APPARATUS FOR SERVICING GAS LINES

摘要

An apparatus and method for working on a section of gas main while it is in service comprising a work chamber formable around a section of the gas main and having means for admitting a tool thereto in a manner that it can be manipulated from outside the work chamber; means for removing the tool from the work chamber while maintaining the work chamber under gas pressure and means for safely evacuating the work chamber of gas.