Another Formula for an Unequal Tee
Page 78
Another Formula for an
Unequal Tee
Information Required: ODI for both sizes of
pipe.
Step 1: Draw a base line with a 90-degree
vertical line at each end. Plan enough room
to draw the rest of the layout.
Step 2: Using half the ODI of the large
diameter insulation, draw a 90-degree arc
on the left vertical line as shown in figure 1.
Do the same for the smaller ODI on the
right vertical line.
Step 3: Draw a 90-degree vertical line
between the 2 arcs and label it A.
Step 4: Trisect or bisect the small arc into
equal parts (in this case 3)
Step 5: Draw parallel horizontal lines from
the right bisected or trisected points on the
90 degree lines down to the base line
Step 6: Label the vertical lines 1 to 4 starting
at the base line and extend those lines to
the points on the small arc as shown in
figure 3.
Step 7: Divide half the circumference into
size equal parts and draw line A at 0-
degrees to vertical lines for the sketch out.
Step 8: From figure 3 set dividers on the line
A and line 1 on the large arc. Transfer this
measurement to line 1 on your sketch-out.
Do the same for the rest of the sketch-out,
by advancing to the next number up each
time. Fro the other half of the fitting add a
lap.
Step 9: For the body portion of the fitting
cut a piece of material half the
circumference of the large ODI and draw a
center line as in figure 3.
Step 10: From figure 3, set dividers at point
1 and point 2 on the large arc and transfer
this measurement to the stretch-out as
shown in figure 3. Do the same but stepping
up from 2 to 3 then 3 to 4. Draw 0- degree
lines on both sides of the center line
through the points obtained and label those
lines 1, 2, 3, & 4 as in figure 3.
Step 11: From figure 3 set dividers at the
base line and point 4 on the large arc.
Transfer this measurement to line 4 on the
stretch-out in figure 3. Do the same for 3
and 2. 1 is just to a point. Connect all the
points to obtain half the hole cut-out for
the other half of the fitting. Add for a lap.
In some instances, tabs may be required to
lock the stem to the body.