Ultrasonic Phased-Array advanced techniques for the inspection of circumferential welds in small diameter pipes

Sillero, José; TECNATOM S.A.; Spain

Sillero, A.J.; Tecnatom S.A.; Spain
Fernández, F.J.; Tecnatom S.A.; Spain
Godínez, F.A.; Tecnatom S.A.; Spain

ID: ECNDT-0477-2018
Download: PDF
Session: PAUT-Nuclear Industry
Room: H2
Date: 2018-06-13
Time: 09:20 - 09:40

According to ASME Case Code N-659-2, related to Section III (Construction), it is possible to replace the radiographic inspection of welds by an ultrasonic inspection under some specific conditions. For the case of welding in small diameter pipes, Tecnatom has developed an inspection technique that uses the phased-array technology that allows to save the time of inspection and the dose to the personnel that perform this work in nuclear facilities.

The aim of this paper is to show the development carried out for the detection of parallel and perpendicular defects in circumferential welds of pipes using Phased-Array Ultrasonic Testing (PAUT). To this end, different inspection techniques have been developed in a limited series of reference blocks with realistic defects, while qualification of the inspection procedure and personnel have been performed in a larger sample of blocks with the postulated defectology.

The scope of the project covers the inspection of welds in carbon steel pipes with diameters ranging from 50 to 100 mm, wall thickness between 5 and 8 mm, access to welding from one or two sides and severe restriction on the free height between components. The postulated defects are lack of fusion, incomplete penetration, cracks and porosity. Tecnatom have defined the mechanical system and the electronic equipment suitable for the execution of the inspection, making the necessary improvements and adaptations to meet the requirements. During the project, several methodologies for axial and circumferential inspection based on pulse-echo and emission-reception techniques have been developed, configuring the acquisition electronics with different types of sectorial scans and transmitting the ultrasonic beams to the material through specific developed wedges. The inspection procedure has been qualified using the ENIQ type methodology, based on a technical justification by means of theoretical and experimental evidence together with the practical demonstration.