| 摘要 |
<p>A connection for and a method of connecting the ends of two joints of low modulus, low hardness, low strength plastic pipe. The connection includes a threaded box (10) on one joint and a threaded pin (12) on the other joint. The box has tapered, internal, generally dovetail-shaped threads (14) with stab flanks (16) and load flanks (18) and flat roots (20) and crests (22) that are parallel to the longitudinal axis of the pipe. The pin (12) has tapered, external, generally dovetail-shaped threads (24) with stab flanks (26) and load flanks (28) and flat roots (30) and crests (32) that are parallel to the longitudinal axis of the pipe for mating with the internal threads of the box (10). The threads increase in width in one direction on the box and in the other direction on the pin. When the connection is made up the roots, crests, and flanks of the threads move into engagement to form seals that resist the flow of fluids between the threads. The roots, crests, and flanks remain in engagement even after the compressive stresses created in the pin and/or the tensile stresses created in the box when the connection is made up is relieved by cold flow and continue to seal against internal pressure by the locking effect of the dovetailed-shaped threads.</p> |
