Volume-II of IV - GAIL

MECON LIMITED
REGD. OFF: RANCHI (BIHAR)
PROCESS & PIPING
DESIGN SECTION
NEW DELHI
TITLE PIPING FABRICATION AND
ERECTION
STANDARD SPECIFICATION
1.10 Qualification of Ultrasonic Testing Operators
SPECIFICATION NO. PAGE 54 OF 62
MEC/S/05/62/06 REVISION 0
Before the inspection begins or during the same inspection, the COMPANY may
require a qualification test for the ultrasonic equipment operators.
1.11 Evaluation of Indications given by Ultrasonic Tests
Each time that echoes from the weld bead appear during production testing, the
instrument amplification shall be altered to coincide with the reference
amplifications and the probe shall be moved until maximum respond is obtained
paying attention all the time to the probetube coupling.
If, under these conditions, the height of the defer echo is equal to or greater than
that of the reference echo, the defect shall be evaluated. If the defect has also
been detected by the radiographic and or visual examination, the dimensions
shall be judged according to the type of examination which detects the greater
defects. Returns which are less than 50% of the reference echo, will not be
considered. It returns are above 50% but lower than 100% of the reference
echo, and if the operator has good reasons to suspect that the returns are
caused by unfavorably oriented cracks, he shall inform the COMPANY.
Moreover, when there is a defect to be repaired such defect shall be removed
for a length corresponding to the one where no more return echo is given.
1.12 Other Equipment
The use of rules calibrated in centimeters, attached if possible to the probe, for
the precise location of the position of welding defects, it recommended. Defect
location is effected by measuring the projection distance between the probe
output and the reflecting surface.
The operators carrying out the tests shall have besides the probing instrument,
tools for cleaning the pipe surface (files, brushes, etc.) as well as the coupling
liquid or paste appropriate for the temperature of the section to be examined.