SPECIFICATION RT-218 ISSUE 4 Page 3
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4.3 TEST PROCEDURES
Unless otherwise specified, perform tests on specimens which have been fully recovered for
3 minutes in a 200 ± 5ºC (392 ± 9ºF) oven. Prior to all testing, condition the test specimens (and
measurement gauges, when applicable) for 3 hours at 23 ± 3ºC (73 ± 5ºF) and 50 ± 5 percent relative
humidity. Use mechanical convection type ovens in which air passes the specimens at a velocity of 100 to
200 feet (30 to 60 m) per minute.
4.3.1 Dimensions and Longitudinal Change
Measure three 6-inch (150-mm) specimens of tubing, as supplied, for length ± 1/32 inch (± 1 mm), and inside
diameter in accordance with ASTM D 2671. Recover and condition the specimens in accordance with
Section 4.3, measure the wall thickness and remeasure the length and inside diameter. Calculate the
longitudinal change as follows:
C =
L
1
- L
0
L
0
x 100
Where: C = Longitudinal Change [Percent]
L
0
= Length Before Recovery
L
1
= Length After Recovery
4.3.2 Tensile Strength and Ultimate Elongation
Determine the tensile strength and ultimate elongation in accordance with ASTM D 2671 using
1-inch (25-mm) bench marks and a 1-inch (25-mm) initial jaw separation. Use a rate of jaw separation of 2.0
± 0.2 inches (50 ± 5 mm) per minute.
4.3.3 Secant Modulus
The secant modulus of the tubing shall be tested in accordance with ASTM D 671 using specimens in the as-
supplied condition
4.3.4 Low Temperature Flexibility
For tubing of expanded diameter 1/4 inch (6 mm) or greater, cut three strip specimens, 1/4 inch
(6 mm) wide and 12 inches (300 mm) long, from the expanded tubing. For tubing of expanded diameter less
than 1/4 inch (6 mm), cut three tubular specimens, 12 inches (300 mm) long, from the expanded tubing.
Recover the specimens in accordance with Section 4.3 and condition with appropriate mandrels for 4 hours at
-55 ± 2ºC (-67 ± 4ºF). Use mandrels with a diameter 10 times the specimen thickness, ± 10 percent. For
tubular specimens, use the outside diameter as the specimen thickness. While at the specified temperature,
and without removing the specimens from the cold chamber, wrap the specimens 360 degrees around the
mandrel in approximately 2 seconds. Visually examine for evidence of cracking. Disregard any side
cracking caused by flattening of the specimens on the mandrel.
4.3.5 Heat Shock
Condition three 6-inch (150-mm) specimens of tubing for 4 hours in a 300 ± 5ºC (482 ± 9ºF) oven. Remove
the specimens from the oven, examine for evidence of dripping or flowing, cool to 23 ± 3ºC (73 ± 5ºF), wrap
180 degrees around a mandrel selected in accordance with Table 2, and then visually examine for evidence of
cracking. Disregard side cracking caused by flattening of the specimen on the mandrel.
