Hex plugs are used to stop fluid movement in the piping system. It has a male threaded end. The NPT (tapered) thread connection makes it easy to assemble and disassemble during maintenance and installation. Hex plugs are inexpensive and they are commonly used.
Class 150, or #150 fittings are categorized under low pressure fittings and are made in accordance with ASTM A351 standard. These fittings are commonly used to extend system pipeline and regulate low pressure fluid and gas. The maximum working pressure is up to 150 PSI. As such, they are the top selection when it comes to non-critical and low-cost applications in the water, oil, and gas (WOG) system. #150 fittings are threaded which provides a tighter seal upon installation. Do keep note that the connection needs to correspond to each other. The material used is stainless steel 316. This steel grade contains molybdenum (Mo), which increases the chemical and corrosion resistance as compared to the standard 304 grade.