Piping Hints for Hydraulics

Iron and steel pipes were the first kinds of plumbing used to conduct fluid between system components. At present, pipe is the least expensive way to go when assembling a system. Seamless steel pipe is recommended
for use in hydraulic systems with the pipe interior free of rust, scale and dirt.

Early classifications of pipe wall thicknesses were: standard, extra heavy and double extra heavy.

Today, pipes are classified by schedule number as specified by the American National Standards Institute (ANSI). The schedule numbers vary from 10 through 160. The larger the number, the heavier the wall thickness. The outer pipe diameter stays the same for a given pipe size, while the inside opening becomes smaller as schedule number increases.

A comparison of early classifications versus the ANSI classification follows:
  Standard – Schedule 40
  Extra Heavy – Schedule 80

The double extra heavy classification does not compare with a schedule number. However, the inside diameter of a double extra heavy pipe is approximately one half that of a schedule 160 pipe.

In many cases, flanges are welded to the pipe ends and gaskets or “O” rings are used to seal the connections.
Various pipe fittings are used to route the piping to and from each system component. These fittings can be
threaded or welded in place as the need arises. Threaded connections are used in low pressure applications and welded connections are used if high pressure, high temperature, or a severe mechanical load exists.

All piping should be secured with clamps to prevent vibration and excessive stress due to the weight of the fluid. Do not weld the clamps to the pipe as it may weaken the pipe and cause a stress crack.