Electrically insulating pipe union

Claim 1

A method of manufacturing a pipe union comprising the steps of forming at the ends of two pipes frustoconical outwardly flared end portions having a predetermined conicity, said ends of said frustoconical type end portions having end faces spaced from each other a predetermined distance; placing about said frustoconical outwardly flaring pipe end portions a deformable insulating means including an annular central core portion having a width substantially equal to the distance between said end faces and located between the same, spaced at least partly from the same, and projecting outwardly therefrom, and two flange portions located outwardly of said flaring pipe end portions and having a conicity smaller than the conicity of said flaring pipe end portions; surrounding said insulating means with a tubular substantially cylindrical integral retaining member including opposite end portions; and applying at least to said end portions of said tubular retaining member radially inwardly directed pressure of such magnitude so as to compress and deform the same, the flange portioNs of said insulating means and said flaring pipe end portions to reduce the conicity of the latter whereby the end faces of said pipe end portions are moved into compressing contact with said core portion and said flanges of said insulating means are firmly pressed against said flaring pipe end portions firmly connecting the same to each other while air-tightly sealing the space between the end faces thereof and electrically insulating them from each other.

Claim 2

A method of manufacturing a pipe union comprising the steps of forming at the ends of two pipes frustoconical outwardly flared end portions having a predetermined conicity, said ends of said frustoconical type end portions having end faces spaced from each other a predetermined distance; placing about said frustoconical outwardly flaring pipe end portions a deformable insulating means including an annular central core portion having a width substantially equal to the distance between said end faces and located between the same, spaced at least partly from the same, and projecting outwardly therefrom, and two flange portions located outwardly of said flaring pipe end portions and having a conicity smaller than the conicity of said flaring pipe end portions; surrounding said insulating means with a tubular substantially cylindrical integral retaining member including opposite end portions; and applying at least to said end portions of said tubular retaining member radially inwardly directed pressure of such magnitude so as to compress and deform the same, the flange portioNs of said insulating means and said flaring pipe end portions to reduce the conicity of the latter whereby the end faces of said pipe end portions are moved into compressing contact with said core portion and said flanges of said insulating means are firmly pressed against said flaring pipe end portions firmly connecting the same to each other while air-tightly sealing the space between the end faces thereof and electrically insulating them from each other.