
Reg. 208
STAYS
Bolts and Studs
a) 
Bolts and studs connecting
parts by boilers such as shell, end plates, tube plates,
furnaces, up takes, externally fitted manhole covers,
mountings, etc. may be made either of steel or good quality
wrought iron. 
b) 
The maximum working pressure
for the bolts or studs shall be calculated by the following
formula: 
W. P. = 
N x C

(
D  
1.28 
)^{2} 
Eqn.(45) 
A 
n 
where
D is the diameter of bolt or stud over threads in inches
N is the number of bolts or studs securing the part,
n is the number of threads of screws per inch,
C = 4,700 for steel bolts or studs of 28 tons/sq. in.
minimum ultimate tensile stress where the diameter over
thread is less than 3/4 inch,
C = 5,100 for steel bolts or studs of 30 tons/sq. in.
minimum ultimate tensile stress where the diameter over
thread is less than 3/4 inch
C = 5,600 for steel bolts or studs of 35 tons/sq. in minimum
ultimate tensile stress where the diameter over thread
is less than 3/4 inch.
C = 5,600 for steel bolts or studs of 28 tons/sq. in minimum
ultimate tensile stress where the diameter over thread
is not less than 3/4 inch and not greater than 7/8 inch.
C = 7,000 for steel bolts for studs of 28 tons/sq. in
minimum ultimate tensile stress where the diameter over
thread is greater than 7/8 inch.
When the material is iron, a reduction, of 15 per cent
shall be made in the working pressure as calculated by
the formula.
A is the area in square inches of the surface supported
by the bolts or studs. For jointed flanges the area shall
be taken to extend to midway between the pitch line of
the bolts and the inner edge of the flange by which the
part is secured. 

