Is IPS compatible with NPT?(Explained)

Is IPS compatible with NPT?

Note: As an amazon associate I may earn a small commission from qualifying purchases if you click to amazon from my site and choose to make a purchase.You can read my complete affiliate disclosure for more details

Is IPS compatible with NPT?

American National Pipe Tapered Thread (NPT) is a pipe thread standard used in plumbing, most notably on water supply pipes.

Tapered threads characterize the NPT fittings on pipe and fittings to create a seal you can easily undo with minimal force yet still provides an adequate seal.

No! IPS is not compatible with NPT. The inside and outside pipe sizing on an NPT system differs and that the pressure connections would be too big for an IPS system. Also, the position on the main pressure inlets on an IPS system is higher than on an NPT system.

IPS connections would have no place to connect their valves because the size of the NPT valves blocks the space.

Even if IPS valves were used in an NPT system, they would get clogged by the other valves and would not function properly.

There are many types of IPS systems, some of which use valves bigger than usual. This is because the inside diameter of their pipes is bigger, so they have to use more pressure to make the water flow through their pipes.

The main issue here is that the pressure connections on an IPS system are higher.

This means that the valves for each leg of the IPS supply will be in direct contact with the source water when installed and shut off after a closing test.

If this connection is leaky, the valve won’t shut off properly, which will cause an excess flow condition downstream of the filtering system.

IPS Vs. NPT: Which is Better?

SizingBoasts a straightforward threadHas a tapered thread
ThreadsIPS threads are closer togetherNPT threads are farther apart
InstallationInstalling an IPS sink and copper pipe assembly is the easiest.

Copper can be expensive and can dent easily
NPT pipes can be challenging to install, especially if the pipe fits snugly against the wall, wallboard, or other pipes in the area you cannot move.

This is because of their tapered shape, which requires specially designed fittings.
FittingsYou can remove and re-solder IPS pipes and fittingYou cannot remove NPT pipes and fittings.
BreachesRepairs are relatively inexpensiveRepairs are upwards of $100 per repair.
FlexibilityCan move as much as 5% without breakingMust not bend at all. If you need to bend it, you should use flexible nylon tubing instead or stainless steel and re-route the water to avoid bending the pipe.
Size and LengthComes in multiple sizes, and fittings can be cut down if limited to 2 sizes and can only be cut if you have the right tools.

Iron Pipe Size Vs. Copper Tube Sizes: How They Differ

FactorIron Pipe SizeCopper Tube Sizes
Outside DiameterThe OD of an iron pipe is 1″ for a typical pipe.The outside diameter of copper tubing ranges from .13″ to .65″.
Wall ThicknessIron pipes have a wall thickness that’s much thicker than copper pipes.

This helps them withstand the pressure subjected to them when you fill them with water.
Copper tubes are significantly thinner than iron pipes and are not resistant to high water pressure.
MaterialIron is a mineral you find in the earth’s crust. You can melt and heat it to form a pipe shape.Copper is an easily malleable metal you can melt to form pipes.
Inside DiameterThe size of the pipe itself determines the inside diameter of an iron pipe.

There’s no specific measurement for an iron pipe’s inside diameter.
Copper tubing is made from the copper wire you press together and roll into a shape.

The copper wire’s thickness determines the outside diameter of the copper tubing.

What does the IPS connection mean?

IPS connection is an acronym for Iron Pipe Straight thread, which stands for all the different types of connections, including pipe nipple threads, pipe NPT threads, and pipe BSP threads.

This pipe has an internal diameter of 1/2 inch and a threaded shaft with a 6-32 male or female thread on the outside, usually in stainless steel.

Is IPS compatible with NPT?

You can use this pipe to connect a water filter, pump, water pipe, or aquarium because it can fit the threads on these different pieces.

Its internal diameter is 1/2 inch, meaning that whatever you connect to the end of this piece will have to have the same diameter.

If you want to connect something smaller, you need to use some coupling or adapter.

There is a male and a female version of this pipe. The female version boats threads on the outside, and the male version has an opening on the outside that needs a connection to a piece of pipe with threads.

Sometimes there are other versions with handles or other attachments on them. You want to ensure you know what you’re buying before you do so because they’re different sizes and many different types.

What Is the Difference Between IPS And NPS Pipe?

MaterialBoasts carbon steel, red brass, PVC, and 304 & 316 Stainless Steel material.Made of cast iron
Outside DiameterTypically 2-6 inches outside diameterTypically, 3-6 inches outside diameter.
Flow RateHas a flow rate of 0.9792 gallons/ft. Per minute.Has a flow rate of 1.5 gallons/ft. Per minute.
Type of FittingsComes with male and female threads for connection to fittings other than the original pipe valve type that came with the system.Has male and female threads standard on all sizes
Threaded LengthsComes in lengths from 6″ to 36″.Come in a 6″ minimum length, and all lengths are up to the limit of the pipe size.
Specialty FinishAvailable in PTFE and chrome finishes on copper, brass, and carbon steel.Available in PTFE, chrome, or standard finish on cast iron.

Sizing for IPS (Iron Pipe Straight)

Select Your LengthYou need to know the length you want your IPS (Iron Pipe Straight).

A general rule of thumb is the length times 2 equals the number of lengths, if a 120′ IPS is needed, order 240′.  Select 180′ for a 90′ run
Decide On Your HeightThe height denotes how high you want your IPS (Iron Pipe Straight) to be off the ground and out of obstacles such as gutters, driveways, or patios.

Select a height that’s adequate for the space you have.
Add On the Correct SagSAG (Snow Load) denotes the weight the IPS (Iron Pipe Straight) can handle. The higher the SAG, the more weight it can handle.

A general rule of thumb is to add 0.25″ to each foot of height at a time.

For example, if you order 100′ L100′, select a SAG of 55 (100’×0.25″ =25′, 25+20=45′, 45+45=90′). This would be 100′ IPS with a 20′ post spacing and a SAG of 55.

Select a SAG based on the area of use.
Choose Your Hardware and FastenersSelect hardware and fasteners to match the length, height, SAG, and number of IPS (Iron Pipe Straight) ordered.
Add Your Post CapsSelect the cap(s) that are most aesthetically appealing to you.
Pick Up Your IPS (Iron Pipe Straight) OrderGo to a Home Depot Store to pick up your IPS (Iron Pipe Straight). You can locate this in the lumber section.

Please have your order # and picture ID ready when picking up your IPS (Iron Pipe Straight).

Sizing for NPT (National Pipe Tapered)

Choose the correct pipe sizeYou can measure the National Pipe Tapered size by the wall thickness of the pipe.
Use the National Pipe Tapered Size Chart on the back of your plumbing supply manual. In most cases, NPT sizes are given in inches or millimeters and can be converted using a formula such as:

P = .472 x L where P is pipe threads, and L is inches or mm
Choose the correct length of pipe you will needLeave at least 1/2″ (13mm) clearance from the top of your appliance to the top of your sink.

Ensure the pipe is at least 6″ (150mm) longer than your pipe run.

This allows for easy plumbing and bends. If a 90-degree bend is required, allow for extra room as well.

Do not use elbows or caps that are less than three times the diameter of the pipe above it.

Do not use T connectors or adapters between the ends of your pipe.
Get a new end-to-end rubber gasket for an air-tight sealUse the correct size for your pipe:

3/4″ (19mm) for NPT 1″ (25mm) for NPT 2″ (50mm) for NPT PEX *; 1/2″ (13mm) for PEX *; 3/4″ (19mm) for PEX *
Drill a hole in between the threads of your pipe capUse a 1/8″ (3mm) drill bit. Drill the hole in between the threaded holes and not through either one.

Where to Use the NPT Pipe Connection?

1. Kitchen Sink

You can use the NPT pipe connection to the kitchen sink to dump the sink and rinse water. The kitchen sink is the most common point at which any centralized plumbing system begins. 

2. Washing Machine Drain

A washing machine uses an NPT pipe connection to throw water from its drain. This is a very useful application for most family laundry room plumbing systems.

3. Sink

The sink is also typical to have an NPT pipe connection, especially if it has no garbage disposal, as they are mostly used to let water flow out of the respective plumbing system.

4. Showerhead Spout

You can use the NPT pipe connection to the showerhead spout for a showering system.

You can use it for a washing machine under the stand or even in dryer rooms, depending on your plumbing system arrangement, as long as you work with a radius of less than 20 feet.

5. Toilet Flush Valve Connection

You can use the NPT pipe connection to the toilet flush valve for a centralized plumbing system. This is a very important and useful application since this is what enables your waste water to flow out.

6. Bathtub Faucet Connection

For a centralized plumbing system, you can also use a NPT pipe connection to the bathtub faucet. The bathtubs in bathrooms are usually connected for this purpose.

7. Sink Drain and Overflow Connection

For a centralized plumbing system, you can also use an NPT pipe connection to the skimmer and any other drains on the sink. This is a good selection if you want water outside your property.

What Are the Three Types Of Pipes?

1. Copper

For a long time, copper has been used for piping and is still in use today. Unlike other metals, it is resistant and barely reacts to water and oxygen.

This can last up to 100 years if the conditions are kept constant. The elasticity of copper also allows it to handle pressure surges better than other metals, making it safer for public use.

Copper also boasts a wide usage range, such as hot water heating and steaming. It is also safe and comfortable to use in a shower.

Copper pipes are also available in a more cost-effective form, where the ends are not fully joined together. This is to prevent leakage as well as leaks from being common.

2. Plastic

Plastic is primarily used when there are no potentially harmful chemicals, and can withstand a temperature range of up to 80-100 degrees Celsius.

Different plastic pipes contain various minerals and plastics, from soft to rigid. They are usually more flexible than metal pipes and, thus, easier to install.

You can use plastic pipelines for water supply, irrigation, drainage systems, and low-pressure heating systems. These plastic pipes do not corrode or expand with fluctuations in pressure.

3. Stainless Steel

Stainless steel is a good choice for plumbing pipes because it does not corrode or rust easily and has the strength to withstand chemicals.

Stainless steel is also resistant to heat and has chemical resistance.

For sizes, the average size is 2 inches in thickness, but you can use small pipes. Otherwise, you should choose the right size because joining the ends of different segments with the same size will often cause leakage.

According to taste and cost, you can choose one of the above three types of pipes to install. The type of use and the existing conditions in your house determine the most suitable.

Is NPT Tapered or Straight?

NPT threads are tapered or straight. This means that one end is round or elliptical, and the other is sharp or angular.

You can often see a larger diameter at one of the ends, meaning that you can use the smaller diameter to screw into the larger diameter.

NPT tapered threads are popular for water supply as they present no danger of bursting and can be attached to various pipes.

The threading on this kind of thread is such that it can tighten without causing any damage or deformation on the threads. A tapered thread has a smaller diameter at one end and a larger diameter at the other.

Because of the reduced radius at the larger end, it is possible to screw in and tighten the nut without deforming or damaging the threads.

Is IPS compatible with NPT?

This can be very useful to tighten a bolt against a tight surface or while using it in an area where you want to avoid damaging the threads.

You can use the cut-off on this thread so that any cuts you make due to excess force are made at the tapered end of the thread.

If you have a project requiring you to drill holes or make notches in the pipe, then there are better options than a tapered thread.

Using too much force while tightening can permanently damage the threads. Also, if you need to use solvent cement, be careful because it may not hold since one side of your thread is damaged.


NPT pipe connectors are one of the plumbing system’s most commonly found parts. They are a good choice for connecting pipes of different diameters.

Understanding the difference between NPT and IPS is essential to choose the suitable connector for your project.


Hi! I I faced many questions from customers about different products, and there was hardly any help on the internet. After learning all the things about these products as a manager the hard way, I decided to start a blog and help other people.

Recent Posts