Can flare nut wrenches be used on regular nuts?

Flare nut wrenches are a specialized type of wrench designed specifically for gripping and turning flare nuts, which are a type of nut with a flared end used to connect tubing. However, some people wonder if a flare nut wrench can also be used on regular hex nuts and bolts. In this article, we’ll look at what makes flare nut wrenches different from regular wrenches, the advantages and disadvantages of using them on regular nuts, and provide a recommendation on whether this is a good idea.

What are Flare Nut Wrenches?

Flare nut wrenches, sometimes called tube nut wrenches, are designed to grip and turn metal nuts that have a flared end. The flared end prevents the nut from slipping off the tubing.

Flare Nut Design

The key feature of a flare nut that makes it different from a regular hex nut is that the end of the nut body is rimmed and angled outward. This flare provides an increased bearing surface that keeps the nut from being pulled off the tubing.

Wrench Design

To grip these flared nuts, flare nut wrenches have a unique shape. The opening end of the wrench has a curved interior surface that matches and grips the angled flare of the nut. This allows the wrench to get a solid grip on the nut without slipping.

Common Uses

Flare nut wrenches are commonly used in automotive applications, hydraulics, pneumatics, HVAC systems, and other tubing connections using flared fittings. The flared end and matching wrench provide a strong, reliable metal-to-metal tubing joint.

Difference Between Flare Nut Wrenches and Regular Wrenches

While a flare nut wrench may look similar to a regular open-end wrench, there are some important differences that make them suited for different purposes.

Opening Size and Shape

The opening end of a flare nut wrench has a rounded interior surface to match the rounded flare of a nut. A regular wrench has straight, parallel interior surfaces to grip flat sides of hex nuts and bolts.

Gripping Mechanism

A flare nut wrench grips from the outside edge of the nut flare. A standard wrench grips the flat sides of a nut. This means a flare nut wrench can’t get a good grip on regular hex nuts.

Materials

Flare nut wrenches are typically made from softer steel alloys so they can flex and contour to the flare. Standard wrenches are harder for gripping flat surfaces tightly.

Sizes

Flare nut wrench sizes refer to tubing diameters, while regular wrench sizes refer to bolt/nut widths across the flats. The dimensions are not interchangeable.

Can You Use a Flare Nut Wrench on Regular Nuts?

While a flare nut wrench may be able to physically fit onto some regular hex nuts and bolts, it is not recommended to use them for that purpose regularly. Here are some pros and cons to consider:

Pros

Can fit some standard hex nuts if they are small enough

Curved surface provides more points of contact for gripping
Softer steel can flex to fit different shapes

Cons

Not designed to grip flat sides, so can round off corners

Curved surface does not make full contact with flat sides
Softer material can wear out faster on hard nuts
Can slip and damage soft nut material

Does not work well on large bolts/nuts

Recommendation

While a flare nut wrench may be made to work occasionally in a pinch on some smaller hex nuts, it is generally not recommended for regular use on standard hex fasteners for a few key reasons:

The curved surface does not grip flat sides well, leading to stripping/rounding bolt and nut corners.

The softer material of the wrench can wear out quickly from use on hard nuts and bolts.
Flare nut wrenches are sized for tubing, not hex bolt/nut widths, so it’s hard to find a good fit.
A standard wrench designed for hex nuts and bolts will work significantly better.

For standard hex nuts and bolts, a non-flare nut regular open-end or box-end wrench is a far better choice. The flat, hard steel jaws will grip the flat sides of the nut/bolt securely without slipping or rounding.

Overall, it’s best to use the proper wrench designed specifically for the job. Flare nut wrenches for flare nuts, and standard wrenches for regular hex nuts and bolts.

When Can You Use a Flare Nut Wrench on Regular Nuts?

The only times when it may be reasonable to use a flare nut wrench on a regular hex nut or bolt include:

In an emergency when you need to remove or lightly tighten a small nut and don’t have the proper wrench.
If you modify the flare nut wrench like grinding the interior surface to make it flat.
For very occasional, light use on small, soft nuts/bolts where some rounding or wear is acceptable.

However, even in these situations, you run the risk of rounding the nut/bolt so you must use extreme care and avoid applying too much torque. The proper standard wrench is still the recommended choice.

Tips for Using a Flare Nut Wrench on Regular Nuts

If you do find yourself needing to use a flare nut wrench on a regular hex nut/bolt, here are some tips to reduce the risk of damage:

Choose smaller nut/bolt sizes that the wrench can fit better.

Tighten the nut very gradually, avoiding high torque.
Visually inspect contact surfaces frequently to check for rounding.
Use on softer nuts like nylon lock nuts, avoiding hardened steel.

Consider filing the inner curved surfaces to flatten them.
Always have a proper standard wrench available for immediate replacement use.

Taking precautions by suitable nut selection, careful torque, and surface protection will reduce the chances of damaging the nuts, bolts, or wrench. But again, this should only be done as an emergency fix. For regular applications, the proper standard wrench is a must.

Flare Nut Wrench Alternatives

If you find yourself without the proper standard wrench, there are some alternative options to try before using a flare nut wrench on hex nuts/bolts:

Adjustable Wrench

An adjustable wrench can grip many nut and bolt sizes well, though risk of rounding is higher. Protect corners with a cloth.

Pliers

Locking pliers or regular pliers can grip small to medium nuts in a pinch. Use padding to prevent damage.

Socket Wrench

A socket wrench with various socket sizes can accommodate many hex nuts/bolts if you have the set. Impact wrenches require care to avoid over torque.

Improvised Wrench

Cut a correctly sized hex notch into a sturdy piece of wood or metal as an improvised wrench. Ensure smooth flat surfaces.

Buy Proper Wrench

Picking up an inexpensive standard open-end or box-end wrench in the needed size is the best permanent solution.

Trying one of these alternative options first is wise before attempting to use a flare nut wrench incorrectly on standard hex nuts and bolts.

Key Takeaways

– Flare nut wrenches have a specialized shape for gripping flared tubing nuts, while standard wrenches are made for hex nuts/bolts.

– It’s not recommended to use a flare nut wrench regularly on hex nuts/bolts as it can round off corners and wear down fast.

– In an emergency, a flare nut wrench may work on smaller, softer nuts but proper wrenches are still the go-to choice.

– Take precautions if forced to use a flare nut wrench on hex nuts and consider alternatives like adjustable wrenches first.

– For regular use on hex nuts/bolts, always choose a standard non-flare wrench for best grip, torque, and longevity.

Conclusion

While it’s possible to use a flare nut wrench on some regular hex nuts and bolts in a pinch if no standard wrench is available, it is generally not a good idea for regular applications. The curved surface of the flare nut wrench does not properly grip flat sides, creating risks of slippage, corner rounding, and fast wear down. It’s far better to use the proper standard, non-flare wrench designed specifically for hex nuts and bolts for a solid, lasting grip. In a jam, alternatives like adjustable wrenches or pliers may work better than a flare nut wrench on regular hex fasteners. But for routine use, having the right standard open-end or box-end wrench is the wise choice both for fastener protection and long-lasting performance. With the right wrench for the job, you can apply proper torque and avoid damage in any application.