Machinist Inc. Now Offers Helium Leak Testing

Often times in business, a unique opportunity presents itself. In this case, that unique opportunity involved a process called helium leak testing.

For years, Machinists Inc. had been subcontracting helium leak testing to another firm. But once the other firm stopped offering the service, Machinists jumped at the opportunity to offer their own helium leak testing, for customers like Lawrence Livermore Labs, so they would not have to send it to some other place in the U.S. to be processed.

"We do leak testing in chambers we are building for high tech companies. These are high end vacuum type chambers where specific tests are performed, including laser testing," said Jeff Tomson, Machinists Inc., director of marketing. "All the welds and all of the assemblies, ports, everything on this chamber have to be leak tight."

The helium leak testing is typically used in an environment of very high vacuum. It is a chamber where the vacuum is being pulled down, so it has to be free of any contaminants or interfering gases. This allows you perform test for various products.

The chamber itself has be leak tight.

"No contaminants can be introduced during the vacuum pull down process. For our client, Lawrence Livermore Labs, we use a large diagnostic chamber with various types of testing media inside," Tomson said. "The test media is then pushed out into the laser testing stream."

Hydrogen is the smallest atom, but because hydrogen forms diatomic molecules (which helium doesn't do), helium "molecules" are smaller. That is why helium is used in leak detection in vacuum systems. When you pull the vacuum, the helium leak detector, a Varian system, is inline with the vacuum system.

"You go around with helium gas and allow it to flood the areas of weld or the gasket outside the chamber. So if there was a leak, it would pull the helium through the weld or through an O-ring and it would show up on the test equipment," Tomson said.

The chamber is used for various filters and equipment used in the laser testing process. It has to be perfectly clean, with absolutely no contaminants. There can't be any erroneous leaks in the overall test, performed in a full vacuum.

Now that Machinists Inc. has the service, Tomson figures they will be leak testing several times a year and more in the future, once people know they offer it.

"Typically a leak tester is fairly unique, but it is used in the aerospace and spacecraft industry quite often," Tomson said. "Testing the integrity of the welds on chambers and integrity of the welds on anything that would hold pressure or vacuum. It is critical that you know its not going to leak before you start testing it."

For more information contact Jeff Tomson, Machinists Inc., 206-763-0990 -

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