Quote from a book about tubing for reference:
"It is often necessary to choose between tubing and small diameter piping. Where
mechanical damage is not a hazard, tubing offers several advantages. It is faster and
less expensive to form and install tubing than to fit up threaded or socket weld
piping; tubing has less mass and therefore undergoes less stress at connections in
vibrating service; and in most systems it has fewer connections, and therefore fewer
potential leaks. Tubing is not recommended for process service. The most common
services are instrument air, utilities, instrument process leads, and steam tracing."