Patent ID: 8720466
Filing Date: 2014-05-13
Classification: F16L,Y10T

Abstract:
1. A process for accessing an underground pressurized gas main for retirement or replacement of a gas service pipe connection that is connected to the gas main under gas main operating pressure, without creating a gas blow, comprising the steps of: (a) evacuating an opening in the ground to access an underground gas main and connected gas service pipe; (b) providing a gas main fixture, a service tee adapter and pressure chamber; (c) connecting the service tee adapter to the pressure chamber and to the gas main fixture; (d) then mounting the gas main fixture with the connected service tee adapter and pressure chamber onto the gas main so that the service tee adapter is above a tee plug on the gas service pipe connection and with the pressure chamber in substantial alignment above the tee plug on the gas service pipe connection; (e) then closing the pressure chamber against gas discharge to atmosphere and while the pressure chamber is closed to atmosphere, unscrewing the tee plug from the gas service pipe connection and removing the tee plug through the service tee adapter and pressure chamber while limiting gas discharge to atmosphere to only an amount of main gas that is in the pressure chamber; (f) then reaming a plug hole in the gas main through the pressure chamber and service tee adapter while the pressure chamber is closed to atmosphere; (g) then tapping a straight, fine thread in the plug hole in the gas main through the pressure chamber and service tee adapter while the pressure chamber is closed to atmosphere; (h) providing a main plug having a straight, fine screw thread sized to mate in a tight fit with the tapped thread of the plug hole and a flange at its upper end to engage the outside of the gas main and thereby limit the depth of threaded engagement of the main plug into the gas main; (i) then screwing the main plug into the tapped plug hole in the gas main in a tight fit engagement with the tapped hole until its flange is disposed against the outer surface of the gas main, through the pressure chamber and service tee adapter while the pressure chamber is closed to atmosphere; and (j) then removing the gas main fixture, service tee adapter and pressure chamber from the gas main.