Global Refining Industry Utilizes Ultrasonic Inspection Technology

Introduction

The refining industry has applied ultrasonic-based intelligent pigging to inspect serpentine coils in fired heaters since the 1990s. Today, thousands of serpentine coils in fired heaters are inspected annually at process facilities around the globe. Many plants have drastically reduced or completely eliminated the practice of applying manual NDE spot checks (e.g. ultrasonic, diametrical tube strapping, etc.) and now apply ultrasonic-based intelligent pigging as a matter of routine practice. Based on years of experience and success, many corporate best practice guidelines within major refining and chemical facilities mandate the use of ultrasonic-based intelligent pigging as a significant component of their standard heater management programs. These changes are easily justified considering the increased inspection coverage, accuracy of test results, repeatability of test results and time required to complete inspection of heater coils. Industry-accepted and recommended practices, such as RP API-573, have also acknowledged and documented the benefits of applying intelligent pigging as part of an effective heater inspection program.

The Challenge

Serpentine coils in heaters are a challenge to properly inspect when applying conventional Non-Destructive Testing (NDT) approaches. Limited access to the fired heater’s convection section, combined with external raised surfaces (e.g. fins, studs) makes this portion of the coil nearly impossible to inspect by conventional means. In the heater’s radiant section, it is common for external scale (see Figure 1) to build up on the exterior surface of the coils, limiting the effectiveness of both visual and contact NDT approaches. Ultrasonic-based intelligent pigging tools provide a technologically advanced alternative and eliminate the challenges associated with most of these features.