Understanding End Connection Terms


3000 lb forged stainless steel fittings

NPT Threads

Brass, galvanized, stainless steel and other non-copper fittings are most often threaded. The standard used is most often isthe National Pipe Thread (NPT) standard.

NPT is interchangeable with IPS (Iron Pipe Size). Threaded PVC fitting also use NPT.. When pipe is measured using IPS dimensions, the corresponding fitting size matches the IPS measurement: a 3/4" pipe will take a 3/4" IPS fitting.

MIPS or FIPS refers to male or female iron pipe size.

Sometimes NPT threads are referred to as MPT ('Male Pipe Thread'), MNPT, or NPT(M) for male (external) threads.

FPT ('Female Pipe Thread'), FNPT, orNPT(F) for female (internal) threads. An equivalent designation is MIP (Male iron pipe) and FIP (Female iron pipe).


Copper C

(C) C x C / SWT (Sweat) / Socket

This type of unthreaded fitting is meant to be soldered or "sweated" onto a copper pipe. They are threadless or non-threaded.

"Flux" is used to clean and prepare the pipe. Solder is then applied and melted around the joint which creates a permanent, leak-free seal. This is among the oldest and most trustworthy methods of connecting pipes. Copper fittings are sized nominally (inside), meaning you'll have to subtract 1/8" from the outside diameter measurement of the pipe being worked with.

You may also seend item with a "FTG" end - this sizing matches that of the pipe, meaning that end can be connected directly into another fitting (just as a pipe would), but not over that size pipe.

For non-plumbing applications, such as refrigeration, outside diameter may be used to describe both the pipe/tubing and the fittings.

Copper C

Slip/Hub

Slip fittings are also unthreaded and require the use of another material to seal the connection. Slip fittings are used with plastic piping (ABS, CPVC, and PVC). They are joined together using a primer that cleans and pre-softens the plastic. Then a glue is applied that binds pipe and fitting together, making one piece out of two. Due to its chemical composition, ABS does not require the primer step.

PVC and ABS slip connections follow IPS sizing, while most CPVC uses Copper Tube Sizing (CTS), meaning the types are not interchangeable.

Shop All QuickBites

Push-In/Push-to-Connect/Push-to-Fit (Quickbite)

These fittings are aimed at ease and simplicity and can easily be removed and reused. To install - simply push the pipe or tubing into the fitting to secure a watertight connection. Used with copper pipe (not tubing), CPVC, and PEX (a special insert called a stiffener is used to maintain the integrity of PEX when using these fittings), the connection is made possible by a combination of specially-designed o-rings and metal teeth that grip and hold the pipe or tube in place.

These are not permanent connections, but do require the use of a special tool to disconnect in the case of Quickbite. While every connection benefits from having a clean, smooth deburred end, it's particularly important with these fittings: relying only upon an o-ring and teeth for a connection means that any sharp edges or debris can hold a more destructive threat than normal. Quickbite fittings require a particular insert depth depending on the size fitting being used (this can be done manually, or using a special "Depth Deburr Gauge". Push-to-fit fittings typically use CTS (copper tube sizing)

 

Hose Barb / Barb Connections

Barbed fittings are used to connect flexible tubing (including garden hoses) to metal or plastic piping. The barbed end of the fitting is pushed into the hose, and a clamp tightened around it to secure a seal. Barbs are sized by the ID of the hose to be connected. The other end typically utilizes an IPS (MIPS or FIPS), GHT or slip connection. These types of fittings are commonly used in commercial beverage applications, such as tap lines or soda fountains.