Management of Hazards Associated with Location of Process Plant Portable Buildings

API RECOMMEDED PRACTICE 753 FIRST EDITION, JUNE 2007

REAFFIRMED, AUGUST 2020

Management of Hazards Associated with Location of Process Plant Portable Buildings

Downstream Segment

API RECOMMENDED PRACTICE 753 FIRST EDITION, JUNE 2007

REAFFIRMED, AUGUST 2020

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, con- sultants, or other assignees represent that use of this publication would not infringe upon pri- vately owned rights.

Users of this recommended practice should not rely exclusively on the information con- tained in this document. Sound business, scientific, engineering, and safety judgement should be used in employing the information contained herein.

API is not undertaking to meet the duties of employers, manufacturers, or suppliers to warn and properly train and equip their employees, and others exposed, concerning health and safety risks and precautions, nor undertaking their obligations to comply with authorities having jurisdiction.

Where applicable, authorities having jurisdiction should be consulted.

Work sites and equipment operations may differ. Users are solely responsible for assessing their specific equipment and premises in determining the appropriateness of applying the RP. At all times users should employ sound business, scientific, engineering, and judgement safety when using this RP.

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 publi- cation may conflict.

API publications are published to facilitate the broad availability of proven, sound engineer- ing 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 prod- ucts do in fact conform to the applicable API standard.

All rights reserved. No part of this work may be reproduced, 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, 200 Massachusetts Avenue, NW, Suite 1100, Washington, DC 20001.

Copyright © 2007 American Petroleum Institute

FOREWORD

The purpose of this recommended practice (RP) is to provide guidance for reducing the risk to personnel located in portable buildings from potential explosion, fire and toxic release hazards. The document is based on the following guiding principles, (1) locate personnel away from covered process areas consistent with safe and effective operations, (2) minimize the use of occupied portable buildings near covered process areas, (3) manage the occupancy of portable buildings, especially during periods of increased risk including unit start-up or planned shut-down operations, (4) design, construct, install, and maintain occupied portable buildings to protect occupants against potential hazards, and (5) manage the use of portable buildings as an integral part of the design, construction, maintenance, and operation of a facility. The recommended practice is organized into five sections with two appendices which provide the user with additional technical background and guidance.

Section 1 defines the purpose and scope of the document. Section 1 also provides the guid- ing principles for the development of this document and direction regarding implementation and change control.

Section 2 addresses management of personnel in portable buildings. The topics include iden- tification of essential personnel and their use of portable buildings. Further, Section 2 addresses personnel that are not essential and makes recommendations regarding their loca- tion relative to covered process areas, including during times of non-routine operations. Sec- tion 2 also discusses portable buildings used for various purposes and identifies those that require evaluation for siting relative to covered process areas. This includes criteria such as occupancy and purpose of the portable building.

Sections 3, 4 and 5 address explosion, fire, and toxic release hazards respectively. This docu- ment is based on a philosophy that portable buildings are primarily sited (located) in relation to explosion hazards in the area as described in Section 3. Risks associated with fire and toxic release hazards are managed as described in Sections 4 and 5.

The Appendices include two parts. Appendix A describes the technical bases of certain key topics or criteria provided in this document. Appendix B provides guidance on determining congested volumes used in vapor cloud explosion calculations along with examples to dem- onstrate that guidance.

As used in this document, “shall” denotes a minimum requirement in order to conform to the recommended practice. “Should” denotes a recommendation, or that, which is advised but not required in order to conform to the recommended practice.

Nothing contained in any API publication is to be construed as granting any right, by impli- cation 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 rec- ommended practice. Questions concerning the interpretation of the content of this publica- tion 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, 200 Massachusetts Avenue, NW, Suite 1100, Washington, DC 20001. Requests for permission to reproduce or translate all or any part of the material published herein should also be addressed to the director.

iii

Generally, API recommended practices 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 Depart- ment, telephone (202) 682-8000. A catalog of API publications and materials is published annually and updated quarterly by API, 200 Massachusetts Avenue, NW, Suite 1100, Washington, DC 20001.

Suggested revisions are invited and should be submitted to the Standards and Publications Department, API, 200 Massachusetts Avenue, NW, Suite 1100, Washington, DC 20001, standards@api.org.

CONTENTS

Page

1. GENERAL 1

   1. Introduction 1

   2. Purpose 1

   3. Guiding Principles 1

   4. Scope 1

   5. Implementation and Change Control 1

   6. Relationship to API RP 752. 1

   7. Definitions 1

   8. References 2

2. MANAGEMENT OF PERSONNEL IN PORTABLE BUILDINGS 3

   1. Essential Personnel and Use of Portable Buildings 3

   2. Portable Buildings Intended for Occupancy 3

   3. Portable Buildings Not Intended for Occupancy 4

   4. Other Occupied Portable Structures 4

3. METHODS FOR LOCATING PORTABLE BUILDINGS FOR EXPLOSION HAZARDS 5

   1. Simplified Method 6

   2. Detailed Analysis 6

   3. Light Wood Trailer Overpressure Damage Levels 7

   4. Portable Building Blast Resistance Requirements 8

   5. Additional Explosion Risk Reduction Practices 8

4. FIRE HAZARDS 9

5. TOXIC RELEASE HAZARDS 9

APPENDIX A BASES FOR FIGURE 1 AND TABLE 2 11

APPENDIX B GUIDANCE FOR LOCATING PORTABLE BUILDINGS 13

Figures

1 Portable Buildings Location Guidance 5

1. Example No. 1 Hypothetical Process Unit 15

2. Example No. 2 Site Layout 17

3. Close up of Process Areas that Represent Congested Volumes 18

4. Zone 3 to Zone 2 Transition Distances for Each Congested Volume 19

5. Zone 2 to Zone 1 Transition Distances for Each Congested Volume 20

6. Zones Created by Connecting the Outermost Transition Distances

   from Figures B.4 and B.5 21

7. Zones for Locating Occupied Portable Buildings 22

Tables

1. Allowable Locations and Personnel for Portable Buildings Intended for

   Occupancy 6

2. Overpressure Effects on Light Wood Trailers 7

A.1 Separation Distances from Figure 1 for Selected Congested Volumes 12

B.1 Zone Transition Distances 16

v

Management of Hazards Associated with Location of Process Plant Portable Buildings

1. General

   1. INTRODUCTION

      Occupied permanent buildings (e. g., control rooms, operator shelters) located near covered process areas are typically con- structed to be blast and fire resistant. In contrast, conventional portable buildings (i.e., light wood trailers) are typically not con- structed to be blast and fire resistant. Past explosion accidents have demonstrated that occupants of conventional portable buildings are susceptible to injuries from structural failures, building collapse, and building debris and projectiles.

      
      

   2. PURPOSE

      The purpose of this recommended practice is to provide guidance for reducing the risk to personnel located in portable buildings from potential explosion, fire and toxic release hazards.

      
      

   3. GUIDING PRINCIPLES

      This recommended practice is based on the following guiding principles:

      • Locate personnel away from covered process areas consistent with safe and effective operations

      • Minimize the use of occupied portable buildings in close proximity to covered process areas

      • Manage the occupancy of portable buildings, especially during periods of increased risk including unit start-up or planned shut-down operations

      • Design, construct, install, and maintain occupied portable buildings to protect occupants against potential hazards

      • Manage the use of portable buildings as an integral part of the design, construction, maintenance, and operation of a facility

        
        

   4. SCOPE

      This recommended practice was developed for refineries, petrochemical and chemical operations, natural gas liquids extraction plants, and other facilities such as those covered by the OSHA Process Safety Management Standard, 29 CFR 1910.119.

      
      

   5. IMPLEMENTATION AND CHANGE CONTROL

      This recommended practice provides information that can be used when establishing or updating policies or procedures concern- ing the placement of portable buildings. Specific portable building siting guidelines and procedures for managing change shall be developed for the use and location of portable buildings. Examples of changes that should be managed include:

      • Reassigning personnel

      • Changing process conditions

      • Adding a building

      • Modifying a building

      • Reclassifying a building function (e. g., temporary to permanent)

      • Relocating a building

      • Introducing new hazards affecting a building

      Formal written approval by senior management should be required for deviations from established company policies or procedures.

      
      

   6. RELATIONSHIP TO API RP 752

      This document supersedes API Recommended Practice 752 with regard to portable buildings.

      
      

   7. DEFINITIONS

For the purpose of this recommended practice, the following definitions apply:

1