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API 2350: Your Guide to Overfill Prevention in Petroleum Storage Tanks

In the 1990’s,The American Petroleum Institute (API) came together to come up with a standard for the safe storage of Class 1 and Class 2 petroleum products. One crucial aspect of this safety is preventing overfills in storage tanks. Now in its 5th edition, API 2350 is a well-respected standard, and a recommended practice by the Environmental Protection Agency (EPA) to minimize the risks associated with overfills in above-ground petroleum storage tanks. 

What is API 2350?

API 2350 is a globally recognized standard that outlines a comprehensive set of overfill prevention practices (OPP’s) for storage tanks containing Class I (flammable) or Class II (combustible) liquids like gasoline, jet fuel, diesel fuel oil, and other petroleum products. The standard applies to various facilities, including:

  • Refineries

  • Marketing

  • Terminals

  • Pipeline Terminals

  • Or any atmosphere storage tank that contains an NFPA Class I or Class II liquid

While not mandatory by law, API 2350 serves as a best practice guideline for overfill prevention programs (OPP). Implementing its recommendations significantly reduces the risk of spills, fires, or environmental damage caused by product overflow.

Petroleum tank alarm and shut down devices act as a crucial safety barrier in above ground storage systems. Installed within the tank, they constantly monitor the fuel or liquid level. When the product level reaches a pre-programmed “level of concern”, an alarm sounds, notifying the operator to stop filling, or divert flow.

Key Components of API 2350

The 5th edition of API 2350 focuses on two major elements:

  • Management System: This refers to the overarching framework for implementing and maintaining an OPP within your facility. It emphasizes clear roles and responsibilities, documentation procedures, and training programs for personnel.

  • Operating Parameters: These are tank-specific details required to effectively utilize the standard. This includes crucial data points like:

    • Critical High Levels: The critical high level is the highest level in the tank without detrimental impact, such as:

      • Overfill of product

      • Exceedance of the allowed tank shell design stresses

      • Leakage from a corroded area or temporary repair

      • A level designated by the owner/operator considering

        • Mechanical contact of the floating roof, floating roof seals, floating roof legs, fire retardant foam chamber deflectors or foam dams, or other appurtenances with the tank roof or platform ladder structure.

        • Floating Roof Seals rise to a level where they are in contact with the vents or the top of the tank shell

  • Levels of Concern (LOCs): Predetermined liquid levels within the tank that are calculated using risk category, maximum flow rates, and response times. An example of these device actions include alarms, and/or the shut off and diversion of the flow of product to another tank. Some examples of common LOC’s are “High”, “High High”, and Maximum Working Level (MWL).

Benefits of Implementing API 2350

Following the API 2350 guidelines offers several advantages:

  • Enhanced Safety: Reduces the risk of spills, fires, and personnel injuries associated with overfills.

  • Environmental Protection: Minimizes the potential for environmental damage from petroleum leaks.

  • Regulatory Compliance: Demonstrates adherence to various industry regulations and environmental protection standards.

  • Improved Efficiency: Optimized tank management practices can lead to cost savings through reduced product loss and improved inventory control.

How to Get Started with API 2350

For facilities that store petroleum products, following API 2350 in conjunction with Electro-Optical Distance Ranging (EODR) strapping charts and capacity tables, is a proactive step towards ensuring safety, environmental responsibility, and efficient operations. Here are some initial steps to consider:

  1. Obtain the Standard: Purchase the latest edition (5th) of API 2350 from the American Petroleum Institute here.

  2. Conduct a Gap Analysis: Evaluate your current overfill prevention practices against the requirements outlined in API 2350.

  3. Develop an Overfill Prevention Program (OPP): Create a program that incorporates the management system and operating parameters defined in the standard, including new strapping charts and other reports.

  4. Seek Professional Guidance: Consult with the qualified and experienced professionals at Gauge Point Calibration to ensure adherence to API 2350.


Contact Gauge Point Calibration today to discuss your API 2350 compliance, strapping chart, and capacity table needs!

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