The Development of Figure 2

Page 35

Figure IV: Development of a

half segment, seam on the

outside.

With the centre point S and

the previously measured radius

of curvature Sd in figure I

draw a 90º arc and divide it

into the desired number of

segments observing that at the

two ends only half segments

are needed.

Then draw the semicircle with

centre at point d and divide it

into six equal parts. Draw the

necessary perpendiculars,

finding points A to G and a to

g. Then, at a distance of 3 to 5

mm draw a parallel line to the

base line a g containing points

a1 to g1 (allowance for beaded

piece).

The Development of Figure

2

Lay off the full circumference

as mentioned in Table 1 on a

base line d-d and at the found

point a1 to g1 draw 13

perpendiculars. On these lines

lay off on both side the

respective line segments Aa,

Bb, Cc etc of figure I and

connect the newly found

points. The developed

segment then has the so-called

fish shape. The developments

as in figure III and figure IV,

with seams on the inside and

outside respectively, are

obtained in the same way. The

developments differ

only in order of the generating

lines.

2.5 Segmental Joints

(Simplified)

Figure I : Elevation.

Figure II: Development.

On the base line Sp lay off the

measured radius of curvature

from point to d.

With d as the centre, draw a

semicircle with the radius of

the outer diameter of the

insulation. Divide it into six