New API2350 Atmospheric Tank Storage Overfill Standard Explained in Detail

20140403-090624.jpgEmerson’s Carl-Johan Roos shared ways to comply with the new API2350 standard for overfill protection on tanks.

CJ opened noting there is no reward for risk takers when it comes to overfill protection. He is a member of the API2350 committee.

Overfills occur one out of 3,300 fillings according to insurance company data. The vast majority don’t result in explosions or fires, but do result in the need for environmental cleanup operations.

For tank management, a multitude of layers of protection are used. Beyond the process control layer to manage level, the safety layer is designed to shutdown fill operations before the tank overflows.

CJ stressed the importance of the tank gauging system at the control system layer to manage level control. This is the foundation of effective tank management.

How does API2350 fit with the global safety standard, IEC 61511? CJ noted that API2350 is specific to tank level applications, so it fits very well with the IEC 61511 standard. API2350 is now at edition 4 and was a consensus standard ratified by 40 committee members.

The scope of API2350 is storage of hydrocarbon products in non-pressurized tanks. A fundamental part of the standard, a management system includes the control, safety, work processes, and documentation to manage the tanks through the lifecycle of their operations.

CJ referred to the API 2350 Guide that the Emerson team managing the Rosemount tank gauging products developed. It details the requirements in the standard. For instance, the overfill prevention system must be separate and independent from the tank gauging or control system managing the tank.

A change he sees is tank operators changing out discrete Hi-Hi level switches with continuous level measurement, such as guided wave radar transmitters. This continuous measurement can be compared against the tank gauging level measurement. Deviations can create alarms and the proof testing process is greatly simplified. The problem with switches is that you don’t know whether they are working or not until you test them or they switch in a tank high level event.

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