Millwright Level 1 Practice Exam

What are the two types of tapered thread forms?

1. NPT and NPTF

2. UNC and UNF

3. BSP and NPT

4. 16 TPI and 18 TPI

The correct answer is: NPT and NPTF

Tapered thread forms are essential in creating pressure-tight seals in piping systems, and the two types are NPT (National Pipe Tapered) and NPTF (National Pipe Tapered Fuel). Both of these are designed for use in applications where they need to create a secure and leak-proof connection without the need for additional sealing materials. NPT threads are commonly used in plumbing and hydraulic systems, and their design incorporates a taper that provides a mechanical seal as the threads are tightened. NPTF threads, although similar in shape, are designed to provide a tighter seal and are often used in fuel applications, reducing the risk of leaks in critical situations. The other options do not represent tapered thread forms. UNC (Unified National Coarse) and UNF (Unified National Fine) are straight thread forms used primarily in screws and bolts, not for achieving a tight seal in piping systems. BSP (British Standard Pipe) is a different standard used in the UK and other nations, encompassing both tapered and parallel threads but is not classified under the same thread forms as NPT and NPTF. The mention of TPI (Threads Per Inch) refers to how many threads are present within an inch of length, which is a measurement characteristic but does