Inspectioneering Journal

Inspecting On-Stream Process Piping at Support Areas Using EMAT Ultrasound

By David Silverling at Tubular Ultrasound, L.P., Jason Hicks at Tubular Ultrasound, L.P., and Paul K. Davidson at WIS, Inc. This article appears in the January/February 2001 issue of Inspectioneering Journal.
1 Like

This article describes a new inspection technology for rapid, on-stream, quantitative examinations of piping under support areas. This portable production system has been in commercial operation in the major U.S. Gulf Coast refineries for the past two years.

The amount of installed process piping operating in the petroleum and chemical industries is vast, and represents one of the country’s largest reported potential industrial risks and the oldest existing industrial infrastructures.To date, there has been no satisfactory method that can determine the remaining wall thickness of on-stream piping at its most critical point - the pipe support location, short of removing the support or lifting the pipe.

The Support Inspection® technology has been providing the first quantitative inspection of pipe support locations on live, in-situ process piping. By monitoring ultrasonic Lamb wave mode and velocity changes, the system performs both defect detection and sizing at support locations. The technology generates Lamb waves using EMAT (Electro Magnetic Acoustic Transduction) sensors, which are non-contact, couplant free, ultrasonic transducers that use magnetic waves and high current tonebursts to generate specialized ultrasonic waves. The technology allows inspectors to determine the remaining wall of on-stream process piping in previously uninspectable locations (i.e., underneath pipe supports).

Support Inspection® operates by generating plate waves, known as Lamb waves, which propagate circumferentially around the pipe (see Figure 1). The EMAT transducers are housed in a scanner assembly that moves axially along the length of the pipe. Mode and velocity changes of the Lamb waves are measured and converted into direct readings of remaining wall/wall loss over the entire test area of the pipe support location. This procedure represents one of the first quantitative applications of EMAT ultrasonic wave theory under which wall loss severity is evaluated without direct access to either surface of the material. The Support Inspection® technique depends heavily on the properties of Lamb waves. An example of the dispersion curves for Lamb waves is seen in Figure 2. This graph is a result of the current research, and was generated by means of the WIS Lamb Wave Solver Software.

This content is available to registered users and subscribers

Register today to unlock this article for free.

Create your free account and get access to:

  • Unlock one premium article of your choosing per month
  • Exclusive online content, videos, and downloads
  • Insightful and actionable webinars
Interested in unlimited access? VIEW OUR SUBSCRIPTION OPTIONS

Current subscribers and registered users can log in now.

Comments and Discussion

There are no comments yet.

Add a Comment

Please log in or register to participate in comments and discussions.

Inspectioneering Journal

Explore over 20 years of articles written by our team of subject matter experts.

Company Directory

Find relevant products, services, and technologies.

Training Solutions

Improve your skills in key mechanical integrity subjects.

Case Studies

Learn from the experience of others in the industry.


Inspectioneering's index of mechanical integrity topics – built by you.

Industry News

Stay up-to-date with the latest inspection and asset integrity management news.


Read short articles and insights authored by industry experts.

Expert Interviews

Inspectioneering's archive of interviews with industry subject matter experts.

Event Calendar

Find upcoming conferences, training sessions, online events, and more.


Downloadable eBooks, Asset Intelligence Reports, checklists, white papers, and more.

Videos & Webinars

Watch educational and informative videos directly related to your profession.


Commonly used asset integrity management and inspection acronyms.