In the oil and gas (O&G) industry, EPC contractors have been performing film radiography (RT) for many years. In the later stages of piping shop fabrication and field construction; however, a backlog of piping circumferential welds to be radiographed can accumulate and grow day by day because of the unexpected work volume. This growing RT backlog can cause delays in the schedule. In order to reduce RT backlogs and avoid project schedule delays, low intensity RT techniques and non-radiation recordable UT, such as PAUT and Time of Flight Diffraction (TOFD), have been employed in addition to, or instead of, film RT. Moreover, PAUT has advantages over RT in the field because of its real time data acquisition and the fact that it does not use radiation.
However, PAUT has still not been able to improve the situation significantly for the following reasons:
(a) Flaws detected by PAUT are shown as being larger than when detected by RT, which can increase the rejection rate.
(b) PAUT is still regarded as a special inspection method, even though it was introduced as a field inspection technique a couple of decades ago.
One of the latest UT techniques in the O&G industry is Full Matrix Capture / Total Focusing Method (FMC/TFM), which has been used since the 2010s for detailed inspections, such as High Temperature Hydrogen Attack (HTHA) detection, but it has not yet been used for piping welding NDE in O&G construction. FMC/TFM has the potential to overcome and improve the issues noted above.
This presentation shows the performance of FMC/TFM to determine whether or not it can replace PAUT for field piping welding NDE and provides the optimal evaluation technique for FMC/TFM.