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what is the smallest size of type m copper tube available
The smallest m copper tubing available is 1/4.
what is copper tubing used for
Copper tubing is most often used for heating systems, and as a refrigerant line in HVAC systems.
does copper tubing have a weakness
Copper water tubes are susceptible to cold water pitting caused by contamination of the pipe interior, erosion corrosion caused by turbulent flow, and stray current corrosion.
what are the types of copper tubing
There are two basic types of copper tubing, soft copper and rigid copper.

Question: what is replacing the tubing
Self-contained rewrite: what is replacing copper tubing