Tri-Groove Security Nuts

“Trident” Tri Groove Security Nuts

Tri Groove security nuts are nuts that are installed with a very unconventional drive. These nuts have three slots in them, making them unique in shape and appearance. They have a cone shape, designed to be gripped only by the device intended to tighten and loosen them.

You can commonly find these in places where security or vandalism is a concern. To test these nuts we decided to install one ourselves and test a couple of different tools to see if we could remove them quickly.

tri groove nut install

First, we installed the nut using a tri-groove socket tool specially designed for this drive style. After install, we attempted to tamper with this fastener ourselves to determine what it would take to remove it.

how to break tri groove nut

We tried using an adjustable wrench. That didn’t work, the cone shape of the nut showed no gripping areas to lock the wrench into. We also tried pliers which had the same effect. Vice grips were our last attempt to break this nut loose with a conventional tool. However, the cone shape made it incredibly difficult to find a locking point. So we attempted to grab the lip and the base of the installation. The lip proved to be too small to get a good grip, leading us to our conclusion.

attempt to break tri groove nut with wrench tool
attempt to break tri groove nut with tool


Having tested several different removal methods for removing this nut, we have determined that without either the proper tool or physically altering the shape of the nut (perhaps with a grinder) to provide a gripping point for more conventional tools, it is unlikely that this nut will be easily tampered with when installed correctly.

*Although these nuts are fairly secure there is still a chance that someone could have enough know-how or time to alter the shape of the nut or may have come across the proper tool to remove them.

Installing & Removing Tri-Groove Tamper Proof Security Nuts | Fasteners 101 See Full Video in Our Youtube Channel.

What are Security Screws?

What are Tamper Proof Screws?

Tamper Proof, Tamper Resistant and Security Screws

Tamper Proof Fasteners are screws, Nuts and Bolts best characterized by their unconventional drive style. Tamper Proof Fasteners are used in areas where an assembly is accessible to the public, as a means to deter or prevent vandalism or disassembly. Tamper proof security screws, or Tamper resistant security screws, are distinguished by having an unconventional drive, making tampering with the screw more difficult, if not impossible without the matching driver. Security Screws are used for securing materials from being tampered with, such as gutters, license plates, grills in jails, schools, boats and cars. They are also used in food prep and processing areas. You will often see security screws used in bathroom stalls, particularly toilet partitions and other public locations.

What is an “Unconventional Drive Style”?

Unconventional Drive Styles come in many varieties, but all share one common goal: difficult (if not impossible) installation or removal without the corresponding security Bit or Driver.

One Way Screws

Stainless Steel One Way Screws

One Way Screws (sometimes called Irreversible Screws or One Direction Screws) get their name because of their drive style. The head of the screw features a slotted drive that is designed to instantly cause cam out if the driver is turned in the wrong direction. This is achieved by manufacturing the drive in quadrants that are gradually raised to accept the driver bit when turning the screw right, and reject it when turning the screw left. The One Way drive makes installation of the screws easy, requiring only a standard slotted bit, but removal of the screw difficult (if not impossible) without the corresponding bit or a specifically designed removal tool.

One Way Screws are commonly seen in public areas such as bathroom fixtures and partitions, license plate frames on cars, wall or floor mounted safes, and wherever tampering after installation becomes a security issue. Generally speaking, all Tamper Proof Screws are used to deter vandalism or theft because the removal of the screw is difficult, if not impossible, without the corresponding unconventional bit. One Way Screws are particularly difficult to remove, which means that they should be used for long-lasting applications.

Shop Stainless Steel One Way Screws

Spanner (Snake Eye) Security Screws

Stainless Steel Spanner Screws

Tamper Proof Spanner or “Snake Eye” security screws are installed using a spanner bit. Spanner Screws are commonly referred to as “Snake Eye” because of the two dot drive system. Spanner security screws are used for securing materials from being tampered with, such as gutters, license plates, grills in jails, schools, boats and cars. They are also used in food prep and processing areas. You will often see security screws used in bathroom stalls and other public locations. Spanner screws can only be installed or removed with a spanner bit, which fits a pin into each of the screw’s two drive holes. Since Spanner screws can only be installed or removed through spanner bits, they are very resistant to tampering.

Shop Stainless Steel Spanner “Snake Eye” Screws & Bits

Torx (6 Lobe with Pin) Security Screws

Stainless Steel Torx Screws

Torx® with pin security drive can only be driven with security bits and are used to prevent tampering and theft. Security Screws in this variety are characterized by the 6 lobe, or star drive with a central pin. The pin grants additional tamper resistance as it prevents conventional screwdrivers and grabbing devices from tampering with the original installation.

Shop Stainless Steel Torx Tamper Proof Screws, Bits & Drivers

Tri-Groove Security Nuts

T Groove Nuts

Tri Groove security nuts feature a tapered diameter, making the nuts resistant to gripping devices. Security nuts are installed using a special Tri-Groove socket, which grips the indentations along the outside of the fastener to turn the nut along a thread. Tri Groove nuts are also referred to as T Groove, Trident Drive and Cone Trident Drive Nuts are tamper resistant.

Shop Tri-Groove Nuts & Drivers

In This Video:

Our Fastener Expert goes over many of the popular security fasteners available for your builds.

For more information on Tamper Proof Fasteners and to shop our selection click here.

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