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Generally, the performance of the fastener in a given concrete strength will increase with
greater embedment depths in a certain range. Depending on the fastener style and base
material strength, embedment depths range from 5/8” to 1-1/2”. For depths greater than this
range, there is the possibility of fastener bending or fishhooking which may decrease expected
load capacities and create a safety hazard.
During the driving action, some localized surface spalling of the concrete may occur. Normally,
this is a surface effect which does not effect the performance of the fastener. However, it may
pose an aesthetic problem for exposed applications where a fixture is not used. In cases such as
this, two methods can be used to improve the appearance of the fastening. A stop spall adapter
mounted on the powder actuated tool can help to reduce surface spalling. Another method used
is to drive the fastener through a steel washer to improve the appearance of the application.
FUNCTIONING IN STEEL
The load performance of a powder actuated fastener when installed into steel base materials is
based on the following factors:
1. Thickness of the steel
2. Tensile strength of the steel
3. Shank diameter of the fastener
4. Depth of point penetration through the steel
5. Fastener spacing and edge distance.
When a powder actuated fastener is driven into steel, it displaces the steel laterally 360˚ around
the shank of the fastener. Since steel is an elastic material, it presses back against the shank of
the fastener to hold it in place. As the diameter of the fastener shank is increased, the load
capacity obtained will generally increase provided the steel thickness is sufficient to accept the
fastener. To further increase fastener performance in steel, some fasteners have a knurled shank
which allows the steel to form a key lock into the grooves to provide higher capacities than
those obtained with a smooth shank. For optimum performance, the fastener point should
completely penetrate the steel. Normally, a minimum of 1/4” is allowed for the point length. An
increase in performance can be expected until the fastener no longer completely penetrates
through the steel. At this point, the elastic properties of the steel cause a compression force to
be developed at an angle against the fastener point which reduces load capacity. In thicker steel
base materials, adequate load capacities may be obtained for applications in which the point of
the fastener does not fully penetrate the steel. Job site performance tests are recommended.
Fasteners should not be used in areas that have been welded or cut with a torch as these
procedures may have caused local hardening of the steel. Over driving of the fastener should be
avoided as the rebound created may reduce the load capacity or cause damage to the fastener.
When fastening into unsupported long steel members, it may be necessary to provide support in
the area of the fastening to prevent spring action which can cause inconsistent penetration and
a reduction in load capacity.
SUITABLE BASE MATERIAL
While powder actuated fasteners can be used successfully in concrete, certain masonry
materials, and A 36 steel, some materials are completely unsuitable. Fasteners should never be
fired into hard or brittle materials such as cast iron, tile, glass, or rock. These materials can
shatter easily resulting in a potential safety hazard. In addition, soft base materials such as
wallboard, plaster, or wood are not appropriate as the fastener could pass completely through
these materials. The user should never guess when fastening into any base material. Failure to
follow the recommended installation and safety guidelines can result in severe injury or death to
the tool operator and/or bystanders.
CENTER PUNCH TEST
A center punch test should always be performed to determine the suitability of the base
material for a powder actuated fastening. This test is relatively simple and can help to insure a
safe, successful fastening. Be sure to wear the appropriate eye protection when performing this
test. To begin, select the fastener to be used for the job. Then, place the point of the fastener
against the proposed base material. Strike the fastener with a single hammer blow, then
examine the point. If the point of the fastener is not blunted and the base material has a clear
point indentation, it is acceptable to proceed with the first test installation.
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