474 Molesworth’s pocket-book
Boilers. Board of Thade and Lloyd’s Kules.
D = Mean diameter of shell in inches (T4 = outside diani.).
P = 'Working pressure, lbs. per square inch.
F = Factor of safety (see page after next).
T = Thickness of plate in IGtbs of an inch.
t = „ „ in Inches.
p = Pitch of rivet or stay in inches.
(For diagonal riveting take -6p + -id.)
d = Diameter of rivet, inches (not less than t).
n = Number of rows of rivets.
a — Sectional area of a ilvet in sqxiare inches.
(For double shear take 1-75 a.)
R = Percentage of strength of jointor rivet (least of the two).
„, v-d na „ n a
= 100------; or 100 —- for drilled, or 90 — for punched,
P pt pt ’
holes.
L — Length of flue between rings in/eet
S — Surface supported by stay, square inches.
G = Depth of stay girder iu inches.
I =Span „ „ „ ■
& — Breadth „ „ „
w — Distance apart of ditto ,, (centres).
K, k, Q, C, and c. Constants (see next page).
Circular)
Shell J
Elite or )
Furnace;
Flat 7
Plates j
Collapse .
Girder }
Stays j
Board of Trade. Lloyd’s.
p_KR{. n p F p_**K PD
DF ’ KE 5 1>'; Fl?
|p_ Q T3________ t _ ,/P(L + i) For Superheaters niul-
, D(L + 1)’ v q tiplyfcbyf.
lp=C(T-!P . T^/P(S^ , ,'p,eT\T_A/P^
S —6 ’ C ’l p'1 ’ c
i 89600«3. PLDt
1 -JTdT" ’ — 89600
_ M G» & f Where M = 12000 for 1 bolt, = 13500 for 2
, p w I — 12000 for 3 = 12754 for 1 bolts per girder.