SIS Manufacturing--Welding and Brazing Shops

The SIS shops have the capability to do TIG welding, soldering, brazing and small parts spotwelding. Our shops consist of several TIG systems for the precision weling of stainless steel parts for vacuum systems as well as other applications. We also have a high sensitivity Alcatel leak detector to test all welds to assure that they are vacuum tight for low pressure vacuum applications. We also do small precision brazing of metals as well as some glass with our micro brazing equipment.

Welding and Brazing Capabilities at SIS

Our shops use a variety of techniques to join various metals together as described below. One of the most popular techniques used for many scientific instruments is silver soldering. We use silver soldering to join metals such as stainless steel, copper and brass. This technique it used to repair gas transfer lines on GC injection ports and to repair mass spec sources. However parts that are silver soldered have an upper temperature limit of around 450 degrees C.

For higher temperature applications and for vacuum sealing of instrument parts such as mass spec flanges the technique of choice is Tungsten Inert Gas (TIG) welding. This technique involves the fusing of metal surfaces in an inert atmosphere. The resulting weld is very strong, vacuum tight and usable at high temperatures.

When welding is done on parts used for vacuum applications, all welds are tested in our facilities using a Helium leak tester. This instrument is actually a mass spectrometer tuned to detect helium gas. It can detect the smallest leaks in welded joints and feedthroughs.

TIG Welding

Tungsten Inert Gas (TIG) welding is the preferred welding technique for repairing and manufacturing vacuum components. The technique utilizes an electric arc in an inert Argon atmosphere to join stainless steel components. We repair transfer lines, replace bellows and feedthroughs on flanges, as well as making manifolds and other parts with this technique.

Vacuum feedthroughs replaced on a 6" flange. We can also custom make vacuum flanges with various feedthroughs.

Our large capacity TIG welder is capable of welding complete vacuum chambers and can also be used to weld aluminum.

Movable transfer lines can be completely repaired using TIG welding and brazing techniques

The bellows on the Finnigan MAT 8200 series mass spectrometers can be replaced with a new welded style bellows for longer life.

Vacuum Testing

After TIG welding the welds should be tested to assure that they are leak tight. AT SIS we use an Alcatel ASM182T Leak detector to test all of our vacuum welds down to assure that the welds will not leak even at very low vacuum levels. All vacuum fittings that are TIG welded and brazed in our shops are leak tested before they are returned to our customers. Shown below is the new helium leak tester which can detect leaks down to 2 x 10-11 atm.cc/sec. This leak detector utilizes a rugged turbo pump design for fast pump down and superior performance. If you have parts which you feel may be leaking, give us a call and we can test them for you.

Leak testing the internal metal bellows on a Finnigan MAT GC/MS transfer line.

Brazing and Silver Soldering

S.I.S. also provides high temperature silver soldering of parts where TIG welding can not be utilized. Silver soldered joints have a maximum use temperature of 450 degrees C. All joints are helium leak tested and thoroughly cleaned.