We’ve put together a list of the most common PVC terms and jargon to make them easy to understand. All terms are listed in alphabetical order. Find below the definitions of the PVC terms you want to know!

ASTM – stands for American Society for Testing and Materials. Known today as ASTM International, it is a leader in international standards for safety, quality and consumer confidence. There are many ASTM standards for PVC and CPVC pipes and fittings.

Flared End – One end of a flared end tube flares out, allowing another tube to slide into it without the need for a connection. This option is usually only available for long straight pipes.

Bushings – Fittings used to reduce the size of larger fittings. Sometimes called “reducer bushing”

Class 125 – This is a large diameter 40 gauge PVC fitting that is similar in all respects to a standard 40 gauge but fails the test. Class 125 fittings are generally less expensive than standard sch. 40 PVC fittings of the same type and size, so are often used for applications that do not require tested and approved fittings.

Compact Ball Valve – A relatively small ball valve, usually made of PVC, with a simple on/off function. This valve cannot be disassembled or easily serviced, so it is usually the cheapest ball valve option.

Coupling – a fitting that slides over the ends of two pipes to connect them together

CPVC (Chlorinated Polyvinyl Chloride) – A material similar to PVC in terms of stiffness, corrosion resistance and chemical resistance. However, CPVC has higher temperature resistance than PVC. CPVC has a maximum operating temperature of 200F, compared to 140F (standard PVC)

DWV – stands for Drainage Waste Vent. PVC system created to handle non-pressurized applications.

EPDM – (Ethylene Propylene Diene Monomer) A rubber used to seal PVC fittings and valves.

Fitting – A part of a pipe that is used to fit pipe sections together. Accessories can come in a variety of shapes, sizes and materials.

FPT (FIPT) – Also known as female (iron) pipe thread. This is a threaded type that sits on the inner lip of the fitting and allows connection to MPT or male threaded pipe ends. FPT/FIPT threads are commonly used in PVC and CPVC piping systems.

Furniture Grade PVC – A type of pipe and fittings designed for use in non-liquid handling applications. Furniture grade PVC is not pressure rated and should only be used in structural/recreational applications. Unlike standard PVC, furniture grade PVC does not have any marks or visible imperfections.

Gasket – A seal made between two surfaces to create a leak-free watertight seal.

Hub – A DWV fitting end that allows pipe to slide into the end.

ID – (Inner Diameter) The maximum distance between the two inner walls of a length of pipe.

IPS – (Iron Pipe Size) Common sizing system for PVC pipe, also known as Ductile Iron Pipe Standard or Nominal Pipe Size Standard.

Modular Seal – A seal that can be placed around a pipe to seal the space between the pipe and surrounding material. These seals typically consist of connectors that are assembled and screwed to fill the space between the pipe and the wall, floor, etc.

MPT – Also known as MIPT, Male (Iron) Pipe Thread – A threaded end on PVC or CPVC fittings where the outside of the fitting is threaded to facilitate connection to a female pipe threaded end (FPT).

NPT – National Pipe Thread – American standard for tapered threads. This standard allows NPT nipples to fit together in a watertight seal.

NSF – (National Sanitation Foundation) System of Public Health and Safety Standards.

OD – Outside Diameter – The longest straight line distance between the outside of one section of pipe and the outside of the pipe wall on the other. Common measurements in PVC and CPVC pipes.

Operating temperature – the temperature of the medium and the surrounding environment of the pipe. The maximum recommended operating temperature for PVC is 140 degrees Fahrenheit.

O-Ring – An annular gasket, usually made of elastomeric material. O-rings appear in some PVC fittings and valves and are used to seal to form a watertight joint between two (usually removable or removable) parts.

Pipe Dope – Slang term for pipe thread sealant. This is a flexible material that is applied to the threads of the fitting prior to installation to ensure a waterproof and durable seal.

Plain End – Standard end style for pipes. Unlike flared end tubes, this tube has the same diameter the entire length of the tube.

PSI – Pounds Per Square Inch – A unit of pressure used to describe the maximum recommended pressure applied to a pipe, fitting or valve.

PVC (Polyvinyl Chloride) – a rigid thermoplastic material that is corrosive and resistant to corrosion

PVC (Polyvinyl Chloride) – A rigid thermoplastic material that is resistant to corrosion and chemicals. Commonly used in a variety of commercial and consumer products around the world, PVC is known for its use in media handling piping.

Saddle – A fitting used to create an outlet in a pipe without cutting or removing the pipe. The saddle is usually clamped to the outside of the pipe, and a hole can then be drilled for the outlet.

Sch – short for Schedule – the wall thickness of a pipe

Schedule 40 – Usually white, this is the wall thickness of PVC. Pipes and fittings can have various “schedules” or wall thicknesses. This is the thickness most commonly used for home engineering and irrigation.

Schedule 80 – Usually grey, Schedule 80 PVC pipes and fittings have thicker walls than Schedule 40 PVC. This allows the sch 80 to withstand higher pressures. Sch 80 PVC is commonly used in commercial and industrial applications.

Sliding – see socket

Socket – A type of end on a fitting that allows the pipe to slide into the fitting to form a connection. In the case of PVC and CPVC, the two parts are welded together using a solvent adhesive.

Solvent Welding – A method of joining pipes and fittings by applying a solvent chemical softener to the material.

Socket (Sp or Spg) – A fitting end that fits within another socket-and-socket fitting of the same size (Note: This fitting cannot be fitted in a pipe! No pressure fittings are designed to fit in a pipe)

Thread – An end on a fitting in which a series of interlocking tapered grooves come together to form a watertight seal.

True Union – A style valve with two union ends that can be unscrewed to remove the valve from surrounding piping after installation.

Union – A fitting used to connect two pipes. Unlike couplings, unions use gasket seals to create a removable connection between pipes.

Viton – A brand name fluoroelastomer used in gaskets and O-rings to provide sealing. Viton is a registered trademark of DuPont.

Working Pressure – The recommended pressure load on a pipe, fitting or valve. This pressure is usually expressed in PSI or pounds per square inch.