And any parts showing leakage shall be repaired and

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Unformatted text preview: ons, it shall provide a positive seal within the manufacturer’s recommended range of maximum joint deflection. Not more than two splices in each ring shall be permitted. 10 SPECIALS 10.1 Fabrication 12 WORKMANSHIP AND FINISH The steel for fabricated steel plate specials, is cut, shaped and welded so that the finished special has the required shape and internal dimensions. Adjacent segments are jointed by butt welding. Before lining and coating, the welding of specials shall be tested by use of hot oil or dye penetrant according to IS 3658 and defects, if any shall be rectified. The steel plate thickness for specials shall be as given in IS 1916. 12.1 Deviation from the Straightness When measured by means of a one metre straight edge the deviation from straight per metre length shall not exceed 5 mm. 12.2 Finish Pipe shall be free from local depressions or bulges greater than 5 mm extending over a length, in any direction, greater than twice the thickness of barrel. The external surface of the pipe may be sand faced, when coating of cement mortar is applied. In die penetration test, a white wash is applied over the weld on one side of the cylinder; on other side when coloured paraffin or similar product is applied over the weld, no coloured spot shall appear on the whitewash before 4 h. If any coloured spots appear before 4 h, weld shall be repaired and retested. 13 TEST 13.1 Design Proving and Manufacturing Approval Test in Factory 10.2 Lining and Coating Steel plate specials are lined and coated with concrete or cement mortar or other approved materials, as agreed between the manufacturer and the purchaser. The proportion of cement to total aggregate shall not be leaner than 1:3 by mass. Process As Won os 4 to 5 pipes are made, these shall be installed and site pressure test shall be conducted, to prove and finalize pipe and joint design and joint dimension tolerances, etc. For one diameter and different pressure, only the test for highest pressure shall be done. For this test no external load shall applied. 10.3 Reinforcement For concrete or cement mortar coating, reinforcement shall be suitably tack welded to the shell. The reinforcement shall be wire rods and spirals or wire mesh or wire fabric. 13.2 Hydrostatic Factory Test The pipe shall be tested in accordance with IS 3597. The pipe must not show leakage. Damp or wet patches shall be accepted. If the pipe fails to pass the test, it can be cured or repaired to improve its water tightness and then retested. In case the pipe does not stand the rated internal pressure, it shall be accepted for lower pressure, purchaser at his own discretion may accept the pipes for lower pressure to which it withstands, provided all other requirements are conforming to this standard. 10.4 Jointing Between Special and Pipe The special shall be jointed to the pipe by same robberring joint as for pipes or by caulking with mortar. For this purpose steel collars shall be welded to steel specials to allow caulking o...
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This document was uploaded on 10/01/2013.

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