be the most effective and economical of such cements.

The materials for the band are all commercially available. Reticulated polyurethane foam, for example, is manufactured by the Scott Paper Company's Foam Division in Chester, Pa. The Portland cement is conventional and is available widely. A non-woven polyester fabric for sheath 22 is obtainable from a wide variety of suppliers. All the separate materials are assembled by a fabricator skilled in the art of commercial textile production.

Each band preferably is packed individually in a waterproof plastic bag so as to avoid premature hydration of the Portland cement. A number of such bags are packaged into a cardboard container and the container is shipped to the field.

Field investigations of joints protected by the method of the present invention, in different types of soils for significant periods of time, have shown that this method protects effectively against corrosion. These investigations have demonstrated also that this method is readily and easily performed by relatively inexperienced personnel. Where bell and spigot bands of reticulted polyurethane foam impregnated with Portland cement are used in accordance with the present invention, no additional protection to the joint is required and most particularly application of grout to the outside of the joint and mortar to the inside of the joint are obviated.

It will be understood by those familiar with pipe design and installation that wide deviations may be made from the foregoing preferred embodiment without departing from the main theme of invention set forth in the following claims.

Claims

1. A distortable band, suitable for being fit into a joint between first and second continuous successive lengths of pipe made of ceramic earthen material wherein a bell formed on one end of the first length is engaged by a spigot formed on an end of a second length, the band made of a cellular water invadable material impregnated with a dry hydratable cement which is reactive with water to hydrate thereby depositing a water impervious hard substance in the joint.

2. The band of claim 1 comprising a reticulated polyurethane foam.

3. The band of claim 1 with the cement being Portland cement.

4. The band

of claim 1 and a water-permeable sheath around the band. 5. The band

of claim 7 with the cement being Portland cement. 6. The band of claim 7 with the sheath being a nonwoven polyester fabric. 7. A distortable band, suitable for being fit into a joint between first and second continuous successive lengths of pipe made of concrete, wherein a bell formed on one end of the first length is engaged by a spigot formed on the end of a second length, the band made of a cellular water invadable material impregnated with a dry hydratable cement which is reactive with water to hydrate thereby depositing a water impervious hard substance in the joint, a water permeable sheath around the band.