3.1.3
Weld Backing Strips
Strips that are not to remain in place shall be removed and all sharp edges
and valleys shall be eliminated by grinding or other mechanical means.
3.1.4
Dirt
All loose scale, rust, paint, and dirt shall be removed from the coupling
surface.
3.2
INSPECTION PROCEDURE
**************************************************************************
NOTE: When necessary, the designer will indicate on
the drawing the area to be examined, the contact
surface, and if welds are to be inspected from one
or both sides.
**************************************************************************
When possible, all welds shall be examined from both sides of the weld and
from one surface. If complete inspection cannot be accomplished from one
surface, inspection shall be made from another surface that is part of the
same joint. Preliminary scanning techniques using an increased instrument
gain shall be used to locate possible defects. When possible, gain shall
be increased to a minimum of twice (6 dB) the reference level setting.
Final acceptance or rejection shall be evaluated with the equipment
properly calibrated and the gain control set at the reference level. The
reject/repair line shall be used to evaluate quality of the weld. If a
periodic calibration check shows that the equipment is not operating
properly or that the system's sensitivity has decreased more than 20
percent (2 dB) from the established sensitivity level, all welds inspected
since the prior calibration shall be reexamined. If penetration of the
shear waves is questionable, the angle search unit shall be placed in
position on one side of the weldment with the waves directed through the
weldment. A disconnected angle search unit, plastic or metal wedge or
disk, or any good reflector shall be placed in the wave path of the search
unit on the far side of the weld to reflect the sound. When good
reflections cannot be obtained by either shear or longitudinal waves, the
Contractor shall modify the procedures in accordance with paragraph GENERAL
REQUIREMENTS.
3.2.1
Test Frequency
The test frequency for ferrous materials shall be as specified in AWS
D1.1/D1.1M, Section Inspection, subsection Ultrasonic Equipment, except for
thicknesses below 13 mm 1/2 inch, frequencies between 2.25 and 5 MHz may be
used to obtain increased sensitivity. For materials that are difficult to
penetrate, any frequency within the operating range of the equipment may be
used. The effective depth of penetration and sound beam divergency shall
be demonstrated to the Contracting Officer.
3.2.2
Couplants
**************************************************************************
NOTE: The designer will prohibit the use of any
couplant considered injurious to the item to be
inspected. Edit the following paragraphs as
applicable.
**************************************************************************
SECTION 05091A
Page 20
Previous Page
