What are the various methods of connecting valves to piping?

By "Apollo" Valves
July 25, 2018

For valves to function as they are supposed to, they must be connected to a piping system. In any piping system, it is highly crucial that any connections – be it pipe to pipe or valve to pipe – are undertaken carefully to avoid any mistakes that can facilitate leakage. Valve and pipe connections are therefore of great importance in any plumbing or industrial piping system.

Valves can be connected to piping systems in several ways, and they are sometimes even classified according to the type of end connection created. The three primary classifications are:

• Threaded connections
• Flanged connections
• Welded connections

Threaded connections

In this type of connection, the valve is linked to a pipe using threads. It is arguably the most basic type of valve-to-pipe connection and is primarily used on relatively small valves (less than 2 inches) in low-pressure systems. Unlike other types of joints, a threaded link does require additional parts such as bolts and nuts to hold the connection together, making it cheaper and quicker to execute.

There are two types of threading: internal and external threads, and parallel and tapered threads. Many valves use the tapered thread connection. However, threaded connections can be difficult to repair in case of leakage and often call for a replacement.

Flanged connections

Flanged connections are the most common method of connecting valves to piping systems regardless of pressure levels and valve size. They are made by using two flanges, which are attached using stud bolts and nuts. They are quick and easy to assemble and disassemble for repair or replacement purposes.

Welded connections

In this connection, the valve is directly welded onto the piping system to create a tighter and leak-free joint. These connections are more expensive than flanged connections but guarantee top-of-the-range linking between pipes, valves, and fittings. Welded connections are typically used in areas where complete leakage shutoff is crucial, such as in high-pressure and high-temperature pipeline systems.

There are two main types of welded connections:

Butt weld – In this welding connection, the valve and pipe ends are butted to each other and then welded to create a link. Butt weld connections are common on steel valves but are ideal for all types of valves regardless of size.

Socket weld – Here, the welded end of the valve is shaped into a socket, and then the pipe is inserted in it for welding. The connection uses fillet welds to link the two components. It is used with small valves not exceeding 2 inches.

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