Development of system and materials for detecting leaks in cocoon protective coatings are discussed. Method of applying materials for leak determination is presented. Pressurization of system following application of materials will cause formation of bubble if leak exists

Hauser, R. L.

Kochansky, M. C.

English

NASA Technical Reports Server

July 1972	 B72-10380 
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 Office, NASA, Code KT, Washington, D.C. 20546. 
Expandable Coating Cocoon Leak Detection System 
A new leak detection method involves wrapping a 
Parafilm tape over a connection or weld and then coat-
ing the tape with a sealing compound. If a leak is pre-
sent, the coating and tape will blister or bubble. The 
tape and coating solution are applied according to the 
following procedure: (1) A strip of Parafilm tape is 
pulled tightly against the tubing at one edge of the separ-
able connector at least 2 mm beyond threads, insert, or 
nut. (2) The short end of the tape is pulled tightly against 
the tube, and then it is folded toward the nut. The first 
. wrap of the tape covers this short end. (3) The tape is 
wrapped around nut and threads and pulled tightly into 
a helical pattern with at least 3-mm overlap for each 
turn. (4) The tape is pulled tightly as it makes the tran-
sition between nut and thread diameter. The tape is 
terminated at a distance 3-4 mm beyond the last thread 
or insert. Termination is accomplished by stretching the 
Parafilm tape and breaking it at the tube. (5) The Para-
film tape wrap is now inspected to insure that a com-
plete "mummy wrap" exists with no voids. 
Void volume within the Parafilm tape wrap must be 
minimized. To do this, the bundle of elastic threads is 
wrapped around the fitting at threads, inserts, bridges, 
or any place where the film is not in close contact with 
the hardware. The tape is again inspected to insure that 
there is a complete, void-free envelope. A smooth brush 
coat of a coating solution is applied over the Parafilm 
tape, extending 2-3 mm onto the tubing or fitting. After 
a two to three hour dry, a second brush coat of solution
is applied. After the coating has dried 12 to 16 hours, 
it should be inspected to insure that complete coverage 
has been obtained and to insure that the edges of the 
Parafilm tape have been sealed by the coating. During 
or after system pressurization, the expanded bubble is 
inspected by both sight and touch. If the bubble is not 
obvious, a finger can discern whether the film has lifted 
from the hex nut of the separable connector. 
Note: 
Requests for further information may be directed to: 
Technology Utilization Officer 
Code A&TS-TU 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B72-10380 
Patent status: 
Inquiries about obtaining patent rights for the com-
mercial use of this invention may be made to: 
Patent Counsel 
Code A&TS-PAT 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Source: R. L. Hauser and M. C. Kochansky of
Hauser Laboratories
under contract to

Marshall Space Flight Center 
(M FS-2 1848) 
S
Category 06 
This document was prepared underthe sponsorship of the National
	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	 will be free from privately owned rights.
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Expandable coating cocoon leak detection system

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