SEISMIC LOADING FOR STORAGE TANKS
Evaluate & Mitigate Seismic Loading Concerns
Comply with New Seismic Regulations and Safeguard Your Critical Assets
New regulations in Washington State have established a higher standard for the seismic integrity of aboveground storage tanks. WAC 173-180 mandates rigorous analysis and protective measures to mitigate spill risks from seismic events. As regulatory requirements evolve across North America’s seismically active zones, proactive compliance is essential for maintaining operational continuity and asset safety.
Equity Engineering provides specialized engineering consulting services to help owner-operators navigate these new and often complex requirements. Our multi-disciplinary services are focused on managing the entire asset lifecycle to deliver practical recommendations that improve safety and mitigate risk in existing storage tanks.
Proactive Strategy for Future Regulations
WAC 173-180 signals a trend toward more stringent seismic regulations in other regions of Western USA and Canada. Equity Engineering will help you “future-proof” your assets to ensure you can integrate necessary upgrades into long-term capital plans.
Benefits
Mitigate operational disruption
Prevent catastrophic failure
Conduct proactive capital planning
Comply with new seismic regulations
What is WAC 173-180?
In July 2023, the Washington Department of Ecology published WAC 173-180 which introduces specific, non-negotiable requirements for existing storage tanks and attached piping. For facilities in Washington State, understanding the technical nuances of this law is critical for ensuring compliance. Failure to comply may result in operational shutdowns, significant financial penalties, and increased risk of environmental damage from a seismic event.
Key Mandates of WAC 173-180:
- Compliance Deadline: Facilities must achieve full compliance by July 2033, with potential extensions based on API 653 inspection schedules.
- Technical Standard: If elected as the means of achieving compliance, seismic analysis of existing tanks must adhere to the 2020 version of API 650 Annex E, using new design allowable stresses. API 653 allowable stresses are not sufficient for this requirement.
- Required Protective Measures: Additional compliance options are available for existing tanks such as adequate piping flexibility, pile-supported foundations, and mechanical anchors to reduce seismic risk. Evaluation of these existing components may be sufficient, or retrofit/reinforcement of existing but sub-standard features may provide the most economical means of compliance.
- Risk Evaluation: Owners must identify the seismic use group (SUG) for all tanks and perform comprehensive data gathering to support a thorough analysis.
Our Approach to Seismic Loading
We leverage advanced analysis and a multi-disciplinary team to ensure your existing storage tanks meet the regulatory requirements while also optimizing safety and cost-efficiency.
Step 1: Site Seismic Hazard Analysis
Navigating changes to ASCE 7 and how these impact analysis per API 650 Annex E is critical to determining appropriate seismic demands for each tank. We apply our nuanced understanding of these standards and have discussed code interpretations with state regulators to ensure the seismic analysis we perform follows acceptable protocols. We can also assist in establishing site soil classifications, determining tank seismic use group designations, and developing site-specific response spectra to potentially reduce design values to as low as 80% of mapped curves.
Step 2: Comprehensive Compliance and Retrofit Engineering
If our analysis identifies vulnerabilities, we deliver practical and effective mitigation solutions. We provide detailed recommendations for approved protective measures, including operational adjustments like reduced fill heights, anchorage evaluation or retrofit, or piping flexibility analysis. Our goal is to find the most efficient path to compliance.
Step 3: Documentation and Action Planning
We prepare clear and comprehensive documentation for compliance submission and are committed to working through the review and feedback process with owners and regulators. Whether the proposed solution is operational, analytical, or requires retrofit, communication is critical to achieving the common goal of reducing risk. We partner with our clients through this process to develop action plans including documenting any operational and maintenance changes required to ensure long-term reliability of critical storage tank assets.
Partner with the Experts in Asset Integrity
Safely operating your facilities is essential to protecting personnel and the environment. You need to be confident in the long-term reliability of your equipment. We deliver the specialized consulting and engineering services required to manage risk and ensure the integrity of your most critical assets.
Take the first step toward securing your facility and ensuring regulatory compliance. Contact Equity Engineering today for more information.
