Requirements for Safe Entry and Cleaning of Petroleum Storage Tanks

API STANDARD 2015

EIGHTH EDITION, JANUARY 2018

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Foreword

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1. Scope 1

   1. General 1

   2. Non-applicability and Other Tank Cleaning Applications 1

2. Normative References 1

3. Terms and Definitions 3

4. Administrative Controls and Procedures 13

   1. General Requirements 13

   2. Written Tank Cleaning/Entry Programs 14

   3. Written Tank-specific Cleaning/Entry Plans 14

   4. Regulatory Requirements 15

   5. Tank Cleaning/Entry Overview 16

5. Preparing the Tank for Entry and Cleaning 19

   1. Initial Preparation 19

   2. Removal From Service 20

   3. Isolating The Tank 20

   4. Control of Ignition Sources 21

   5. Vapor and Gas Freeing, Degassing, and Ventilating 23

   6. Initial Tank Cleaning 24

6. Testing the Tank Atmosphere 24

   1. Atmospheric Testing Procedures 24

   2. Atmospheric Testing Instruments 24

   3. Atmosphere Testing 25

7. Storage Tank Hazards 27

   1. General 27

   2. Oxygen Deficiency and Enrichment 27

   3. Fire and Explosion Hazards 28

   4. Toxic Substances 29

   5. Physical and Other Hazards 32

   6. Floating Roof Hazards 33

   7. Heat Stress 33

   8. Pyrophoric Iron Sulfide 34

   9. Hazard Assessment 34

8. Personal Protective Equipment 34

   1. Protective Clothing and Equipment 34

   2. Respiratory Protection 35

9. Tank Cleaning/Entry Personnel 38

   1. General 38

   2. Entry Supervisors 39

   3. Entrants 41

   4. Attendants 42

   5. Non-entry Supervisor Permit Issuers 43

10. Entering and Working Inside the Tank 44

    Contents

    Page

    1. General 44

    2. Entry Permit 44

    3. Floating Roof Stabilization 46

    4. Heat Stress 47

    5. Continuous Forced Air Ventilation 47

    6. Tank Safe (Cold) Work, Maintenance, and Repairs 47

    7. Undesirable Product, Sludge, and Residue Disposal 48

11. Hot Work and Tank Repairs 48

    1. General 48

    2. Hot Work Permits 49

    3. Hot Work Hazards 50

    4. Hot Work In Leaded Service Tanks 51

    5. Fire Prevention 51

12. Emergency Planning 51

    1. Emergency Response Plan 51

    2. Outside Rescue Services 52

    3. Employer Rescuers 53

    4. Rescue Equipment 53

    5. Other Emergencies 54

    6. Medical Emergencies 54

13. Return To Service 55

    1. General 55

    2. Preparation 56

    3. Refilling Tanks 56

    4. Sampling and Gauging Tanks 57

    5. Control of Ignition Sources 58

14. Training 58

    1. General 58

    2. Training Requirements 58

    3. Training Verification 58

    4. Qualification 58

Annex A (informative) Petroleum Storage Tank Hazards 59

Annex B (informative) Vapor Freeing and Degassing Procedures 88

Annex C (informative) Tank Cleaning and Floating Roof Stabilization 101

Annex D (Reserved for Future Use) 115

Annex E (informative) Oxygen, Combustible Gas, and Toxic Substance Testing Instruments 116

Annex F (informative) Safe Tank Entry for Activities Other than Tank Cleaning 121

Bibliography 135

Figures

A.1 Lateral Movement of Floating Roof 82

A.2a Rim Space Blocking With Rim Wedges 82

A.2b Rim Space Blocking With Rim Jacks 82

A.3a Rotational Movement of Floating Roof 83

A.3b Spiral Collapse Caused by Floating Roof Rotation 83

A.4a Welded Blank Nuts, Shackles, and Chain-type Anti-rotation System 83

A.4b Manway-anchored Anti-rotation 83

A.4c Radial Beam and Anti-rotation Bracket System 83

A.6 Leg Kickout 84

A.6a Jack Post for Vertical Support 84

A.6b Timber for Vertical Support 84

A.6c Cribbing Stack for Vertical Support 84

A.7a Elevation Diagram Showing High-leg and Low-leg Positions 85

A.7b Improper Pinning (Leaving One Leg in High-Leg Position) 85

A.7c Improper Pinning (Leaving One Leg in Low-Leg Position) 85

A.8a Water Accumulation on Floating Roof 86

A.8b Water Accumulation in Floating Roof Pontoons 86

1. Liquid in the Floating Roof Panel Sections 86

2. Concentrated Loads of Staged Materials 87

3. Vacuum or Uplift on Floating Roof from Venting 87

4. Working Under Suspended Load 87

1. Example of Eductors Used for Tank Agitation 102

2. Example of Water Balancing 103

vii

Requirements for Safe Entry and Cleaning of Petroleum Storage Tanks

1. Scope

   1. General

      
      

      This standard is applicable to stationary atmospheric and low-pressure (up to and including 15 psig) aboveground petroleum storage tanks used in all sectors of the petroleum and petrochemical industry, including:

      
      

      • crude oil and gas production,

        
        

      • refining,

        
        

      • petrochemicals,

        
        

      • pipelines and terminals,

        
        

      • bulk storage,

        
        

      • ethanol facilities.

        
        

        This standard provides requirements for safely planning, coordinating, and conducting tank entry and cleaning operations, from removal from service through return to service.

        
        

        This standard does not and cannot cover every possible unique hazard or situation that may arise during tank cleaning operations. Site, product, and tank-specific hazards and situations shall be addressed by employers using the appropriate principles and considerations provided for by this standard.

        
        

   2. Non-applicability and Other Tank Cleaning Applications

      
      

      This standard does not apply to the following types of tanks or vessels:

      
      

      • pressure vessels and pressurized tanks exceeding 15 psig,

        
        

      • cryogenic or refrigerated vessels or pressure tanks,

        
        

      • vessels and tanks maintained under a vacuum,

        
        

      • process vessels,

        
        

      • underground storage tanks.

      
      

      Although API Standard 2015 is not intended to cover these types of tanks and vessels, many of the safe tank cleaning and entry principles and requirements in this standard apply and should be considered.

      
      

2. Normative References

The following referenced documents are indispensable 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 Bulletin E2, Bulletin on Management of Naturally Occurring Radioactive Materials (NORM) in Oil and Gas Production

1