It's a standard to decrease the cost of fabrication.
you can choose the better sch for your uses, depend of :
_ the pressure inside the pipe
_ life time and corrosion
_ mechanical stress
_ ...
20, 40 and 80.
pipe schedule is an American definition to define pipe thickness and how much pressure can the pipe stand, schedules are 10,20,40,80.., pipe schedule is nearly close to the eurobian definition for pipe class.
Schedule 10 , 40 and 120
Clay pipe, Bricks, Asbestos cement, Cast Iron various schedules , preformed pipe and concrete forms (ducts)
That is the correct spelling of pipe, which has a number of uses.
Compression uses a ferrule or brass ring around the pipe that is compressed by the nut into the pipe and against the fitting. There is no such thing as Female Pipe Threads. There are Male and Female fittings, the pipe is the Male side and the fitting is Female. The Male goes inside of the Female. They both have pipe threads. Pipe thread, Compression, and Flare all have different thread pattern so that they cannot be mixed. They all do different jobs.
There are currently 41 different schedules listed at http://www.gsaelibrary.gsa.gov/ElibMain/home.do.
To study different subjects at different time.
The Man in the Brown Suit
Yes
Some uses for a half pipe would be in reference to sporting competitions. Snowboarding, skateboarding and BMX bike competitions all utilize the half pipe to perform tricks.
NFL schedules for 2013 can be found from many different resources. The most reliable resource for NFL schedules is directly from the official NFL website.