Mechanical Fundamentals II.txt

A chemical reaction. The action process, or eating away (corroding) due to chemical reaction.

The action process, or eating away (eroding) due to mechanical action. Most condenser areas condenser flows.

• Any two pieces which are not parallel, or straight, when connected.
• Also applies to improper valve, or system alignment.

Two types of misalignment are: parallel, and angular.

The comparison of any measuring device / instrument with a set standard.

The removal of impurities from a fluid.

The natural frequency an item will vibrate at, based on its material, length, and thickness. Noticed greatly when bringing up a chiller. The vibration while bringing up to the governor.

A device used to connect parts of machinery, or pipes together. Made up of 2 halves, a male and a female. Each piece is welded, soldered, or threaded together. They require no gasket and are easily taken apart.

Another way of connecting 2 pieces of piping together. Made up of 2 flat disks that are threaded, welded, or soldered to the pipe, then bolted together. They require a gasket to prevent leaks and are easily taken apart to allow removal of the pipe.

Used where pipes tend to expand and contract. (Steam lines) Flexible so they will not break. They are placed between solid hangers.

Allow the connecting of two pipes like unions and flanges. A coupling is made up of 1 solid piece. The two pipes are threaded, soldered, or welded into the coupling. Does not allow for easy separation.

Used to reduce the (step-down) pipe size. There are concentric and eccentric reducers available. Concentric reducers step down in uniform increments like a cone. Eccentric reducers will have the reduced portion off to one side.

Screws into the end of a pipe to plug it.

Screws, soldered, or welded on the outside of the pipe to cap it

Used to blank off a line. Must be ASME approved rated by pressure.

A blind flange inserted between 2 flanges to isolate a system. Must be ASME approved

• Tubing is measured by outside diameter.
• Piping is measured by inside diameter.

Uses a liquid that can be seen by a black light. Spray the penetrant on the surface; wipe off excess, spray on the developer. Use a black light; the developer will cause the penetrant to glow. Finds surface cracks.

Sprinkle iron fillings on the area to be inspected. Place the magnetic field to the surface, the filings will line up along surface cracks.

Sound waves reflect of the internal thickness of the surface. Can check wall thickness and large defects.

Uses X-ray machine to find internal and external cracks. Hazardous.

The leading edges of the teeth are not parallel to the axis of rotation, but are set at an angle. Since the gear is curved, this angling causes the tooth shape to be a segment of a helix.

Helical gears can be meshed in a parallel or crossed orientations. The former refers to when the shafts are parallel to each other; this is the most common orientation. In the latter, the shafts are non-parallel.

• Spur gears or straight-cut gears are the simplest type of gear because the edge of each tooth is straight and aligned parallel to the axis of rotation.
• These gears can be meshed together correctly only if they are fitted to parallel axles.

An Internal Spur Gear, similar to a regular spur gear. However, with an Internal Spur Gear, the gears make internal contact.

External spur gears are cylindrical gears with straight teeth parallel to the axis.

They are used to transmit rotary motion between parallel shafts and the shafts rotate in opposite directions.

They tend to be noisy at high speed as the two gear surfaces come into contact at once.

Worm gears resemble screws. A worm gear is usually meshed with an ordinary looking, disk-shaped gear, which is called the gear, wheel, or worm wheel.

A bevel gear is shaped like a right circular cone with most of its tip cut off.

When two bevel gears mesh their imaginary vertices must occupy the same point. Their shaft axes also intersect at this point, forming an arbitrary non-straight angle between the shafts. The angle between the shafts can be anything except zero or 180 degrees.

Bevel gears with equal numbers of teeth and shaft axes at 90 degrees are called miter gears.

The length of the used bolt may be Necked (or Stretched) out.

You can thread on a new nut to see if it accepts it without difficulty.

Finally you can compare thread pitch between new and used.

Torque values normally are based on dry bolts. If lubrication is added, reduce the torque approximately 30%.

Use the torque chart for wet torque.