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X線検査の置き換えとしてのフェーズドアレイ超音波探傷(英語)


An example of carbon steel pipe corrosion that can be mapped using a scanner

Summary

In nondestructive evaluation (NDE), or nondestructive testing (NDT), many codes allow inspectors to substitute one inspection method with another, as long as certain requirements are met. Additionally, non-code-based inspection methods are constantly being reviewed to improve processes and reduce costs. Ultrasonic methods have become a popular and accepted substitute in inspections that previously employed radiographic methods.

Introduction

Radiography and ultrasound are complimentary NDT techniques. Both can volumetrically inspect welds and components for defects like cracks, lack of fusion, porosity, etc. The choice of one over the other often depends on external process decisions or small differences in the detection capability for a particular test. However, ultrasound has gained momentum as a replacement for radiography both in practice and in the codes of major organizations such as ASME (American Society of Mechanical Engineers) and API (American Petroleum Institute). Although most codes do not specify the ultrasonic method, phased array (PA) ultrasound, in particular, has become the most popular replacement method in inspection processes. PA is often also combined with time-of-flight diffraction (TOFD) when inspectors use acquisition units and scanners that can accommodate both methods simultaneously. In the past, code-based inspection processes typically followed code cases or appendixes. However, after increasing use and acceptance in industry, ultrasonic inspection processes are being added directly to the main body of major codes, for example, ASME Sec. V. Art. 4 from 2010 onwards. Phased array ultrasonic equipment is becoming more portable, affordable, and easier to use, making ultrasound a practical, safe replacement for radiography.

Typical Advantages of Ultrasound (over Radiography):

  • High probability of detection (POD), especially for cracks and lack of fusion:
    • Ultrasound tends to detect planar flaws better than radiography in most studies.
  • Accurate sizing of defect height and fewer rejects or repair using Engineering Critical Assessment:
    • Ultrasound permits defect height measurement, which enables volumetric consideration of flaw severity (instead of only flaw type and length).
  • Does not emit radiation, does not cause hazards, and does not require additional licensing or personnel.
  • Does not require screened-off areas. Work in proximity to ultrasonic testing can continue uninterrupted.
  • Does not generate any chemical or waste material (as opposed to film-based radiography, which does).
  • Real-time ultrasonic analysis of welds can provide instant evaluation and feedback to a welder.
  • Setup and inspection reports are in electronic format (as opposed to film format in radiography).

Examples of Codes with Ultrasound Replacing Radiography

  • ASME Code Case 2235
  • ASME Code Case 179
  • ASME Code Case 168
  • ASME Code Case N-659
  • ASME Code N-713
  • API 620/650 App. U
  • ASME Sec. V Mandatory Appendixes

Typical Ultrasonic Equipment and Inspection Requirements

  • An acquisition unit with full, raw A-scan data retention and position-encoding ability (for example, an OmniScan® flaw detector or FOCUS PX instrument).
  • A scan plan and procedure that documents the inspection strategy and essential parameters (for example, parameters that are set up using the NDT SetupBuilder software).
  • An industrial scanner (with position encoder) that can repeatedly scan a weld or component (semiautomatically or automatically):
    • The choice of scanner model is based on the number of welds, pipe diameter, and other application variables.
  • Deliverable data:
  • Demonstrated performance of equipment, procedure, operator, and inspection process.
  • Alternative acceptance criteria, as required.
  • Probes, wedges, couplant delivery equipment, and other accessories.
  • Proper training and certification of personnel.

An example of carbon steel pipe corrosion that can be mapped using a scanner
The OmniScan MX2 (multi-group capable) [left] and OmniScan SX (single group) flaw detectors.

Using the RollerFORM scanner to inspect flat bottom holesAmplitude C-scan using the OmniScan flaw detector


Fully automatic WeldROVER scanner (left) and semiautomatic HSMT-Compact scanner with an OmniScan MX flaw detector.

Conclusion

The replacement of radiography with ultrasound has become an industry trend, as well as a code-accepted practice. Easy-to-use and affordable portable phased array equipment and associated software are accelerating the use of ultrasound. The main reasons for this continuing trend include savings in process cost and time, improved safety of operators and others in surrounding areas, and the use of alternative acceptance criteria. The increased use of ultrasound has led to a decrease in part rejection and repairs.

Olympus IMS

この用途に使用される製品
NDTセットアップビルダーは、探傷のセットアップとビームのシミュレーションを画像化する、新しいPCベースのソフトウエアです。 このソフトウェアは、すばやく簡単に包括的な検査プランの詳細を表示する機能を多数備えており、そのデータをOmniScan MX2に直接インポートすることができます。
探傷する面に対してプローブを正確に配置できるかどうかは、検査の精度に大きな影響を及ぼします。 オリンパスは、検査員をサポートするために多岐に渡る工業用スキャナーやアクセサリー類を提供しています。 スキャナーは、手動または電動の1軸または2軸エンコードを含めさまざまな構成をご用意しています。
TomoViewは、超音波信号の設計やデータ収集、画像化と分析を行うパワフルで柔軟なPCベースのソフトウェアです。
この新ソフトウェアは、OmniScanデータ解析のための効率的で低価格のオプションソフトウェアです。 OmniScan搭載のソフトウェアの同じ解析ツールを備えており、PC上で自在に操作することができます。
シングルグループで軽量のOmniScan SXは、読み取りやすい8.4インチ(21.3cm)のタッチスクリーンを搭載し、コスト効果に優れたソリューションを提供しています。 OmniScan SXには、SX PAおよびSX UTの2種類のモデルを用意しています。 SX PAは、16:64PRの装置で、UT専用のSX UTと同様に、従来型UTチャンネルを備え、P/E、P-CまたはTOFD検査に対応しています。
フェーズドアレイ用途専用のプローブは、周波数範囲0.5 MHzから18 MHzで、エレメント数16、32、64、128のものを取り揃えています。 特殊なプローブにはエレメント数が数百のものもあります。
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