PVC End Types Explained
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Time to read 6 min
If you've worked with PVC pipe for any length of time, you will know that there are many different PVC end types. From spigots to barbed inserts, the look and purpose of different PVC end types vary widely. For newcomers to the wide world of PVC, this may be daunting. However, this blog post will act as a guide and should answer any questions you may have about PVC end types. It may also serve as a refresher for seasoned veterans of piping. After reading this guide, PVC end types will no longer be a mystery!
Sockets and Spigots
To understand these end types, you must first understand the term "slip" as it is used in PVC. Slip refers to the fact that there are no threads or barbs. To secure a slip fitting, glue or some other adhesive must be used. Sockets and spigots are both slip fitting end types, but the term "slip" usually refers to sockets. A socket is a fitting that simply goes over the end of a pipe. A 1" socket end will fit on a 1" pipe. These are extremely common. Many PVC couplings have socketed ends. A commonly used abbreviation for "socket" is "soc."
A spigot fits inside a socket, so it is the same size around as regular pipe. When you need to attach a fitting to another fitting, you use a spigot end. In their function, sockets are the female and spigots are the male. Spigot fittings are often called street fittings. The terms "street," "spg," and "spigot," are all the same thing and refer to spigot end fittings. The picture above shows a 1.5" coupling with socket ends and a 1.5" x 1" bushing with a spigot end.
Female and Male Threaded
Female and male threads are pretty self-explanatory. On a female-threaded fitting, the threads are on the inside of the fitting. On a male-threaded fitting, the threads are on the outside of the fitting. This means a male-threaded fitting can be screwed into a female-threaded fitting. These connections do not need glue. Teflon tape is enough to keep it sealed tight. Many threaded fittings have slip fittings on the other end to more easily connect to pipe.
When browsing female-threaded fittings, you may see the abbreviations "FPT" and "FIPT." These stand for "female pipe thread" and "female iron pipe thread." For male-threaded fittings, you will see the same abbreviations with an "M" instead of an "F" and, you guessed it, the "M" stands for "male." Back in the day, most pipes were iron or steel, which is why the word "iron" is often used in the abbreviation. This does not mean the part is made of iron! PVC pipe is simply made to be usable in metal pipelines. The picture above shows a 1.5" female-threaded elbow and a 1.5" male-threaded elbow.
Barbed Insert
Connecting hose to PVC pipe can be useful in irrigation and many other outdoor PVC applications. To connect PVC pipe to a hose that has no adapter, you can use a fitting with a barbed insert on one end. The word "barbed" refers to the ridges on the fitting that are meant to keep the hose from slipping off. To seal and secure a hose onto a barbed insert fitting, you must use a a clamp. Hose expands outwards, so glue doesn't work. When looking for parts, you will often see "barbed insert" shortened to "insert" or "inst." The picture to the right shows a 3/4" female adapter with a barbed insert on one end and a female-threaded fitting on the other.
Inside Connectors
Some fittings have spigot ends that fit inside pipe itself as if it was a socket fitting. These are pipe extenders and inside connectors. They are rare as they are only required for very specific uses. Click here for the full guide to these unique fittings.
Flange
Flange fittings are used when you want to easily take apart sections of a pipeline as they are bolted together. Flange fittings can be more expensive than others because of all the accessories required to make a strong connection. The other end of a flange fitting can be threaded or slip. Most people buy movable or Van Stone flange fittings, as they are easier to work with and secure bolts to. The picture to the right shows a 1" Van Stone slip flange with a slip end that fits straight onto PVC pipe or a spigot fitting.
SSS, SST, SS, ST, etc.
The abbreviations above are just four of the many combinations of "S" and "T" that can be used for PVC fittings. "S" refers to slip fittings, particularly socket fittings. "T" refers to threaded fittings, particularly female-threaded fittings. The number of letters in the abbreviation is how many ends the fitting has. So an SSS fitting would be a fitting with three slip fittings; this is usually a tee. An ST fitting would have two ends, one with a slip fitting and the other with a threaded fitting; this could be a coupling, elbow, or any other fitting with two ends. It is a simple system of categorizing PVC fittings with a large number of possible variations.
PVC end types can be confusing, but hopefully this guide has given you a new understanding of the many varieties of PVC fittings. If you have any more questions, feel free to ask us on our Twitter and Facebook pages!
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Slip Fittings (Sockets vs. Spigots): "Slip" or "Socket" (Soc) ends fit over the outside of a pipe and require adhesive. "Spigot" (Spg) ends have the same diameter as the pipe itself, allowing them to fit inside a socket—essentially acting as the "male" counterpart to the "female" socket.
Threaded Connections (FPT vs. MPT): Threaded ends allow for secure connections without glue using Teflon tape. Female Pipe Threads (FPT/FIPT) are located on the inside of the fitting, while Male Pipe Threads (MPT/MIPT) are on the outside, making them easy to assemble and disassemble.
Specialty Ends (Barbed & Flanged): Barbed inserts feature ridges designed to grip flexible hoses and require a clamp for a leak-proof seal. Flanges are used for heavy-duty systems that need to be bolted together, allowing for easy maintenance and disassembly of pipeline sections.
Abbreviation Guide: The industry uses shorthand like "S" for slip/socket and "T" for threaded to describe fitting ends. For example, an "SSS" abbreviation indicates a tee where all three openings are slip connections, while an "ST" indicates a two-ended fitting with one slip and one threaded end.
FAQs
What is the difference between a Socket and a Spigot end?
A Socket (often abbreviated as "soc" or called a "slip" fitting) is designed to go over the outside of a pipe. A Spigot (abbreviated as "spg") is the same size as the pipe itself and is designed to fit inside a socket. In plumbing terms, the socket acts as the female connection, while the spigot acts as the male connection.
Do threaded PVC connections require glue or solvent cement?
No, threaded connections (Male Pipe Thread/MPT and Female Pipe Thread/FPT) do not require glue. Because they are designed to be screwed together, they can be taken apart later if needed. Instead of glue, you should use Teflon tape (thread seal tape) to ensure a watertight seal and prevent leaks.
What do the abbreviations FPT and MPT stand for?
These abbreviations refer to the type of threading on the fitting:
FPT (or FIPT): Female (Iron) Pipe Thread—the threads are on the inside of the fitting.
MPT (or MIPT): Male (Iron) Pipe Thread—the threads are on the outside of the fitting.Note: Despite the "Iron" in the name, these parts are made of PVC but are designed to be compatible with standard metal pipe threading.
How do Barbed Insert fittings differ from standard slip fittings?
Unlike standard slip fittings that connect to rigid PVC pipe, Barbed Insert fittings are used to connect PVC systems to flexible hoses or tubing. The "barbs" are raised ridges that grip the inside of the hose to prevent it from sliding off. To ensure a completely secure and leak-proof connection with a barbed fitting, you must use a hose clamp over the tubing.
Mark Ligon
Mark Ligon is the marketing manager at PVC Fittings Online, a supplier of commercial PVC and CPVC pipe, fittings and valves. Ligon enjoys educating businesses on the parts of piping systems so managers can make informed decisions. He can be reached at webmaster@commercial-industrial-supply.com.
