In this section

Feasibility of FMC Pitch-Catch for Inspection of Pipeline Girth Welds

Alert: Export Control Check Required

Thank you for requesting a TWI Industrial Members Report.

To meet UK government requirements, your request will undergo an Export Control Check. This process reviews the technical content of the report, identifies the end user, and addresses any concerns.

Please submit your request to CRP@twi.co.uk including your name, member company that you work for and your location. We will contact you regarding the request within 2 working days and any additional information required to complete the necessary checks.

We look forward to receiving your request and processing it through our export control procedure.

Thank you,

TWI CRP Operations Team

This content is only available to Industrial Members, Find out how to become a Member of TWI.

By Miles Weston and Calum Hoyle

Industrial Need

The combination of time-of-flight diffraction (ToFD) and pulse-echo techniques in automated ultrasonic testing (AUT) systems has become common place for inspection of pipeline girth welds in the oil and gas industry. AUT is often preferred to radiography, due to the reduced costs, detectability of planar flaw types and health and safety implications associated with ionising radiation.

This project presents the feasibility of replacing conventional ToFD channels with an ultrasonic array FMC pitch-catch setup to determine its reliability of detection, flaw sizing and locational accuracy for planar through wall flaws in pipeline girth weld components in comparison with current industry standard techniques.

By implementing a successful FMC pitch-catch setup there is potential for significant cost savings through reduced operator training, setup and increased reliability of inspection. It also offers the potential to perform FMC pulse-echo and FMC pitch-catch scans simultaneously, using a single pair of ultrasonic array transducers.

Key Findings

Development of FMC pitch-catch calibration routines for system latency and probe separation distance form key steps to ensure reliable flaw detection and accurate through-all flaw sizing.
Inspection of a girth weld pipe sample using the FMC pitch-catch technique, combined with pulse-echo and self-tandem inspection modes, achieved an average through wall sizing accuracy for lack of fusion flaws of 0.3mm. All flaws identified with FMC were present in the sectioning data.
The FMC pitch-catch mode was shown to outperform the other available inspection modes in terms of through wall sizing accuracy by an average of 0.1mm, although all modes were required to ensure detection and sizing of all flaws.
The FMC pitch-catch inspection mode is now included within BS ISO 23865:2021 and is considered ready for use by industry.

FMC girth weld setup, showing a cross sectional image of a 20mm thick plate weld containing a centreline EDM notch, imaged using FMC pitch-catch mode

For more information please email:

contactus@twi.co.uk

Feasibility of FMC pitch-catch for inspection of pipeline girth welds 1166/2023

Feasibility of FMC Pitch-Catch for Inspection of Pipeline Girth Welds

Alert: Export Control Check Required

Industrial Need

Key Findings