Hydrogen Embrittlement Risks Mitigation: Fastener Compliance with CSA O86:24

This article is intended to inform our key partners in the engineering and construction sectors about the recent updates to the CSA O86:24 standard, particularly Clause 17.6.4, which addresses hydrogen embrittlement in fasteners. It outlines the new requirements, enhanced quality control measures implemented by MTC Solutions, and recommended fastener specifications to ensure compliance and safety. While these updates are mandated in Canada, they also serve as a benchmark for best practices in the USA, providing an added layer of safety and reliability for structural applications. Our goal is to emphasize the importance of adopting these standards to safeguard the integrity and longevity of mass timber structures and to exceed industry expectations, ensuring that the fasteners supplied will perform reliably across all structural applications.

As a key partner in the mass timber construction industry, we are committed to providing the highest quality hardware that meets the evolving standards and safety requirements critical to the success of your projects.
 

To support the design and construction communities, the following fastener specifications are recommended for inclusion in project documentation:

1. All fasteners for timber applications shall conform to the current edition of CSA O86 as a minimum.
2. All case-hardened, carbon-steel, self-tapping wood screws must have a core hardness ≤ 390 HV, in accordance with ISO 2702. For case-hardened, carbon-steel fasteners used in wet service conditions, the core hardness must be ≤ 360 HV. Wet service condition application will require additional measures to prevent corrosion.
3. All case-hardened, carbon-steel, self-tapping wood screws with core hardness between 360 HV and 390 HV must have an additional quality assurance plan in accordance with ASTM F606 Clause 7 or ISO 15330.
4. Electroplated fasteners must be manufactured per ISO 4042 or ASTM F1941, with a zinc coating thickness of at least 8 μm.
5. Follow the manufacturer’s installation instructions, including recommended tools, drive-in torque limits, and pre-drilling requirements.
6. For dry service conditions, the timber moisture content (MC) should average 15% or lower throughout the year and must not exceed 19% at any time.
7. Fasteners before installation must be stored in a dry environment to prevent exposure to moisture and other corrosive elements.
8. All fasteners must be approved by the Structural Engineer of Record (EOR) before installation.

MTC Solutions Standard Quality Control

In addition to the rigorous Quality Control (QC) conducted by manufacturing partners, MTC Solutions has implemented an enhanced QC process to ensure our fasteners meet the highest standards, particularly in mitigating Internal Hydrogen Embrittlement (IHE) and Environmental Hydrogen Embrittlement (EHE). The QC process, aligned with CSA O86:24 requirements, includes:

Core Hardness Testing. Fasteners are tested to ensure that core hardness does not exceed 390 HV, in compliance with ISO 2702. Hardness testing in the areas of expected high stress will be conducted on a random sample selection.

Tension Testing.As a part of the MTC standard QC, testing in accordance with ISO 15330 is completed to confirm the unlikelihood of hydrogen embrittlement in MTC fasteners.

All fasteners meet the requirements outlined in the CSA O86:24, particularly Clause 17.6.4, which is dedicated to the mitigation of hydrogen embrittlement.
 

Additional Service Offered by MTC Solutions

Recognizing that certain projects may require more stringent measures, MTC Solutions offers  supplementary services upon request to ensure the utmost reliability and safety of all structures. For connections expected to bear loads exceeding 50% of the screw Ultimate Tensile Strength (UTS) permanently, or where connection integrity is critical, additional QC testing can be provided if specified and requested by the EOR. These services may include specifying fasteners with enhanced protection against hydrogen embrittlement and conducting specialized tests beyond standard procedures, offering an extra layer of assurance for the most demanding applications.

1. Custom Compliance Reports: Supplementary reports can be produced, including batch numbers, hardness testing results as per ISO 2702, and tension testing results as per ISO 15330. These reports are available for review and approval by the EOR before procurement and installation.
2. Technical Consultation and Support: The MTC Solutions team is available to assist with fastener selection, best practices for installation, and ensuring all aspects of projects meet the necessary standards for safety and durability.

Ensuring the integrity and longevity of mass timber structures is paramount, and the updated CSA O86:24 standards provide essential guidelines to mitigate the risks associated with hydrogen embrittlement in fasteners. By implementing these recommended specifications and adhering to rigorous quality control measures, MTC Solutions is committed to supporting the engineering and construction communities in delivering safe and reliable projects. The additional services offered by MTC Solutions further reinforce this commitment, providing tailored solutions for the most demanding applications. Adopting these practices not only ensures compliance but also sets a benchmark for excellence in both Canadian and U.S. markets, ultimately safeguarding the future of mass timber construction.