Guided wave ultrasonic testing: applications, limitations, and new developments

This paper entitled “Guided Wave ultrasonic testing: applications, limitations and new developments” was presented at IPEIA 2023 in Jasper, Alberta, by Timothé Falardeau, integrity engineer at Nucleom.

Long-Range Guided Wave Testing (GWT)

Applications- examples:

• High productivity: GWT of fire piping in a mine. 2km, 100% inspected in 3 days
• Buried piping: GWT of dike crossing in distribution terminal. 8 10 dike crossing / day
• Insulated piping: GWT of high temperature piping. Up to 350⁰C (HT collars)
• Reduced confined spaced exposure: GWT of culvert crossing. 15 culvert crossing / day
• Reduced work at height exposure: GWT of piping in pipe rack. 1 shot every 500 ft

Limitations:

• Qualitative. Defect categorized into severity: Minor 0 25% wall loss, Medium 25 – 50% wall loss, Severe 50+% wall loss
• Direct access required at test point.
• Cannot test through thick coating (ex. Bitumen wrap, yellow jacket).
• Surface prep may be required (remove anything loose).
• Can inspect most metals (steel, aluminium, copper, etc.)
• Diameter: NPS 1.5 NPS 60+
• Radial clearance: 1.5″. Axial clearance: 6″ (12″ recommended)
• Up to 150⁰C (standard rings). Up to 350⁰C (high temp rings)
• Near field/deadzone 3 ft each side (regular collar). Down to 6″ HD collars.
• Range of inspection influenced by multiple factors
• Configuration (elbow/flange/tee)
• Pipe condition
• External environment (noise, soil, insulation)
• Material (optimized for carbon steel)

Short/ Medium range GWT

Applications:

Quantitative measurements (actual thickness measurements)

• Corrosion under pipe support (CUPS) using the QSR1
• Bottom side corrosion (pipe laying on the ground) using the QSR1
• Soil-to-air interface (SAI) testing using the Axial QSR1
• Wall penetration testing using the Axial QSR1

Limitations:

• Axial clearance: 12” (QSR1) 15.4” (Axial QSR)
• Radial Height (circumferential clearance): 3.4” (Axial QSR)
• Surface preparation: Wiped clean of loose debris. Coating thicker than 1mm must be remove under the sensor
• Applications: Non welded simple supports (QSR1)
• Wall penetrations testing / complex supports (Axial QSR)
• Pipe temperature: -20⁰C to 70⁰C
• Length of test (Axial QSR): 2” 20” axially

New development and advanced applications

Long range GWT

High-definition Compact modules

• Interface testing (ex. pipe in concrete) or corrosion at supports
• Reduced near field and deadzone
• Higher sensitivity
• Lower reflection from wall/soil penetration
• Magnetostrictive sensors
• High signal to noise ratio (SNR)
• Tight radial clearance (1”)
• High sensitivity

Permanent monitoring

• Improved accuracy
• Quantitative measurements possible
• Corrosion rate estimation
• Ideal for critical pipelines/piping

High temperature (up to 350 C)

QSR1

• GUL high power sensors increase SNR and transduction power
• GUL ML algorithm (machine learning) can quantify up to 100% wall loss
• GUL ML algorithm (machine learning) in development for corrosion at welded support

3 main points to remember:

• Fast: 15 min/test GWT; 15 min/m QSR
• 100% coverage: GWT for screening; QSR for quantitative measurements
• Trustable: Very high probability of detection (POD)