Volume-II of IV - GAIL

MECON LIMITED
REGD. OFF: RANCHI (BIHAR)
PROCESS & PIPING
DESIGN SECTION
NEW DELHI
TITLE PIPING FABRICATION AND
ERECTION
1.6 Probes
STANDARD SPECIFICATION
SPECIFICATION NO. PAGE 52 OF 62
MEC/S/05/62/06 REVISION 0
• May be powered by a battery or an electric generator. In the first case,
the autonomy of operation (endurance) of the instrument shall be
sufficient to carry on working without frequent interruptions, and the
instrument shall be equipped with an automatic switch which switches it
off when the battery runs down, in the second case, there must be a
voltage stabilising device with a tolerance of 2 volts.
The probes used shall have dimensions, frequencies, and a refraction angle
suited to the type of steel, the diameter the thickness of the pipeline and to the
joint design.
1.7 Reference Sample Pieces
The efficiency of the equipment used, the effective refraction angle of the probe,
and the beam output points, shall be checked using a V1 and V2 sample block,
IIW type or the calibration block ASTM E-428.
For the calibration of runs and the regulation of detection sensitivity during the
test, a calibration piece be used. This piece shall be taken from the production
material, and will be at least 150mm long (measured in the direction of the axis),
and at least 50mm wide (measured in the direction of the circumference), (see
Fig. 4 of this specification).
In the middle of the inside and the outside surface of the calibration piece a
groove shall be made. The groove will have a rectangular cross-section, a flat
bottom and the following dimensions :-
• Depth : 1 +/- 0.1mm
• Breadth (measured parallel to the 150mm side) : 1 +/- 0.1mm
• Length (measured parallel to the 50mm side) not less than 30mm.
In addition, the calibration piece shall have a hole, 2mm in diameter, passing
through its thickness and positioned so that during calibration the echoes
returning from the two grooves do not interfere with those returning from the
hole.