Ultimate Guide: Schedule 40 vs 80 Pipe and Fittings

Comparing Schedule 40 vs 80 Pipe and Fittings

While there is a range of pipe schedules available, this ultimate guide will focus primarily on Schedule 40 vs 80 pipes. There are a few reasons for this. Schedule 40 and Schedule 80 pipes are ideal for most projects at any property. PVC – the preferred pipe material for most projects – is also most commonly manufactured as either Schedule 40 and Schedule 80 pipe.

This means that when our customers at Pipe Xpress, Inc. are selecting the right pipes for their needs, they will almost always be choosing from Schedule 40 PVC pipe and Schedule 80 PVC pipe.

Understanding the differences and similarities between these two different pipe schedules is the first step to completing any PVC piping project.

This guide compares Schedule 40 pipe and Schedule 80 pipe, as well as the corresponding fittings. We’ll discuss the standards and technical specifications of each pipe schedule, the pros and cons, and how they impact PVC pipes and other materials.

pressure per square inch sch 40

Most people don’t. And that’s because it’s not always easy to tell just by looking at them. But understanding the difference is important, especially if you’re working on a construction project.

That’s where Pipe Xpress comes in. We’re experts when it comes to plumbing and construction, and we want to help make your next project a success. We’ll explain the difference between Schedule 40 and Schedule 80 pipe and fittings, so you can make the right decision for your needs.

Contact us today at 610-918-7120 to learn more about Schedule 40 vs Schedule 80 pipe and fittings!

A simple search for PVC pipe – or pipe of any material, for that matter – will quickly have you looking through terms like “Schedule 40 pipe,” “NPS,” “ID,” “OD,” and a variety of different usages, sizes, and more.

If this is one of your first pipe laying projects, or even if you are experienced in a few projects but not necessarily others, all these unfamiliar technical specifications can make it challenging to determine exactly what your project needs and how to navigate all the different pipe that is available.

Every type of property:

  • Residential

  • Commercial

  • Industrial

Is likely to have different requirements, and uses, such as plumbing, landscaping, electricity, and more, all of which affect both the type of pipe you need and its thickness.

What Is The Meaning of ‘Schedule’?

The pipe’s “schedule” is one of the most important factors for choosing a pipe that will be effective and safe for your application. “Scheduling” is a standard that applies to all types of pipe and related fittings, and refers to technical specifications of exterior wall thickness, pressure rating, strength, and interior fluid capacity.

When used alongside “Nominal Pipe Size” (NPS) standards, a pipe schedule provides a simple way to choose a pipe that can withstand the pressure of your system and fit into the available physical space.

Scheduling covers all piping materials, but most consumers are going to see it in relation to PVC pipes. This is because PVC has overtaken most other materials for piping in applications such as residential and commercial plumbing, sewage, drainage, agriculture, and industrial production and waste – or at least offers a reliable and affordable alternative.

In comparison to metal, clay, and even other thermoplastic pipes, PVC pipes are:

  • Durable – Recent studies have proven PVC pipes can last upwards of 50 to 100 years, resisting warping, cracking, and leaks during that time. They are also resistant to pitting and will not deteriorate when in contact with solid elements. As a result, PVC pipes require less frequent repairs and have a lower risk of leaks or leaching fluids and chemicals into the surrounding

  • High Capacity – PVC has a smooth bore (interior surface). This means that any fluids that travel through PVC pipe are able to do so with less resistance and friction. It also means blockages are less likely to occur within the pipe.

  • Non-Corrosive – PVC is non-reactive, meaning it will not deteriorate when in contact with most chemicals inside the pipe or minerals in the soil outside. 

  • Easy Installation – Because PVC is lightweight and rigid plastic is simple to cut, installing PVC at any site does not require special tools or knowledge. Based on the diameter, Schedule 40 or Schedule 80 PVC pipe can weigh between 0.16 to 25 lbs per foot, so it can usually be carried or placed by one or two people. A hand saw or power saw is effective at cutting through the PVC pipe and the installation requires only the correct fittings and PVC cement.

  • Affordable – As a plastic, PVC is one of the most inexpensive piping materials for contractors. Because it is also long-lasting and effective, it is also more cost-effective for property owners.

Because the pipe schedule also applies to HDPE pipes, CPVC pipes, steel pipes, and other materials, much of what we outline in this guide is relevant to Schedule 40 and Schedule 80 in those materials as well in terms of wall thickness, pressure rating, and potential application.

With numbered pipe scheduling, the wall thickness increases as the schedule increases. This increase is done by expanding the wall inward, reducing the volume of the interior rather than expanding the outer diameter. In other words, the pipes do not get bigger as the schedule gets larger, as the thickness increases internally.

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The increasing wall thickness also means the pressure a pipe segment can withstand also goes up. For PVC pipe, the manufactured schedules available are:

  • Schedule 20 Pipe

  • Schedule 30 Pipe

  • Schedule 40 Pipe

  • Schedule 80 Pipe

  • Schedule 120 Pipe

  • Schedule 160 Pipe

While the pressure rating follows an upward trend as the schedule increases, the pressure at each scheduling level decreases as the diameter increases.

For example, a 1” Schedule 40 PVC pipe is rated for 450 PSI. But a 6” Schedule 40 PVC pipe is rated for 180 PSI because while the wall thickness is the same, the larger capacity means that it is able to withstand less pressure. Similarly, a 1” Schedule 80 PVC pipe has a pressure rating of 630 PSI and a 6” Schedule 80 PVC pipe is rated at 280 PSI.

  • Schedule 40 and Schedule 80 pipes make up the majority of all piping across industries. They are mass-produced, and therefore affordable and easy to locate. Between the pressure ratings and flow capacities they offer, the two pipe schedules cover almost all project needs.

  • Schedule 20 is a popular choice for vacuum pipe or gravity drainage systems.

  • Schedule 120 and 160 pipes are used for the highest-pressure applications, which are typically unnecessary for the vast majority of projects.

  • There are still other pipe schedules available, such as Schedule 5 and Schedule 10, but these are not often manufactured from PVC since the thermoplastic would be too small for the thin walls.

  • Even among other piping materials as well, Schedule 40 and Schedule 80 are the most common pipe thicknesses.

The most significant difference between all pipe schedules is their wall thickness and pressure rating. Regardless of the material, the expected pressure of the system determines which pipe can safely be used in the layout.

Schedule 40 PVC Pipe Applications

  • Schedule 40 PVC pipe is one of the most used pipes today. Contractors, plumbers, landscapers, and electricians all rely on Schedule 40 pipe for many of their projects because it is affordable while being sufficient for their needs.

  • It has a pressure range of approximately 130 PSI to 450 PSI depending on the interior diameter. This is beyond the requirements of most residential water supply and drainage systems and is also enough pressure for irrigation and some applications at commercial properties.

This makes Schedule 40 PVC pipe the right choice for:

  • Residential Plumbing

  • Landscape Irrigation

  • Pool and Spa Design

  • Buried or Concealed Electrical Conduit

  • Potable Water Supply

  • Other Uses for Schedule 40 Pipe

  • Photography Labs

  • Water Cooling Systems

  • Rainwater Collections

  • Aquarium or Zoo Piping

  • DIY Crafts

  • Misting Systems

  • and More

Many people will also use Schedule 40 PVC pipe for structural support. Because it is lightweight and rigid, schedule 40 PVC can provide an affordable framework for structures like tents or signage.

Schedule 80 PVC Pipe Applications

  • When Schedule 40 PVC does not provide a high enough pressure rating, Schedule 80 PVC pipe is usually a sufficient alternative.

  • Its pressure rating ranges from 220 PSI for the widest diameter to 850 PSI for the narrowest.

  • Schedule 80 PVC pipe also works in more exposed areas where people or machinery is likely to come into contact with pipes, or where the pipe will be buried under a roadway trafficked by heavy vehicles. Schedule 80 PVC pipe has higher compressive strength and shear strength, enabling it to endure more physical contact before it will fracture.

Between the higher pressure rating and better strength, applications that use Schedule 80 PVC pipe include:

  • Commercial Plumbing

  • Chemical Processing

  • Manufacturing

  • Agriculture

  • Aquaculture

  • Exposed Electrical Conduit

  • Industrial applications

  • and many more

We’ve touched on some of the differences between sch 40 and sch 80 PVC pipe. But in this section, we’ll go into greater detail examining what makes these pipes so different from each other, and why you may prefer one pipe over another.

Schedule 40 and Schedule 80 pipes are two different types of pipes that have different thicknesses. Schedule 40 pipe has thinner walls compared to Schedule 80 pipe, so it is often used for applications where there is not a lot of pressure, such as in drain lines. Schedule 80 pipe has thicker walls and can withstand more pressure, so it is often used in industrial applications.

The thickness of the pipe determines the Nominal Pipe Size (NPS)

  • Schedule 40 pipe has an NPS of 1/8″ to 24″

  • Schedule 80 pipe has an NPS of 1/8″ to 12″

  • The NPS is the outside diameter of the pipe, not the inside diameter.

  • Pipes with a larger NPS have a larger outer diameter and a smaller inside diameter, while pipes with a smaller NPS have a smaller outside diameter and a larger inside diameter.

Schedule 40 and Schedule 80 pipes can both be used for certain applications, but it is important to choose the right type of pipe for the job. Schedule 40 pipe is usually sufficient for most applications, but if more pressure is needed, Schedule 80 pipe can be used.

  • The inner diameter (ID) is what varies the most between Schedule 40 and Schedule 80 PVC pipes as it corresponds to the wall dimension.

  • As the outer diameter (OD) stays the same, the added thickness in the pipe wall causes the inner diameter (ID) to shrink.

  • The difference ratio changes slightly at the various nominal sizes. For 1” pipes, Schedule 40 PVC has a wall thickness of 0.133” and Schedule 80 PVC has a thickness of 0.179”. At an NPS of 16”, the wall thickness is 0.5” vs 0.843”.

  • Because the ID decreases as you move from Schedule 40 to Schedule 80, there is a drop in interior volume. 

  • There is usually no loss in capacity despite a decrease in interior diameter because a higher pressure system will force through more water, although this can impact pipe layouts where a Schedule 80 pipe is used pressure is consistently low.

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Pressure Ratings for Schedule 40 and Schedule 80 PVC Pipe

Because both the wall thickness and diameter are standards, this pressure rating is also a standard.

  • The rating is based on the schedule and the NPS. It increases with schedule and decreases with diameter.

  • Between only Schedule 40 PVC pipe and Schedule 80 PVC pipe, pressure ratings vary between approximately 100 PSI and a maximum pressure rating of 1000 PSI.

  • Most residential applications are in the low 100s in terms of pressure requirements, and few commercial and industrial situations yield a pressure near or above 1000 PSI.

As long as the temperature and fluid type are within the requirements for PVC pipe, Schedule 40 and Schedule 80 PVC are affordable options for nearly every project.

Schedule 80 pipe is stronger than sch 40 PVC pipe. It can handle higher pressures and take more intensive external stress without damage than Schedule 40. With these benefits, doesn’t it make more sense to simply use Schedule 80 PVC for every project?

Actually, no. When the fluid transport will be at consistently low pressure, Sch 80 pipes are overkill and can harm the efficiency of the system. Schedule 80 piping has an increased pressure rating, but trades this off with:

  • Reduced Capacity – The thicker wall of the Sch 80 pipe adds material to the inside, not the outside of the pipe. This means that an Sch 80 pipe with the same OD as an Sch 40 pipe will have a significantly smaller ID, often measuring about 8% smaller. This restricts flow capacity from what could be transported in an Sch 40 system at the same pressure.

  • Heavier Weight – A thicker wall requires more material, and subsequently a heavier pipe. The exact increase in weight per foot of pipe increases as the nominal size does. At smaller diameters, the weight increase is a few hundredths of a pound while being about 5 pounds for the largest PVC pipe diameters. This weight can make the pipe more difficult to install and require additional manpower or support.

  • Higher Cost – The additional material also means a higher manufacturing cost. Again, this may be a negligible amount for small orders but will make larger piping projects far more expensive. The cost savings is the deciding factor for many people when choosing between Schedule 40 and Schedule 80 when the lower pressure rating is enough.

Despite the fact that Schedule 40 pipe is the best option whenever it is sufficient for the system pressure, there are some contractors, plumbers, pool designers, and others who will use Schedule 80 in all circumstances.

From their standpoint:

  • There is less risk of a system breaking because of physical damage and there is more leeway with pressure ratings.

  • It also makes it possible to keep only one schedule of pipes and fittings on hand, which can be easier for contractors.

  • However, there is going to be a higher cost at some point, whether the contractor or customer has to pay for it. Some contractors will even offer Schedule 80 pipe as an “upgrade” option for customers.

If you are managing your own piping project, choosing the piping schedule that meets your pressure requirements without going over will help you to fully take advantage of the affordability of PVC pipe.

Distinguishing Schedule 40 and Schedule 80 By Color

Color is another standard that differentiates Schedule 40 PVC pipe from Schedule 80, although there can be exceptions here.

  • In general, the Schedule 40 PVC pipe is white and the Schedule 80 PVC pipe is grey. This can help you identify a pipe schedule on sight when completing repairs or purchasing pipe.

  • However, additives during the manufacturing process can produce differently colored pipes.

  • You may sometimes find grey Schedule 40 pipes, or even pipes in blue, green, orange, or black. The same is possible for Schedule 80 PVC pipes.

Another exception to the coloring scheme is for PVC conduit for electrical applications. Schedule 40 and Schedule 80 PVC conduit is grey to distinguish it from PVC pipe for plumbing and other uses and discourage people from cutting into the conduit without knowing what wiring is inside.

Flexible PVC Pipe as an Alternative

Piping schedules refer to rigid PVC pipe, but flexible PVC offers another option for projects.

  • Flexible PVC has a similar pressure rating to Schedule 40 rigid PVC and can be used for many of the same applications like irrigation, pool and spa design, and landscaping.

  • Flex pipe uses a double helix design that lets the installer manipulate or bend the pipe without losing any of the benefits of rigid PVC pipe.

  • Flexible PVC pipe still has a smooth interior bore, is durable, and is non-corrosive. When buried, this pipe is resistant to crushing.

  • The true benefit of flex pipe is in the installation. With the ability to bend, you can install flexible PVC around corners without needing connectors.

  • This saves time and enables you to use PVC pipes in locations where rigid PVC does not fit.

  • The main drawback is that, in comparison to rigid Schedule 40 and Schedule 80 PVC, the flex pipe is the most expensive option.

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Looking for an alternative to traditional rigid PVC pipe?

Pipe Xpress offers a flexible PVC pipe that offers many benefits over the traditional rigid PVC pipe. It’s more durable, easier to install, and can be used in a variety of applications.

Pipe Xpress Flex Pipe is the perfect solution for any application where traditional rigid PVC pipe just won’t work. It’s ideal for use in construction, irrigation, and many other applications.

Learn more about Pipe Xpress today on our website!

  • A pipe system using Sch 40 PVC pipes will need Sch 40 PVC fittings.

  • One using Sch 80 pipes needs Sch 80 PVC fittings. A piping system of a different material, like HDPE, needs HDPE fittings.

  • Using fittings of the same schedule as the pipes in a system ensures that the entire layout has the necessary technical requirements and there are no weak spots that are likely to fail.

  • Unlike pipes and fittings, valves are identified by their pressure rating.

  • Wall thickness does not play a part in their classification, so scheduling does not apply.

  • Rather, you will select valves that can handle the pressure in your system without regard for the pipe schedule you are using.

Could you, for instance, replace a damaged Schedule 80 system with a length of Schedule 40 pipe? Or could you use an extra Schedule 80 fitting you have on hand when installing a Schedule 40 irrigation system?

Generally, the answer is no. Using pipes and fittings of two different schedules is not recommended because:

  • A single Sch 40 pipe segment or fitting reduces the entire system to the Sch 40 pressure rating, even if the rest of the layout is constructed from Sch 80

  • Using Sch 80 pipes or fittings in a predominantly Sch 40 system is an unnecessary expense, so most people choose not to

  • Different IDs and pressure ratings between Sch 40 and Sch 80 pipes can lead to an uneven water flow

So if you are building a low-pressure sprinkler system and have some leftover Schedule 80 fittings from another project, you can safely use those. If your household plumbing system was constructed from Schedule 80 PVC pipes, but never gets above a low pressure, you could potentially replace a damaged portion with Schedule 40 pipe.

But for a professional job and optimal system function, it is always best to choose the correct schedule and use only pipes and components in that schedule.

It does not matter if you use Schedule 40 PVC or Schedule 80 PVC when it comes to installation. Both are extremely simple to install and use the same process depending on what purpose the piping system will serve.

Every system will be a combination of pipes, fittings, valves, and accessories like pumps or tanks. Some systems may also include hoses or require multiple pipe materials for main and branching lines.

Sch 40 and Sch 80 PVC pipes are both lightweight and easy to cut to size with standard tools. From there you will use connector fittings to hold lengths of pipe together. The exact joining method depends on the project. For PVC pipes, solvent welding using PVC cement is one of the most common methods.

The PVC solvent creates a strong and leak-resistant seal between couplings, valves, and pipes. Threading can also be used with some systems to screw fittings, valves, and pipes together.

No matter the piping schedule you are using, the installation process for PVC pipes should be quick and straightforward without requiring special equipment or experience.

This guide is designed to answer some of the most common questions between Schedule 40 and Schedule 80 classifications, but we know it is also impossible to cover every use case for versatile PVC pipes.

Here at Pipe Xpress, Inc. we gladly offer this advice to our customers. Our team is an expert in PVC piping, scheduling, pressure ratings, and all of the details involved with piping systems. We have worked with Schedule 40 and Schedule 80 PVC pipes ourselves and supplied PVC pipes and fittings to customers in dozens of industries.

We can answer additional questions or provide further information about Schedule 40 PVC pipe, Schedule 80 PVC pipe, and the associated fittings for your project. Simply call our team at (610)-918- 7120.

Pipe Xpress, Inc. is the one place where you can find everything you need. We make it possible for you to buy pipes online through our website and deliver them directly to you with fast nationwide shipping or rapid local delivery for those in Southeastern Pennsylvania.

We hope we have answered all your scheduled 40 vs 80 queries.