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through the radiator by passing cold air across
the fin surfaces. The radiator is shown in Fig.
3.4.20 as it appeared when received from the test
site.
The entire radiator was leak checked by pressur-
izing it under water and observing it to locate the
origin of air bubbles. This procedure revealed
the point of failure, which is indicated by the
arrow in Fig. 3d.20. The radiator was then
sectioned for further examination, as shown in
UNCLASSIFIED
7.17511
Fig. 3.4.20. NaK-to-Air Radiator PWA No. 2
That Failed in Service. Arrow indicates point of
failure,
UNCLASSIFIED
V.175116
Fig. 3.4.21. NaK-to-Air Radiator PWA No. 2
After Sectioning for Metallographic Examination.
PERIOD ENDING JUNE 10, 1956
Fig. 3.4.21. The side portions of the support
members were removed by using a rubber-bonded
masonry wheel in a portable, electric handsaw
adjusted for a shallow cut. Each bank of fins
was separated by slicing the support members and
the bottom flanged plate, as shown, with a fine-
toothed, high-speed, steel hacksaw blade in a
portable electric drill equipped with a portable
power-saw attachment. The failed area was then
carefully removed for metallographic preparation
on a standard wet-cutoff machine equipped with
an abrasive wheel.
The area of the failure was again pressurized
under water to locate the exact position of the
leak before additional preparation for metallo-
graphic examination was undertaken. The failure
was found to exist in the comer tube on the
periphery which faced the side support member.
The support member was subsequently removed
for unobstructed observation of the emergence of
the water bubbles. The point of failure may be
seen in Fig. 3.4.22.
Fig. 3.4.22. Failed Tube After Removal from
NaK-to-Air Radiator PWA No, 2 as Viewed from
the Support Member Side of the Radiator.
191