At the centre 2 1513 socket and spigot diameters 15131

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Unformatted text preview: the two points B and B, along the circumference of socket (see Fig. 1); BB, gives the sway. Colour Length Gauges for ends ‘Go’ 1 mm less than —ve tolerance ‘No Go’ 1 mm more than + ve tolerance Example: Green Suppose the theoretical diameter of socket D =1383mm Orange =+2mrn -0.5 mm The. maximum diameter = Dl = 1385 mm The minimum diameter = Dz = 1382.5 mm The sway = S= 2 x [h x (D, – h)]05 Assume h = 5 mm (see Fig. 1) Sway S = 2 x [5 x (1385 – 5)]05 =2x83 Permissible variation Gauges for centre ‘Go’ 1 mm less than – ve tolerance ‘No Go’ 1 mm more than + ve tolerance Green with white bands Orange with white bands Example: Suppose theoretical diameter of pipe= 1200 mm and length of pipe 5 m. Tolerance Ends +9 ‘Go’ 1200– = L2 = = = L= Length of gauge 8=l192mm ‘No Go’ 1 200+ 10= 1 210mm Centre * 12 ‘Go’ 1 200– 11 = 1189 mm 166 mm. (S/2)2 + (D1 – h)2 (166/2)2+(1 385- 5)2 6 889+ 1904400 1382.5 mm This should not be more than the minimum permissible inside diameter. ‘No Go’ 1 200+ 13 = 1213 mm 9 ., ..,, IS 784:2001 SWAYS F -1 1 1 7 L 1 .- Gauge for Measuring Sway FIG. 1 ARRANGENIIN FOR MEASURING SWAY 15.1.4 Straighlne.r.s Therefore, in this case Length of gauge, L Maximum permissible sway The straightness shall be measured by a one metre long gauge . The deviation from straight line taken between two points one metre apart, along the pipe barrel shall not exceed 5 mm (see Fig. 3). 5mm ~1 f“ = 1382.5 mm = 166 mm. 15.1.3.2 Spigot Diameter The gauge as shown in Fig. 2 shall be used. Examp[e: ~ Suppose the theoretical outside diameter spigot = 1200 mm Permissible variation = + 1 mm The maximum diameter = 1201 mm The minimum diameter = 1 199 mm. of 1000 FIG. 3 GAUGE FOR MEASURING STRAIGHTNESS 16 MARKING 16.1 The following information shall be clearly marked on each pipe: To enable gauge to pass over the spigot surface, the diameter must be more by 1 mm than the maximum spigot diameter. a) Source of identification of the manufacturer, b) Size and hydrostatic factory test pressure, and c) Date of manufacture. The clearance between gauge points = 1 200+1 + 1 = 1202 mm. 16.2 Each pipe may also be marked with the Standard Mark. For checking. spigot, the gauge is held in the position as shown in Fig. 2. Then by keeping point ‘X’ fixed, other end ‘Y’ of gauge is moved over the circumference of spigot, where the gap between spigot surface and gauge is maximum, a strip 2.5 mm, thick and 25 mm wide (straight side) (1 201 – 1 199 = 2.0 mm) is inserted. It should not go. Two checks shall be done at 90° to each other. 16.2.1 The use of the Standard Mark is governed by the provisions of Bureau oflndian Standards Act, 1986 and the Rules and Regulations made thereunder. The details of conditions under which a licence for the use of Standard Mark maybe granted to manufacturer and producers may be obtained from the Bureau of Indian Standards. STRIP 3.5 NOTTO GO ‘b u .--p, ..e:.~.@. .;.8 .e . “*. - ..4. . .,..:-......
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This document was uploaded on 10/01/2013.

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