pressure hose is the connection of the hose to the fitting. Another disadvantage of hoses is the shorter life of rubber which requires periodic replacement, usually at five to seven year intervals. Tubes and pipes for hydraulic n applications are internally oiled before the system is commissioned. Usually steel piping is painted outside. Where flare and other couplings are used, the paint is removed under the nut, and is a location where corrosion can begin. For this reason, in marine applications most piping is stainless steel. Seals, fittings and connections Components of a hydraulic system [sources (e.g. pumps), controls (e.g. valves) and actuators (e.g. cylinders)] need connections that will contain and direct the hydraulic fluid without leaking or losing the pressure that makes them work. In some cases, the components can be made to bolt together with fluid paths built-in. In more cases, though, rigid tubing or flexible hoses are used to direct the flow from one component to the next. Each component has entry and exit points for the fluid involved (called ports) sized according to how much fluid is expected to pass through it. There are a number of standardized methods in use to attach the hose or tube to the component. Some are intended for ease of use and service, others are better for higher system pressures or control of leakage. The most common method, in general, is to provide in each component a female-threaded port, on each hose or tube a female-threaded captive nut, and use a separate adapter fitting with matching male threads to connect the two. This is functional, economical to manufacture, and easy to service. Fittings serve several purposes; To join components with ports of different sizes. To bridge different standards; O-ring boss to JIC, or pipe threads to face seal, for example. To allow proper orientation of components, a 90°, 45°, straight, or swivel fitting is chosen as needed. They are designed to be positioned in the correct orientation and then tightened. To incorporate bulkhead hardware to pass the fluid through an obstructing wall. A quick disconnect fitting may be added to a machine without modification of hoses or valves A typical piece of machinery or heavy equipment may have thousands of sealed connection points and several different types: Pipe fittings, the fitting is screwed in until tight, difficult to orient an angled fitting correctly without over or under tightening. O-ring boss,