Notable work – Birring

Anmol Birring – Notable work in nondestructive testing

It is not just doing NDT, it is doing it the right way – Birring

Automated UT of Pipelines using zonal, TOFD and creeping waves qualification (DNV-OS-F101)

  • AUT Temperature qualification – Temperature qualification is done when AUT is done immediately after welding while the pipe is still hot.  Findings –  Heating the pipe OD surface quickly and measuring the skin temperature results in a significantly higher qualification temperature. For proper qualification, the pipe should be uniformly heated  across the thickness and then scanned.  Also found that response of AUT at higher temperatures depends on flaw location. The first flaw that is lost with increase in temperature is ID root crack. AUT qualification should therefore always include ID root cracks in addition to mid-wall and OD flaws. The qualification temperature dropped by  25°C when a root defect was added and the pipe was fully heated to a steady state. In general pipe AUT done above 65°C can be questionable.
  • The so called creeping waves do not have any surface wave component. They are in fact  75 degree refracted longitudinal wave probes and have almost no sensitivity to surface cracks  more than 10 mm  from probe.

Time of Flight Diffraction (TOFD) – Calibration

  • TOFD has a dead zone produced by lateral wave. This dead zone can be 4 to 10 mm depending on the probe (frequency and size) and the spacing. The use of OD notch for TOFD calibration  provides a false sense of coverage to OD surface.   To confirm coverage below dead zone, TOFD calibration should include 2 mm side drilled holes at a depth of 4 or 5 mm from OD surface, T/4, 3T/4 and a 2 mm ID notch. OD notch should not be used for TOFD calibration.

Shear wave of Welds – Finding the best Manual UT inspectors

  • Found during manual UT qualification that inspector skill level  played a major role in  performance. Less experienced inspectors with higher skill level performed better than inspectors with many years of experience.

Phased Array of Welds – Probe Selection

  • Found that phased array probe selection is very important in weld inspection. The most important parameter being the probe active aperture. Larger active aperture improves focusing and therefore flaw definition. What is important in probe selection is active aperture and not just the number of elements. The recommended active aperture should be about  0.4 x weld thickness.

PAUT of Corrosion resistant alloy (CRA) welds – L-wave Calibration

  • Found that codes have mistakes on refracted L-wave calibration. Refracted L-waves  when calibrated on side drilled holes as per some codes have 16 dB lower sensitivity on ID  and can easily miss ID cracks. click here for more info on CRA weld inspection.
  • Corrosion resistant alloy (CRA) welds with  CRA clad are made in many configurations and there is no single standard technique for such inspections. The selection of PAUT technique is specific to each configuration

Angle Beam UT of Ring Forgings (ASTM 388) – Calibration

  • There is a major loss in sensitivity if flat calibration blocks are used for inspection of ring forgings. Tests found that a flat calibration block when used to inspect a 24″ OD x 2.8″ t ring forging resulted in sensitivity loss of 14 dB. ASTM 388 does not address this issue. Calibration on 3 % notch should be done on a forging of same  size (diameter and thickness) .

High Temperature Hydrogen Attack (HTHA) – Technique

  • In 1989, developed ultrasonic backscatter technique for High Temperature Hydrogen Attack (US Patent 489046). The technique has been used world wide for HTHA inspections.
  • Applied ultrasonic technique for detection of hydrogen damage in boiler tubes and reduced the boiler forced outage rate.
  • In 2004 detected high levels of HTHA in a reactor vessel at refinery in Le Harve,  France. The vessel was immediately taken out of service.

Eddy Current Testing of Tubing – Technique

  • Flaw sizing during tubing inspection is typically done using either the f180 or f90 frequency. Found that frequency significantly affects sizing accuracy of ID flaws.
  • Provided key support to RDTech in development of the analysis software used for the instrument TC 5700

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