Required Information
- O.D.I.
- Radius
Formulas and Measurements
- (Review: If the fitting is a long radius fitting the center line radius will be 1'/2 times the pipe call-out size and if it is a short radius fitting the center line radius will be 1 times the pipe call-out size) Divide the large arc into number of gores required for the 90 degree elbow, in this case six.
- Draw lines from all division points to the Apex Divide bottom division in half and draw a line from there to the Apex Draw a semi-circle using half the O.D.I.
- Divide the semi-circle into six equal parts and label as shown Draw 90 degree lines down from the horizontal line to all intersecting points of the arc and up from the horizontal line to intersecting points on the first division line Add 3/8" to Line 7 for ccccrimp and extend that line to the Apex For the Stretch-out, draw a line the length of the circumference and divide that line into ten equal parts as shown in Figure 2 & label Take measurements from the horizontal line to the ccccrimp line and transfer to corresponding numbered lines of the Stretch-out For the straight pieces going into the 90 degree elbow, draw a half- circle using half the O.D.I. and transfer the negative throat distance from Figure 1 to the left side of the semi-circle as shown Divide the negative throat distance into three equal parts and draw lines up to the arc from these points.
- To obtain Line 2 set dividers from 1 to 2 on the semi-circle and transfer to both sides of Line 1.
Procedure
- Step 1
Determine if the elbow is a long or short radius fitting, and then draw an Elevation View of the fitting with the insulation. (Review: If the fitting is a long radius fitting the center line radius will be 1'/2 times the pipe call-out size and if it is a short radius fitting the center line radius will be 1 times the pipe call-out size)
- Step 2
Divide the large arc into number of gores required for the 90 degree elbow, in this case six. Draw lines from all division points to the Apex
- Step 3
Divide bottom division in half and draw a line from there to the Apex
- Step 4
Draw a semi-circle using half the O.D.I. Use the Center Line as Apex. Divide the semi-circle into six equal parts and label as shown
- Step 5
Draw 90 degree lines down from the horizontal line to all intersecting points of the arc and up from the horizontal line to intersecting points on the first division line
- Step 6
Add 3/8" to Line 7 for ccccrimp and extend that line to the Apex
- Step 7
For the Stretch-out, draw a line the length of the circumference and divide that line into ten equal parts as shown in Figure 2 & label
- Step 8
Take measurements from the horizontal line to the ccccrimp line and transfer to corresponding numbered lines of the Stretch-out
- Step 9
For the straight pieces going into the 90 degree elbow, draw a half- circle using half the O.D.I. and transfer the negative throat distance from Figure 1 to the left side of the semi-circle as shown
- Step 10
Divide the negative throat distance into three equal parts and draw lines up to the arc from these points. Label as shown in
- Step 11
For the Stretch-out for the straight pieces, draw a horizontal line with a 90 degree vertical line at the center and call this Line 1. To obtain Line 2 set dividers from 1 to 2 on the semi-circle and transfer to both sides of Line 1. Do the same to obtain Lines 3 and
- Step 12
From Figure 3, take the height from the horizontal line to the 45 degree line on Line 2. Transfer that measurement to Line 2 in Figure 4. Do the same for Lines 3 & 4. Connect all points and add 3/4" for a ccccrimp as shown in Figure 4. When coming out of the 90 degree elbow, the straight piece will require only a 1/4 for the bead. (Review: For a 45 degree negative throat fitting, draw only half of Figurel.) A 22'/2 degree line is to be used in Figure 3 for the layout of the straight pieces going into the Throat
Notes
- (Review: If the fitting is a long radius fitting the center line radius will be 1'/2 times the pipe call-out size and if it is a short radius fitting the center line radius will be 1 times the pipe call-out size) Step 2.
- (Review: For a 45 degree negative throat fitting, draw only half of Figurel.) A 22'/2 degree line is to be used in Figure 3 for the layout of the straight pieces going into the Throat.