Inspectioneering
Inspectioneering Journal

Corrosion Surveys of NPS 6 and Smaller Lines with High Production Digital Radiography

By Chris Bishop, CR and DDA Subject Matter Expert at IRISNDT, and Ana Benz, Chief Engineer at IRISNDT. This article appears in the July/August 2021 issue of Inspectioneering Journal.
24 Likes

Introduction

Piping failures account "for 60% of mechanical integrity losses [1]." Traditionally, we have monitored piping corrosion losses with ultrasonic thickness testing (UTT) based corrosion surveys. While these surveys are valuable, their information for small diameter piping can be challenging to interpret. In contrast, for NPS 6 and smaller lines, digital radiography (DR) based piping corrosion surveys give clearer and much broader information: an image showing wall loss, weld condition, threaded connection integrity, potential problems with insulation, internal product buildup, and often much more.

Using profile radiographic techniques (PRT) for small diameter lines is not a new concept. The API 570 "Piping Inspection Code: In-service Inspection, Rating, Repair and Alteration of Piping Systems" has clear guidelines for PRT of small-bore piping. This article illustrates the significant value of digital radiography as an efficient tool to visualize corrosion and other small bore piping anomalies without disturbing insulation. It also highlights the importance of properly interpreting radiography images and using PRT in conjunction with UTT to survey small diameter lines.

Some Key Benefits of Profile Digital Radiography

Profile radiography is described in detail in API RP 583 "Corrosion Under Insulation and Fireproofing." As stated in the RP, "The exposure source is usually iridium-192, with cobalt-60 being used for heavier wall piping … can also be done using X-ray sources." A typical exposure setup is illustrated in Figure 1. All DR digital detector array (DDA) images shown in this article were obtained using iridium-192.

Figure 1. Image illustrating a profile radiography setup.
Figure 1. Image illustrating a profile radiography setup.

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
GET STARTED
Interested in unlimited access? VIEW OUR SUBSCRIPTION OPTIONS

Current subscribers and registered users can log in now.


Comments and Discussion

Posted by Kevin Wieland on September 10, 2021
Great article that emphasizes that not only one... Log in or register to read the rest of this comment.

Posted by Ana Benz on September 10, 2021
Thank you, Kevin. Log in or register to read the rest of this comment.

Posted by UDAYAN PATEL on September 30, 2021
It is a great article. However there are couple... Log in or register to read the rest of this comment.

Posted by Ana Benz on October 1, 2021
Hi, Udayan, We have been using DDA to identify... Log in or register to read the rest of this comment.

Posted by Chris Bishop on October 4, 2021
Hi Udayan, For the second question , this is... Log in or register to read the rest of this comment.

Posted by UDAYAN PATEL on October 19, 2021
Thanks for response. It is vey helpful Log in or register to read the rest of this comment.

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.

Integripedia

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.

Blog

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.

Downloads

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

Videos & Webinars

Watch educational and informative videos directly related to your profession.

Acronyms

Commonly used asset integrity management and inspection acronyms.