COBEM99

S13 Integridade Estrutural

Title:

EQUIPAMENT FOR AUTOMATIC EXAMINATION OF INDUSTRIAL GAS CYLINDERS

Summary :

ABSTRACT: CYLINDERS USED TO TRANSPORT COMPRESSED GASES HAVE TO BE INSPECTED AND TESTED PERIODICALLY FOR SAFE OPERATION. ALONG LIFE TIME, THOSE CYLINDERS ARE SUBJECTED TO CORROSION, PITTING, OR DANGEROUS DEFECTS. ULTRASONIC EXAMINATION IMPROVES SAFETY, BY IDENTIFYING AND MEASURING WALL THICKNESS, PITTING AND CRACKING. THIS PAPER PRESENTS THE DEVELOPMENT OF AN EQUIPMENT FOR AUTOMATIC ULTRASONIC EXAMINATION OF GAS CYLINDERS. AN ULTRASONIC TRANSDUCER HEAD SCANS THE EXTERNAL SURFACE OF THE CYLINDER THROUGH A MECHANICAL SCANNING DEVICE WHICH TURNS THE CYLINDER ALONG ITS SYMMETRY AXIS WITH CONSTANT RPM AND TRANSLATES LONGITUDINALLY THE SCAN HEAD ON ITS SURFACE. THE TRANSDUCER HEAD HAS ONE 10 MHZ LONGITUDINAL WAVE TRANSDUCER TO MEASURE THE WALL THICKNESS AND FOUR 5 MHZ SHEAR WAVE TRANSDUCERS TO DETECT CRACKS. IT IS USED A WATER FILM FOR THE ACOUSTIC COUPLING. EACH TRANSDUCER IS CONTROLLED BY A TRANSMITTER-RECEIVER BOARD AND THE EQUIPMENT IS CONTROLLED BY A 486 PC AND A DEDICATED MICROPROCESSOR BOARD. A PROTOTYPE WAS BUILT AND TESTED IN THE LABORATORY. THE RESULTS SHOWN THAT THE EQUIPMENT CAN MEASURE PRECISELY THE WALL THICKNESS WITH RESOLUTION BETTER THAN ±0.1MM AND CAN IDENTIFY CRACKS AS SMALL AS THOSE OF 0.4MM DEPTH AND 0.4MM WIDE. KEYWORDS: ULTRASOUND, NON DESTRUCTIVE EXAMINATION, EXAMINATION OF INDUSTRIAL GAS CYLINDER, AUTOMATIC INSPECTION, GAS CYLINDER

Author :

Adamowski, Julio Cezar
Buiochi, Flávio 0
Furukawa, Celso Massatoshi

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