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Reg. 310, Reg. 311, Reg. 312

Test

 
1) The permanent set in the spring (defined as the difference between free height and height measured ten minutes after the spring has been compressed solid three additional times, after pre-setting at room temperature) shall not exceed 0.5% of the free height.
2) Torsion bars shall not show a permanent distortion after being twisted to an angle fifty per cent in excess of the working angle.


Reg. 311

Extension Springs

Extension springs shall be made from round section wire.


Reg. 312

Number of Effective Coils

The number of effective or free coils in a compression or extension spring shall be determined from the following formulae:-

(i) For Round or Square Wire: -

N = KCd4 Eqn.(85)
SD³


(ii) For Rectangular Wire: -

N = 66 B³ H³ K Eqn.(86)
(B² + H² ) SD²

where,
N = Number of effective coils.
K = Compression or tension in inches at set pressure.
C = 22 for round, 30 for square steel.
d = diameter or side of square steel in 16th of an inch.
S = Load on spring in lbs. at blow off pressure.
D = Mean diameter of coil in inches.
B = Breadth of wire in 16th of an inch.
H = Depth of wire in 16th of an inch.
 
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Message from Chairman of Central Boilers Board About Central Boiler Board History of Indian Boiler Regulations Foreword Contents Chapter Wise Contents Regulation Wise List of Amendments
Indian Boilers Act 1923 Ibr Forms Home Search Help Contact Us