Non destructive inspections were carried out using those techniques commonly used in the industry at shut downs, such as Magnetic Particle Inspection (MPI) on both inner and outer surfaces and manual Ultrasonic Technique (UT) for all weld zones as well as more sophisticated mechanized UT to characterize the defects for length and depth. Two automatic UT, one based on Time of Flight Diffraction (TOFD) and the other automatic UT inspection, based on pulse-echo mode, were used at selected locations to characterize the defects. Manual UT inspections were carried out by several organizations on selected locations. Failure behaviour of each of these vessels during the burst tests were predicted using the defect geometries given by the manual UT. The Phase 1 vessel was hydro tested to failure, whereas the Phase 2 vessel was pressurized with a hydrogen sulphide solution to failure after an eight-day saturation period. After the burst test, the failed Phase 2 vessel was inspected at selected locations to establish any crack growth.

Post failure analyses were conducted after completion of the burst test. Sections containing those defects that were characterized by various NDE techniques prior to the burst test were removed and real crack depths were measured. The paper will present the results of the nondestructive evaluation and will discuss the effectiveness of the conventional NDE techniques in sizing the defects.