piping/insulation material incompatibility 1

[NIWEngineer]

Hey all,
I posted this over in the HVAC forum but got nothing.

Do you know if there is a standard, recommended practice, or other accepted reference stating the the MEP of record should check for material incompatibility between piping and insulation?

Specifically, closed cell rubber foam insulation and copper pipes. The hypothesis is that when brazing a joint of the copper pipes, the insulation in the nearby straight sections heats up from the torch to the point where ammonia is released. Ammonia and copper don't mix nicely.

 

[JohnBreen]

There may be many such material dependent considerations (you might want to Google piping and insulation - also there is a National Insulation Association Internet site).

For example, you want the insulation on Stainless steel piping to be free of chlorides.

From

http://www.mcnallyinstitute.com/04-html/4-1.html

"........The basic resistance of stainless steel occurs because of its ability to form a protective coating on the metal surface. This coating is a "passive" film which resists further "oxidation" or rusting. The formation of this film is instantaneous in an oxidizing atmosphere such as air, water, or other fluids that contain oxygen. Once the layer has formed, we say that the metal has become "passivated" and the oxidation or "rusting" rate will slow down to less than 0.002" per year (0,05 mm. per year).

Unlike aluminum or silver this passive film is invisible in stainless steel. It's created when oxygen combines with the chrome in the stainless to form chrome oxide which is more commonly called "ceramic". This protective oxide or ceramic coating is common to most corrosion resistant materials.

Halogen salts, especially chlorides easily penetrate this passive film and will allow corrosive attack to occur. The halogens are easy to recognize because they end in the letters "ine". Listed in order of their activity they are:

* fluorine
* chlorine
* bromine
* iodine
* astatine.

These are the same chemicals that will penetrate Teflon and cause trouble with Teflon coated or encapsulated o-rings and/ or similar coated materials. Chlorides are one of the most common elements in nature and if that isn't bad enough, they're also soluble, active ions; the basis for good electrolytes, the best conditions for corrosion or chemical attack..................."

 

[PEDARRIN2]

You have two issues - material compatibility and incorrect brazing operation.

To me there is no issue with using closed cell insulation with copper pipe from a material compatibility perspective.

However, the operation described has a problem. If the soldering/brazing operation is causing the insulation to degrade (emit ammonia), there is a problem with how the operation is occuring. It sounds like more of the insulation should be removed so that it is not as close to the hot metal.