There are many available types of pipe for the pipefitting trades. I've worked with all of them. From black steel to blue brute underground piping, you name it and I've installed it at one time or another around the Los Angeles area. While you may think if you have seen one type of pipe then you have seen them all, think again. The wrong pipe installed in the wrong location can spell financial and structural disaster in just a few short months.
Black Steel - the standby for sprinkler and gas lines. This type of pipe is available in varying wall thickness, called "schedule". The standard thickness for black steel pipe is schedule 40, which is more than enough steel to allow for machine threading. Black Steel piping can never be used for water supply lines; it is used primarily for gas lines and for automatic fire protection systems.
In recent years, the high cost of steel has spawned a thinner schedule pipe that is less expensive to manufacture but still allows for machine threading. While the thinner schedule piping can significantly save on material costs (especially when installing a new system in a high-rise building or equally large structure), there have been many instances when the thinner piping could not handle machine threading and ultimately had to be uninstalled due to leaks or pipe ruptures.
Most contractors (and installers) prefer to use schedule 40 pipe even though it is more expensive to purchase. The lower schedule (thinner) piping is perfectly fine for machine-grooved installations that require the use of mechanical couplings.
PVC Plastic - Most common piping used for drain lines inside and outside of the house. This type of piping is easy to work with and can seemingly last forever. When used on supply lines, extra care must be taken during installation because PVC joints have been known to fail during prolonged use under pressure.
CPVC (chlorinated polyvinyl chloride) - CPVC has proven itself as a replacement to copper piping. It can handle high supply pressure, is easy to install, is immune to aggressive water that would otherwise eat through copper piping, and can handle 180 degree water temperature.
CPVC is substantially less expensive when compared to purchasing and installing copper piping. When working within your house, CPVC is by far the easiest piping to work with. However, not all cities have adopted CPVC for residential use. Check with your local planning department to find out if this type of piping is approved for use in your city.
Galvanized Steel - well known for being the strongest piping available for supply lines, Galvanized steel requires special threading dies and cutters. In the mid 90's, I installed an entire Galvanized steel sprinkler system for a 3,000 square foot office in Beverly Hills. Our fabricator mistakingly used the wrong dies for threading the pipe. The result: leaks, leaks, and more leaks!
The system had over 100 leaks throughout the suite and we worked for weeks to try to fix each individual leak before realizing the error had been made by the fabrication company. Eventually, we had to tear the system out and completely reinstall it with black steel piping.
Copper Pipe - This is the most common piping used for supply lines. It is available in both rigid and flexible format. Copper Piping can be connected by two different methods: soldering and compression fittings. The better piping will require soldering.
Ductile Iron Pipe - This is the ideal choice for high pressure, underground water supply lines. It is stronger and easier to tap into for future water supply. Compared to other piping made from other materials, it requires much less support and provides a better flow of water.
Those are the primary types of piping available to fire sprinkler fitters, plumbers, and steam fitters. Each trade has its own preferred (and often required) type of piping. And every pipe type requires special tools and skills in order to cut, prepare, and install.
Interested in working with pipe for a living? The pay is great and work is always plentiful. Check with your local pipefitters union to learn more about your local pipe trades.