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NDT Crack Detector Uses Eddy Current Array

Tuesday, February 15, 2011

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Olympus has introduced the OmniScan MX, which uses eddy current array testing for detection of stress corrosion cracking in pipelines and other pressure containment equipment.

Eddy current array can be used to detect surface breaking cracks of the type caused by stress corrosion cracking in pipelines. This technique can be applied on both curved surfaces and flat plates. Both austenitic and ferromagnetic materials can be inspected.

The technique produces no waste and is thus environmentally friendly, the manufacturer says.

The battery-operated, modular OmniScan MX easily switches from ultrasound phased array to conventional UT, eddy current, or eddy current array, according to the manufacturer.

Pipeline Cracking

Stress corrosion cracking develops in carbon steel and stainless steel pipelines due to absolute hoop, tensile, fluctuating stress and other environmental factors. Other factors include material (steel) type, number of inclusions, surface roughness, coating integrity, and soil pH.

Detection of anomalies in pipelines is essential to continued safe operation, Olympus notes. Numerous catastrophic events have occurred due to anomalies created by manufacturing and environmental conditions.

Two types of SCC are found in pipelines: high pH (9 to 11) and near-neutral pH (6 to 8). Cracks are usually oriented in longitudinal direction but may exist in other orientations depending on the direction of applied stress. Cracks tend to occur in clusters—from several cracks to hundreds—and tend to interlink to form long shallow flaws that can grow to cause ruptures.

According the the manufacturer, eddy current array testing offers:

• Minimal surface preparation;

• Rapid scanning of large surface areas;

• Determination of the approximate depth of the cracks detected;

• C-Scan imaging of the area, for reporting and subsequent inspection comparison; and

• Identification of the deepest crack(s) within a cluster.

Features and Specs

The OmniScan MX offers a high acquisition rate and powerful software features to efficiently perform manual and automated inspections, the manufacturer says.

Designed for harsh field conditions, the unit is built of solid polycarbonate-based casing and rubber bumpers, to protect it during drops and shock. The unit weighs 4.6kg (10.1 pounds) and will run for six hours with its two Li-ion batteries.

An 8.4-inch real-time display with an SVGA resolution of 800 x 600 allows clear viewing of defects and details under any light conditions. A scroll knob and function keys allow are designed for easy browsing and selection of functions. A mouse and keyboard can be connected for a more PC-like interface, and the unit can generate a wide variety of reports.

The instrument can be switched among different test modules on location. When a new module is connected, the instrument detects the module and its supported technology, setting the configuration and test environment automatically.
 
The OmniScan connector has a probe ID feature that enables physical detection and recognition of the probe connected to the instrument.

The unit can operate in temperatures ranging from 0-40°C (0-35ºC with 32:128 PA) or 32-104 ºF (32-95ºF with 32:128 PA).

More information: http://www.olympus-ims.com/en/omniscan-mx/.