Each pipe should have a length of approximately 1.5 m. The
test pipe should be prepared with permanent joints and fittings intended
to be used. Only valves and straight joints versus elbows and bends
should be tested as the adhesive in the joint is the primary point
of failure. The number of pipe specimens should be sufficient to test
all typical joints and fittings. The ends of each pipe specimen should
be closed. One of the ends should allow pressurized water to be conducted.
If the insulation contains, or is liable to absorb, moisture
the specimen should not be tested until the insulation has reached
an air-dry condition. This condition is defined as equilibrium with
an ambient atmosphere of 50% relative humidity at 20 ± 5°C.
Accelerated conditioning is permissible provided the method does not
alter the properties of the material.
Special samples should be used for moisture content determination
and conditioned with the test specimen. These samples should be so
constructed as to represent the loss of water vapour from the specimen
by having similar thickness and exposed faces.
The pipe samples should rest freely in a horizontal position
on two V-shaped supports. The friction between pipe and supports should
be minimized. The supports may consist of two stands, as shown in Figure 2.
A relief valve should be connected to one of the end closures
of each specimen.
Figure 2 Fire Endurance Test Stand with Mounted Sample