6.4.2.4 LOWERING OF PIPES AND FITTINGS

All pipes, fittings, valves and hydrants shall be carefully lowered into the trench by means of derrick, ropes or other suitable tools or equipment to prevent damage to pipe materials and protective coatings and linings. Pipes over 300 mm dia shall be handled and lowered into trenches with the help of chain pulley blocks.

6.4.2.5 CLEANING OF PIPES AND FITTINGS

All lumps, blisters and excess coating material shall be removed from socket and spigot end of each pipe and outside of the spigot and inside of the spigot shall be wire-burshed and wiped clean and dry and free from Oil and grease before the pipe is laid.

After placing a length of pipe in the trench the spigot end shall be centered in the socket and the pipe forced home and aligned to gradient. The pipe shall be secured in place with approved back fill material tamped on both sides except at socket.

The socket end should face the upstream while laying the pipe line on level ground; when the pipe line runs uphill the socket ends should face the up gradient. When the pipes run beneath the heavy loads suitable size of casing pipes or culverts may be provided to protect the casing of pipe. High prssure mains need anchorage at dead ends and bends as appreciable thrust occur which tend to cause draw and even "blow out" joints. Where thrust is appreciable concrete blocks should be occur. Anchorages are necessary to resist the tendency of the pipes to pull a part at bends or other points of unbalanced pressure, or when they are laid on steep gradients and the resistance of their joints to longitudinal or shear stresses is either exceeded or inadquate. They are also used to restrain or direct the expansion and contraction of rigidly joined pipes under the influence of temperature changes. Anchor or thrust blocks shall be designed in accordance with IS 5330 -1984.