Quartz pipe joint

A quartz pipe joint, comprising:

• a joint body having a pipe receiving portion into which a quartz pipe is to be inserted, the quartz pipe having an outer peripheral face and an annular groove formed in the outer periphery;
• a cylindrical sealing member to be externally fitted onto the quartz pipe, said cylindrical sealing member having an inner peripheral face, one end face and another end face, said fitting causing said inner peripheral face and said sealing member to closely contact with the outer peripheral face of the quartz pipe;
• a tapered receiving face formed on said one end of said sealing member which has a diameter gradually decreasing toward a front end of said one end of said sealing member;
• an outwardly extending tapered pressing face disposed in said pipe receiving portion of said joint body, said pressing face overlapping said receiving face of said sealing member;
• a lock ring deformable to increase its diameter and reduce its diameter, said lock ring being fitted into the annular groove formed on the outer periphery of the quartz pipe at a predetermined location in an axial direction, an inner periphery portion of said lock ring being engageable in the axial direction with a groove wall of the annular groove under a state in which said ring is fitted into the annular groove;
• a nut to be externally fitted onto the quartz pipe and threadedly connected to said joint body;
• a pressing piece which is disposed in said nut, said pressing piece cooperating with said pressing face to, when said nut is threadedly connected to said joint body, clamp said lock ring which is fitted into the annular groove of the quartz pipe, and said sealing member which is externally fitted onto the quartz pipe;
• and
• an outwardly extending tapered face which is formed on an inner peripheral portion of said other end face of said sealing member, said outwardly extending tapered face extending around the groove wall of the annular groove of the quartz pipe when said sealing member is clamped together with said lock ring by said pressing face of said joint body and said pressing piece of said nut, whereby the inner peripheral face of said sealing member is closely contacted with the outer peripheral face of the quartz pipe at a position which is separated from the annular groove.