Twentieth century hand-book for steam engineers and electricians, with questions and answers .. . nt offive rivets, four of which pass through both theinside and outside butt straps, while the fifth rivetpasses through the inside strap only, and the resist-ance is 5D x T x C, equivalent to .9375 x 5 x 90,000 =184,570. The strength of the unit strip of plate before drillingisPxTx , or x .4375 x 60,000 = 177,187, andthe efficiency is 152,578x100-177,187 = 86 percent. With the constantly increasing demand for highersteam pressures, the necessity for higher efficiencies inthe riveted join
Twentieth century hand-book for steam engineers and electricians, with questions and answers .. . nt offive rivets, four of which pass through both theinside and outside butt straps, while the fifth rivetpasses through the inside strap only, and the resist-ance is 5D x T x C, equivalent to .9375 x 5 x 90,000 =184,570. The strength of the unit strip of plate before drillingisPxTx , or x .4375 x 60,000 = 177,187, andthe efficiency is 152,578x100-177,187 = 86 percent. With the constantly increasing demand for highersteam pressures, the necessity for higher efficiencies inthe riveted joints of boilers becomes more apparent,and of late years quadruple and even quintuple-rivetedbutt joints have in many instances come into use. Thequadruple butt joint when properly designed shows a THE BOILER 309 high efficiency, in some cases as high as per 100 illustrates a joint of this kind, and thedimensions are as follows: T=y2 in. D = i| in. A = .69 in. P, inner rows = 3^ in. ?, 1st outer row = jy2 in. P, 2d outer row = 15 in. The two inner rows of rivets extend through the. FIGURE 100. main plate and both the inside and outside coverplates or butt straps. The two outer rows reach through the main plateand inside cover plate only, the first outer row havingtwice the pitch of the inner rows, and the secondouter row has twice the pitch of the first. 310 ENGINEERING Taking a strip or section of plate 15 in. wide (pitchof outer row), there are four ways in which this jointmay fail. 1. By tearing of the plate at the outer row of resistance is P â , or 15 â .9375 x 60,000 = 421,875. 2. By shearing eight rivets in double shear and threein single shear. The strength in resistance is 19A x S,or .69 x 19 x 45,000 = 589,950. 3. By tearing at inner rows of rivets and shearingthree rivets. The resistance is P - 4D x T x +3A x S, or 15-(.9375 x 4) x .5 x 60,000+ .69 x 3 x45,000 =430,650. 4. By tearing at the first outer row of rivets, wherethe
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