Methods of sealing annular space between inner and outer gas mains for tie-overs

US4009732A · kind A · utility

Inventors

• Luther Martin · Champaign, US
• Richard L. Smith · Macedonia, US

Key dates

• Filing date: Mar 1, 1976
• Grant date: Mar 1, 1977
• Expiry date: Mar 1, 1996

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F16L55/10
• WIPO field: Mechanical elements
• WIPO sector: Mechanical engineering

Abstract

A method of tying over an individual customer service connection from a live outer gas main to an inner gas main inserted therein. The inner main is centered within the outer main and an annular region is defined upstream from the customer service connection which is to be tied over. An opening is formed in the side wall of the live outer main intermediate the ends of the annular region and a quantity of a high-density froth foam such as, for example, urethane foam, sufficient to fill the annular region is injected into it. The foam is allowed to harden to prevent gas from flowing downstream below the annular region to the service connection to be tied over. The outer main may then be cut away downstream from the annular region and the new customer service connection made through the side wall of the inner main exposed by cutting away the outer main. In the first embodiment of the method, a special centering tool contains a valve. This centering tool is used at the downstream end of the annular region and customer service connections below this downstream end are closed. At the beginning of the foam-injection step, the valve in the special centering tool is opened. As the foam fill…