Preparing Tank Bottoms for Hot Work

API RECOMMENDED PRACTICE 2207 SEVENTH EDITION, JUNE 2017

Special Notes

API publications necessarily address problems of a general nature. With respect to particular circumstances, local, state, and federal laws and regulations should be reviewed.

Neither API nor any of API's employees, subcontractors, consultants, committees, or other assignees make any warranty or representation, either express or implied, with respect to the accuracy, completeness, or usefulness of the information contained herein, or assume any liability or responsibility for any use, or the results of such use, of any information or process disclosed in this publication. Neither API nor any of API's employees, subcontractors, consultants, or other assignees represent that use of this publication would not infringe upon privately owned rights.

API publications may be used by anyone desiring to do so. Every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them; however, the Institute makes no representation, warranty, or guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any authorities having jurisdiction with which this publication may conflict.

API publications are published to facilitate the broad availability of proven, sound engineering and operating practices. These publications are not intended to obviate the need for applying sound engineering judgment regarding when and where these publications should be utilized. The formulation and publication of API publications is not intended in any way to inhibit anyone from using any other practices.

Any manufacturer marking equipment or materials in conformance with the marking requirements of an API standard is solely responsible for complying with all the applicable requirements of that standard. API does not represent, warrant, or guarantee that such products do in fact conform to the applicable API standard.

All rights reserved. No part of this work may be reproduced, translated, stored in a retrieval system, or transmitted by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior written permission from the publisher. Contact the Publisher, API Publishing Services, 1220 L Street, NW, Washington, DC 20005.

Copyright © 2017 American Petroleum Institute

Foreword

Nothing contained in any API publication is to be construed as granting any right, by implication or otherwise, for the manufacture, sale, or use of any method, apparatus, or product covered by letters patent. Neither should anything contained in the publication be construed as insuring anyone against liability for infringement of letters patent.

This document was produced under API standardization procedures that ensure appropriate notification and participation in the developmental process and is designated as an API standard. Questions concerning the interpretation of the content of this publication or comments and questions concerning the procedures under which this publication was developed should be directed in writing to the Director of Standards, American Petroleum Institute, 1220 L Street, NW, Washington, DC 20005. Requests for permission to reproduce or translate all or any part of the material published herein should also be addressed to the director.

Generally, API standards are reviewed and revised, reaffirmed, or withdrawn at least every five years. A one-time extension of up to two years may be added to this review cycle. Status of the publication can be ascertained from the API Standards Department, telephone (202) 682-8000. A catalog of API publications and materials is published annually by API, 1220 L Street, NW, Washington, DC 20005.

Suggested revisions are invited and should be submitted to the Standards Department, API, 1220 L Street, NW, Washington, DC 20005, standards@api.org.

iii

Contents

Page

1. Scope 1

2. Normative References 2

3. Terms, Definitions, Acronyms, and Abbreviations 3

   1. Terms and Definitions 3

   2. Acronyms and Abbreviations 7

4. Precautions 8

   1. General Precautions 8

   2. Specific Precautions 9

5. Inspection Procedures 11

   1. General Inspection Procedures 11

   2. Specific Inspection Procedures 11

6. Work Procedures and Safety Precautions 12

   1. General 12

   2. Minor Repairs 12

   3. Major Repairs 12

   4. Perimeter Repairs 13

   5. Double-bottom Installation 13

   6. Sectional Repairs 14

7. Summary of Significant Safety Considerations 14

Bibliography 18

v

Introduction

The 7th edition of API Recommended Practice 2207, Preparing Tank Bottoms for Hot Work, is significantly updated from prior editions. A new Section 7, “Summary of Significant Safety Considerations,” provides a quick review and can be used to guide users to content in the body of this recommended practice.

Two API Individual Certification Programs (ICPs) are referenced in this recommended practice. The API 653 Aboveground Storage Tanks Inspector Certification Program evaluates individual personnel qualifications to inspect and determine conformance with API Standard 653, Tank Inspection, Repair, Alteration, and Reconstruction. Because tank entry is often an integral part of the process, the API Tank Entry Supervisor Individual Certification Program provides a tool for certifying supervisors who will evaluate hazards to minimize any risks associated with tank entry.

API 2207 primarily discusses work practices that have been used safely and is not a regulatory compliance document. However, it does update the listing of potentially relevant regulations. Federal, state, and local regulations or laws may contain additional requirements that must be taken into account when a tank repair program is developed for a specific facility. Since the essential elements of this publication are based on current industry safe operating practices and existing consensus standards, these listings have also been updated and expanded.

References made to “OSHA” refer to U.S. Federal regulations. Comparable or more restrictive requirements may exist in other jurisdictions (states or countries), and the appropriate requirements should be used. Where no regulations or other legal requirements exist, the OSHA standards provide a useful reference and are readily available for download from the Internet at www.osha.gov.

This recommended practice provides information to assist safe performance of hot work on the bottoms of storage tanks that have been in service to store flammable products. This work activity has specific precautions and work practices. The understanding of potential hazards, relevant precautions, and techniques, and application of this knowledge, can help improve safety performance and reduce the probability of incidents.

Tanks that previously have contained flammable or combustible liquids, regardless of their age and type of construction, must be considered unsafe for hot work until inspected and approved by a qualified person. These inspections include visual examination and atmospheric testing to evaluate physical and atmospheric hazards (flammability, oxygen deficiency, and potentially toxic contaminants). Emphasis is on special techniques required in the performance of hot work to prevent the ignition of flammable gases or vapors that may be trapped under the tank bottom.

Each repair of tank bottoms must receive careful consideration and individual evaluation. The safety procedures described in this recommended practice provide various methods that have been used successfully for preparing tank bottoms for hot work. These procedures will apply to most situations; however, each job must be independently evaluated to ensure safe work.

vii

Preparing Tank Bottoms for Hot Work

1. Scope

   
   

   1. This recommended practice addresses only the safety aspects of hot work performed on petroleum

      storage tank bottoms. It discusses safety precautions for preventing fires, explosions, and associated injuries. The term “hot work,” as used in this publication, is defined as an operation that can produce a spark or flame hot enough to ignite flammable vapors. API 2009 provides more in-depth information on safe hot work practices, and its requirements are not duplicated here.

      
      

   2. This recommended practice does not contain all safety precautions and procedures that may be

      required prior to, during, or after a specific hot work activity. All hot work should be performed in compliance with applicable federal, state, and local regulatory requirements and recognized industry practices. Work practices of concern for working on tank bottoms include, but are not limited to, confined space entry, lockout/tagout, atmospheric testing, ventilation, and requirements for use of personal protective equipment (PPE). API 2015 provides guidance for tank entry consistent with OSHA regulations noted in Section 2, Normative References. This recommended practice does not repeat the detailed information provided in the referenced documents. Some of the relevant OSHA regulations from 29 CFR Part 1910 and 29 CFR Part 1926 are included in the references. It is the responsibility of each organization to review and comply with applicable regulatory requirements.

      
      

   3. This recommended practice does not cover:

      
      

      • guidance for compliance with safety or environmental regulations or codes;

        
        

      • engineering specifications for tank construction or rebuilding (see API tank standards);

        
        

      • specific guidance for repair of shop-fabricated tanks, which is addressed by STI/SPFA SP031. These tanks include those built to UL 142, API 650 Appendix J, STI/SPFA aboveground tank standards, as well as others;

        
        

      • specific guidance for tank entry (see API 2015);

        
        

      • welding techniques, craft skills or qualification of welders (see referenced welding standards);

        
        

      • normal “safe work” practices such as fall protection, PPE, slip/trip/fall, etc.;

        
        

      • entry or work in inert environments (see API 2217A);

        
        

      • entry into confined spaces for construction activities (see OSHA 29 CFR Part 1926, Subpart AA, and Part 1926.1200).

      
      

   4. Concepts of Hazard and Risk

      
      

      1. Hazards are properties of materials (or situations) with the inherent ability to cause harm. Flammability,

         toxicity, corrosivity, and stored chemical or mechanical energy all are hazards associated with various industrial materials or situations. Risk requires exposure. A fire or hot surface can cause thermal skin burns or a corrosive acid can cause chemical skin burns, but these can occur only if there is contact exposure to skin. In an empty tank, a floating roof represents a “stored mechanical energy” hazard that might fall on persons working underneath, and so must be properly secured to reduce the risk of contact before performing entry work.

         
         

      2. There is no risk when there is no potential for exposure.

         
         

      3. Determining the level of risk involves understanding hazards and estimating the probability of

exposure and severity of consequences that could lead to harm. While the preceding examples relate hazards to the risk to people, the same principles are valid for evaluating property risk. For instance, a flammable

1