255.717 Transmission lines: permanent field repair of leaks.

Each permanent field repair of a leak on a transmission line, or distribution main operating at 125 psig (862 kPa) or more in a Class 3 or 4 location, must be made according to the following requirements:#

(a)If feasible, the segment must be taken out of service and repaired by cutting out a cylindrical piece of pipe and replacing it with pipe of similar or greater design strength.#

(b)If it is not feasible to take the segment out of service, repairs must be made by one of the following methods:#

(1)install a full encirclement welded split sleeve of appropriate design;#

(2)if the leak is due to a corrosion pit, the repair may be made by installing a properly designed bolt-on-leak clamp;#

(3)if the leak is due to a corrosion pit and is on pipe with a SMYS of not more than 40,000 psi 267 MPa), the repair may be made by fillet welding a steel plate patch with rounded corners, of the same or greater thickness than the pipe, and not more than one-half of the diameter of the pipe in size;#

(4)apply a method that reliable engineering tests and analyses show can permanently restore the serviceability of the pipe.#