. Tentative revised boiler safety orders. sidered in one transverse plane and on one side of vertical axis of boiler s = transverse spacing of crown stays in crown sheet, in. E = minimum efficiency of wrapper sheet through joints or stay holesi = thickness of wrapper sheet, = radius of wrapper sheet, =r working pressure of boiler, lb. per sq. 000 = allowable stress, lb. per sq. A cylindrical furnace which requires staying shall be stayedas a flat surface as indicated in Table 4, except that the pitch may 56 REPORT OF BOILER CODE COMMITTEE, be increased to pi, a
. Tentative revised boiler safety orders. sidered in one transverse plane and on one side of vertical axis of boiler s = transverse spacing of crown stays in crown sheet, in. E = minimum efficiency of wrapper sheet through joints or stay holesi = thickness of wrapper sheet, = radius of wrapper sheet, =r working pressure of boiler, lb. per sq. 000 = allowable stress, lb. per sq. A cylindrical furnace which requires staying shall be stayedas a flat surface as indicated in Table 4, except that the pitch may 56 REPORT OF BOILER CODE COMMITTEE, be increased to pi, as provided in the following formula PR PB — 250rin which Pi = equivalent pitch for a cylindrical surface. p zzz maximum pitch for a flat surface measured as specified in Par. : maximum allowable working pressure, lb. per sq, = internal radius of furnace, = thickness of plate in sixteenths of an inch., 213 Staying Segments of Heads. A segment of a head shallbe stayed by head to head, through, diagonal, crowfoot or gusset. Fig. 15 Method of Determining Net Aeea of Segment of a Head stays, except that a horizontal return tubular boiler may be stayedas provided in Pars. 225 to 229. 214 Areas of Heads to he stayed. The area of a segment of ahead to be stayed shall be the area enclosed by lines drawn 2 the tubes and at a distance d from the shell as shown in Figs. 15and 16. The value of d used may be the larger of the followingvalues: (1) d = the outer radius of the flange, not exceeding 8 timesthe thickness of the head 5Xr (2) d = Si P where d = unstayed distance from shell in inches T = thickness of head in sixteenths of an inch P = maximum allowable working pressure in lb. per sq. in. NEW INSTxiLLATIONS, PART I, SECTION I, POWER BOILERS 57 In water-tube boilers, the tubes of which are connected to drumheads, the area to be stayed shall be taken as the total area of thehead less the area of an annular ring of width d measured fromthe inner circumference of
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