On length shall be 1 percent of the specified length

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Unformatted text preview: ices, each splice shall be thoroughly visually checked by twisting the ring through 360°. Splices showing visible separation or cracks shall be rejected. Not more than two splices in each ring shall be permitted. All sealing rings shall be protectt?d from direct rays of the sun and stored in dry place. 5.3.2 Internal Diameter For pipes of length less than 4 m, the tolerance shall be *5 mm for diameter upto and including 350 mm. For diameter above 350 mm, the tolerance shall be *IO mm. 2 .. . IS 784:2001 diameters shall be furnished by the manufacturer for inspection. The indicative dimensions of socket and spigot are given in Annex B. For pipes of length 4 m and above, the tolerance shall be as given below: Tolerances Internal Diameter 7 DESIGN A % / Up to 900 mm Over 900 mm and upto 1 600 mm Over 1600 mm In areas within 600 mm c)fan end of the pipe mm *6 Over rest of the pipe +9 in Annex C. 7.2 All pipes shall be designed to withstand the combined effects of internal water pressure and external loads. mm *9 * 12 + 12 7.1 Information to be supplied by purchaser is given + 12 7.3 The design of the prestressed concrete pipes shall cover all such stages, which may induce stresses in any section of the pipe. For investigation of these design stages, the likely extreme conditions of stresses shall be considered in the order of their occurrence, during the process of manufacture, handling, erection and under service. Table 1 Nominal Internal Diameter and Minimum Core Thickness of Pipes (Clause 5.1) Nominal Internal Diameter of Pipe mm Minimum Core Thickness mm Nomianl Internal Diameter of Pipe mm (1) (2) (3) 1300 7.4 Design Pipes Minimum Core Thickness mm (4) 200 250 300 350 400 450 500 600 700 800 900 1000 1 100 1200 35 35 35 35 35 35 35 40 40 45 55 60 65 70 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400 2500 Criteria for Non-Cylinder Pressure The pipes shall be designed to meet the requirements given in subsequent clauses. 7.4.1 Longitudinal Prestressing Requirements 75 75 80 85 The permissible stresses for various load combinations shall be as follows: Description of Loading Combination 90 95 100 105 110 115 120 125 130 a) Longitudinal prestress (after losses) in barrel NOTES I Internal diameter of pipes other than those mentioned in this table may be suppliedby mutualagreementbetween the purchaser and the manufacturer.For higherpressure the core thickness have to be increase~ in such cases: a) the diameter will be correspondingly reduced (This is to enable use of same moulds), and b) multiple layers of circumferential prestressing wire shall be adopted. 2 This standardincludesprovisionupto 2500 mm diameterpipes. Pipes of diameter beyond 2500 mm maybe supplied in special cases by mutual agreement between purchaser and manufacturer subject to additional precautions taken in design, manufacture, testing and construction of the pipe. b) Longitudinal prestress during circumferential prestressing (temporary) c) Longitudinal prestress after losse...
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This document was uploaded on 10/01/2013.

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