Test procedures and results are given for three types of semipermanent sleeve-type connections for stainless-steel tubing. Subject to the limited resistances to corrosion and vibration, all three types are found to be suitable for extremes in reliability and environment, if given close control during manufacture

Cahill, J. B.

English

NASA Technical Reports Server

NASA TECH BRIEF 
Type GB -	 Braz?ng Filler
°'re Weld 
September 1970
	 Brief 70-10417 
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 Clearinghouse for Federal Scientific and Technical 
Information, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
Testing of Brazed and Welded Connections of Stainless-Steel Tubing 
Three types of semipermanent sleeve-type connec-
tions for stainless-steel tubing (see fig.) were tested 
comprehensively; outside diameters ranged from 0.25 
to 1.5 in. (see documentation). Type-NW was TIG- 
welled by NASA; types AB and GB were brazed 
(80% Au-20% Ni) by two of its contractors. The 416 
specimens underwent 2395 tests. 
Specimens were subjected to: (1) 180 days of in- 
termittent immersion in 3.5% solutions of NaCl; (2) 
proof pressure testing at a delivery pressure of _<8000 
lb/in 2 (350 specimens; no failures); (3) leak testing 
(348 specimens; no failures); (4) 2-yr storage on a 
rooftop (66 specimens; no failures); (5) long-term 
pressurization with gaseous nitrogen (194 specimens; 
no failures); (6) submersion in liquid nitrogen while 
pressurized with He at 3000 lb/in 2 (194 specimens; 
no failures); (7) baking at :5600°F while pressurized 
with He (193 specimens; no failures); (8) 300,000-
cycle vibration stressing at 500 0 , 700 (18,000 to 22,500 
lb/in), and -320°F (26,500 to 33,200 lb/in); (9) im-
pulse testing (194 specimens; no failures); (10) tensile 
tests (prior vibration had no effect); (11) metallo-
graphic examination; and (12) burst testing at from 
125 to 30,000 lb/in 2 (141 specimens; no failures). 
Only types AB and GB were corroded by salt water, 
at the interface between the brazing alloy and the 
sleeve or tubing; two of 19 AB specimens subsequently 
leaked. More-closely controlled manufacture may 
permit increase in the tabulated allowable limits for 
resistance to vibration. Vibration caused some hard-
ening, and some cracks developed near changes in 
cross section. In all instances the tensile specimens 
failed under stresses lower than the averages for one-
piece tubes; the scatter may be attributable to var-
iables in manufacture.
After Weld 
I YPW FLJ 
Three Types of Connection 
The metallographic examination disclosed various 
faults including improper depth of insertion of the 
tubing into the sleeve, improper clearance between 
tubing and sleeve, improper flow of brazing alloy, 
and nonuniform or off-center welding seams. The fact 
that some such faults are ot readily detectable in the 
finished joints necessitates close control during man-
ufacture. 
Subject to the limited resistances to corrosion and 
vibration, all three types are suitable for extremes in 
reliability and environment, given close control during 
manufacture. 
Notes: 
1. The aircraft industry, mechanical, marine, and 
refrigeration engineers, and manufacturers of tub-
ing may be interested.
(continued overleaf) 
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=19700000402 2020-03-17T00:46:39+00:00Z
2. The following documentation may be obtained 
from:
Clearinghouse for Federal Scientific 
and Technical Information 
Springfield, Virginia 22151 
Single document price $3.00 
(or microfiche $0.65) 
Reference: 
NASA-CR-613 10 (N70-11363), Inves-
tigation of Brazed and Welded Connec-
tions
Patent status: 
No patent action is contemplated by NASA.

Source: J.B. Cahill of

Brown Engineering Company

under contract to

Marshall Space Flight Center

(MFS-20806) 
Brief 70-10417
	 Category 08


Testing of brazed and welded connections of stainless-steel tubing

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