Inspectioneering Journal

Mechanical Integrity Management Using Remaining Wall Thickness and Data Analysis

Part 1

By Art Leach at Krautkramer. This article appears in the May/June 1999 issue of Inspectioneering Journal.
This article is part 1 of a 2-part series.
Part 1 | Part 2


Keeping critical equipment on-line can be a challenging task. Monitoring the wall thickness of equipment subjected to corrosive chemicals, temperature and operational changes is both a safety and manufacturing concern. Thus, on-line testing of equipment is common in most plants. A traditional testing method is digital ultrasonic thickness gauging for the measurement of wall thickness. This one method has become the most widely used method of assuring mechanical integrity of equipment items that are prone to erosion / corrosion.

Using current technology digital ultrasonic thickness gauges and the right transducers (probes), the inspection or mechanical integrity department can accurately measure remaining wall thickness on pipes, vessels, tanks, boilers or any equipment prone to erosion / corrosion. These inspections are often done while the equipment is on line, thus avoiding production down time.

The inspector uses “couplant” as a medium to enable the ultrasonic waves to pass from the probe into the test material. The probe is placed on the test location of the equipment and a digital thickness value is displayed on the instrument. The inspector can store the reading into the internal memory of the instrument (this is referred to as data logging) or manually record the reading.

Internal memory gives the ability to store thousands of thickness data values for single or multiple surveys. Users can download the data to computers by using specific software programs supplied by the instrument manufacturer. These programs range from simple data transfer programs to complex analysis programs having the ability to make service life predictions, schedule new inspections and give the user a wide variety of decision making tools.

Petroleum Refining, Chemical Production, Oil and Gas Production, Power Generation and Gas Transmission are only a few of the industries using new technology to improve data management, increase safety, conform to code compliance and reduce inspection frequency and costs.

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