All butt welds of tubes shall
be tested as required hereunder:-
(i) Components greater than 178 mm (7 inch) bore.- All
Welds shall be non-destructively tested by radiographic
or other approved methods.
(ii) Tubes greater than 102 mm (4 inch) bore and upto
and including 178 mm (7 inch) bore.- 10 per cent of the
welds by each welder, selected at random with a minimum
of 2 welds per welder, shall be subjected to non-destructive
examination by radiographic or other approved method.
(iii) Tubes 102 mm (4 inch) bore and under.- Sample welds
simulating the production welds shall be provided for
mechanical testing either at a rate of 2 per cent or after
each 150 welding hours with a minimum of one sample weld
per welder.
Butt
welded joints as indicated in clause (h) shall be subjected to non-destructive
examination by radiographic, radioscopy or other
approved methods such as ultrasonic testing, magnetic
particle inspection or liquid dye penetrant inspection.
When radioscopic examination is to be performed
in lieu of radiography on welded components, the
following requirements shall be met, namely:-
(1)
A written procedure shall be submitted for
approval to the Inspecting Authority which shall contain
the following:
(i)
material and the thickness range;
(ii)
equipment qualifications;
(iii)
test object scan plan;
(iv)
radioscopic parameters;
(v)
image processing parameters;
(vi)
image display parameters;
(vii)
image archiving requirements;
(viii)
accept-reject criteria (Code reference);
(ix)
performance evaluation;
(x)
Operator identification.
(2)
The system shall be aided with an image processor
to enhance the quality of the radioscopic images and
system performance quality shall exhibit-
(i)
a thin section contrast sensitivity of 3%;
(ii)
a thick section contrast sensitivity of 2%;
(iii)
a spatial resolution of 3 line pairs per mm;.
(iv)
IQI sensitivity - 2% of the joint thickness when
wire IQI's are to be used, the wire diameter axis shall
be oriented along the axis of the least sensitivity of
the system.
(3)
Radioscopes are to be properly marked to
co-relate with particular part of joint represented.
(4)
The radioscopic examination data shall be
recorded and stored on videotape, magnetic disk or
optical disk at the maker's plant for a sufficient
period after the date of radioscopic examination as
specified by the Inspecting Authority, efficient
radioscopic examination record recall shall be made
available at any time over the record retention period
and shall be traceable to the test objects.
(5)
When repair has been performed as a result of
radioscopic examination, the repaired areas shall be
re-examined using the same radioscopic technique to
evaluate the effectiveness of the repair.
(6)
To aid in proper interpretation of the
radioscopic examination data, the details of the
technique used shall accompany the data. As a minimum, the information shall include the approved
procedure requirements and system performance test data.
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