Drive it home

Pre-assembled hangers that can be installed with powder-actuated tools can make a difficult job fast and easy. Proper selection, training and installation are keys to success.

Take a powder-actuated tool, load it up with the right load and put a combination pin and hanger in place and you can drive home fasteners with speed, accuracy and efficiency.

But each component — the pin, load and hanger — must work as a system and be matched to the job at hand, says Bill Georges, powder-actuated tool product manager at Simpson Strong-Tie.

The selection of the proper powder-actuated anchor starts with building codes that guide design engineers to the right anchor that can take the loads the application will exert. Vibration, seismic concerns and sheer loads must be considered.

“Usually, the design engineer specifies the type of pin and fastener that should be used, but it is up to the installer to select the correct load to get the anchor to seat correctly,” says Georges.

The substrate matters
Concrete and steel can vary greatly between jobs and even on jobsites. That’s why it’s important to pay attention to fastener performance throughout the installation process.

The speed in which a powder-actuated fastener enters steel or concrete is responsible for its holding power. “When a powder-actuated fastener is driven into concrete or masonry block, it displaces a volume of concrete around the embedded area of the fastener shank. As this occurs, the concrete directly surrounding the fastener is compressed and in turn presses back against the shank of the fastener. The driving action also generates heat which causes particles within the concrete to fuse to the fastener’s shank. This combination of compression and fusion holds the fastener in the concrete base material,” says Len Colasuanno, vice president of sales at Powers Fasteners.

In concrete, the fastener’s holding capacity is affected by the strength of the base material, the hardness and concentration of the aggregate, shank diameter of the fastener, embedment depth into the base material, fastener spacing and fastener distance from the edge.In steel, the powder-actuated fastener is held in place by the elastic pressure of the steel up against the force exerted on the fastener, explains Colasuanno. “Generally, as the diameter of the fastener shank increases, so does load capacity, as long as the steel is thick enough to accept the fastener. Some fasteners have a knurled shank that allows the steel to lock into the grooves, which increases capacity when compared with smooth shanks,” he says.

Like concrete, the steel’s properties greatly affects load capacity. Steel thickness, its tensile strength, the fastener’s shank diameter, depth of point, depth of penetration through steel and fastener spacing and edge distance contribute to the holding power of the anchor.

Start low and work your way up
In concrete or steel, the variations in materials can impact the fastener’s performance. The experts suggest monitoring the depth that the fastener is driven to assure it can do its job.

Georges suggest testing the hanger-pin combination and the load on an inconspicuous spot before starting installation. “First, do a suitability test by taking the pin you plan to use and hitting it into the substrate with an average hammer blow. If the pin makes a small impression in the material and the pin is not damaged, the pin and the substrate are a good match. This is key for safety. Trying to install a pin in a substrate that is too hard can cause damage or injury,” he says.

Conversely, if you can drive a pin partially into the substrate with one hammer blow, the substrate is too soft to use a powder-actuated fastener.

 “The next step is to start with the lowest-powered load and see if it is capable of installing the pin. If it isn’t, go to the next power. If you have an adjustable-power tool, you can use the adjustment to match the power to the installation,” says Georges.

Typically, the specifications call for pins to be driven at least 1" into concrete to achieve rated holding capacity. “Plus, the base material should be at least three times as thick as the length of the embedded pin,” Georges adds.

In steel, the pin should penetrate far enough so that just the tip of the pin is exposed on the back side. “The steel should be at least as thick as the diameter thickness of the pin,” Georges adds.

Pre-assembled pins the way to go
It is tempting to use a separate pin and a conduit strap together, but Georges says that can be a dangerous situation. “Always use a pre-assembled pin, and don’t go through a hole in a hanger or in an electrical box. If the pin hits the edge of the hanger or box, it could fish-hook. That leads to an improper installation and could injure the installer or bystanders,” he says.

There is a wide variety of pin-and-hanger combinations available. To achieve greater productivity and effective installation on jobsites, work with your powder-actuated tool

distributor to select the right pin and hanger combination that meets the design engineer’s criteria and your need for fast, efficient installation.

Spalling may be a concern in some applications. Colasuanno says this normally does not affect pin or hanger capacity, but may affect aesthetics. To control spalling, he suggests using a pin with a steel washer or using a stop-spall adapter on the powder-actuated tool. Either method helps spread the impact force over the surface of the concrete, which helps reduce any localized spalling.

If a pre-assembled pin and hanger won’t do the job, consider using a threaded stud. Here, the fastener is driven into the base material, leaving a 1/4" or 3/8" threaded stud exposed. “These are good in applications where you may want to remove it at some point. It’s important not to over-tighten the nut on the stud because that force can pull the fastener out of the substrate,” Georges says.

Safety first
Powder-actuated tools are very powerful devices that must be used in the safest manner possible.

Every installer using a powder-actuated tool must be licensed to operate it. While the training is simple, it reinforces best operating and safety practices, says Georges. Training can be obtained through your powder-actuated tool distributor.

Under heavy use conditions, Georges recommends that users clean the powder-actuated tool daily. “It makes the tool easier and safer to use, plus it will help the tool last longer,” he says.

Published in the November/December 2002 issue of Contractor Tools and Supplies magazine.

 back to top