13. When tightened, dry seal threads A. are crushed to make a leakproof seal. O B. compress an O-ring to prevent leaks. O C. can be easily loosened and tightened again. D. make a 45-degree flare in the tubing.

2. UNC thread diameter D=3/4 in. Number of threads/in N= 10 Calculate: a. Pitch, b. Width of the flat, c. Depth of the thread, d. Minor diameter e. Pitch diameter, f. Tap drill size, g. Helix angle

Note National Hardware 15G wire nail bright finish to the right. Use the concept of pressure to describe how the nail is designed to connect wooden boards.

Hydraulic hose couplings do not seal on their connecting threads. They seal on the mating of two surfaces (male & female). What is the common seal angle of these surfaces? 47 degrees   23 degrees   None of these   37 degrees   Varies by tube diameter