In paper, in a frame of case study, the ultrasonic inspection of austenitic girth butt welds in storage tank of LNG terminal for the range of diameter till 60 m and thickness range 10 ÷ 40 mm was studied.
There are presented the fundamental problems arise by ultrasonic testing of austenitic coarse grained welds. The examination technique selection based on accessible knowledge, existing standards and tests on representative weld specimen is followed through in a frame of case study.
It is presented the scan plan of testing the austenitic girth welds using conventional ultrasonic system, based on the multiprobe scanning. There is presented a range and sensitivity setting on reference block manufactured on the base of representative austenitic weld with reference reflectors dedicated to each area of interest of inspected weld volume.
It is also presented the new modern solution of scanner with only two probes. Each of them is dual matrix phase –array probe working in pitch-catch mode and cold symbolic PA DMA-TRL. They are connected with phase-array apparatus controlled localization and acquisition of experimental data. There are discussed advantages such a modern examination technique reached highest level of NDT techniques.
The presented case study is an assumption formulation example of examination procedure for technically important and responsible object – like assessment of requirements agreement with technical regulations for the austenitic welds in storage tanks of liquid gas LNG.