Flexible plastic tubing is used in water handling, chemical transfer, laboratory equipment, irrigation, and industrial fluid systems. Choosing the correct connection method helps prevent leaks, tubing damage, and accidental disconnections.
Several types of fittings are available for plastic tubing, including hose barb, compression, and push-to-connect fittings. Each uses a different method to grip and seal the tubing.
Step 1: Identify the tubing material and size
Start by identifying the tubing material, inside diameter, outside diameter, and wall thickness.
Tubing dimensions are especially important because different fitting types use different sizing methods.
| Fitting type | Important tubing measurement |
|---|---|
| Hose barb | Inside diameter |
| Compression | Outside diameter and compatible wall thickness |
| Push-to-connect | Outside diameter, material, and required wall support |
Confirm the tubing’s pressure rating, temperature range, and chemical compatibility before choosing a connection method.
Step 2: Cut and prepare the tubing
Use a suitable tubing cutter to make a clean, square cut.
Remove burrs and sharp edges that could interfere with the fitting or damage its internal seals.
Inspect the tubing for scratches, flattening, cracks, and other damage. Damaged tubing may not seal properly even when the fitting is installed correctly.
Method 1: Installing a hose barb fitting
Hose barb fittings use raised ridges to grip the inside of compatible flexible tubing.
- Select a barb sized for the tubing inside diameter.
- Slide a suitable hose clamp over the tubing if the connection requires one.
- Push the tubing fully onto the hose barb.
- Position the clamp over the appropriate sealing area.
- Tighten the clamp according to its installation requirements.
- Inspect the connection and perform an approved leak test.
Avoid overtightening the clamp, which can damage the tubing.
Method 2: Installing a compression fitting
Compression fittings grip and seal tubing as a nut is tightened against the fitting body.
- Cut the tubing square and remove burrs.
- Insert the tubing through the back of the fitting nut and any required gripping components.
- Push the tubing completely into the fitting until it reaches the internal tube stop.
- Hold the tubing firmly against the stop while hand-tightening the nut.
- Finish tightening the nut according to the specific fitting instructions.
- Inspect the connection and perform a leak test.
Some compression fittings use a preassembled nut with an internal gripper and sleeve. These fittings may not need to be disassembled before tubing insertion.
For one common fitting design, the installation instructions specify an additional 1-1/2 to 2 wrench turns after hand tightening. That value is specific to that fitting design and should not be applied to every compression fitting.
Some designs also require the nut to be retightened when the system reaches its operating temperature.
Important: Tubing must reach the internal stop. A partially inserted tube may leak or disconnect.
Method 3: Installing a push-to-connect fitting
Push-to-connect fittings use an internal gripping mechanism and an O-ring to secure and seal compatible tubing or pipe.
Some designs include a locking cap that must be tightened after insertion.
- Make a square cut and remove sharp edges.
- Inspect the tubing surface for scratches or damage.
- Install a tube support insert if required for the tubing material.
- Make sure the fitting is in its unlocked position, if applicable.
- Push the tubing fully into the fitting until it reaches the internal stop.
- Engage the locking mechanism according to the fitting design.
- Gently pull on the tubing to confirm that it is secure.
- Pressure-test the connection using an approved method.
The tubing must pass through the gripping mechanism and sealing O-ring before reaching the tube stop.
How to disconnect a push-to-connect fitting
Always depressurize the system first.
For a fitting with a locking cap, return the cap to its unlocked position.
Press the release collet squarely against the fitting body while withdrawing the tubing.
Inspect the tubing and fitting before reuse. Not every push-to-connect fitting uses the same release mechanism or permits reuse.
Common tubing connection mistakes
- Choosing a fitting using the wrong tubing diameter
- Using tubing incompatible with the fitting
- Making angled or rough cuts
- Leaving burrs on the tubing end
- Failing to insert tubing completely
- Forgetting a required tube support insert
- Overtightening compression fittings
- Leaving a locking fitting unlocked
- Mixing components from incompatible fitting systems
- Failing to test the completed connection
How to choose the right tubing connection
Hose barb fittings are commonly used with flexible tubing where the barb provides internal grip and a clamp may provide additional retention.
Compression fittings are useful when tubing dimensions match the fitting’s gripping and sealing components.
Push-to-connect fittings provide a convenient assembly method when the tubing material and dimensions are approved for the fitting.
Regardless of the connection type, verify the material compatibility, pressure rating, operating temperature, and installation requirements before placing the system into service.