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2020.03 DOUBLE DISC GA1'F, VALVE511411vCt1r:S - sb ltvcnr.b Unless otherwise appro ed in writing, all Gate Valves for direct buried service in the City's distribution system, 14 inches through 3 inches in diameter shall conform strictly with the latest specification C-500 of the American Water Wor s Association Standards and must comply with the following supplementazy details, changes or addit'on. (a) Bodv ' Gate valves shall be iro body designed for a working pressure of 200 psi. All valves shall be hydrostatically tested at 300 psi and hell tested at 400 psi. Any leakage during testing shall be cause for rejection. For ease of repair the body, onnet and stuffing box shall be flanged together with ASTM A-302 bolts and nuts. Each valve shall have tlhe maker's initials, pressure rating, and yeaz in which manufactured cast in the body. I (b) Stems Stems shall be machined from manganese bronze rod, or manganese bronze castings, with an integral trust collar machined to size. he stems shall be non-rising and equipped for nut operation, which shall be opened by tuming to the left ( ounter clockwise). (c) Stem Seals The seals shall consist ~f one "O" ring above and one "O" ring below the thrust collaz. An anti-friction washer shall be located ab ve the thrust collar for operating torque. (d) Stem Nut The stem nut shall be A TM B-62 Bronze and shall be integrally cast with the valve disk in a manner that will provide rigidity and ositive travel stop, which shall be by metal to metal contact. (e) Gates Gates shall be cast iron with bronze gate rings. (f) Wedgin Dg_ evice May be solid bronze or ast iron bronze mounted wedges. Bronze mounting shall be built as an integral unit mounted over or supp rted on a cast iron base and shall be of sufficient d'unensions to be structurally sound and adequate for th forces that shall be imposed upon it. Thin plates or shapes doweled or screwed into the cast iron surfaces i such a manner that the screws or dowels that cany the load shall not be acceptable. Wedging surfaces shall bronze to bronze. Other moving surfaces integra] to the wedging action shall be bronze to iron. 'i 2020.04 All valves furnished un er these specifications shall be painted on the exterior with asphalt varnish. All fenous meta] surfaces in the internal part of the valve shall be protected with a two-paR thermoset epoxy coating to a nominal t'ckness of 4 mils for corrosion protection and shall be of a color that is easily identified as an epoxy coating. The coating shall meet Ihe requirements set forth in Item 2024.02 (g) of these specifications on Butterfly, Valves. Item 2020-2