A system has been designed to reduce the hydrogen molecule content in inert gases that are used for shielding the welding arc and molten weld area during the manual fusion, automated welding, and induction brazing process. Two desiccant pipeline dryer cartridges are connected together using either aircraft or KC .250 fittings, and are installed in-line between the inert-gas facility source (argon and helium) and the welding machine. This process helps maintain alloy grain structure and integrity to engineering specifications during the welding and brazing processes. Also, this method enhances weldability when joining similar and dissimilar alloys. It is easy to restore the system to original drying capabilities by using a nitrogen purge or by oven drying. This design has low schedule impact or down time when being installed on machines or in systems. There is also a sight glass to indicate when servicing is needed.

Reducing the moisture level in ultra-high-purity gasses also lowers costs. The total cost of the system described here was less than $1,000 (at the time of this reporting). It has been in operation for 4.5 years with no maintenance or drying. The last test of the system indicated the gas moisture level was less than 2 ppm, with a dew point of less than –97 ºF (–72 ºC). Before the line dryers were installed, the inlet gases had a moisture rating of 15 ppm. With the installation of a one-canister system, the inert gas moisture level dropped to 3 ppm. When a two-canister system was installed, the inert gas moisture level dropped to 0.7 ppm.

These two pipeline dryers also act as a mixing chamber for both argon and helium gases, which is crucial for applications of certain critical welding processes. This innovation is applicable to any process or system that requires a reduction of any inert gas moisture level (in ppm). It may also be used in any process or system, such as avionics, that uses inert gases with a low moisture level requirement of 1 ppm or lower, depending on the cubic feet per minute (CFM) flow rate.

This work was done by Jerry Goudy of United Space Alliance for Kennedy Space Center. KSC-13189

NASA Tech Briefs Magazine

This article first appeared in the August, 2009 issue of NASA Tech Briefs Magazine.

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