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The Opfiue copper pipe extension joint connectors are brass unions for joining 1/4 inch or 3/8 inch copper tubing with flare nuts instead of solder. They suit AC, refrigeration and small plumbing repairs where you can flare the tube ends. This Opfiue copper pipe connector review is based on the Amazon listing; confirm the size option you pick before you order.
Quick specs at a glance
| Item | Per the listing |
|---|---|
| Brand | Opfiue |
| Type | Flare union / extension joint connector |
| Sizes mentioned | 1/4 inch and 3/8 inch tubing |
| Pack contents | 2 union connectors and 4 flare nuts |
| Material | Brass, with copper described in the listing |
| Joining method | Wrench-tightened; no soldering or welding |
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What it is and who it suits
This pack gives you two joint connectors with four nuts, enough to repair or extend a pair of lines or one line in two places. Because it covers two common tube sizes, it is a handy option for small-line AC work and mixed copper projects.
It is less useful if you want a permanent joint inside a wall, where brazed joints are more common, or if you do not own a flaring tool.
How to check it fits your setup
- Pick the size first. Choose the 1/4 inch or 3/8 inch option that matches your tube’s outside diameter.
- Check the flare angle. Standard HVAC flares are 45 degrees. A mismatch between tool and fitting causes leaks.
- Check wall thickness. Thin or thick wall tube can flare differently; use tube suited to flaring, usually soft copper.
- Make sure the nuts’ thread matches the union. Buy nuts and unions as a set.
- Check access. You need room for two wrenches at the joint.
Pros and limitations
- Pro: two common sizes in one product line.
- Pro: no heat required, so no fire risk near insulation or other parts.
- Pro: joint can be taken apart for service.
- Limitation: needs a proper flare; poor flares are the biggest cause of leaks.
- Limitation: listing claims about gas systems should be taken with care. Verify ratings.
- Limitation: brass unions and copper tube can both be damaged by over-tightening.
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Installation tips
- Cut and deburr the tube. A rough cut makes a poor flare.
- Put the nut on first, then flare the tube end.
- Do not use thread sealant on the flare face; the flare seals by contact.
- Hold the union steady with one wrench while tightening the nut.
- Leak test with soapy water if the line holds gas or pressure.
- Insulate and support the tubing so the joint is not stressed by vibration.
If the line carries refrigerant, remember that handling and venting refrigerant is regulated in the US. Hire a licensed technician for charging and recovery.
Alternatives and related guides
- A 1/4 inch-only pack is covered in the AC copper pipe connectors review.
- For a soldered straight joint, see the straight copper coupling fittings review.
- For a different union style, see the Patikil 1/4 copper coupling review.
- For a cross-pipe union, see the Patikil copper union cross pipe fitting review.
Frequently Asked Questions
How do I know whether I need the 1/4 inch or 3/8 inch connector?
Measure the outside diameter of your copper tube. Nominal 1/4 inch tube measures about 1/4 inch OD, and 3/8 inch tube measures about 3/8 inch OD. Check the listing’s size options and match nut and union to the tube, not to the pipe thread.
Do I need a flaring tool for these connectors?
Yes, if they are flare unions as the included flare nuts suggest. Each tube end must be flared to seat in the union. A tube cutter, deburring tool and flaring tool are the minimum kit, plus two wrenches.
Are these suitable for natural gas or propane lines?
Do not assume so. Gas piping is regulated and uses specific fittings and installers. The listing mentions HVAC and plumbing; ask a licensed gas fitter before using any fitting on a fuel-gas line.
Can I reuse a flare union after taking it apart?
The union body can often be reused if the seat is undamaged, but the flared tube end is usually deformed. If the flare looks marked or thin, cut it off and make a new flare before reassembling.
Conclusion
These Opfiue connectors are a flexible, torch-free option for 1/4 and 3/8 inch copper tube, if you can flare the tube correctly. Check the size, flare angle and system rating first.
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