Schedule 40 vs Schedule 80 Pipe and Fittings
What Is Pipe Scheduling?
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:
Is likely to have different requirements, and uses, such as plumbing, landscaping, electricity, and more, all which affect both the type of pipe you need and its thickness.
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, 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.
Comparing Schedule 40 & Schedule 80 Pipe and Fittings
While there is a range of pipe schedules available, this ultimate guide will focus primarily on Schedule 40 and Schedule 80 pipes. There are a few reasons for this. Schedule 40 and Schedule 80 pipe 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. We also go in depth on which pipe schedule is right for various applications to give you the knowledge to choose the right materials for your next project.
Overview of PVC as a Piping Material
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 the 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 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 pipe scheduling 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.
Pipe Schedules Available for PVC Pipes and Fittings
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 outside diameter. In other words, the pipes do not get bigger as the schedule gets larger, as the thickness increases internally.
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 schedule 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.
Although these are all standardized pipe schedules, Schedule 40 and Schedule 80 pipe make up the majority of all piping across industries. They are mass produced, and therefore affordable and easy to locate. Between pressure ratings and flow capacities they offer, the two pipe schedules cover almost all project needs.
Other pipe schedules are often required for more specialty projects. For instance, 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.
How Different Pipe Schedules Are Used
The most significant difference between all pipe schedules is their wall thickness and pressure rating. Regardless of material, the expected pressure of the system determines which pipe can safely be used in the layout.
As mentioned above, a thicker pipe wall gives a pipe superior burst pressure, or the amount of interior pressure it can withstand before it will fail. In PVC pipe, failure will most often cause the PVC cement bonding and fitting to leak or the pipe to entirely detach from the fitting. This leads to leaks which will require accessing the pipe to repair it, as well as cause a safety concern if toxic drainage or chemicals are leaching from the pipe.
The pressure rating that results from the pipe schedule and the interior diameter is the maximum pressure that the system can withstand. Since pressure ratings increase as pipe schedule goes up, the general rule is that Schedule 40 is for low pressure systems and Schedule 80 is for higher pressure applications. That’s very generalized, however, so read on to see which pipe is right for specific uses.
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 Sch 40 PVC pipe the right choice for:
Almost all homes use Schedule 40 pipes. Previously, these pipes were metal or clay. Today, Schedule 40 PVC pipe is what contractors and developers use in new construction. When replacing deteriorating pipes in older homes, property owners will often update to PVC as well, taking advantage of its low cost, longevity, and safety.
Whether using metal or PVC, the pressure capabilities of Schedule 40 pipe is more than high enough to handle the average water pressure at a home which often tops out at 70 PSI. Schedule 40 PVC pipe ranges from 150 PSI to 450 PSI depending on the interior dimensions of the pipe. Even with water temperatures over the 73 degree Fahrenheit operating temperature for pressure rating measurements, residential water pressure will remain within safe levels for Schedule 40 pipe.
Schedule 40 PVC pipe is the preferred piping schedule for landscapers servicing residential and commercial properties. Many property owners or contractors working with large scale landscape irrigation, like golf courses or athletic fields, also use Schedule 40 pipe as an affordable solution.
Components of residential sprinkler systems often operate at pressures between 15 PSI and 50 PSI, which is considered a low flow and meets the pressure specifications of Schedule 40 pipe. Sch 40 PVC pipe can reliably transport water from the main water source to the risers for sprinkler heads and the drip lines. Because this lateral piping system is buried, there is little risk of physical damage to the pipe, eliminating any need for a pipe sturdier than Schedule 40.
Although irrigation for commercial or municipal recreational spaces use higher pressure sprinkler systems, they usually still fall under the pressure rating for Schedule 40 PVC pipe. Many golf courses and sports fields will use a sprinkler system operating at approximately 110 PSI. Schedule 40 pipe enables the correct combination of pressure and flow rate for effective watering.
Pool and Spa Design
Pool and spa builders generally use Schedule 40 PVC pipe for both above ground and in ground pools, spas, and hot tubs. The pipe can reliably handle the low pressure of a pool filtration system, including suction lines and return lines. PVC pipe in particular will not corrode when in contact with the chlorine formulations used to clean pools or the minerals in the soil if the pipes run underground.
The nominal pipe dimensions most frequently used for pools and hot tubs is 1.5” or 2”. Both sizes have a high enough pressure rating (330 PSI and 280 PSI, respectively) to safely transport water at ambient temperature and a hot tub temperature of up to 105 degrees. While some pool builders will use Schedule 80 PVC, most designers agree this is unnecessary and not worth the higher cost.
Buried or Concealed Electrical Conduit
Unlike other projects that depend on fluid pressure to determine if Schedule 40 pipe is the right option, electrical conduit piping requires the correct physical strength. The electrical conduit pipe protects the wires running through it. Because Schedule 40 PVC conduit has thinner walls, it works best in areas that will not be exposed or are not at high risk of sustaining a physical impact.
Locations where Schedule 40 conduit is appropriate include wires running behind walls or ceilings, buried underground, or surrounded by poured concrete, as in accordance with the NEC 352 standard for conduit piping. Schedule 40 PVC conduit can safely be exposed to sunlight as long as it is in a protected area.
While Schedule 40 PVC pipe and Schedule 40 PVC conduit share similar measurements, they are in fact two different products and are not interchangeable.
Potable Water Supply
At residential properties and for some commercial applications, the water supply lines are lower pressure. However, when conveying drinking water, the pipe must have an NSF/ANSI 61 certification indicating that the thermoplastic materials are approved for potable water. Essentially, while Schedule 40 PVC pipe is an ideal choice for water supply lines, not every Schedule 40 pipe is suitable for this usage.
Other Uses for Schedule 40 Pipe
While these are the most common uses for Schedule 40 PVC pipe, they are far from the only ones. Schedule 40 pipe is an affordable solution for any low pressure water or fluid system such as:
- 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 pipe will be buried under a roadway trafficked by heavy vehicles. Schedule 80 PVC pipe has a 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:
General contractors, plumbers, and others working with commercial properties need piping solutions that are stronger than Schedule 40 pipe. Office complexes, multifamily residential buildings, and commercial spaces have more intensive demands for water pressure, capacity, and durability with frequent use.
Recall that the higher the schedule, the thicker the interior walls. One would think that this would decrease capacity considerably, but schedule 80 PVC pipe works because of its smooth interior that promotes optimal flow. The pipe will also last for years despite daily use by building residents, visitors, customers, and more.
Balancing pressure is a primary concern in many commercial buildings with multiple floors. The overall plumbing system needs sufficient pressure to convey water to the higher floors, often fighting against gravity to do so. In order to have the correct water pressure at upper floors, water supply lines near the base of the building are exposed to high pressure. Schedule 80 pipe is rated for the different high pressures throughout the building.
Schedule 80 pipe may be used as the main supply line or branching lines. The use of Schedule 80 PVC pipe is limited on some commercial properties by local building codes because the water in the system will exceed 140 degrees or sun exposure will degrade the pipes. When heat or UV rays are a concern, Schedule 80 CPVC pipe is the best alternative for commercial properties.
Manufacturing and industrial plants will often use Schedule 80 pipe for carrying, processing, or refining chemicals. The higher pressure capabilities and the improved physical strength provides a safer alternative to Schedule 40 pipe that will meet the standards for handling chemicals. Chemical processing industries that use Schedule 80 PVC pipe in their production systems include flavorings, fragrances, petrochemicals, pesticides and fertilizers, polymers, rubber, and ceramics.
PVC in particular is a good material choice for chemical applications. Because PVC is inert, it does not react with the majority of chemical compounds, including acids, and will not corrode when exposed to chemicals. The exceptions are limited, and include chlorinated hydrocarbons, aromatics, ketones, and some other solvents.
It is important also to remember that pressure ratings for Schedule 80 PVC pipe are given for water at 73 degrees. Changes in fluid density and viscosity for a chemical compound, as well as the temperatures at which chemicals are processed, can change the nominal pipe size needed for individual applications.
Schedule 80 PVC pipe can transport water, food and beverage products, and chemicals. In bottling plants, canning, and pasteurization, it can continuously convey consumable products with minimal need for maintenance and repairs.
You will also find Schedule 80 PVC pipe as part of production lines in refineries, paper processing plants, textile mills, metalworks, and other industries. The PVC pipes have the necessary pressure to serve as supply lines and effluent lines.
Larger scale agricultural properties often require higher pressure than landscaping irrigation to effectively move water throughout the property. Many irrigation lines may also have parts of the system placed above ground and Schedule 80 pipe offers additional impact strength.
Schedule 80 PVC piping systems on farms can also disperse fertilizer and pesticides as the majority of these products will not react with the PVC and cause the pipe to deteriorate.
For fish farming, fish hatcheries, and processing plants, many aquaculturists will use Schedule 80 PVC pipe. The pipe can transport food, water, and brine for processing. You can also use PVC to construct a cage to keep fish confined in a larger body of water. With thicker walls, Schedule 80 pipe is well adapted to withstand movement from waves without cracking.
HDPE is another popular choice for aquaculture where wave movement is involved as it is more flexible than PVC and will better absorb any shock without breaking. Like PVC, it is available in Schedule 40 and Schedule 80 to meet the requirements of the hatchery or farming plant.
Exposed Electrical Conduit
When the placement of electrical wires results in the conduit being exposed, especially in an area where foot traffic or activity occurs regularly, Schedule 80 PVC conduit provides the additional strength needed to withstand a physical hit. Schedule 80 PVC pipe can handle as much as three times the external PSI as Schedule 40 PVC and has a much lower risk of cracking or shattering.
Electricians can use Schedule 80 PVC conduit in any of the same locations as Schedule 40 – underground or encased behind walls and ceilings. It is also suitable for exterior use in all weather conditions and high traffic areas.
Like Schedule 40 PVC conduit, Schedule 80 PVC conduit cannot replace pipe meant for fluid conveyance and Schedule 80 PVC pipe cannot safely enclose electrical wiring per standards from the NEC.
Differences Between Schedule 40 and Schedule 80 Pipe: A Comparison
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.
Nominal Pipe Sizes for Schedule 40 and Schedule 80 Pipe
Pipe schedule is the first relevant standard when selecting a PVC pipe. The second is Nominal Pipe Size, often referred to as NPS. The NPS is the approximate size of the exterior diameter of the pipe. The most common nominal sizes for PVC pipes are:
- ½ inch
- ¾ inch
- 1 inch
- 1 ½ inch
- 2 inch
- 2 ½ inch
- 3 inch
- 4 inch
- 6 inch
- 8 inch
- 10 inch
- 12 inch
- 14 inch
- 16 inch
As nominal sizes, these are more equivalent to the approximate size of pipe’s outside dimensions. If you were to measure the cross section of a pipe, the exact diameter would be different. For instance, a pipe with a 2” NPS has a 2.375” actual diameter. A 6” pipe has a diameter of 6.625”.
Instead, the optimal usage of nominal pipe sizes is as a standard that remains the same across all pipe schedules. Recall that the inner diameter (ID) decreases as the schedule increases in order to achieve a thicker wall. The outer diameter (OD) stays the same. The result is that a pipe with a 2” NPS will have the exact same OD measurements whether it is a Schedule 40 pipe or Schedule 80 pipe. Both will measure 2.375” across.
The NPS standard makes it easier to determine which valves, fittings, and other accessories you can use to complete a piping system. There is also no need to carefully measure pipes to a precision of a thousandth of an inch in order to determine which pipes are in use.
But for this same reason, don’t be confused when you are replacing a segment of pipe and you measure the outer diameter at 2.375”, but cannot find that size at your local pipe supplier. The pipe you need is one with a nominal pipe size of 2”. At Pipe Xpress Inc., we can walk you through this if you need some additional help understanding nominal pipe sizing.
Wall Thickness on PVC Pipes of Different Schedules
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 OD stays the same, the added thickness in the pipe wall causes the 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 but pressure is consistently low.
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.
The pressure listed for the technical specifications when you purchase pipe is measured for water at a temperature of 73 degrees Fahrenheit. Cooler temperatures will result in a lower pressure and higher temperatures yield a higher pressure. Other fluid types can also change the pressure.
These various factors also need to be taken into account when selecting the PVC pipe schedule. A system that uses warm water (up to 140 degrees in the case of PVC) will have a higher average and maximum pressure, which may make a pipe with a higher pressure rating a necessity.
The pressure in a system may be determined by external water mains, pumps, or gravity. The average pressure should be well below the pressure rating for the pipe as continuous relative high pressure will put stress on the pipe over the long term, causing it to wear out more quickly.
The highest pressure for the system must also be below the pressure rating for the pipe schedule and nominal size. One instance of excessive high pressure over the standard rating can be enough to cause failure in the line.
Between only Schedule 40 PVC pipe and Schedule 80 PVC pipe, pressure ratings vary between approximately 100 PSI and 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 temperature and fluid type are within the requirements for PVC pipe, Schedule 40 and Schedule 80 PVC are an affordable option for nearly every project.
Pros and Cons of a Thicker Pipe Wall on Schedule 80 PVC
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 a consistent 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 Sch 80 pipe adds material to the inside, not the outside of the pipe. This means that a Sch 80 pipe with the same OD as a Sch 40 pipe will have significantly smaller ID, often measuring about 8% smaller. This restricts flow capacity from what could be transported in a Sch 40 system at the same pressure. At higher pressures, this reduced capacity is offset. But at lower pressures, the reduced capacity will have an effect on the system. To achieve the same interior capacity, a larger nominal Sch 80 pipe is necessary, which will take up more physical space.
- 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 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 a small order, 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. This can be useful for systems that have an average pressure near the maximum pressure rating for a Schedule 40 pipe or have a widely fluctuating pressure that could potentially exceed the pressure rating.
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, Schedule 40 PVC pipe is white and Schedule 80 PVC pipe is grey. This can help you identify a pipe schedule on sight when completing repairs or purchasing pipe.
It is worth noting, however, that 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 noncorrosive. 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, flex pipe is the most expensive option.
Other Considerations When Choosing Pipe Schedule for Your Project
A final difference between Schedule 40 and Schedule 80 pipes is the price. Schedule 40 PVC will always be more affordable than Schedule 80 PVC pipes of the same nominal size simply because they require less material to manufacture and less cost to ship. It is still necessary to choose a pipe that meets the technical requirements of your job and building codes, but as long as pressure and capacity ratings are sufficient, the lower cost of a lower schedule pipe can save you money on your project.
All pipe schedules are available in a variety of lengths. For Sch 40 and Sch 80 PVC pipes, the most common lengths are 10 feet and 20 feet. PVC is easy to cut down to the required size with a hand saw or power saw, even when using thicker wall Schedule 80 pipe. The length has no impact on pressure ratings and is ordered instead based on the needs of your project.
While PVC is a cost efficient and durable choice for many applications, there are some projects where another pipe will work better or is required. Temperature is one reason. PVC is only suitable for liquids up to 140 degrees. After that, the heat will damage the plastic. CPVC, or chlorinated PVC that contains an extra chlorine ion, can handle temperatures up to 200 degrees.
Certain types of fluids such as fuels, ketones, and chlorinated hydrocarbons are also damaging to PVC or PVC is not a permitted piping material. For these, a different pipe material with a corresponding pressure rating is necessary.
Other plastic pipes include polyethylene (PE), high density polyethylene (HDPE), acrylonitrile butadiene styrene (ABS), polypropylene, and more. There are also metal pipes made from steel, cast iron, and copper. While the pressure ratings will change with the material, the guidelines for where Schedule 40 and Schedule 80 piping remain largely consistent.
PVC pipe of any schedule is also never suitable for transporting compressed air or gases, and is not permitted by OSHA standard. The pressure ratings for Schedule 40 and Schedule 80 pipes refer to fluid pressure, and do not translate to air pressure. Using a PVC pipe for air is very dangerous and can cause a pipe to shatter as it explodes, launching shards of plastic. Stronger plastic pipes such as HDPE and ABS or metal pipes should be used instead.
How Pipe Scheduling Applies in PVC Fittings
A common phrase to describe pipes and their fittings is that a system is only as strong as its weakest point. This makes it necessary to choose not only the right pipe schedule for a project, but also the fittings that provide the correct pressure rating and strength.
Luckily, fittings are also classified by the same schedule and have a similar nominal size, thickness, and temperature requirements as the pipes themselves. 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.
Is It Necessary to Consider Pipe Schedule When Choosing Valves?
The third component in a piping system are the valves to control the flow of fluid for daily use or to facilitate repairs and maintenance. Valves also manage pressure and provide safety checks.
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.
There can be confusion here as some manufacturers or PVC pipe suppliers will describe valves as being for Schedule 40 or Schedule 80 use. Many ball valves are colored white or grey as well, leading people to assume they are for a particular schedule.
Can You Use Schedule 40 PVC Pipe and Schedule 80 PVC Pipe Together?
Since Sch 40 and Sch 80 pipes have the same NPS and OD, they do fit together. Schedule 80 fittings will fit onto Schedule 40 pipes and vice versa. When people are getting started with a piping project, they will often wonder if pipes and fittings from a different schedule can be used together.
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.
Installation Process for PVC Pipe
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 a 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 pipe should be quick and straightforward without requiring special equipment or experience.
Learn More About Schedule 80 and Schedule 40 PVC Pipe from Pipe Xpress, Inc.
If you are tackling your first PVC piping project or even if you have already completed dozens of projects, there are always questions when determining which pipe will help you complete a job safely, affordably, and with lasting results. 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.
This is when it can be helpful to get personalized advice on the right materials for your specific project. And here at Pipe Xpress, Inc. we gladly offer this advice to our customers. Our team are experts 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 pipe 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.
When you are ready to buy PVC pipes and the fittings, valves, tools, and accessories for your project, 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.