When it comes to connecting pipes and tubes in plumbing and hydraulic systems, compression fittings vs flare fittings is an important decision you’ll need to make. Each type has its own unique characteristics, applications, and installation processes. In this article, we’ll walk through the key differences between these two fittings, help you decide which one is best for your project, and offer step-by-step guidance for installation. If you have any questions along the way, feel free to reach out to us. We are always here to help.
Compression Fitting vs Flare Fitting
Before diving into the specifics of each fitting type, let’s take a moment to understand their general definitions, dimensions, and key features.
Compression Fitting

A compression fitting is a type of mechanical fitting used to connect two pieces of pipe or tubing by using a compression ring (also known as a ferrule) to form a tight seal. This fitting does not require the tube to be flared.
Dimensions: Commonly available in sizes ranging from 1/8 inch to 2 inches, depending on the application.
Application | Common Sizes | Remarks |
Residential Plumbing | 1/4 inch – 1 inch for copper, plastic, and PEX pipes | Must match the pipe size precisely for a proper seal |
Commercial Plumbing | Up to 2 inches or more | Larger sizes for more substantial plumbing systems |
Key Features:
- Simple to use.
- Suitable for various materials, including copper, brass, and plastic.
- Can be used for both high-pressure and low-pressure applications.
- Easy to install without requiring special tools or skills.
Flare Fitting

A flare fitting involves creating a conical shape at the end of a tube, which then fits securely into a matching flare fitting. The fitting is sealed by tightening a nut, which presses the flared tube end against the fitting.
Dimensions: These are typically found in sizes from 1/8 inch to 2 inches, with many available in both SAE (Society of Automotive Engineers) and BSPT (British Standard Pipe Thread) standards.
Application | Common Sizes | Remarks |
Automotive Fuel Lines | Typically 1/4 inch – 3/8 inch for most passenger vehicles | Must match the fuel line size accurately |
Small – Scale Plumbing in Tight Spaces | 1/8 inch – 1/2 inch | Designed for more compact piping setups |
Key Features:
- More durable under high-pressure conditions.
- Ideal for use in gas lines, refrigeration, and HVAC systems.
- Requires the use of a flaring tool to create the proper cone shape.
- More complex installation process compared to compression fittings.
Common Applications of Compression and Flare Fittings
Understanding when to use compression vs flare fittings can save time, money, and potential headaches during installation. Here’s a breakdown of where each fitting type is most commonly used:
Compression Fittings:
- Plumbing systems: Used for connecting copper, PVC, or PEX pipes in water supply systems.
- Low-pressure gas applications: Often used for connecting gas pipes in domestic or small-scale commercial systems.
- Automotive and HVAC systems: Found in some vehicle cooling or heating systems where moderate pressure is involved.
Flare Fittings:
- High-pressure systems: Flare fittings are commonly used in gas lines and refrigeration systems where the pressure is higher, and a secure, leak-proof seal is essential.
- Gas lines and fuel lines: These fittings are a standard choice for connecting fuel and gas lines in both commercial and industrial applications.
- Hydraulic systems: Due to their resistance to high pressure, flare fittings are often used in hydraulic tube applications.
Key Differences Between Compression and Flare Fittings

Now that we’ve established the basics, let’s dive deeper into the flare vs compression fittings comparison, focusing on the most crucial differences.
1. Sealing Mechanism
- Compression Fittings: Use a compression ring or ferrule to create a tight seal around the tube. This simple mechanism makes them easy to install without special tools.
- Flare Fittings: Rely on the flared end of the tube creating a tight seal against the fitting. This requires the use of a flaring tool to shape the tube properly.
2. Installation
- Compression Fittings: Easy to install, simply insert the pipe, add the compression ring, and tighten the nut.
- Flare Fittings: Requires more steps, including flaring the tube end and then attaching the nut to secure the fitting.
3. Pressure Handling
- Compression Fittings: Ideal for low to medium-pressure applications.
- Flare Fittings: Preferred for high-pressure systems as the flared connection creates a more durable and leak-resistant seal.
4. Material Compatibility
- Compression Fittings: Suitable for copper, brass, plastic, and other materials.
- Flare Fittings: Primarily used for metal tubes, especially copper and steel.
5. Cost
- Compression Fittings: Generally more affordable than flare fittings, due to the simpler design and installation process.
- Flare Fittings: Slightly more expensive due to the need for a flaring tool and more precise installation.
Feature | Compression Fitting | Flare Fitting |
Sealing Mechanism | Compression ring | Flared tube end |
Installation Complexity | Simple | Complex (requires flaring tool) |
Common Uses | Plumbing, low-pressure systems | Gas lines, refrigeration, high-pressure systems |
Pressure Handling | Low to medium | High |
Material Compatibility | copper, brass, plastic, | copper and steel |
Cost | cheap | expensive |
How to Choose Between Compression and Flare Fittings
When choosing between compression fittings vs flare fittings, consider the following factors:
- Pressure Requirements: For high-pressure applications (e.g., gas lines,hydraulic systems), flare fittings are the better choice.
- Ease of Installation: If you’re looking for a simple, quick installation, compression fittings are ideal.
- Material Type: Compression fittings are more versatile and can be used with a broader range of materials.
- System Type: For domestic plumbing, compression fittings are usually sufficient, while flare fittings are better suited for gas, refrigerant, or hydraulic systems.
Installation and Precautions
Compression Fittings Installation
Step 1: Prepare the Pipe
Cut the pipe to the desired length using a pipe cutter or hacksaw. Make sure the cut is clean and square.
Step 2: Assemble the Fitting
Slide the compression nut onto the pipe first, followed by the olive. The olive should be facing the end of the pipe.
Step 3: Insert the Pipe into the Fitting
Insert the pipe into the fitting body until it reaches the stop.
Step 4: Tighten the Nut
Using an adjustable wrench, tighten the compression nut. First, hand-tighten it as much as possible, and then use the wrench to give it an additional 1/4 to 1/2 turn. Be careful not to over-tighten, as this can damage the fitting, the pipe, or the olive.
Precautions:
- Wear Protective Gear: Always wear safety glasses and gloves to protect yourself from any sharp edges or potential flying debris.
- Check for Leaks: After installation, turn on the water supply (if it’s a water-related application) and check for any leaks. If there are leaks, carefully loosen the nut, check the position of the olive, and retighten.
Flare Fittings Installation

Step 1: Cut the Pipe
Cut the pipe to the correct length with a clean, square cut.
Step 2: Flare the Pipe
Use a flaring tool according to the manufacturer’s instructions. Place the pipe in the flaring tool and gradually create the flare. Make sure the flare is evenly formed and has the correct angle.
Step 3: Assemble the Fitting
Slide the nut onto the flared pipe, followed by the fitting body. The fitting body should be placed over the flare.
Step 4: Tighten the Nut
Using an adjustable wrench, tighten the nut until the flare is firmly seated against the fitting seat. Apply the appropriate amount of torque, being careful not to over – tighten, which could damage the flare or the fitting.
Precautions:
- Practice Flaring: If you’re new to flaring, practice on some scrap pipes first to get the hang of it. A poorly – formed flare can lead to leaks.
- Check for Leaks: Similar to compression fittings, after installation, test the system for leaks. In the case of fuel lines or hydraulic systems, any leak can be extremely dangerous, so a thorough check is essential.
Conclusion
When deciding between compression vs flare fittings, consider your application’s pressure requirements, installation ease, and material compatibility.
Compression fittings offer a straightforward, low-cost option for a wide variety of applications, while flare fittings excel in high-pressure and gas-related systems. If you’re uncertain about which fitting is right for your project, feel free to reach out to us for expert advice.
If you’re interested in our products, visit our homepage or contact us for our product catalog. We specialize in customized fittings, offering a full range of high-quality options to meet your needs.
FAQs About Compression Fitting vs Flare Fitting
Are flare fittings better than compression fittings?
It depends on the application. Flare fittings are better suited for high – pressure and high – vibration environments like automotive fuel lines and aircraft hydraulic systems. They provide a more secure seal under such conditions.
However, for general plumbing applications in homes and commercial buildings with stable conditions, compression fittings are often preferred due to their ease of installation and wider pipe material compatibility. So, there’s no one – size – fits – all answer, and it’s about choosing the right fitting for the specific requirements of the project.
Do professional plumbers use compression fittings?
Yes, professional plumbers use compression fittings extensively. Their ease of installation, reusability, and versatility make them a popular choice for various plumbing projects.
Compression fittings are commonly used in residential and commercial plumbing for connecting water supply lines, drainage pipes, and in heating and cooling systems. They offer a quick and reliable way to create connections, which is highly valued in the plumbing industry.
What is the advantage of flare fittings?
The main advantage of flare fittings is their ability to maintain a leak – tight seal in high – pressure and high – vibration environments. The flared end of the pipe creates a very tight and secure connection when mated with the fitting seat and tightened with a nut.
This makes them ideal for applications like automotive fuel lines, where any leak could be extremely dangerous, and aircraft hydraulic systems, where reliability is crucial. Additionally, once installed correctly, they offer a long – lasting and stable connection.
Is it okay to use compression fittings on gas?
In some cases, compression fittings can be used for gas lines, but it’s important to ensure that they are specifically rated for gas applications. Gas – rated compression fittings are designed to meet the safety and sealing requirements for gas systems.
However, local building codes and regulations should always be followed. In some areas, certain types of compression fittings may be prohibited for gas use, and other connection methods like soldering or flaring (in the case of copper gas lines) may be required. It’s crucial to consult the local authorities and use fittings that are approved for gas service.
How tight should you tighten a compression fitting?
When tightening a compression fitting, first hand – tighten the nut as much as possible. Then, use an adjustable wrench to give it an additional 1/4 to 1/2 turn. Over – tightening can cause damage to the fitting, the pipe, or the olive.
Under – tightening can result in a leak. If you’re using a torque wrench, refer to the manufacturer’s specifications for the recommended torque value. This ensures that the fitting creates a proper seal without causing any damage to the components.
What are the differences between Barb vs Compression Fittings?
Barb fittings have a tapered end with ridges (barbs) that grip the inside of a flexible hose or tubing. They are often used for applications where a quick and easy connection is needed, such as in some irrigation systems or for connecting hoses to pumps. Compression fittings, on the other hand, use a nut and an olive to create a seal on the outside of a pipe.
Compression fittings are more suitable for rigid pipes like copper, plastic, and PEX and provide a more secure and leak – tight connection in high – pressure plumbing systems. Barb fittings are generally easier to install and remove but may not be as suitable for high – pressure applications as compression fittings.
Where to buy fittings?
For a wide selection of fittings, including customized solutions, feel free to contact us at Dingfeng. We offer a complete range of fittings for all your needs. Reach out anytime for a personalized quote or product catalog.