What You Need to Know About the New API 2350 Tank Overfill Standard

The Three Prior Editions of the Standard Required the Typical Instrumentation and Tests, but They Didn't Include Evaluating the Risks in Individual Applications and Responding Appropriately

By Jim Montague

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Cups running over are an expression of abundance and gratitude. Oil and chemical tanks overfilling are not.

In fact, overfilling is a chronic and dangerous problem in many process industries, but thankfully some new and powerful help is on the way. The fourth edition of the American Petroleum Institute's API2350 --  "Atmospheric Tank Storage Overfill Standard" was released in 2012, and it's giving tank owners and operators more specific guidance and solutions for preventing overfill incidents.

However, all this excellent help is pretty voluminous and can be a little hard for many users to sort out and integrate into their routine operations, so Emerson Process Management's experts are providing some timely assistance in sessions today and Wednesday. Thense Korsbo, manager of technology for Emerson's Rosemount Tank Gauging and an API 2350 committee member, will present "The New API 2350 Atmospheric Tank Storage Overfill Standard Explained in Detail" (2-2349) today (Tuesday) at 10:00 a.m. in Tampa 2, and again at 9:00 a.m. on Wednesday in Captiva 2. A link to Emerson's "Complete Guide to API 2350" will also be provided during the presentation.

"The three prior editions of the standard required the typical instrumentation and tests, but they didn't include evaluating the risks in individual applications and responding appropriately," says Korsbo. "As a result, the standard's first three editions weren't widely used and were less precise than needed."

Korsbo adds that upgrading from API 2350's third edition to its fourth edition was also the result of investigations and findings following several well-known accidents, including the U.K.'s Buncefield oil-storage overflow incident, vapor-cloud explosion and fire in December 2005. "Atmospheric storage tanks cause the most incidents at refineries according to insurance data," reports Korsbo. "So API 2350, Edition 4, requires owners and operators to have good tank management systems in place. However, while overfill systems were previously part of tank management systems, now they also need to have multiple components to assure they're safely in place and sustainable, particularly when risk assessments or updates are needed or when incidents occur. "

Though his presentation will cover many other essential details, Korsbo reports that Emerson's basic guidance on API 2350, Edition 4, explains revisions with respect to:

  • Scope of API 2350, which covers unpressurized tanks larger than five cubic meters containing Class I or II products;
  • Tank management system requirements, which now encompass the entire safety lifecycle of their components. These include implementing formal, written operating procedures, training and qualifying personnel, testing and maintaining equipment, addressing normal and abnormal operating conditions, handling management of change, investigating process for near misses and incidents, and using lessons learned;
  • Performing risk assessments that address operations changes, updating procedures and practices, and changing equipment systems and alarms;
  • Defining levels of concern (LOC) for maximum-working, high-high alarm and critical-high levels in tanks;
  • Implementing automatic overfill prevention systems (AOPS), including sensors, logic solvers, actuators and closed-loop control;
  • Performing proof testing of overfill prevention systems (OPS) upon initial installation and retesting during routine operations; and
  • Using wireless devices where appropriate, except for AOPS.

"The response times on automatic tank-gauging systems (ATGs) and ATGs with independent overfill alarms systems are much quicker than manual readings, so they can increase each tank's storage performance and capacity. The more instrumentation and quicker response you have, the higher you can fill your tanks," adds Korsbo. "The whole idea of API 2350, Edition 4 is that users can assess their plants and categorize them based on their own instrumentation and operations."

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