Pipe coupling

In a coupling for interconnecting plastic pipe ends,

• (a) a tubular coupling member consisting of plastic, and having a bore at its mid-portion, two counterbores respectively intersecting opposite ends of the member, and two annular step shoulders respectively between the counterbores and said bore,
• (b) plastic pipe ends inserted into the counterbores to extend proximate the step shoulders, the pipe ends adhesively joined to the counterbores,
• (c) threaded fasteners extending generally radially through the coupling member to intersect the counterbores, the fasteners having tapered threads and tips that penetrate radially into the pipe ends,
• (d) the fasteners having heads and there being seal means sealing off between the fasteners and the coupling member and pressurized therebetween,
• (e) each fastener having an annular tapered shoulder spaced from the head and located between said head and said tapered thread, the shoulder interfitting a tapered shoulder on the coupling and closer to said thread than said seal means, to limit said pressurization and the penetration of the tips into the pipe ends, the tapered shoulder flaring widely toward the seal means, the seal means comprising elastomeric washers.