Electroplating method seals brazed or welded joints against gas leakage under high pressure. Any conventional electroplating process with many different metal anodes can be used, as well as the build up of layers of different metals to any required thickness

Leigh, J. D.

English

NASA Technical Reports Server

September 1966	 Brief 66-10415 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U. S. space 
program and to encourage their commercial application. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Electroplating Eliminates Gas Leakage in Brazed Areas 
Anodes 
Electroplating 
Bath 
Metal Electroplated 
On Brazed Areas To 
Form a Gas Seal 
.Support
Brazed 
Areas 
Base
Plug Seal 
Thrust 
Chamber
SECTION OF A THRUST 
CHAMBER TUBEWALL 
The problem: 
To develop a method for sealing brazed or welded 
joints against gas leakage under high pressure. Large 
liquid fueled rocket engines are conventionally 
fabricated by brazing together lengths of metal tub-
ing. During firing operations the thrust chamber is 
kept cool by fuel pumped through the tubes that 
form the wall structure. One serious drawback of this 
type of structure is gas leakage through minute holes 
in the brazed areas between the tubes which can 
occur during firing operations. 
The solution: 
Electroplate the throat area of the thrust chamber 
to seal it against gas leakage.
How it's done: 
A liquid-tight plug is placed securely in the base 
of the throat of the thrust chamber, and the throat is 
then filled with an electroplating solution. A direct 
current is applied to the metal anodes and the metal 
tubewall structure serves as the cathode. Metal may 
be deposited to any required thickness on the brazed 
areas to form a seal against gas leakage. During tiring 
operations, the brazed areas of the thrust chamber 
usually reach a temperature of 600'F to 8001F, which 
is well below the melting points of the electroplated 
seals. 
Notes: 
1. Any of the following metal anodes can be used in 
this process: copper, nickel, chromium, tin, silver, 
and gold.
(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=19660000414 2020-03-11T17:36:47+00:00Z
2. Any conventional electroplating process can be 
used. A typical process for plating nickel would use 
nickel anodes to plate the brazed areas between 
the tubes of the thrust chamber. The electrolytic 
solution would consist of: 
NiSO4.7H20	 32 parts 
NiCl2.6H20	 2 parts 
H2B03	 4 parts 
pH	 6±0.2 
Bath Temperature	 1250F±5° 
Cathode current density 20 amp/ft2 
Areas of tubing can be sealed off with adhesive 
insulating tape or coating to limit the deposition 
of metal to the brazed areas. Several layers of dif-
ferent metals can be plated on the brazed areas 
and built up to any required thickness to form a 
seal.
4. This method can be used to seal welded seams on 
metal gas tanks and/or liners as well as joints in 
metal tubes and fittings. 
5. Inquiries concerning this innovation may be di-
rected to:
Technology Utilization Officer 
Marshall Space.Flight Center 
Huntsville, Alabama 35812 
Reference: B66-10415 
Patent status: 
No patent action is contemplated by NASA. 
Source: John D. Leigh 
of North American Aviation, Inc. 
under contract to 
Marshall Space Flight Center 
(M-FS-923) 
Brief 66-10415	 Category 05


Electroplating eliminates gas leakage in brazed areas

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