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Dril-Flex® Structural Drill Screws

When corrosion is an area of concern in a construction project it is one that has to be addressed with a solution that allows for no compromise. Power Bolt and Tool knows the pressure that the construction companies deal with, when it comes to the performance of products needed to complete a project that leaves nothing to be desired. For this reason, metal fastening systems that are beyond reproach such as the Dril Flex Structural Drill Screws are kept in stock and available when the professionals are in need of them.

When projects are comprised of dissimilar metal and a wise choice for a metal fastening system is required then the tradesman can choose Dril Flex Structural Drill Screws with confidence. Among the many applications that these fasteners are geared for is stone veneer, solar projects, building envelopes and where blast protection is a priority. For building materials comprised of Fy33 ksi/Fu45, or aluminum and steel materials this self-drilling fastener has what is needed to get the job done.

They are comprised of a unique alloy steel and are subjected to heat treating to a SAEJ429 Grade 5 which allows them to comply with the standards of strength and ductility to A449. They are compliant with 2012 IBC and 2012 IRC meeting the industry standards. The intense Silver Stalgard® coating is applied in multilayers which enhance the high corrosion resistance that is demanded of them. The Silver Stalgard® coating has performed without exception when subjected to testing of 1000 hours of salt spray.

While the components used to make this metal fastening system is critically important, just as important is the design. In the load bearing section, they are comprised of an HRC 28 to 34 and then a higher hardness of HRC 52 in the drill point and lead threads where it is needed the most.

The design, top performing quality materials and craftsmanship that goes into making these double heated drill screws means that these Dril Flex Structural Drill Screws are not affected by hydrogen embrittlement or delayed HASCC brittle failures. They present the ideal atmosphere for dissimilar metal applications and allow for the galvanic compatibility. As with any of the Elco metal fasteners, they are precision made and designed for performance.

The Dril Flex Structural Drill Screws provide the necessities for the chain of command within any applicable construction project. It begins with the architect who creates his blueprints knowing that the structure has to be able to depend on products such as these metal fastening systems that are going to prevent perils of corrosion. The construction company who is going to be assigned the job will be able to rely on the affordability of the product plus the reduction of waste, as well as the productivity of his tradesmen. The worker can perform his application with ease of use and speed which in turn builds his confidence. The end result rests with the customer having his expectations met not only in the durability of the finished project but in the longevity, integrity and impressive finish that these Elco metal fasteners present.

While it is impressive to have access to such high-quality fasteners having flexibility in choices is an added benefit. These structural fasteners are available in #10-5/16” diameters and #2-#5 self-drilling points. This flexibility allows for more design options and makes for easy structure decisions. It takes mere seconds to drill and tap steel up to ½” thick.

Any construction project has to be able to access critical supplies on demand. For projects that demand the use of the Dril Flex Structural Drill Screws, it means that they have to be easily and readily available. This, in turn, means the industry has to be able to rely on construction providers who recognize the importance of supply and demand, and Power Bolt and Tool is the company that will step up to the forefront and is there when the construction industry needs them.

There are many reasons why Dril Flex screws have been successfully on the market for over ten years. They resolve specific problems that contractors have been dealing with for quite some time now. These fasteners have been tested, researched and approved by many engineering and construction organizations.

However, even though this structural fastener has been on the market for a long time, contractors are still using the wrong fasteners for specific applications. This has resulted in investigations and very, very costly lawsuits, not to mention undesirable and uncalled for accidents. By creating this page, we are looking to educate you on Dril Flex screws and clear up all the misconceptions so you can select the right product for the right application, thereby avoiding any unfavorable circumstances.


The Dril Flex structural fastener resolves multiple problems. The most important one is that this screw does not break from delayed embrittlement failures, no matter how extreme the application. Dril Flex screws have been specially designed and processed so as to ensure that they are immune to hydrogen-induced brittle failures. Each fastener undergoes the unique Flex Technology® dual-hardening process, and this ensures that the fasteners have the optimal combination of ductility and hardness required for maximum performance in the field.

If you have ever restored buildings or houses, we are sure that you must have seen fasteners break, regardless of the material the screw is made of. The main reason for that to happen is due to the hydrogen-induced embrittlement failures. These make the screws weak and breakable.

In order to answer this, we first need to explain Hydrogen-Assisted Stress Corrosion Cracking (HASCC). This phenomenon refers to a time-delayed failure that is aggravated or accelerated by hydrogen generated in the application. This mainly happens when the screw is associated with a dissimilar metal application. Let’s look at an example for better explanation – once you have, attached a stainless-steel fastener to, a window aluminum frame a reaction called galvanic corrosion occurs. Galvanic corrosion can be thought of as an electro-chemical action in which one metal is changed into a chemical or simply eaten away. So, when two metals are in contact with each other, like the example mentioned, in the presence of some electrolyte (Electrolyte may be present in the form of rain, dew, snow, high humidity, ocean salt spray, or even air pollution.), the less active metal (which in our case is the aluminum frame), will act as the cathode and attract electrons from the anode. The anode is the material which corrodes. And basically, the flow of electrons continues as long as the metals exist, and the solution remains. It also keeps going as long as a conductive path connects the two metals. In simple words, the metal becomes really weak and just falls apart.

Now that you understand how the corrosion in this case works or happens, let’s look at why some stainless-steel self-drilling fasteners should not be applied for some application. Most self-drilling fasteners, including 410 fasteners, are encased or similarly hardened, which does provide the necessary hardness for drilling and tapping but leaves the screws vulnerable to Hydrogen Assisted Stress Corrosion Cracking (HASCC) due to their high surface or core hardness.

Dril Flex screws, on the other hand, offer the unique Flex Technology® dual-hardening process. The self-drilling point and lead tapping threads are selectively hardened to a minimum of HRC 52. The load-bearing portion of the screw is held at, or below, the critical HRC34 level. This reduced hardness level also meets SAE J429 Grade 5 and ASTM A449 strength and ductility standards.

Dril Flex structural fasteners also have an extra feature that makes them very unique. After the fastener has been built, it gets coated with a Silver Stalgard® finish, and this provides superior corrosion resistance and enhanced galvanic compatibility. Thanks to the Stalgard® finish, there is no red rust or other base metal corrosion on significant surfaces even after 1000 hours of 5% natural salt spray exposure (ASTM B117).

The combination of this unique dual-hardening process and Stalgard® finish results in a strong, reliable structural fastener that can be used effectively in circumstances and applications where other self-drillers would fail.


  • Self-drilling point.
  • Higher hardness (HRC 52 min.) point and lead threads.
  • Lower-hardness (HRC 28 – 34) load-bearing threads.
  • Silver Stalgard® multi-layered corrosion resistant finish.


  • They are virtually immune to delayed HASCC brittle failures that are common with other hardened fasteners.
  • They provide the same high resistance to hydrogen-assisted failure as a Grade 5 fastener.
  • Their precision self-drilling point ensures consistent, reliable drilling and tapping.
  • They eliminate separate drilling and tapping operations, and this saves you time and money.
  • The fasteners are corrosion resistant and much more superior to zinc- or cadmium-based finishes.
  • They provide enhanced galvanic compatibility in dissimilar metal applications.

Dril Flex screws have been approved by: ICC-ES ER-4780 Legacy | Report: COLA (City of Los Angeles) | Research Report #25095

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