Phased Array Ultrasonic Testing, TOFD and Advanced NDT Methods

Overview

Standards: ASME BPVC Section V Article 4 (phased-array and time-of-flight diffraction), API 941 (high-temperature hydrogen attack), API 571 (damage mechanisms and carburisation). Inspections follow the Olympus and Evident PAUT and TOFD calibration procedures and the Vallen AMSY-6 acoustic emission protocols, and support in-service inspection under API 510 (pressure vessels), API 570 (piping), API RP 572, API RP 574, and API RP 575.

• Code: ASME BPVC Section V Article 4, covering phased array and time-of-flight diffraction.
• API 941: high-temperature hydrogen attack.
• API 571: damage mechanisms and carburisation.
• Equipment: Olympus and Evident instruments.

Time of Flight Diffraction (TOFD)

High-resolution technique for detecting and sizing internal cracks. Diffracted waves give precise flaw depth and length measurements. Effective for weld inspections and critical-component evaluations. Thickness range 9 mm to 300 mm.

• Principle: diffraction of ultrasonic energy from the corners and tips of a flaw.
• Measures: flaw depth and length, precisely.
• Applied to: weld inspection and critical-component evaluation.
• Fitness for Service: a primary tool, because it sizes rather than merely detects.
• Also supplied: customised ToFD scan plans and procedures written to the client's scope.

TCR Engineering specialises in the Time-of-Flight Diffraction (ToFD) technique, an advanced ultrasonic non-destructive testing (NDT) method that relies on the diffraction of ultrasonic energy from the corners and ends of internal structures, primarily defects, within the components being tested. The method sizes flaws independently of signal amplitude, across a wide coverage area.

ToFD is particularly valuable for conducting Fitness for Service (FFS) inspections, making it an essential tool in maintaining the integrity of critical assets. This fast and effective method allows for the rapid scanning of extensive weld areas in a limited timeframe, which is crucial for minimising downtime in industrial operations.

TCR also writes customised ToFD scan plans and procedures to each client's scope. The advantages of ToFD include its ability to deliver precise and reliable defect sizing, comprehensive coverage, and the facilitation of effective decision-making for asset management, all of which are critical for industries such as oil & gas, petrochemical, and power generation.

HTHA, HIC, and Carburisation Detection

High-Temperature Hydrogen Attack detection per API 941. Hydrogen-Induced Cracking damage assessment via PAUT. Carburisation detection in low-alloy steels (P5, P9, P91) per API 571.

TCR Engineering provides advanced online inspection solutions designed to minimise plant downtime and reduce costs for operators. With capabilities to perform inspections at temperatures up to 350°C, TCR’s innovations in high-temperature PAUT (HT), ToFD (HT), and corrosion mapping deliver essential data without halting operations. This technique is vital for in-service piping, vessels, and tanks.

Key Benefits of TCR’s High-Temperature Inspection Services:

• Minimised plant downtime and reduced production losses by conducting inspections online
• Accurate detection of corrosion, wall thinning, and defect growth for engineering evaluations
• Real-time corrosion rate monitoring and defect growth tracking for better maintenance planning
• Supports RBI (Risk-Based Inspection) by delivering critical data for shutdown scheduling
• Online inspection of repairs, including welds and critical areas, up to 350°C
• Immediate feedback with digitised inspection records for future reference
• Enhanced health, safety, and environment (HSE) compliance

By offering in-service inspections, TCR Engineering helps clients avoid costly shutdowns, improve maintenance efficiency, and ensure the safety and reliability of their equipment. Defects are detected in real time, with the equipment at temperature.

High-Temperature Corrosion Mapping

TCR Engineering delivers advanced automated high-temperature corrosion mapping inspections using the straight beam pulse-echo technique with dual element transducers. Our custom-designed high-temperature probes, crafted from heat-resistant plastics and equipped with advanced cooling systems, ensure reliable performance in extreme environments.

• Suitable for equipment and pipelines with thicknesses from 5 mm to 125 mm
• Handles temperatures ranging from 10°C to 350°C
• Effective for pipelines with diameters of 6” and above
• Accurately detects, sizes, and monitors corrosion, erosion, and HIC-SWC damage
• Offers precise damage sizing with 0.1 mm accuracy
• High Probability of Detection (POD) for comprehensive inspection
• Provides recordable corrosion mapping images for detailed analysis
• Enhanced inspection angle range and sizing accuracy

Our advanced technology ensures accurate, reliable inspections, minimising downtime and optimising asset integrity. Cooled probe designs keep the scan running on surfaces up to 350°C.

Detecting High-Temperature Hydrogen Attack (HTHA)

TCR Engineering specialises in Advanced NDT services to detect High-Temperature Hydrogen Attack (HTHA), a critical phenomenon in petrochemical and refinery industries. HTHA occurs when steel, exposed to temperatures above 200°C, reacts with hydrogen, creating methane bubbles at the grain boundary. These bubbles lead to microcracks, weakening the steel and potentially causing catastrophic failures.

Even equipment designed under stringent safety codes may suffer from HTHA damage. Early detection through expert NDT inspections by TCR Engineering ensures safe, long-term operation, minimising risks of equipment failure or accidents.

Industries and Equipment at Risk:

• Catalytic Reformers (CCR & Cyclic)
• Hydrotreating Units (Hydrocracking and Desulphurisation)
• Ammonia and Hydrogen Reformers
• Highly stressed locations like flanges, reducers, and pipe fittings

Key Advantages of TCR’s NDT Expertise:

• Comprehensive assessment of long-term HTHA damage
• Inspection over large, complex areas with external-only access
• Estimation of damage depth without the need for equipment shutdown

Early-stage micro-degradation is difficult to detect; experienced interpretation identifies HTHA once it reaches its critical stages.

High-Temperature UT and EMAT (Up to 600 Degrees Celsius)

Thickness measurement and flaw detection on operating equipment up to 200 degrees Celsius (conventional UT) and up to 600 degrees Celsius (EMAT). EMAT capability at 600 degrees Celsius serves online inspection of high-temperature equipment without shutdown.

High-Temperature Phased Array UT

TCR Engineering's high-temperature PAUT inspections are designed to inspect surfaces up to 350°C, minimising plant downtime. Sectorial scans across a range of angles cover the complete weld volume.

• Suitable for equipment/piping with thicknesses from 3 mm to 300 mm
• Handles temperatures from 10°C to 350°C
• Inspects pipelines with diameters of ¾” and above
• Detects, sizes, and monitors weld defects, corrosion, HTHA, HIC-SWC damage, and stress corrosion cracks
• Effective for one-sided weld inspections and dissimilar weld joints (CS/SS)
• Accurate damage/weld defect sizing with high Probability of Detection (POD)
• Encoded, recordable data/images for detailed analysis
• Compatible with Inconel and other high-performance materials
• Enhanced inspection range and cooling capacity via optimised water jacket design

Applicable Standards:

• ASME Section V (Nondestructive Examination)
• ASME Section VIII (Pressure Vessels)
• API 579-1/ASME FFS-1 (Fitness for Service)
• AWS D1.1 (Structural Welding Code – Steel)

Matrix Array UT (MAUT)

Matrix array ultrasonic testing (MAUT) is targeted at fibre-reinforced plastic (FRP) and glass-reinforced plastic (GRP) composite inspection, where a two-dimensional probe array images the laminate as a plan view, the view in which delamination, disbonding and impact damage in a composite are read.