What does FIP mean in plumbing?

"FIP" stands for Female Iron Pipe.

FIP (female iron pipe) refers to threading on the inside of a fitting.

Alternate names and abbreviations: You may see “FIP” used interchangeably with “FPT” or simply “female thread.”

Description: FIP fittings connect to the outside of a male fitting. Falling under the national pipe taper (NPT) family of fittings, female threads have a taper, meaning the thread is slightly wider at the opening and narrows slightly toward the base of the fitting. This style of threading creates a tighter seal.

"MIP" stands for Male Iron Pipe.

MIP (male iron pipe) is the counterpart to FIP fittings and refers to a pipe that is threaded on the outside.

Alternate names and abbreviations: Other terms for “MIP” include “MPT” and “male threads.”

Description: Like FIP fittings, MIP fittings usually have tapered thread, forming a conical shape that’s wider at the base of the fitting.

"FGH" stands for Female Garden Hose, and "MGH" stands for Male Garden Hose.

FGH (female garden hose) and MGH (male garden hose) fittings couple together to join lengths of hose. As with pipe fittings, the female fitting has threading on the inside, and the male has corresponding threads on the outside.

Alternate names and abbreviations: In addition to “FGH” and “MGH,” you may see these couplings referred to as: 

• GHT (garden hose thread)
• GHF (garden hose female)
• GHM (garden hose male)

These terms are interchangeable and don't typically change the specifications of the threading. In the context of hoses, however, “fitting” refers specifically to the parts that join together. The term “coupling” generally refers to the entire apparatus.

Description: Manufacturers typically make garden hose couplings out of brass. The thread itself doesn’t form a perfect seal on hose fittings. Instead, a washer in the female coupling creates the seal. To avoid damaging the coupling, you should not overtighten the male and female fittings.

"FCM" stands for Female Compression.

FCM (female compression) fittings can connect two pipes, a pipe and a fixture, or a pipe and a valve. Compression fittings create a strong seal without the need for soldering or other joining techniques.

Alternate names and abbreviations: All compression fittings are female, so you may see “FCM,” “compression,” or “female compression” used interchangeably.

Description: Brass is the most common material for compression fittings, but they may also use plastic or stainless steel. FCM fittings use a nut to tighten a sleeve down on the joint. Depending on the pipe size, they may require a wrench to tighten.

"MPT" stands for Male Pipe Thread.

MPT (male pipe thread) is another term for MIP fittings. This abbreviation refers to any NPT fitting with a male thread on the end.

Alternate names and abbreviations: “MPT” and “MIP” typically refer to any male pipe thread, so the terms are synonymous.

Description: MPT fittings have threading on the outside to screw into the threads of a female fitting.

"NPT" stands for National Pipe Taper.

NPT (national pipe taper) refers to any fitting with tapered threading. The threads of NPT fittings have a 60-degree angle between each thread.

Alternate names and abbreviations: In plumbing, “NPT” may also stand for “American national pipe taper” or “national pipe thread,” but both terms mean the same thing. Many fitting types fall under the category of NPT, so the abbreviation can refer to a specific type.

Description: NPT fittings are the most common type for general plumbing applications. They are suitable for pipes channeling gas or liquids.

"NPS" stands for National Pipe Straight.

Unlike NPT fittings, NPS (national pipe straight) fittings have no taper in the threads.

Alternate names and abbreviations: N/A

Description. Because NPS fittings don’t have a taper, they don’t form a perfect seal on their own. This type of fitting requires a rubber gasket or Teflon tape to complete the seal.

"UNS" stands for Unified Special.

UNS (unified special) threads share the same thread angle as NPT.

Alternate names and abbreviations: All of the following are examples of UNS threads:

• UNC
• UNF
• UNEF
• UN

Description: UNS threads are for specialized applications where standard NPT threads aren’t suitable.

"PTF" stands for Pipe Thread Fuel.

PTF (pipe thread fuel) fittings are a shortened version of NPTF threading.

Alternate names and abbreviations: PTF threads may also have the designation of “PTF SAE short.”

Description: Like NPTF threads, PTF fittings have tapered threads but are shortened from the large end.

"BSPT” stands for British Standard Pipe Taper.

As the United States has NPT as the standard thread size, the UK has BSPT (British standard pipe taper). This thread type is used in most countries that use metric dimensions.

Alternate names and abbreviations: BSPT is sometimes referred to as simply “BSP.” The two types are:

• Female: BSPP (parallel)
• Male: BSPT (tapered)

Description: Unlike NPT, BPST has a thread angle of 55 degrees. Its most common use is joining steel pipes.

"GHT" stands for Garden Hose Thread.

GHT (garden hose thread) is the broader category that FGH and MGH fall into.

Alternate names and abbreviations: Depending on if the fitting is male or female, you may see GHT referred to as “FGH” or “MGH.”

Description: See "FGH and "MGH" sections above.

"NPTF" stands for National Pipe Taper Fuel.

NPTF (national pipe taper fuel) is the standard tapered thread rated to carry fuel. 

Alternate names and abbreviations: NPTF is also known as “Dryseal American standard taper pipe thread.”

Description: Unlike other NPT fittings, NPTF creates a seal without the use of Teflon tape.

"NPSM" stands for National Pipe Straight Mechanical.

NPSM (national pipe straight mechanical) fittings join two lengths of pipe but don’t form a perfect seal on their own.

Alternate names and abbreviations: N/A

Description: Many NPSM fittings swivel to reduce the amount of hoses required. The threads are compatible with other NPT types.

"NPSI" stands for National Pipe Straight Intermediate.

NPSI (national pipe straight intermediate) fittings are not tapered.

Alternate names and abbreviations: N/A

Description: The most common application for NPSI fittings is mechanical joints and fixtures.

"NST" stands for National Standard Thread.

NST (national standard thread) is the standard thread type for coupling fire hoses.

Alternate names and abbreviations: Because NST is the standard fire hose thread, it can also be referred to as “NH” or “national hose.”

Description: NST fittings have straight and coarse threads with no taper. They require a gasket to form a seal.

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