Comprehensive Guide to PVC Pipe Fittings

www.petrampvc.ca Comprehensive Guide to PVC Pipe Fittings PVC piping companies receive a lot of questions relating to Plumbing Fittings. People often ask how to choose the right size pipe fittings and what the best types of fittings for each application are. These questions are common since the PVC piping can be confusing to someone who is new to PVC piping systems. This guide will provide all the information you would need to know about pvc fittings along with how and why you should use them.

Pipe Sizes By far the most frequent question asked is why the size label on a PVC pipe is not the actual diameter of that pipe. For example: a pipe labeled 1” does not have a diameter of 1”, its actually closer to 1 5/16”.

Pipe sizes are the nominal pipe size and not the actual diameters due to the ASME pipe standards. The reason for this bizarre feature of pipe fittings is due to the history and circumstances of how the ASME pipe standards that were created in the 1920s came to be. The important thing to note is that all fittings, pipes and valves of a given nominal size are compatible with one another and can be joined together and used in the same piping system.

Pipe Schedule Pipe schedule is another confusing attribute of piping systems. Schedule is a standardized system for specifying the wall thickness of pipes and fittings. In a nut shell, schedules specify the pressure rating of a nominal pipe size which depends on the strength of the piping material and the pipe wall thickness. For example: A PVC pipe has a thicker wall than a steel pipe of the same size and schedule but they have the same outside diameter and pressure rating. This is because PVC has a lower strength than steel so they can use a thinner wall to achieve the same pressure rating. It is important to note that the outside diameter of nominal pipe size is consistent across all the schedules and only the inside diameter changes with the schedule this means that a schedule 40 pipe can fit into a schedule 80 fitting. This helps keep pipe fittings interchangeable across different materials and schedules.

There are many pipe schedules but the most common ones encountered in PVC piping systems are schedule 40 (sch 40), schedule 80 (sch 80) and schedule 120). Sch 40 has a thin wall and can withstand the lowest pressure. Sch 40 pipes and fittings are commonly white and used in low pressure applications such as irrigation and drainage. Sch 80 pipes and fittings can handle a higher pressure than sch 40 but cost more due to the greater material required. Sch 80 is the standard for commercial and industrial applications like water treatment and manufacturing. Sch 120 has the thickest wall and can handle the highest pressure. Sch 120 is not very common and reserved for very specific high pressure applications.

Connection types PVC pipe fittings can be assembled with various connections. The purpose of any connection method is to join pipes, fittings, valves and equipment together without leaks and with varying degrees of permanence. 

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Glue connections – Glue joins, also known as solvent welding joints, are the most common and easiest method of connecting components of PVC piping systems. Pipes or spigot fittings are joined to socket fittings using PVC solvent then PVC cement to permanently join the components together with a chemical bond.

Threaded connections– threaded joints use a variety of thread standards but the primary one used in North America is NPT or National Pipe Thread standard. Male and female threads are screwed into each other using a thread sealant compound or thread sealant tape to create a leak free but removable connection. Threaded connections are typically used for installing instruments, sensors or equipment that is made from dissimilar materials into PVC piping systems.

Flanged connections – Flanges are a common connection method in industrial piping systems or large diameter pipe lines. Flanged connections consist of a mating pair of flanges that are bolted together with a gasket between them. Flanged connections allow for greater misalignment than threaded connections, both linear and angular misalignment. A pair of flanged connections can create a removable pipe section that does not require unthreading, which is suitable for large diameter pipe lines that are fixed in position and cannot be moved to allow for unthreading.

Pipe Fitting Types There are many types of pipe fittings available but there are a few basic fitting types used in almost every piping system. 

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Couplers – at its most basic couplers connect 2 pipes together in a straight line. Other varieties of couplers reduce the diameter of the pipe line either concentrically or eccentrically, i.e. the pipes are directly in line with each other or off center with each other.

Elbows – A type of coupler which connects pipes together at an angle. Common angles are 90° and 45° but other angles are available. Elbows also come with a variety of connection types such as male and female glue joints (also known as socket and spigot connections).

Also available are female and male threaded connections. Elbows can have a mix of any of fitting types to suit a variety of situations.

Tees – Pipe tees add a branch to a pipe line at 90° although a type of tees known as wyes can branch off at other angles. Like elbows a variety of connection types are available. Tees can also reduce the pipe diameter of the branch.

Unions– A type of pipe coupler that have an integrated threaded nut that allows for easy removal. Unions can feature both socket joins and threaded connections.

Adapters – adaptors change the connection or gender of a pipe. For example: a female socket can be adapted to a male threaded connection.

Bushings–Bushings are a special type of fittings that reduces the pipe diameter with a male and female connection. Bushings can be inserted into another fitting with a spigot or male thread and provide a reduced diameter female socket or threaded connection.

Flanges – Flanges provide a robust connection using bolts and a gasket. Flanges can be mounted to pipes using a socket or threaded connection.

Caps / Plugs – Caps close off an open pipe and plugs close an open fitting port. Caps and plugs can be threaded or glue joints.

PVC fitting supplier PVC pipe fittings are a critical component of any piping system. Fittings are what allow straight pipes to form complex systems to transport fluids for a variety of applications. A good supplier of PVC fittings can provide the right parts and support critical to supporting the design and maintenance of your piping system. For a huge selection of PVC fittings, valves and actuated valves check out Petram PVC Supply for the best prices online in Canada.