475 OF ENGINEERING FOBMULÆ.
Boilers. Board of Trade and Lloyd’s Rules continued.
Value of Constants.
K = 940 for shells with the fibre.
K = 81 0 „ against the grain.
K = 600 for superheaters, flame oblique.
K = 448 „ „ at right angles.
Values of k. 0 to f. 0 to i. f to i to 4- A. to *• Above i.
Iron, lap joint punched .. 155 165 170
„ „ drilled.. .. „ butt, 2 straps punched k — —■ 170 — 180 190
k = —— 170 — 180 —- 190
,, „ „ drilled Steel lap joint k =1 — 180 —— 190 - 200
fc = 200 215 — 2.30 240
„ butt, double strap .. k = 215 — 230 — 250 260
Values of Q. For welded seams Q xs 90,000. ' Holes. Drilled. Punched.
j Riveting. Double. Single. Double. Single. *
Butt, single strap .. .. Q = 90,000 80,000 85,000 75,000
„ double ,, .. Lap, bevelled .. .. Q = — 90,000 — 85,000
.. y = 80,000 70,000 75,000 65,000
„ not bevelled .. Q = 75,000 65,000 70,000 60,000
Thickness of single butt straps = 1 J- t; double i t (B. of T.).
Thickness of inside butt strap — it (.Lloyd).
Stay 1 VALUES OF C. fa3teu“g/ Nuts and Washers. Nuts only. Screwed in Plate.
Nut. Riveted.
Not exposed to flame C = 100 90
Exposed (steam contact) C = 60 54 —— 36
„ (water „ ) C = — — 80 60
Values of c. c = 160 140 110 90
„ when t exceeds r'; c = 160 140 120 100
Tensile stress not to exceed 5000 lbs. per sq. in. for iron, or 7i;(J0 for
steel.
Thickness of washer = 11, Diani. = 3 diam. of stay (B. of 'I'.).
» —it, „ = 0*4 pitch of otay (Lloyd).-