System detects defects of .051 cm in diameter and larger. System incorporates scanning head assembly including boot enclosed transducer, slip ring assembly, drive mechanism, and servotransmitter. Ultrasonic flaw detector, prototype recorder, and special recorder complete system

Haralson, H. S.

Haynes, J. L.

Wages, C. G.

English

NASA Technical Reports Server

July 1971
	 Brief 71-10227 
NASA TECH BRIEF 
Marshall Space Flight Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the. Tech Brief program may 
be directed to the Technology Utilization Off ice, NASA, Code KT, Washington, D. f. 20546. 
Ultrasonic Scanning System for In-Place Inspection of Brazed-Tube Joints 
A miniaturized ultrasonic scanning system can be 
used for the in-place inspection of 0.635 through 
1.59 cm diameter (1/4 in. through 5/8 in. diameter) 
Ultrasonic sducer 
Search 
WheelFluid	 Transducer
Rubber Boot   Case
rubber boot designed to conform to contour variations 
in the tube joint: The focused energy is transmitted 
through the liquid into the tube joint and is re-
flected from the inner or back surface of the tube 
wall. Because of a discontinuity in the path of the 
ultrasonic wave, a loss of ultrasonic energy from 
the back surface of the tube wall is an indication 
of a defective brazed area. 
Sealing Band	
Dotter 
Braze Line
	 Output	 Input 
Tube 0.0
Tube I.D.
	 Input	 Output 
Figure 1. Transducer Position on Tube, Schematic 
brazed joints, with limited access clearances, in union, 
tee, elbow, and cross configurations. Tests performed 
on tube joints containing preplaced defects show that 
defects of 0.051 cm (0.020 in.) in diameter and larger 
can be reliably detected using this system. 
Figure 1 illustrates the basic principle of the ultra-
sonic technique employed. Ultrasonic energy from the 
transducer is focused into the tube under inspec-
tion. The transducer is sealed in a liquid-filled flexible
Recorder	 Ultrasonic 
and	 Flaw 
Control Chassis
	 Detector 
Limit
Scanning Head
	 Jlip Ring Switch 
Assembly and 
Servotran sm itter 
Figure 2. Scanning System, Block Diagram 
The system incorporates a scanning head assembly 
which includes the boot-enclosed transducer, a slip 
ring assembly, a drive mechanism, and a servo-
transmitter. A commercially available ultrasonic flaw 
detector, a prototype recorder, and a special recorder 
accessory complete the system (Figure 2). The scan-
ning head assembly provides the X-Y scan move-
ment across the area under inspection. The drive 
mechanism revolves and translates the transducer along 
I coiilruiticd in crlc:uI I 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned .rights.
https://ntrs.nasa.gov/search.jsp?R=19710000226 2020-03-17T02:20:24+00:00Z
the tube, thus generating a continuous helix. One 
revolution of the transducer corresponds to one X-
scan pass, and its translation along the tube is the 
Y-travel, as in conventional X-Y scanning modes. 
Transmit-receive signals flow between the transducer 
and ultrasonic flaw detector by means of the slip 
ring assembly. 
The servotransmitter tracks the revolution of the 
transducer around the tube and synchronizes one rev-
olution to one "X" pass of the recorder C-scan 
printout. The recorder, which provides a developed 
plan view (C-scan) of the braze-line conditions, is 
different from conventional facsimile recorders in 
that the drum containing the helically wound print 
wire rotates continuously in one direction, rather than 
reversing for each X-scan. With the special recorder 
accessory called the "dotter," the recording back-
ground is a series of low-intensity (brown) dashes, 
and braze-defect indications print out as dark (black) 
lines. The brown-dash background prevents the residue 
buildup associated with conventional C-scan recordings 
and provides increased resolution. 
For each tube size, a front and rear alignment 
plate is used to position the joint under test in the 
center of the scanning head. To test a tube joint, 
the scanning is placed on a standard tube joint 
containing preplaced defects of known size, and the 
alignment plates are adjusted to locate the joint in the
center of the head. The limit switches are adjusted 
for the required scan coverage; the transducer posi-
tion is adjusted for proper focus; and the instrument 
is peaked to indicate a defective condition. The scan-
ning heat can now accept and test tube joints of the 
same size as the standard joints. 
Note: 
The following documentation may be obtained 
from:
National Tech nical.lnformation Service 
Springfield, Virginia 22151 
Single document price $3.00 
(or microfiche $0.95) 
Reference: 
NASA-TM-X-64558 (N70-42932), Develop-
ment of Ultrasonic Scanning System for 
In-Place Inspection of Brazed Tube Joints 
Patent status: 
No patent action is contemplated by NASA. 
Source: J. L. Haynes, C. G. Wages, and

H. S. Haralson of

Spaco, Inc.

under contract to

Marshall Space Flight Center

(MFS-21 166) 
Brief 71-10227	 Category 02,06


Ultrasonic scanning system for in-place inspection of brazed-tube joints

Ultrasonic scanning system developed for in place inspection of brazed tube joint

Ultrasonic scanning system for in-place inspection of brazed-tube joints

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server

NASA Technical Reports Server