Overfill Prevention for Storage Tanks in Petroleum Facilities

ANSI/API STANDARD 2350

FIFTH EDITION, SEPTEMBER 2020 ERRATA 1, APRIL 2021

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Copyright © 2020 American Petroleum Institute

Foreword

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Contents

Page

1. Scope 1

   1. Scope 1

   2. Minimum Requirements 1

2. Normative References 1

3. Terms, Definitions, and Acronyms 2

   1. Terms and Definition 2

   2. Acronyms 6

4. Overfill Prevention System (OPS) 7

   1. Overview 7

   2. Requirements for the Management System 8

   3. Requirements for Risk Assessment 9

   4. Defining Operating Parameters 10

   5. Requirements for Overfill Prevention System (OPS) Procedures 14

5. Overfill Prevention Systems 20

   1. Types of Overfill Prevention Systems 20

   2. Tank Category Criteria 21

   3. Instruments and Equipment Used for Overfill Prevention 22

Annex A (normative) Automated Overfill Prevention Systems (AOPS) 26

Annex B (informative) Management Systems (deleted) 30

Annex C (informative) Liquid Level Instrumentation Considerations 31

Annex D (informative) Determining Levels of Concern and Tank Capacity 33

Annex E (informative) Risk Assessment 44

Annex F (informative) Transporter/Owner/Operator Interface 52

Annex G (normative, if used) Tank Categories 55

Annex H (informative) Proof Testing 62

Bibliography 64

Figures

1 Tank Levels of Concern (LOCs) 11

A.1 AOPS Fail Safe Design and AOPS Valve Loss of Motive Power Alarm 28

1. Example 1 Tank Information 35

2. Example 2 Tank Information 37

3. Example 3 Tank Information 40

1. Risk Matrix Example from API 353 48

2. Event Tree Model 49

1. Delivery to a Third-party Facility via Pipeline 52

2. Multiple Concurrent Third-party Operations 53

3. Marine Inbound Operations 53

4. Data Transfer Between Parties 54

1. Illustration of Categories Applied to Overfill Prevention Systems 57

2. Illustration of Category 0 58

3. Illustration of Category 1 Overfill Prevention Systems 59

   v

   Contents

   Page

4. Illustration of Category 2 Applied to Overfill Prevention Systems 60

5. Illustration of Category 3 Applied to Overfill Prevention Systems 61

H.1 Modes of Proof Testing 63

Tables

1. Minimum High-High (HH) Response Time 13

2. Monitoring Product During Receipt. 21

C.1 Commonly Used Types of Liquid Level Sensors 32

1. Example 1 Tank Measurements 35

2. Example 2 Tank Measurements 37

3. Example 3 Tank Measurements 40

G.1 Tank Categories 56

Overfill Prevention for Atmospheric Storage Tanks in Petroleum Facilities

1. Scope

   
   

   1. Scope

      
      

      This document applies to atmospheric storage tanks associated with refining, marketing, pipeline, and terminals that contain NFPA Class I or Class II liquids. This standard does not apply to:

      
      

      • tanks of 1320 US gallons (5000 liters) or less, unless connected to a transporter or marine delivery system;

        
        

      • tanks that are covered by PEI RP 600;

        
        

      • tanks filled exclusively from wheeled vehicles (i.e. tank trucks or railroad tank cars), where the fill rate is less than 630 bbl/hr (440 gpm) (100m3/hour);

        
        

      • dedicated pipeline relief tanks; and

        
        

      • tanks storing LPG and LNG.

      
      

      The purpose of this standard is to assist owner/operators and operating personnel in the prevention of tank overfilling by implementation of a comprehensive overfill prevention system (OPS). The goal is to receive product into the intended storage tank without overfilling or mechanical damage.

      
      

   2. Minimum Requirements

      
      

      This standard is one of minimum requirements. Alternate approaches or variations on the principles of this standard that provide equivalent or more robust overfill prevention are acceptable. Alternate approaches may be needed when the tank system varies from the typical configurations described in this standard. The rationale for the implementation of each overfill prevention process (OPP) should be documented and retained by the owner/operator. This standard is not intended to prevent the use of systems, methods, or devices of equivalent or superior quality, effectiveness, durability, and safety over those provided in this standard. Where the rules in API 2350 conflict with local, state, or federal regulations, the regulations shall take precedence over API 2350. In the event that there are conflicts, the more stringent of API 2350 or the regulations shall be applied.

      
      

2. Normative References

The following referenced documents are necessary for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

API MPMS Chapter 3.1A, Standard Practice for the Manual Gauging of Petroleum and Petroleum Products

API MPMS Chapter 3.1B, Standard Practice for Level Measurement of Liquid Hydrocarbons in Stationary Tanks by Automatic Tank Gauging

IEC 615111, Functional Safety – Safety instrumented systems for the process industry sector – Part 1: Framework definitions, system, hardware, and software requirements (This document is only classified as normative when chosen as an option by the owner/operator.)

Other references in the document, including those in the Bibliography, are provided for information only and are not normative to this standard.

1 International Electrotechnical Commission, 3 rue de Varembe, PO Box 131, CH-1211 Geneva 20 Switzerland, www.iec.ch.