SPECIFICATION RT 1162- ISSUE 7 Page 5
If this document is printed it becomes uncontrolled. Check f
4.3.6 Heat Shock and Longitudinal Change
Mark three 6-inch (150-mm) specimens of tubing with 4 ± 1/32 inch (100 ± 1 mm) benchmarks, centrally
located. Suspend the tubing horizontally in an oven by inserting an 8 x 0.125-inch
(200 x 3-mm) metal mandrel through the tubing and resting the ends of the mandrel on metal blocks.
Condition the specimen for 4 hours at 300 ± 5°C (572 ± 9°F). Remove the test assembly from the oven and
allow to cool at room temperature for one hour. Inspect the specimens for evidence of dripping, flowing or
cracking. Measure the distance between benchmarks, calculate the percentage change in benchmark length
and report this value as the longitudinal change.
LC =
L
1
- L
0
L
0
x 100
Where: LC = Longitudinal Change [percent]
L
0
= Length Before Conditioning [inches (mm)]
L
1
= Length After Conditioning [inches (mm)]
4.3.7 Low Temperature Flexibility
Prepare three 24-inch (600-mm) specimens of tubing and a test fixture . The test fixture shall consist of two
3.5-inch (88.9-mm) diameter mandrels mounted at right angles to a support plate with the distance between
them slightly larger [approximately 1/16 inch (1.59 mm)] than the outside diameter of the specimens.
Condition the specimens and the mandrel assembly for 4 hours at -55 ± 2°C (-67 ± 4°F), keeping the tubing
straight and vertical. While at this temperature, place the tubing between the two mandrels, fixed at the
lower end and alternately flexed
180 degrees around each mandrel for 5 cycles (Figure 2). A cycle shall consist of 180 degree bend in one
direction, 180 degree bend in the other direction and the return to the original or vertical position. Complete
the 5 bend cycles within 2 minutes. Examine the specimens for cracking and subject them to the dielectric
withstand voltage test described in Section 4.3.9.
3.5"
3.5"
180º 180º
Figure 2
