Inspectioneering Journal

Uncertainty in Flaw Sizing by Radiography Method - A Primer Plus

By Sanjoy Das, Scientific Officer - Quality Assurance Division at Bhabha Atomic Research Centre, and B.K. Shah, Quality Assurance Division at BARC. This article appears in the July/August 2005 issue of Inspectioneering Journal.
1 Like

Radiography is the most widely used volumetric examination technique for non- destructive evaluation of components, as it offers the advantage of direct viewing of the flaw image, judging the type of flaw and provides a permanent record. Flaw characterization methods, described by size, shape & location, require classification of the type or nature of flaw, position of flaw and flaw severity. Accurate sizing of the flaw to assess its severity is important. ISO Guide 25 “General Requirements for the Competence of Calibration and Testing Laboratories” (1990), requires one to specify the uncertainty of each measurement. In radiography there are several factors which contribute to uncertainty for quantitative measurement. This paper describes a study undertaken to calculate the uncertainty in flaw sizing and to estimate the real size of discontinuities observed in radiography.


Radiography is widely used in industries for determining the quality of engineering components by detecting and sizing internal discontinuities . In any flaw detection technique, the probability of detection (POD) is less than 1 or 100%. Desired POD in radiography is considered between 0.8 & 0.9. The evaluation of radiographs is done in two steps:

  1. Detecting the flaw
  2. Dimensioning of flaw

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.