About Central Boilers Board •Contents Chapter Wise • Contents Regulation WiseIndian Boilers Act 1923
Reg. 356

Riveted on Flanges

a) Riveted on flanges shall only be used for pipes of 7” bore and above and for a maximum pressure 350 lbs. per sq. in. and/or a maximum temperature of 750°F.
b)

The shear stress in the rivets shall not exceed 6000 lbs. per sq. in. when calculated by the following formula:-

 Sr = Ao x P Eqn.(94) AN

where,

Sr = the shear stress in the rivets in lbs. per sq. in.
Ao = cross sectional area, calculated on outside diameter of pipe in sq. inches.
P = Working pressure in lbs. per sq. in.
N = number of rivets,
A = Area of one rivet hole in sq. in.

c)

The stress in the pipe shall not exceed the specified in Table 3 when calculated by the following formula:-

 Sp = Ao x P Eqn.(95) ( Ao - A1 ) - ( N x d x t )

where,

Sp = the stress in the pipe in lb. per sq. in.
Ao = P and N have the values given above, and
A1 = cross sectional area, calculated on inside diameter of pipe in sq. inches.
d = diameter of rivet hole in inches.
t = minimum thickness of pipe in inches.
d) The flange hub thickness shall not be less than 0.2 in thicker than the minimum thickness of the pipe.
e) The distance from the edge of the hub to the centre line of the rivets shall be not less than one and a half times the diameter of the rivet hole.
f) The pipes shall first be properly expanded into the flanges or alternatively the flanges shrunk on to the pipes, the rivet holes shall then be drilled through the pipe and hub, and the holes afterwards countersunk to remove burrs.
g) After riveting the flange hub shall be fullered at the back.

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