Volume-II of IV - GAIL

MECON LIMITED
REGD. OFF : RANCHI (BIHAR)
PROCESS & PIPING
DESIGN SECTION
NEW DELHI
STANDARD SPECIFICATION
TITLE WELDING OF ONSHORE GAS
SPECIFICATION NO. PAGE 25 OF 48
PIPELINES
MEC/S/05/62/02 REVISION
type and dimensions of transducers
frequency range
details for calibration
coupling medium
inspection technique
record details
reference to the welding procedure where it is intended to adopt the
specification.
temperature range of the joints to be inspected.
15.3 Qualification of Ultrasonic Inspection Procedure
The ultrasonic inspection procedure shall be approved by the COMPANY. Before
inspection begins, the COMPANY may require the qualification test of the
ultrasonic inspection procedure. This specification test consists in testing (under
normal operating conditions) some CONTRACTOR welds made according to the
same production procedure, where there are typical defects the test intends to
detect.
This test shall be conducted in the presence of the COMPANY.
15.4 Test Procedure
Circumferential welds shall be inspected from both sides using angled probes.
The surface with which the probes comes into contact shall be free of metal
spatter, dirt, iron oxide, and scales of any type; therefore it shall be necessary to
clean a strip at least 50mmwide on both sides of the weld with steel wire brushes
and anyhow the cleaned strip must be atleast wide enough to allow full skip
examination.
If, during the test, echoes of doubtful origin appear, it shall be necessary to
inspect a convenient area on the pipe surface, close to the weld, with a straight
beam transducer in order to check whether any manufacturing defects are
present which could have interfered with the ultrasonic beam.
By way of an example, the equipment shall include but not be limited to the
following :-
ultrasonic equipment and coupling medium
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