High Temperature AUT

(High Temperature Ultrasonic Examinations)

INTRODUCTION

The image on the right is an example of shear wave inspection. The sample is a 2-inch thick, stainless-steel block with ID notches for sensitivity calibration. This test was run at 700° F. (371° C).

THE TECHNOLOGY

A-scan representation is the view in which the signal amplitude is shown as a vertical excursion from the horizontal sweep time trace.

The image on the right is an actual C-scan of data sample of ID Thermal Fatigue Cracking in reactor quench elbows operating between 650° and 720° F. (343° and 382°C)

The B-scan and D-scan presentations are twodimensional views of cross-sectional planes through the test object on different axis. This imaging is helpful in distinguishing mid-wall inclusions such as laminations and blistering, from back-wall discontinuities like erosion and corrosion.

The C-scan image is a two-dimensional plan view of the object. Indication of depth is color coded to provide the image with qualities which resemble a topographical map viewed from the inspecting surface.

Couplant Systems

Due to the extreme heat, many couplants and low viscous oils almost immediately become too light to hold position or flash or burn away. Recent developments have brought forth many different substances in the forms of greases, pastes, and oils to provide ample coupling ability when applied properly.

Couplants used for high temperature inspections can also be recycled and re-used when applicable. This helps save on costs, as well as helps keep housekeeping and work area clean.

Couplant flow rate is also an important aspect when inspecting with ultrasonics at high temperatures. A steady, generous flow of couplant to the interface of the test piece is necessary to ensure proper surface wetting and allow transmission of sound into the test material.

The image on the right is an example of a high temperature inspection couplant recycling system.

 

 

 

The image above on the right is an example flow rate for high temperature inspections.

The image above on the left shows a high temperature inspection being performed on a reactor elbow operating at 700° F.

Applications

The image on the right shows an actual crack sample removed from process piping system which was monitored over a two-year period for flaw growth.

 

 

 

Safety

Safety is always the number one concern when working on any job. Performing high temperature inspections are no different. In fact, more planning goes into the safety aspect of these inspections than any other task. Special clothing, such as protective, flame retardant jump suits, gloves, and PPE such as goggles and face shields may be worn to ensure no harm or injury to personnel occurs. All possible precautions must be taken to ensure that no sparks or flames are generated while the inspection is being carried out.

 

 

 

ADVANTAGES OF HIGH TEMPERATURE TECHNIQUES

• No need to stop regular process operation procedures.
• Can be used with ferrous and non-ferrous materials.
• Provides a digital documented record of inspection.
• Easily repeatable for future outages or monitoring projects.

 

Revealing Problems Before There’s A Problem