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

Reg. 593, Reg. 594, Reg. 595

Plain Furnaces of Vertical Boilers

 The maximum working pressure of Plain Furnaces of Vertical boilers shall be the lesser of the two values obtained by Equations XII/25 and XII/26. Where, D = external diameter of the firebox in inches. Where the firebox is tapered the diameter taken shall be the mean of that at the top and at the bottom where it meets the substantial support from the flange or ring. L is length of the firebox in inches between points of substantial support measured from the commencement of flange curvature or from the foundation connection, or from a row of screwed stays which comply with Regulations 550(b), 585(b), whichever is applicable. In no case, however, shall the thickness be more than 7/8 inch. For fireboxes under 2 feet and 6 inches in diameter, the thickness shall be not less than 5/16 inch and for fireboxes 2 feet and 6 inches in diameter and over the thickness shall be not less than 3/8 inch.

Reg. 594

Corrugated Fireboxes of Vertical Boilers

For the semi-spirally corrugated fireboxes of ‘Sentinel’ standard motor wagon boilers the working pressure shall be determined by the following formula-

 W.P. = C(t-1) Equation XII/29 D

W.P. is working pressure in pounds per square inch.
t is thickness of the firebox plate in thirty seconds of an inch.
D is mean of the external diameters of firebox measured over the plain part at each end at commencement of curvature of flange.
C = 390.

No corrugated furnace shall be less than 3/8 inch thick.

Reg. 595

Hemispherical Furnaces of Vertical Boilers

When furnaces are hemispherical in form and subject to pressure on the convex side and are without support from stays of any kind the maximum working pressure shall be found by the following formula:-

 W.P. = 275(t-1) Equation XII/30 R

W.P. is working pressure in pounds per square inch.
t is thickness of the top plate in thirty seconds of an inch.
R is outer radius of curvature of the furnace in inches.
The thickness of these furnaces shall in no case exceed 7/8 inch

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