1. Field of the Invention
The present invention relates in general to a method of forming a fluid tight pipe joint and the gasket for forming the joint. Specifically, the invention relates to a method of forming a pipe joint, and a gasket used to form the pipe joint between a metal spigot pipe and a metal belled pipe, the gasket being extensible from a resting state to an engaged state once the spigot pipe is inserted into the gasket fitted within the bell pipe.
2. Description of the Prior Art
Pipe joints are typically formed between a belled (female) pipe end and a spigot (male) pipe. The belled pipe may have a complex interior surface such as bevels and grooves, which is especially typical in polymer or plastic pipes. Typically, an elastomeric gasket will fit within the circumferential groove of the belled pipe to facilitate the formation of a pipe joint with the spigot pipe. The gasket forms a tight seal between the inside surface of the bell pipe and the outside surface of the spigot pipe inserted therein.
Metal pipes may also be made to have belled ends and gaskets therein. While metal pipes are inherently stronger than most plastic pipes, there are several problems associated with using metal pipes. Metal pipes used as conduits for fluid transport often must be cut or chamfered on the job site in order to facilitate the formation of pipe joints. If the pipe is a corrodible metal such as steel, cutting the metal can lead to rusting, pitting, and other corrosion that will ultimately breach the integrity of the seal between the two pipes. While coating the pipe ends with a paint or other polymer can prevent contact between the fluids and the exposed metal surface, this is often not possible or practical at a job site.
Gaskets are often used in forming pipe joints between metal pipes. However, most gaskets simply fit within the groove of the bell pipe, allowing the spigot pipe and the end of the pipe to be mostly exposed once inserted into the belled pipe having the gasket therein. Thus, the elastomeric gasket may only contact a limited circumferential region of spigot pipe outside surface and leave most of the surface exposed to the fluids that flow there through. The region of contact with the spigot pipe in most gaskets is limited to the size of the seal region that is opposite the region of the gasket that contacts the groove. The area of contact is extended somewhat in gaskets having a flange extending from the seal region. However, this flange in most gaskets serves the purpose of forming an area of pressured contact with the gasket to effectuate a ringed seal around the outside surface of the spigot pipe. This arrangement still leaves potentially cut or chamfered portions of the spigot pipe exposed.
What is needed is a pipe gasket and method of forming a pipe joint that will be advantageous to use with metal pipes that must be cut or shaved in some way at a job site.
Thus, it is one object of the present invention to provide a simpler method of preventing corrosion in metal pipes that are cut or shaved at a job site.
It is another object of the present invention to provide an elastomeric gasket with an extensible sleeve region to form a sleeve around the end of a spigot end of a spigot pipe, thus preventing contact with water.
It is yet another object of the present invention to provide a gasket that will engage the inserted spigot pipe and stop further movement at the proper stage of insertion to thus facilitate the formation of a sealing interface between the gasket and spigot pipe.
These and other objects are achieved by providing a pipe gasket and a method of forming a pipe joint between a spigot pipe having an outside surface and a spigot end, and a belled pipe having an annular groove and terminal face. The method is preferably practiced by providing metal spigot and belled pipes. The method comprises first providing an elastomeric gasket having a seal region and a retainer region joined by a sleeve region there between. The gasket is inserted into the annular groove of the belled gasket such that the seal region abuts the annular groove and the retainer region protrudes away from the terminal face.
The spigot pipe end is then inserted into the belled pipe end having the gasket located therein until the spigot end sealingly engages the retainer region thus preventing further movement of the spigot pipe, the sleeve and retainer regions thereby forming a fluid tight interface against the spigot pipe to prevent contact between fluids flowing through the pipes and the spigot pipe end and outer surface.
There are other specific features of the gasket of the invention that effectuate its function. The sleeve region is extensible, thus allowing the formation of an elastomeric sleeve around the spigot pipe outside surface and spigot end. Typically, the retainer region has a retainer ring therein for forming a fluid tight seal at the spigot pipe end. The retainer ring has a diameter slightly less than the inside diameter of the spigot pipe inside diameter, the ring thus forming a lip around the inserted spigot pipe end. The ring is typically a rigid, metal ring. Finally, the gasket may further have a compression gap in the seal region, the compression gap allowing the seal region to deform and place pressure upon the annular groove of the belled pipe and the outside surface of the spigot pipe.
Additional objects, features and advantages will be apparent in the written description which follows.