- Blinds (also known as paddle blinds because of their flat, round,
or paddle-like shape) are flanges used for temporarily blocking flow in a pipe
to allow work further down the pipe. Blinds can be slipped between flanges to
block the flow in a pipe.
welds connections are unthreaded, with a
chamfer end, and are welded onto pipes or other fittings. They come in various
shapes for reducing, terminating or changing the direction of pipe, and can
offer a superior seal to threaded fittings.
joints are connections used for slipping
over lapped pipe and holding pieces of pipe together. Multiple lap joints can
be bolted together to provide extra connection strength and are often used
because they can be disassembled more easily than welded connections.
- Slip-on connections, also called clamps, slide over pipe and are welded in
place to connect pieces of pipe. Multiple slip-on fittings can be bolted
together for added strength, but overall these flanges are best suited for
welds are unthreaded connections used for
high pressure applications. They have an internal pocket for better flow and
can be internally welded for increased strength.
thread connections have rounded parallel ridges (threads), and are often
used for mechanical fittings where a water-tight seal is not necessary; one can
be created by welding or adding an O-ring. Types include National Pipe Straight
Mechanical (NPSM), National Pipe Straight Locknut (NPSL), National Pipe
Straight Hose (NPSH), garden hose (GHT) and fire hose coupling (NST).
- Threaded connections have parallel ridges (threads) that, when
screwed together with another threaded fitting, form a seal. Threaded pipes are
often used for transporting gases and liquids because of their ability to
create an effective seal. National Pipe Taper Thread (NPT) fittings have a
60-degree thread angle, flattened peaks and valleys, and slightly tapered ends.
When mated, the tapered threads create a seal. FPT (female pipe thread)
fittings have internal threads, MPT (male pipe thread) fittings have external
threads, and both are types of NPT.
- Unthreaded, or plain, connections have smooth surfaces for sliding into
or around pipes to form a seal. They can also be butted up against unthreaded
pipe and welded, cemented or clamped together.