MODERN ULTRASONIC METHODS FOR RESIDUAL WALL THICKNESS MEASUREMENTS OF METAL PRODUCTS UNDER PROTECTIVE COATINGS
Journal: NDT WORLD
Volume 19 № 3
, 2016
Authors:
1.
St. Petersburg Mining University
(kafedra «Priborostroenie», professor)
CONSTANTA Ltd (general'nyy direktor)
Sankt-Peterburg, Russian Federation
CONSTANTA Ltd (general'nyy direktor)
Sankt-Peterburg, Russian Federation
Type:
Article
Pages:
from 4
to 8
Status:
Published
Received:
18.08.2016
Accepted:
20.09.2016
Published:
20.09.2016
Language:
Russian
Keywords:
ultrasonic testing, coating, residual thickness, echo-echo- method
Abstract (English):
With an increasing amount of work on residual thickness measurements of various metal products (petrochemical industry products, marine and bridge structures, transport infrastructure objects, etc.) the task of improving measurement performance is getting increasingly urgent. While measuring the residual wall thickness Hmet of coated metal products with the traditional ultrasonic methods, for example, probe-echo, a significant portion of time is spent to scrape a protective dielectric coating (most often paint) from the testing point and then to restore the coating after the measurements. In recent years the ultrasonic methods, which do not require the coating to be removed for measuring, are intensively developed. The optimal methods are the following: Echo-Echo, different Probe-Echo Coating (including the TopCOAT) and combined. The article describes in detail the physical basis of the methods, block diagrams of two - and four-element double crystal transducers, time charts and algorithms for Hmet computing, which together enable the coating thickness value to be eliminated from the measurement results. The analysis of every method’s merits and demerits and the restrictions on its usage are given. The article also shows the ways to improve parameters of the equipment used for coated products testing as well as measures to increase the reliability of Hmet measurement results.
With an increasing amount of work on residual thickness measurements of various metal products (petrochemical industry products, marine and bridge structures, transport infrastructure objects, etc.) the task of improving measurement performance is getting increasingly urgent. While measuring the residual wall thickness Hmet of coated metal products with the traditional ultrasonic methods, for example, probe-echo, a significant portion of time is spent to scrape a protective dielectric coating (most often paint) from the testing point and then to restore the coating after the measurements. In recent years the ultrasonic methods, which do not require the coating to be removed for measuring, are intensively developed. The optimal methods are the following: Echo-Echo, different Probe-Echo Coating (including the TopCOAT) and combined. The article describes in detail the physical basis of the methods, block diagrams of two - and four-element double crystal transducers, time charts and algorithms for Hmet computing, which together enable the coating thickness value to be eliminated from the measurement results. The analysis of every method’s merits and demerits and the restrictions on its usage are given. The article also shows the ways to improve parameters of the equipment used for coated products testing as well as measures to increase the reliability of Hmet measurement results.
Keywords:
ultrasonic testing, coating, residual thickness, echo-echo- method
ultrasonic testing, coating, residual thickness, echo-echo- method
1. Carodiskey T. J., inventor. Krautkramer Branson, Inc., assignee. Method and apparatus for measuring the thickness of a coated material. USA Patent US 6,035,717. 2000 March 14.
2. Renzel P. Thickness Measurement with Ultrasound NOT Knowing the Sound Velocity. Available at: http://www.ndt.net/forum/files/thickm-w-us-nksv-presentation.pdf (accessed on 03.08.2016).
3. Potapov A. I., Syasko V. A. Nerazrushayushchie metody i sredstva kontrolya tolshchiny pokrytiy i izdeliy [Non-destructive methods and instruments for thickness measurements of coatings and products]. St. Petersburg, Gumanistika, 2009, 904 p. (in Russ.).
