
Reg. 361, Reg. 361 A
STEAM PIPES FITTINGS AND CONNECTIONS
Wrought Bends
b) 
The thickness of the pipes, from which bends are made
shall be such that the minimum thickness required by
equation 91 is maintained throughout after the bending
operation. The deviation from circularity in percentage
at any crosssection of a bend shall be calculated by
the following formula :
C = 
D_{max} .
D_{min} 
x 100 
D 
This deviation
shall not exceed 
20 D 
R 
where,
C = The percentage deviation of circularity.
D_{max}. = maximum external diameter of the pipe as gauged
at the bend.
D_{min} = minimum external diameter of the pipe as gauged
at the bend.
D = nominal external diameter of the pipe.
R = Radius of the bend on the central line of the bend. 
c) 
Fabricated pipe bends may be
made by Welding together bevelled section of straight
pipe, provided:
(i) the angle between the axis of the adjoining sections
does not exceed 30° and
(ii) the thickness is at least:
K  0.5 
times
the minimum thickness required for the straight
pipe to which the bend is joined 
K  1 
The thickness at any point of the bend shall not be less
than 87.5% of the nominal thickness of the bend. The thickness
at any point of the bend shall be such that the minimum
thickness required by equation
91 is maintained throughout after finishing operation.
where,
K = ratio of the radius of the bend (from centre of curvature
to centre of pipe) to the inside radius of the pipe.
Note: Gusseted Bends shall be used for pressure not exceeding
21 kilogram per square centimetre and temperature not
exceeding 260 Degree Centigrade. 
d) 
For the forged bends, the radii
shall be not less than those given below:
Long radii forged bends 
R = 1.5
x d 
Short radii forged bends 
R = 1.0
x d 

Reg. 361 A
Buttwelding fittings
The Buttwelding fittings shall conform to the dimension
and tolerances shown in the fig
&
table.


