Threaded / Screwed Flanges / THRD-RF

• Threaded flange: used frequently in smaller piping systems and includes a threaded connection inside the flange bore, which does not require welding

Some of the most common types of threaded valve connections include:

• NPT: National pipe thread tapered, the US standard for tapered threads used in pipes and fittings, which pulls tight to make a fluid-tight seal.
• NPS: National pipe straight, a standard for straight (non-tapered) threads used in pipes and fittings that, similar to BSPP, requires a gasket or sealant to ensure a fluid-tight connection.
• BSPT: British standard pipe taper threads that include tapered threaded connections and a 55-degree angle of the thread flanks, which does not allow for a fluid-tight seal.
• BSPP: British standard pipeline threads, which do not create a fluid-tight seal on its own but rather pull together two threaded mating parts.

Threaded valve connections are typically available in two subtypes:

• Male vs. female
• Straight vs. tapered

There are several advantages to using this type of valve connection. Threaded valve connections:

• Are quick to install
• Are suitable for low-medium pressure applications and certain high-pressure applications
• Generally require less space than flanged connections
• Are relatively inexpensive

While they can be the right choice in certain applications, threaded valve connections may have some drawbacks. A few notable disadvantages are that threaded valves:

• Are not usable in very high temperature or very high-pressure applications
• Are not as easy to disassemble and service as flanged connections
• May be less foolproof to install as they can be over or under-tightened during installation or maintenance