Don't feel alone John, I confuse myself all the time!

What I was getting at is to look at the fitting and the tubing separately. Swagelok is a tube fitting that is generally approved for copper, stainless steel, aluminum, PE, etc. tubing for all sorts of applications from fuel gas to heating oil to corrosive industrial compounds to medical gases to all sorts of stuff. One common application is on anodeless risers on PE tubing coming from the street out of the ground up to a meter.

IFGC 403.4.4 deals with aluminum. Aside from all the other caveats for this tubing, it states," Aluminum-alloy pipe shall not be used in exterior locations or underground." It also must be "coated to protect against external corrosion where it is in contact with masonry, plater or insulation or is subject to repeated wettings by liquids such as water, detergents, or sewage."

The Commentary reads:"Aluminum pipe is not commonly used for gas service. Because aluminum is a fairly reactive metal, it corrodes readily when exposed to a variety of materials and the environment."

Even stainless steel has its limits and depends a lot on the alloy.

Does this clarify things any?

__________________
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IAFCI Regional Director & Certified Fireplace Inspector
Certified Master Hearth Professional & HPBA BoD