플랜지 용접 품질에 대한 와전류 테스트

고성능 배관 시스템, 특히 원자력과 같은 산업 분야, 석유화학, 석유와 가스, and aerospace—flange weld quality is non-negotiable. 제대로 실행되지 않거나 감지되지 않은 용접 결함으로 인해 누출이 발생할 수 있습니다., 중단 시간, or catastrophic system failures. Among the various Non-Destructive Testing (NDT) methods available, Eddy-Current Testing (ECT) has emerged as a powerful tool for evaluating flange weld quality, offering high sensitivity and rapid results without damaging the component.

In this in-depth SEO article, SASAFLANGE explores how Eddy-Current Testing works, its benefits, key applications for flanges, 업계 표준, and why it has become a preferred choice in quality assurance processes for weld inspections.

What Is Eddy-Current Testing?

Eddy-Current Testing is a non-destructive electromagnetic testing method used to detect surface and near-surface defects in conductive materials. It works by inducing circulating electrical currents—called “eddy currents”—in the material using an alternating magnetic field. Any changes in the flow of these eddy currents, such as interruptions caused by cracks or voids, can be detected and analyzed.

ECT is especially well-suited for detecting:

Surface-breaking cracks
Weld discontinuities
Corrosion near weld zones
Material thickness variation
Improper heat treatment effects

~에 SASAFLANGE, Eddy-Current Testing is integrated into our weld inspection processes for flange connections requiring ultra-high reliability.

Why Flange Welds Require Rigorous Testing

Welds connecting flanges to pipes or equipment must:

Withstand high internal pressure
Handle temperature cycling and thermal stress
Resist vibration and fatigue
Maintain sealing integrity over decades

Because these joints are critical pressure boundaries, weld defects such as porosity, lack of fusion, undercutting, and surface cracks can compromise the entire system. Early detection through ECT ensures that only flawless welds pass inspection.

Advantages of Eddy-Current Testing for Flange Welds

1. High Sensitivity to Surface Flaws

ECT can detect minute surface cracks and subsurface discontinuities, often smaller than what visual or magnetic testing methods can reveal.

2. No Need for Surface Preparation

Unlike dye penetrant testing, ECT requires minimal surface cleaning, allowing for faster inspection and reduced downtime.

3. Immediate Results

ECT provides real-time results, making it ideal for in-process quality control during flange weld fabrication.

4. Non-Invasive and Non-Destructive

No cutting, grinding, or contact damage—just electromagnetic probing. Flanges remain fully intact and usable.

5. Detects Heat-Affected Zone (HAZ) Defects

Welds often fail in the heat-affected zone. ECT can pinpoint microcracks, hard spots, or stress concentrations in these zones.

How Eddy-Current Testing Works on Flange Welds

A probe containing a coil is placed near the weld surface.
An alternating current passes through the coil, generating a magnetic field.
The magnetic field induces eddy currents in the conductive material beneath the coil.
When these eddy currents encounter a flaw, their flow is disrupted, changing the electrical impedance of the coil.
This change is displayed on an oscilloscope or digital readout, interpreted by a trained technician.

For flange welds, specialized probes can be used for:

Circumferential welds
Difficult geometries like socket welds
Automated robotic scanning on large flange faces

SASAFLANGE uses both pencil-type and array eddy-current probes to ensure comprehensive weld coverage.

Standards and Codes Governing Eddy-Current Testing

Eddy-current inspection for flange welds is regulated by internationally recognized codes and standards:

ASME Section V, Article 8 – Standard for ECT in pressure systems
ASTM E2261 – Eddy-current examination of welds
EN ISO 15548 – Equipment and probe calibration
API 570 / API 653 – For piping inspection protocols
Nuclear RCC-M / ISO 9712 – For nuclear-grade flange welds

모두 SASAFLANGE inspection personnel are certified to ISO 9712 or ASNT Level II/III, ensuring skilled interpretation and code compliance.

Typical Weld Defects Detected by Eddy-Current Testing

ECT is especially effective at detecting:

Toe Cracks – Found at the edge of the weld
Hot Cracks – Formed during solidification of the weld metal
Lack of Fusion – When weld metal does not properly join base metal
Underbead Cracks – Subsurface flaws caused by improper heat input
응력 부식 균열 (SCC) – A risk in chemical and nuclear service

These types of defects can severely reduce the mechanical strength and fatigue life of the flange joint.

Limitations of Eddy-Current Testing

While ECT is a powerful tool, it does have limitations:

Best suited for conductive materials (예를 들어, 스테인레스 스틸, 탄소강)
Limited penetration depth—typically 1–5 mm
Geometry of the flange may require custom probe configuration
Difficult to use on rough, 그린, or heavily scaled surfaces

그렇기 때문에 SASAFLANGE often combines ECT with 초음파 테스트 (유타) 또는 magnetic particle inspection (MPI) for a comprehensive weld evaluation package.

Applications of ECT in Flange Weld Inspection

Eddy-current testing is widely used in:

Nuclear power plants (ASME Section III, RCC-M)
Chemical processing systems
Offshore and subsea pipelines
고압 증기 시스템
Aerospace fuel lines and hydraulic piping
Pharmaceutical grade piping with hygienic flange welds

These applications demand zero leakage, and ECT provides a fast, accurate way to inspect the integrity of flange welds.

Integration into Quality Assurance Programs

~에 SASAFLANGE, Eddy-Current Testing is embedded into our QA/QC workflow:

Welders are qualified per ASME IX / EN 287
WPS and PQR are reviewed before production
ECT is scheduled post-weld but pre-final machining
All testing results are logged with traceable serial numbers
Reports are issued as part of the EN 10204 3.1 또는 3.2 자격증

This structured approach ensures that every flange we deliver has been thoroughly tested and verified for integrity.

Documentation Provided by sasaflange

Each flange weld inspection includes:

Eddy-Current Testing Report with defect map (해당되는 경우)
Operator qualification certificates
Instrument calibration records
Visual and dimensional inspection reports
Flange serial numbers and heat traceability

All ECT documentation is prepared to meet the needs of EPC contractors, OEM, and end-users in critical sectors.

결론

Eddy-Current Testing is a high-precision, 믿을 수 있는, and non-invasive method for ensuring the weld quality of flanges in demanding environments. It delivers immediate feedback, high flaw sensitivity, and cost-effective inspection capabilities—making it a vital part of modern flange manufacturing and quality control.

~에 SASAFLANGE, we apply industry-leading ECT practices to safeguard your projects, minimize downtime, and deliver certified flange assemblies ready for service in the world’s toughest environments.