The choice of couplant is optional with the Contractor, except as follows:
a. The couplant shall be the same as that used for equipment
qualification and calibration.
b. Couplants that may corrode the reference standards and material
being tested or leave objectionable residues shall not be used.
c.
Oils shall not be used in systems intended to handle liquid oxygen.
d. Couplants shall be of the proper viscosity to give good coupling
for the surface roughness.
3.2.3
Shear Wave Inspection
Shear wave inspection shall be performed as follows: The search unit shall
be placed on the contact surface at a distance from the weld equal to that
used when calibrating the equipment.
3.2.4
Longitudinal Flaws
To detect longitudinal flaws, the search unit shall be slowly moved toward
and away from the weld far enough to cover its entire cross section,
approximately 90 degrees to the weld centerline. The search unit shall be
radially oscillated to the left and right, covering an angle of
approximately 30 degrees. During the foregoing movement, the search unit
shall be continually advanced parallel to the weld centerline. The rate of
movement shall depend on the operator's ability to clearly see and identify
all reflections. The amount of movement shall be calculated to ensure that
the inspection distance will be great enough to traverse the weld. [For
plate thicknesses 50 mm 2 inches and greater with an unmachined stainless
steel overlay covering the welded joint, the inspection distance shall
range from a minimum of one thickness (T) or the first node back from the
near fusion line to a distance exceeding T plus 2/3, the maximum width of
the weld deposit at the surface. The inspection shall be repeated from the
other side of the weld on the same surface if accessible or if not, from
another surface that is part of the same joint as indicated above. The
surface of the weld metal in the joint shall be ground smooth and blended
with the base metal.]
3.2.5
Transverse Flaws
To detect transverse flaws when the welded surface is ground flush, the
search unit shall be moved along the welded surface in each direction
parallel to the centerline of the weld metal with the wave radiating
parallel to the weld centerline. To detect transverse flaws when the
welded surface is not ground flush, the search unit shall be moved parallel
to the weld in each direction, on the adjacent base metal at the top of the
weld, with the wave directed at an angle of 30 degrees to the weld
centerline.
3.2.6
Longitudinal Wave Inspection
This inspection shall be made as follows:
a. The search unit shall be placed on the contact surface with the
wave directed in a straight line through any intervening base metal and
through the weldment.
SECTION 05091A
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