Piercing valve for tapping pipelines

Claim 1

In a line tap valve of the type having upper and lower blocks with registering grooves therein for assembly secured abutting and telescoping a normally circular transverse cross section pipeline to be tapped, the upper block mounting a generally vertically adjustable and peripherally sealed piercing needle selectively movable downwardly through a needle opening penetrating the upper block groove to transversely pierce an opening in an upper part of the pipeline, said needle being then movable back upwardly providing communication through the pipeline pierced opening and the needle opening into a transfer passageway of the upper block; the improvements comprising: an annular seal chamber in said upper block surrounding said needle opening including an enlargement at a lower portion of said needle opening communicating inwardly into said needle opening and downwardly into said upper block groove; an annular seal in said seal chamber enlargement spaced at all times outwardly of said piercing needle and said pipeline pierced opening, said seal being generally vertically compressed upwardly against said upper block and downwardly against said pipeline sealing said pipeline pierced opening upwardly from said upper block groove; said lower block groove being formed semi-circular in transverse cross section, said upper block groove being formed semi-elliptical in transverse cross section, a lower portion of said upper block groove being formed with a greater radius than an upper portion of said groove with the surfaces of said groove upper and lower portions blending smoothly one into the other; said block grooves and said pipeline being respectively dimensioned so that said assembled securement of said blocks into abutment around said pipeline forces deformation of said pipeline against said blocks and totally conforming to said block grooves including said upper part of said normally circular cross section pipeline being deformed into and conforming to said upper block groove semi-elliptical transverse cross section to increase the rigidity of said upper part of said pipeline and avoid deformation of said upper part of said pipeline and leakage about said seal during piercing thereof by said downwardly moving piercing needle.