api 752 management of hazards

Management of Hazards Associated with Location of Process Plant Permanent Buildings

API RECOMMENDED PRACTICE 752 THIRD EDITION, DECEMBER 2009

Copyright American Petroleum Institute Provided by IHS under license with API Licensee=BP International/5928366101

Not for Resale, 04/03/2012 11:02:49 MDTNo reproduction or networking permitted without license from IHS

--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---

Management of Hazards Associated with Location of Process Plant Permanent Buildings

Downstream Segment

API RECOMMENDED PRACTICE 752 THIRD EDITION, DECEMBER 2009



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---

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.

Users of this recommended practice (RP) should not rely exclusively on the information contained in this document. Sound business, scientific, engineering, and safety judgment 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.

Information concerning safety and health risks and proper precautions with respect to particular materials and conditions should be obtained from the employer, the manufacturer or supplier of that material, or the material safety datasheet.

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 judgment 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 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 © 2009 American Petroleum Institute



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---

Foreword

This recommended practice (RP) provides guidance for new and existing building siting evaluation and references documents concerning technical aspects of building siting evaluation including hazard identification, consequence modeling, structural analysis, and risk. Among the hazards that potentially could affect building occupants are explosion, fire, and toxic material releases.

This third edition of API RP 752:2009 supersedes all previous editions, including the technical data provided in those documents. Significant research and development of technology pertinent to building siting evaluations has been performed since the publication of the previous editions of API RP 752. Examples of updated technology include prediction of blast damage to buildings, determination of occupant vulnerabilities, and estimates of event frequencies. Prior versions of API RP 752 and the technical data included in them should not be used for building siting evaluations.

The second edition of API RP 752:2003 covered all building types both permanent and portable. This third edition of API RP 752:2009 does not cover portable buildings. Portable buildings are now covered by API RP 753:2007. It is recognized, however, that portable buildings specifically designed for significant blast load represent a potential area of overlap between API RP 753 and API RP 752. In accordance with 1.3 of this document:

“Buildings described in API RP 753, Management of Hazards Associated with Location of Process Plant Portable Buildings, First Edition, June 2007, as ‘portable buildings specifically designed to resist significant blast loads’ and intended for permanent use in a fixed location are covered in this document (API RP 752). All other portable buildings are covered by API RP 753.”

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.

Shall: As used in an RP, “shall” denotes a minimum requirement in order to conform to the RP.

Should: As used in an RP, “should” denotes a recommendation or that which is advised but not required in order to conform to the RP.

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 RPs 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, [email protected].

iii



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---

Contents

Page

1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Guiding Principles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3 Relationship with API RP 753, First Edition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2 Normative References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

3 Terms and Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

4 Determination of Buildings Requiring Building Siting Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34.1 Buildings Included in the Building Siting Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34.2 Buildings and Structures Excluded from the Building Siting Evaluation. . . . . . . . . . . . . . . . . . . . . . . . . . . 44.3 Buildings Evaluated on a Case-by-case Basis for Inclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5 Building Siting Evaluation Processes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55.2 Assessment Approach and Scenario Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65.3 Building Siting Evaluation Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75.4 Existing Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95.5 Design of New Buildings or Modifications to Existing Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95.6 Personnel Performing Building Siting Evaluation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115.7 Management of Building Occupancy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115.8 Management of Change (MOC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

6 Building Siting Evaluation for Explosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116.2 Explosions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136.3 Determining the VCE Blast Loads on Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146.4 Building Analysis and Design Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156.5 Occupant Vulnerability from Explosions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156.6 Blast Evaluation of Existing Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166.7 Siting of New Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166.8 Design of New Buildings, Additions and Structural Modifications to Existing Buildings . . . . . . . . . . . . 16

7 Building Siting Evaluation for Fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167.2 Spacing Table Approach. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177.3 Factors Influencing Potential and Type of Fires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177.4 Determining the Fire Effects at Buildings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187.5 Occupant Vulnerability from Fire. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187.6 Concept Selection for Buildings Exposed to Fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187.7 Determining if Existing Buildings Require Mitigation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197.8 Siting and Design of New Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

8 Building Siting Evaluation for Toxic Material Release . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198.2 Determining the Toxic Effects at Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218.3 Occupant Vulnerability from Toxic Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218.4 Concept Selection for Buildings Exposed to Toxic Material Release . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218.5 Determining if Existing Buildings Require Mitigation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228.6 Siting and Design of New Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

v



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---

Page

Annex A (informative) Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Figures1 Overall Building Siting Evaluation Flow Chart. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 Building Siting Evaluation for Explosions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 Building Siting Evaluation for Fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174 Building Siting Evaluation for Toxic Material Release . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Tables1 Hierarchy of Mitigation Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 Primary Effects Associated with Fire Type. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---

1

Management of Hazards Associated with Location ofProcess Plant Permanent Buildings

1 Scope

1.1 General

This recommended practice (RP) provides guidance for managing the risk from explosions, fires and toxic material releases to on-site personnel located in new and existing buildings intended for occupancy. This RP was developed for use at refineries, petrochemical and chemical operations, natural gas liquids extraction plants, natural gas liquefaction plants, and other onshore facilities covered by OSHA 29 CFR 1910.119 [1].

Buildings covered by this RP are rigid structures intended for permanent use in fixed locations. Tents, fabric enclosures, and other soft-sided structures are outside the scope of this document.

1.2 Guiding Principles

This RP is based on the following guiding principles:

a) locate personnel away from process areas consistent with safe and effective operations;

b) minimize the use of buildings intended for occupancy in close proximity to process areas;

c) manage the occupancy of buildings in close proximity to process areas;

d) design, construct, install, modify, and maintain buildings intended for occupancy to protect occupants against explosion, fire, and toxic material releases;

e) manage the use of buildings intended for occupancy as an integral part of the design, construction, maintenance, and operation of a facility.

1.3 Relationship with API RP 753, First Edition

Buildings described in API RP 753, Management of Hazards Associated with Location of Process Plant Portable Buildings, First Edition, June 2007, as “portable buildings specifically designed to resist significant blast loads” and intended for permanent use in a fixed location are covered in this document (API RP 752). All other portable buildings are covered by API RP 753.

2 Normative References

There are no normative references for this document.

References in this document and the bibliography are provided for information only and are not part of this RP.

3 Terms and Definitions

For the purpose of this publication, the following terms and definitions apply.

3.1blast loadThe load applied to a structure or object from a blast wave, which is described by the combination of overpressure and either impulse or duration.



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---

2 API RECOMMENDED PRACTICE 752

3.2buildingA rigid, enclosed structure.

3.3building siting evaluation The procedures described in this document used to evaluate the hazards and establish the design criteria for new buildings and the suitability of existing buildings at their specific location.

3.4confinementA physical surface that inhibits the expansion of a flame front of a burning vapor cloud in at least one direction. Examples include solid decks, walls, or enclosures.

3.5congestionA collection of closely spaced objects in the path of the flame front that has the potential to increase flame speed to an extent that it can generate a damaging blast wave.

3.6consequenceThe potential effects of an explosion, fire, or toxic material release. Consequence descriptions may be qualitative or quantitative.

3.7consequence-based approachThe methodology used for building siting evaluation that is based on consideration of the impact of explosion, fire, and toxic material release which does not consider the frequency of events

3.8essential personnelPersonnel with specific work activities that require them to be located in buildings in or near a process area for logistical and response purposes. The identification of essential personnel will vary with operation and work activities including normal operation, start-up, and planned shutdown. Examples of essential personnel include, but are not limited to, operators and maintenance personnel. Examples of persons who are not essential personnel include, but are not limited to, designers, timekeepers, clerical staff, administrative support, and procurement staff.

3.9hazardAn inherent physical or chemical characteristic (e.g. flammability, toxicity, corrosivity, stored chemical energy, or mechanical energy) that has the potential for causing harm to people, property, or the environment.

3.10maximum credible event MCEA hypothetical explosion, fire, or toxic material release event that has the potential maximum consequence to the occupants of the building under consideration from among the major scenarios evaluated. The major scenarios are realistic and have a reasonable probability of occurrence considering the chemicals, inventories, equipment and piping design, operating conditions, fuel reactivity, process unit geometry, industry incident history, and other factors. Each building may have its own set of MCEs for potential explosion, fire, or toxic material release impacts.



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---

MANAGEMENT OF HAZARDS ASSOCIATED WITH LOCATION OF PROCESS PLANT PERMANENT BUILDINGS 3

3.11occupant vulnerabilityProportion of building occupants that could potentially suffer a permanent disability or fatality if a potential event were to occur.

3.12on-site personnelEmployees, contractors, visitors, service providers, and others present at the facility.

3.13process areaAn area containing equipment (e.g. pipes, pumps, valves, vessels, reactors, and supporting structures) intended to process or store materials with the potential for explosion, fire, or toxic material release.

3.14quantitative risk assessmentThe systematic development of numerical estimates of the expected frequency and consequence of potential accidents based on engineering evaluation and mathematical techniques. The numerical estimates can vary from simple values of probability/frequency of an event occurring based on relevant historical industry or other available data; to very detailed frequency modeling techniques.

3.15riskA measure of potential injury, environmental damage, or economic loss in terms of both the incident likelihood and the severity of the loss or injury.

3.16risk-based approachA quantitative risk assessment methodology used for building siting evaluation that takes into consideration numerical values for both the consequences and frequencies of explosion, fire, or toxic material release.

3.17spacing tables approachThe “spacing tables” approach uses established tables to determine minimum separation distances between equipment and buildings intended for occupancy. Industry groups, insurance associations, regulators, and owner/operator companies have developed experience-based spacing tables for minimum building spacing for fire.

3.18toxic materialAn airborne agent that could result in acute adverse human health effects.

4 Determination of Buildings Requiring Building Siting Evaluation

4.1 Buildings Included in the Building Siting Evaluation

Buildings intended for occupancy shall be included in the building siting evaluation.

A building is intended for occupancy if it has personnel assigned [with the exception listed in 4.2 b)] or it is used for a recurring group personnel function.

Examples of buildings intended for occupancy include, but are not limited to:

— buildings which may become occupied during emergencies (e.g. buildings/rooms designated as shelter-in-place for fire and/or toxic material release, emergency command centers);



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---


— change houses;

— conference rooms;

— control rooms;

— field operator buildings (i.e. buildings where operators are routinely located, sometimes referred to as “operator shelters”) (see A.3.8);

— guardhouses;

— laboratories with assigned personnel;

— lunchrooms;

— maintenance shops with assigned personnel;

— offices;

— orientation rooms;

— training rooms;

— warehouse buildings with assigned personnel;

— “buildings within buildings” (i.e. buildings intended for occupancy located within other buildings; see A.3.5);

— rooms intended for occupancy (e.g. office, shop, control room) within an enclosed process area (see A.3.7).

4.2 Buildings and Structures Excluded from the Building Siting Evaluation

Categories and examples of structures and buildings excluded from building siting evaluation are shown as follows.

a) Structures with roofs and no walls whose primary function is to provide limited protection to personnel from weather include, but are not limited to:

— bus stops,

— pavilions,

— welding covers,

— truck loading canopies,

— covered walkways,

— smoking canopies.

b) Enclosed process areas where only essential personnel are assigned to perform activities similar to those performed at an outdoor process area.



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---


c) Buildings which do not have personnel assigned and require at most, only intermittent access. Examples of such buildings include, but are not limited to:

— analyzer buildings;

— field sampling/testing stations;

— electrical substations and motor control centers (MCCs);

— remote instrumentation enclosures;

— equipment enclosure buildings;

— abandoned buildings (i.e. removed from service, unused for any function, and no longer intended for occupancy);

— operator shelters with intermittent use;

— buildings which primarily house materials (see A.3.4).

4.3 Buildings Evaluated on a Case-by-case Basis for Inclusion

Buildings with no personnel assigned but occupied by individuals for a short duration may be included or excluded in a building siting evaluation on a case-by-case basis. The basis for the building’s inclusion or exclusion should consider the number and frequency of visitors and the cumulative level of occupancy among all visitors. These buildings include, but are not limited to:

— smoking shelters,

— weather shelters,

— dock attendant stations,

— loading rack personnel stations,

— restroom buildings.

5 Building Siting Evaluation Processes

5.1 General

A systematic process for building siting evaluation for new and existing buildings is shown in Figure 1.

Owners/operators shall document the following elements of the building siting evaluation:

— assessment approach (see 5.2.1);

— scenario selection basis (see 5.2.2);

— analysis methodologies (see 6.3, 7.4, and 8.2);

— applicability of analysis methodologies;

— data sources used in the analysis;



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---


— applicability of data sources;

— building siting evaluation criteria (see 5.3);

— results of the analysis.

Documentation of mitigation plans are also required as discussed in 5.4.

Where specific features [e.g. heating, ventilation and air conditioning (HVAC), building blast resistance, gas detection system, and/or safety instrumented systems] are used to meet the building siting evaluation criteria, the performance and/or design requirements shall be documented. The active features shall be monitored and maintained over the life cycle of the building. Where procedures are used to meet the building siting evaluation criteria, it should be verified that they are:

1) implemented,

2) effective, and

3) in continuous use over the life cycle of the building.

5.2 Assessment Approach and Scenario Selection

5.2.1 Assessment Approach

Owners/operators may choose one or more of the following three approaches as a building siting evaluation method for new and existing buildings for explosion, fire, and toxic material release scenarios.

a) The “consequence-based” approach takes into consideration the impact of explosion, fire, and toxic scenarios. This approach shall be based on maximum credible events (MCEs) for each building and type of hazard considered.

b) The “risk-based” approach is quantitative and takes into consideration numerical values for both the consequences and the frequencies of explosion, fire, and toxic material release scenarios.

c) The “spacing tables” approach uses established tables to determine minimum separation distances between equipment and buildings intended for occupancy. Industry groups, insurance associations, regulators, and owner/operator companies have developed experience-based spacing tables for minimum building spacing for fire, however, these fire-specific tables are not appropriate for building siting evaluation for explosion and toxic material release. Scenario selection is not required for experience-based fire spacing tables. Spacing tables may be found in various references including Guidelines for Facility Siting and Layout [2]. The spacing tables approach for fire only, also includes index methods (e.g. Dow’s Fire & Explosion Index [3], Mond Index [4]).

Owner/operators may develop site-specific spacing distances for each building type considered, to cover explosions, fires, or toxic material release. These distances shall be based on MCEs. This is considered an application of a consequence-based approach and not the spacing tables approach as discussed above.

The consequence-based and risk-based approaches may range from simple to complex analyses. Complex analyses can take into account details of the site layout, geometry, and the scenarios. Simplified analyses should use conservative assumptions as a means to account for the details not included in the analyses. Additional guidance may be found in Section 6, Section 7, and Section 8.



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---


5.2.2 Scenario Selection for Consequence-based and Risk-based Approaches

The scenario selection process includes, where applicable, hazards associated with the operations including loss of containment, releases from flares, process vent stacks, and atmospheric relief devices.

The scenarios should be based primarily on the process area specific factors such as equipment failure rate data, design of the equipment in the process area, process stream composition, and operating conditions. Consideration should be given to relevant company and industry loss of containment data on similar types of processes and equipment when selecting scenarios.

5.3 Building Siting Evaluation Criteria

5.3.1 General

Prior to starting a building siting evaluation, owners/operators should select the building siting evaluation criteria for new and existing buildings consistent with the selected assessment approach(es).

5.3.2 Building Siting Evaluation Criteria for the Consequence-based Approach

Building siting evaluation criteria for the consequence-based approach can be expressed as building exposure criteria or consequence criteria. These criteria are specific to the materials of construction, building design, and hazard type (explosion, fire, toxic material release).

Building exposure criteria are typically expressed as:

— blast load,

— thermal flux and exposure time,

— flammable gas concentration, or

— toxic concentration and exposure time.

Consequence criteria are typically expressed as:

— occupant vulnerability,

— potential building damage, or

— building internal environment degradation (i.e. inability to support human life).

5.3.3 Building Siting Evaluation Criteria for the Risk-based Approach

Building siting evaluation criteria for the risk-based approach shall address the risk to the building occupants as a group (aggregate risk) and the risk to an individual. An owner/operator may choose to establish a single risk criterion that addresses both individual and aggregate risk. Building siting evaluation criteria may be expressed as numerical values of individual risk, aggregate risk or exceedance values. They can also be expressed as graphical formats which include cumulative frequency vs consequence (F/N) curves, or matrices with numerical axes.

5.3.4 Building Siting Evaluation Criteria for the Spacing Tables Approach

When a spacing tables approach is used, the building siting evaluation criteria are the appropriate values in the spacing table. The criterion is satisfied when the separation distance in the spacing table is met or exceeded.



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---


Figure 1—Overall Building Siting Evaluation Flow Chart

START

Is building withinthe scope of

API 752?(Section 1)

Is buildingincluded in the

siting evaluation?(Section 4)

STOP

Include building inmitigation plan.

Develop and implement mitigation plan. .

(5.4.2)

YES

NO

NO

YES

Arebuilding siting

evaluation criteriamet? (5.4)

Is it a newbuilding or

modification toexisting building?

Design building (includingextensions and modificationsto existing buildings) to meet

building siting evaluationcriteria

(5.5, Section 6,Section 7, Section 8).

NO

YES

Carry out building sitingevaluation.

(5.4, Section 6,Section 7, Section 8)

Choose building sitingevaluation approach(es)

and criteria(5.2 and 5.3).

Is buildingimpacted by

explosion, fire ortoxics?

(6.1, 7.1, 8.1)

YES

NO

Implement management ofbuilding occupancy (5.7)

and/ormanagement of change (5.8).

YES

NO



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---


5.4 Existing Buildings

5.4.1 Building Siting Evaluation for Existing Buildings

Owners/operators shall carry out building siting evaluations for existing buildings intended for occupancy in accordance with Section 6, Section 7, and Section 8.

5.4.2 Mitigation Plan for Existing Buildings

Owners/operators shall develop a prioritized list of all buildings intended for occupancy that fail to meet the building siting evaluation criteria (see 5.3). The basis for the prioritization may include, but is not limited to:

— combination of building damage and building occupancy;

— mitigation measures that can be implemented more quickly than others such as:

— relocation of personnel (especially those who are not categorized as essential personnel),

— provision of blast resistant modular buildings,

— window hazard mitigation;

— risk.

Owners/operators shall develop and implement a mitigation plan and an associated schedule to address all existing buildings requiring mitigation. This plan may include measures described in 5.4.3. The building mitigations may be phased-in consistent with other relative risk mitigation efforts.

5.4.3 Hierarchy of Mitigation Measures

Each building’s potential exposure to explosion, fire, or toxic material release is unique. Table 1 provides examples of possible options to consider in the mitigation plan to reduce the consequence or frequency of scenarios. The list of measures shown in Table 1 is not all inclusive.

Owners/operators may elect to implement measures that reduce the consequence and/or frequency of scenarios. Measures are listed in order of decreasing reliability (passive, active, or procedural) and categorized by type (eliminate, prevent, control, and mitigate). When selecting a mitigation measure it is important to evaluate how effective the measure will be in reducing the consequence or the frequency of the scenario.

Protection of building occupants requires a balanced approach between passive, active, and procedural measures. Owners and operators should be cautious when relying upon active and procedural measures in mitigation for vapor cloud explosions (VCEs) because time between the initial release of flammable material and the VCE may be insufficient for these measures to be effective.

5.5 Design of New Buildings or Modifications to Existing Buildings

Owners/operators shall carry out building siting evaluations for new buildings intended for occupancy in accordance with Section 6, Section 7, and Section 8.

Owners/operators shall design new buildings intended for occupancy, modifications to buildings intended for occupancy, and building additions intended for occupancy to meet the building siting evaluation criteria.



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---


Table 1—Hierarchy of Mitigation Measures

Example Measure

Pass

ive

eliminate hazard substitute with nonhazardous material/process conditions

prevent release

(i.e. reduce frequency of scenario)

upgrade metallurgy or design of equipment

reduce leak sources (eliminate flanges, drains, small bore piping, etc.)

rate equipment for maximum upset pressure

control size of scenario

minimize confinement

minimize congestion

utlitize spill control dikes, curbs, etc., to limit extent of pool fires and limit vapor dispersion from pools of flashing liquids

minimize release rate—provide process flow restrictions (either limiting pipe size or adding restricting orifices) to reduce the potential severity of a release from downstream equipment

reduce inventory of hazardous material (can reduce duration of fire and gas release scenarios)

mitigate effect to building occupants

relocate personnel (especially personnel that are not essential)

design or upgrade existing building to protect occupants from explosion, fire, or toxics

tightly seal windows and tight double doors (airlocks) to minimize toxic/flammable gas and smoke ingress

Act

ive

prevent release

(i.e. reduce frequency of scenario)safety instrumented systems

control size of scenariofire and gas/emergency shutdown systems (reducing quantity released)

fixed/automatic active fire fighting systems

mitigate effect to building occupantsissue occupants with personal protective equipment (PPE) for hazards

HVAC air intake shut down on detection of flammable/toxic gas

Proc

edur

al

prevent release

(i.e. reduce frequency of scenario)

mechanical integrity inspection

permits for hot work, lockout/tagout, line breaking, lifting, etc.

sampling to prevent contamination of reactive material

control size of scenario manual active fire fighting systems

mitigate effect to building occupantsemergency response plan including, as appropriate: evacuation, escape routes, shelter-in-place, etc.

evacuate building occupants during start-up and planned shutdowns



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---


5.6 Personnel Performing Building Siting Evaluation

Personnel performing the building siting evaluation shall have competence in the analytical methods used in the evaluation. Areas of competency include, as appropriate, the application of the methodology being employed, hazard identification, scenario development, flammable and toxic gas dispersion modeling, fire modeling, explosion modeling, blast response of structures, design of buildings to resist thermal loading and gas ingress, frequency assessment, and quantitative risk assessment techniques.

5.7 Management of Building Occupancy

Owners/operators shall develop policies and practices to address housing of personnel located in buildings intended for occupancy considering exposure level to explosion, fire, and toxic material release. Personnel (essential and nonessential) may be located in a building intended for occupancy that meets the owner/operators’ building siting evaluation criteria. Consideration should be given to locating nonessential personnel as far as practicable from the hazard and discouraging congregation of personnel in buildings close to process areas.

Owner/operators should periodically confirm that buildings not intended for occupancy remain unoccupied.

5.8 Management of Change (MOC)

Owners/operators shall identify situations that require MOC. Situations that may require MOC evaluation include, but are not limited to:

— changes to plant operations, processes or equipment (including decommissions or additions) cause a change in potential for, or severity of, explosion, fire, or toxic impacts at the building location;

— a new building intended for occupancy is added to the facility;

— a modification or addition to an existing building occurs that could cause a change in the potential for, or severity of, explosion, fire, or toxic material release impacts;

— the building’s occupancy status changes from not intended for occupancy to intended for occupancy;

— the number of personnel or time spent inside the building increases either permanently or for a defined period of time (see A.3.6).

The actions from the MOC evaluation may vary depending on whether the change is permanent or for a defined period of time. Where the change is permanent, a revision of the building siting evaluation may be necessary. For change which is for a defined period of time, interim risk mitigation measures may be appropriate (see A.3.6).

6 Building Siting Evaluation for Explosion

6.1 General

Owners/operators shall determine if the building intended for occupancy under consideration could be impacted by explosion. Where no potential explosion scenario is identified which could adversely affect the building under consideration, a building siting evaluation for explosion is not required.

A systematic process for building siting evaluation for external explosions is shown in Figure 2. The process is applicable to both new and existing buildings intended for occupancy.



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---


Figure 2—Building Siting Evaluation for Explosions

START

Could buildingbe impacted by

explosion?(6.2)

Building sitingevaluation forexplosion not

required.


modification toexisting

building?

STOP

Complete a buildingdamage level

assessment (6.4) ora detailed structural

analysis (6.4).

YES

NO

YES

NO

Determine blast loadson building (6.3).

Determine blast loadson building (6.3).

Carry out moredetailed

analysis?(6.6)

YES

Include building inmitigation plan.

(6.6)

Does buildingmeet buildingsiting criteria

for explosion?(6.6)

YES

Implement management of building occupancy (5.7) and/or management

of change (5.8).

NO

NO

Design building(including extensions

and modificationsto existing buildings)

to meet building sitingevaluation for explosion

(6.7, 6.8).



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---


6.2 Explosions

6.2.1 General

VCEs are typically the dominant explosion scenarios for refineries and petrochemical plants. Other explosion types may dominate at some facilities. The following sections describe the building siting evaluation process for external VCEs. A similar approach may be used for other explosion hazards, such as:

— internal VCEs, such as inside enclosed process units or other enclosures;

— condensed phase chemical explosions;

— dust explosions;

— pressure vessel bursts (PVBs);

— reactive chemical explosions;

— boiling liquid expanding vapor explosion (BLEVE).

See the fire and explosion section in the bibliography for additional information on other types of explosions.

6.2.2 Factors Influencing the Potential for VCEs

The five conditions necessary for VCEs to occur are:

— release of flammable material,

— sufficient mixing with air to produce a flammable mixture,

— delay which allows the flammable cloud to grow,

— ignition of the dispersed vapor cloud, and

— congestion with or without confinement to accelerate the flame front.

Releases of flammable liquids and gases have the potential to form a flammable vapor cloud. Under elevated process temperatures or pressures, releases of combustible liquids can also result in a flammable cloud.

Parameters such as pressure, temperature, weather conditions, ignition timing, discharge area, location, and orientation of the release affect the size of a vapor cloud.

Although processes may handle materials with the potential to generate a flammable vapor cloud, only some areas of the site may have conditions suitable for a VCE to occur. The main conditions that can determine whether a VCE will occur are the degree of congestion and degree of confinement. The congested and confined region may be the process area which is the source of the flammable material, or a nearby process area or even a congested/confined area containing equipment in nonhazardous service. Inherent properties of the material such as flammability range, vaporization and dispersion properties, and flame propagation properties affect the severity of a VCE.



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---


6.3 Determining the VCE Blast Loads on Buildings

6.3.1 General

The explosion evaluation shall include calculation of blast loads on buildings. There are several methods available for calculating VCE blast loads, with different levels of complexity and data requirements. Additional information on blast load calculation methods is provided in 6.3.2.

The TNT equivalency method shall not be used to assess VCE blast loads for building siting evaluation. The TNT equivalency method does not recognize differences in fuel reactivity or variations in flame speed due to congestion or confinement. In addition, the magnitude and duration of the modeled TNT explosion can be significantly different from VCEs. Other methods are more suitable for modeling VCEs.

6.3.2 VCE Modeling Tools

6.3.2.1 General

This section provides an overview of modeling techniques that may be utilized to determine the blast loads from potential VCEs. The techniques are listed below by increasing complexity.

6.3.2.2 Blast Curve Techniques

This is the most commonly used technique for the purposes of building siting evaluation. It uses site-specific input information to calculate the blast load based on the reactivity of the fuel released and an analysis of the congested volume. The TNO multienergy method, the Baker-Strehlow-Tang (BST) method, and the congestion assessment method (CAM) are examples of this technique. Blast curves can be applied in several approaches, two of which are listed below.

— Filled Congested Volume—It is assumed that there are releases that could completely fill the congested volume with a flammable cloud. In this approach, the source of the release is not needed as it is assumed that there is a scenario that could completely fill the congested volume.

— Dispersion Calculated Congested Volume—A leak scenario is utilized in conjunction with dispersion analysis (using process specific information) to determine the flammable cloud size. The smaller of the actual congested volume(s) or the volume of the flammable cloud within the congested volume(s) is used for the VCE calculation

6.3.2.3 Advanced Blast Simulation Technique

This technique utilizes computational fluid dynamics (CFD) models to characterize the interaction of the release and the evolving vapor cloud with plant equipment to calculate a blast load. Due to its complexity, CFD has been used less frequently than blast curves techniques for building siting evaluations. CFD models typically have extensive data input requirements and require users with advanced experience, but may provide additional specificity.

CFD calculations are sensitive to many parameters, and can have long processing times in some situations. This technique can be useful in at least the following situations:

— modeling detailed dispersion analysis;

— evaluating flame front acceleration in nonuniform geometries (congestion and confinement configurations) to determine a source term for use with blast curves;

— analyzing blast loads on buildings located inside the combustion zone of a VCE;

— evaluating complex blast wave interaction such as shielding and focusing of blast pressure on buildings;



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---


— modeling dispersion and explosions inside enclosed process areas; and

— modeling the impact of blast mitigation options (e.g. vent panels, water spray, etc.).

6.4 Building Analysis and Design Tools

6.4.1 General

The response of a building intended for occupancy exposed to blast loads is assessed to determine the potential building damage and/or consequences to the occupants of the building. Buildings intended for occupancy located within other buildings should be assessed for potential impacts resulting from the blast load and the response of the outer building.

The structural design and analysis methods for blast loads typically allow some level of permanent deformation. As a result, building response is evaluated based on the degree of permanent deformation.

There are two approaches for evaluating the response of buildings to blast load:

— building damage level assessment,

— detailed structural analysis.

6.4.2 Building Damage Level Assessment

A building damage level assessment uses tools that relate blast load to overall building performance or damage levels. Charts (or software that automate use of charts) have been developed based on the assessment of representative buildings. Tables listing the lowest overpressures from the charts that cause specific damage levels (pressure asymptotes) may also be used.

Owners/operators should use appropriate tools to evaluate the building response. Building damage tables that only cite overpressure values may be based on short duration loads and may not be appropriate for long duration blast loads such as from vapor cloud explosions.

Buildings that are not an appropriate structural match to the representative buildings should be analyzed using a detailed structural analysis or by selecting a weaker building for a conservative building damage level assessment.

6.4.3 Detailed Structural Analysis

A detailed structural analysis uses appropriate dynamic analysis methods to assess response of structural components (beams, columns, slabs, frames, etc.) to blast load. As part of the detailed structural analysis process, structural response criteria for building components shall be established. These criteria are discussed in various references [5, 6, 7].

6.5 Occupant Vulnerability from Explosions

Building damage assessment results can be used to estimate the potential vulnerability of building occupants. The primary hazards to personnel located indoors are building collapse and debris. Debris may include building materials thrown from exterior walls or dropped from ceilings/roof. Building contents located on, against, or near external walls may also become debris. Occupant vulnerability can be estimated based on published methodologies. Different models use different definitions of occupant vulnerability and are appropriate for specific types of construction. Occupant vulnerability has been correlated to building damage for some building types. Measures of building damage can be used as a criterion in lieu of occupant vulnerability; however, owners/operators should understand and document the basis for the correlation and assess its applicability.



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---


6.6 Blast Evaluation of Existing Buildings

6.6.1 General

Either a building damage level assessment or a detailed structural analysis may be used for evaluating the response of existing buildings to blast load. The evaluation shall also address nonstructural components that may present debris hazards from roofs, walls, windows, doors, ceilings, and mechanical services. Owners/operators may choose to start with a building damage level assessment and proceed to a detailed structural analysis as appropriate. Alternatively, owners/operators may decide to utilize detailed structural analysis from the outset.

Buildings constructed of brittle materials such as, but not limited to unreinforced masonry (e.g. block, brick, or clay tile), unreinforced concrete, poured gypsum and cement-fiber/asbestos panels lack ductility and fail in a brittle manner when blast loads exceed their capacity. Conventionally constructed buildings using masonry (masonry block, brick, or clay tile) are designed for only the loads specified by building code requirements (i.e. blast loading is not included). Conventional masonry may be unreinforced or minimally reinforced only to meet the building code. Conventional masonry load-bearing wall construction is vulnerable to blast damage since there is little or no ductility and excessive deflection of a single wall can potentially result in wall failure and roof collapse. Blast loading on buildings in or near process areas can be complex due to potential interaction of the building with the combustion process, shielding, and focusing of blast waves (portions of the building could see higher localized pressures). Due to the lack of ductility, the potential consequences of an overload with conventional masonry load bearing construction, and the complexity of blast loading in or near process areas; this type of construction in or near process areas is of particular concern [5, 7].

6.6.2 Determining if Existing Buildings Require Mitigation

Existing buildings intended for occupancy shall be compared with the owner/operators building siting evaluation criteria. Buildings which fail to meet the building siting evaluation criteria shall be included in the mitigation plan or subjected to a more detailed analysis.

6.7 Siting of New Buildings

When siting new buildings intended for occupancy, blast loads shall be taken into account in selecting the type of building construction. Design blast loads may be calculated using a consequence-based or risk-based approach.

6.8 Design of New Buildings, Additions and Structural Modifications to Existing Buildings

When new buildings, additions and modifications to existing buildings are designed for blast loading, a detailed structural analysis shall be used. Building damage level assessment tools shall not be used in the final design for blast loads. The design shall also address nonstructural components that may present debris hazards from roofs, walls, windows, doors, ceilings and mechanical services.

Buildings constructed of brittle materials such as, but not limited to unreinforced masonry (e.g. block, brick, or clay tile), unreinforced concrete, poured gypsum and cement-fiber/asbestos panels lack ductility and fail in a brittle manner when blast loads exceed their capacity. These materials shall not be used for exterior walls (both load-bearing and non-load-bearing) for new buildings intended for occupancy that are potentially subject to blast loads unless justified by analysis.

7 Building Siting Evaluation for Fire

7.1 General

Owners/operators shall determine if the building intended for occupancy under consideration could be impacted by flammable vapor release or thermal radiation. Where no potential fire scenario is identified which could adversely affect the building under consideration, a building siting evaluation for fire is not required.

A systematic process for building siting evaluation for process-related fire hazards is shown in Figure 3. The process is applicable to both new and existing buildings intended for occupancy.



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---


Figure 3—Building Siting Evaluation for Fire

START

Could buildingbe impacted by

fire?(7.1)

Building sitingevaluation for fire not

required.

Is a spacingtable approach

used?(5.2, 7.2)

Carry out more detailedanalysis. (7.7)

If needed, include building in mitigation plan (7.7) andimplement mitigation plan

(5.4.2).


modification toexisting building?

Determine fire effects atbuilding (7.4) and select thefire protection concept (7.6).

YES

NO

Are separationdistances met?

YES

NO

NO

NO

YES

NO

YES

Design building tomeet building sitingevaluation criteria.

(7.8 )

Does buildingmeet building

sitingevaluation

criteria? (7.7)

YES

STOP


and/ormanagement of change (5.8).

Include building in mitigationplan (7.7) and implement

mitigation plan (5.4.2).

Carry out more detailedanalysis (7.7).

If needed, include buildingin mitigation plan (7.7) andimplement mitigation plan

(5.4.2).





--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---


7.2 Spacing Table Approach

When a spacing table approach is used, building siting for fire hazards is assumed to be adequate when the separation distance in the spacing table is met or exceeded.

7.3 Factors Influencing Potential and Type of Fires

Fires in process areas can be pool fires, jet fires, flash fires or fireballs. The type of fire is largely determined by the properties and quantity of material released and the release conditions (temperature, pressure, and geometry of release site). The duration of the fire is governed by factors including the fuel inventory available, rate of material release, drainage, and the effectiveness of fire suppression mitigation.

7.4 Determining the Fire Effects at Buildings

Modeling may be used to predict the effects and durations of fires at building locations. A variety of models are available (see bibliography for examples).

The following lists the primary effects associated with each fire type:

Fireballs and flash fires outside buildings are typically short duration events and not normally considered in building siting evaluation studies.

7.5 Occupant Vulnerability from Fire

Building occupant vulnerability from fire may result from any of the following effects:

— temperature rise within the building,

— ingress and ignition of flammable material,

— ingress of smoke and fumes,

— thermal radiation affecting evacuating occupants.

The building may initially shield occupants from thermal radiation associated with external fires allowing time for evacuation and emergency response. Several factors including building construction, locations of exits, and severity of fire exposure can affect the vulnerability of occupants during evacuation.

7.6 Concept Selection for Buildings Exposed to Fire

7.6.1 General

There are two protection concepts to choose from:

— shelter-in-place for fire,

Table 2—Primary Effects Associated with Fire Type

Fire Type Effect

pool fires thermal dose (flux and duration)

jet fires flame impingement, thermal dose (flux and duration)

internal flash fire or VCE (if a flammable vapor cloud enters a building and finds an ignition source)

thermal dose, blast overpressure, building debris, products of combustion



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---


— evacuation for fire.

Owners/operators shall choose at least one of these concepts. The concept for protection of building occupants from fire hazards should be reflected in the site emergency response plan, building design features, escape route design, and other emergency response elements.

7.6.2 Shelter-in-Place for Fire

When the “shelter-in-place for fire” concept is chosen for a building intended for occupancy, owners/operators shall determine the fire resistance requirements (e.g. the fire rating of the building envelope) using either a consequence-based or risk-based approach. For this concept to be effective, the building shall be designed/assessed based on the longer of:

— length of time personnel are required to remain in the building, or

— length of time that the flammable material or fire impedes escape from the building.

In addition, if the building could be exposed to smoke or an external flammable mixture, the building shall have features to prevent infiltration and formation of smoke or a flammable mixture inside the building. The features may be similar to those listed in 8.4.2.

7.6.3 Evacuation for Fire

When the “evacuation for fire” concept is chosen, owners/operators shall provide the following emergency response features:

— emergency action procedures and training that will facilitate evacuation,

— emergency exits and safe evacuation routes,

— evacuation plan that directs personnel to a designated “shelter-in-place” or specified assembly area,

— means to warn building occupants of the presence of a flammable release or fire,

— plan to account for occupants,

— PPE as necessary for scenario potential exposure.

7.7 Determining if Existing Buildings Require Mitigation

Existing buildings intended for occupancy shall be compared with the owner’s/operator’s building siting evaluation criteria for fire. Buildings which fail to meet the building siting evaluation criteria shall be included in the mitigation plan or subjected to more detailed analysis.

7.8 Siting and Design of New Buildings

New buildings intended for occupancy shall be sited and designed to meet the building siting evaluation criteria for fire.

8 Building Siting Evaluation for Toxic Material Release

8.1 General

Owners/operators shall determine if the building intended for occupancy under consideration could be impacted by a toxic material release. Where no potential toxic material release scenario is identified which could adversely affect the occupants of the building under consideration, a building siting evaluation for toxic material release is not required.



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---


A systematic process for building siting evaluation for toxic material release is shown in Figure 4. The process is applicable to both new and existing buildings intended for occupancy.

8.2 Determining the Toxic Effects at Buildings

The owner/operator may assume that on-site buildings intended for occupancy can be impacted by releases of toxic materials or they may choose to carry out toxic gas dispersion modeling for each building intended for occupancy.

If a gas dispersion modeling approach is selected, owners/operators shall establish thresholds for use as building siting evaluation criteria for toxic material release. The threshold may be either a toxic material concentration/dose external to the building (which could impair escape) or toxic material concentration/dose inside the building. Owners/operators may use one or more gas dispersion models to calculate the concentration of toxic material at specified outdoor locations. A variety of models are available (see bibliography).

8.3 Occupant Vulnerability from Toxic Material

Building occupant vulnerability from toxic material depends on the dose (concentration and duration) inside the building. A building may initially shield occupants providing a finite period of time to enact protection measures such as shutdown of ventilation systems, sealing of openings, or donning of PPE. Occupant vulnerability from exposure to toxic materials can be estimated based on the concentration of toxic material that infiltrates the building and the associated exposure time.

8.4 Concept Selection for Buildings Exposed to Toxic Material Release

8.4.1 General

There are two protection concepts:

— shelter-in-place for toxic material release,

— evacuation for toxic material release.

Owners/operators shall choose at least one of these concepts. The selected concept for the protection of building occupants from toxic materials shall be reflected in the site emergency response plan, building design features and escape route design.

8.4.2 Shelter-in-place for Toxic Materials Release

When the “shelter-in-place for toxic materials release” concept is chosen, owners/operators should consider providing the following features for each building intended for occupancy:

— HVAC systems capable of shutdown of the system or placement in recirculation mode, whichever is more appropriate;

— systems to notify occupants of external material release;

— emergency communications equipment (telephones are acceptable);

— PPE as necessary;

— seals for windows, doors, and penetrations.



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---


Figure 4—Building Siting Evaluation for Toxic Material Release

START

Isthere potential

for a toxicrelease? (8.1)

Building sitingevaluation for toxic

not required.


modification toexisting

building??

YES

NO

NO

YES

Perform toxic gasdispersion modeling. (8.2)

NO

YES

NO

Are buildingsiting evaluation

criteriaexceeded? (8.5)

YES

Is it assumedthat building is

impacted?

Select protection conceptfor toxic material. (8.4)

Design building tomeet building sitingevaluation criteria.

(8.6 )

STOP


andmanagement of change (5.8).



Carry out more detailedanalysis (8.5).

If needed, include building in mitigation plan (8.5) and

implement mitigation plan (5.4.2).



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---


The performance requirements for these features may be designed/assessed based on:

— length of time personnel are required to remain in the building;

— length of time that the toxic material impedes escape from the building; or

— appropriate industry standards, guidelines and practices.

Some materials are both toxic and flammable. A toxic exposure could precede or follow a fire or explosion. The building siting evaluation should consider potential explosion damage, which may compromise their performance as a shelter-in-place for toxic material release.

8.4.3 Evacuation for Toxic Material Release

When the “evacuation for toxic material release” concept is chosen, owners/operators shall provide the following emergency response features for each building intended for occupancy:

— emergency action procedures and training that will facilitate evacuation,

— emergency exits and safe evacuation routes,

— evacuation plan that directs personnel to a designated “shelter-in-place” or specified assembly area,

— means to warn building occupants to the presence of a toxic material release,

— plan to account for occupants,

— PPE as necessary for scenario potential exposure.

8.5 Determining if Existing Buildings Require Mitigation

Existing buildings intended for occupancy shall be compared with the owner’s/operator’s building siting evaluation criteria for toxic material release. Buildings which fail to meet the building siting evaluation criteria shall be included in the mitigation plan or subjected to more detailed analysis.

8.6 Siting and Design of New Buildings

New buildings intended for occupancy shall be sited and designed to meet the building siting evaluation criteria for toxic material release.



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---

23

Annex A(informative)

Examples 1

A.1 IntroductionThe examples in this annex are intended to guide the user in applying the concepts presented in this publication. The examples are designed to illustrate a specific aspect of the application of this publication and do not attempt to convey the complexity or to make trivial the issues associated with building siting evaluation. Any numerical values used in these examples are for illustration purposes only.

A.2 Permanent and Portable Buildings—Section 1.3Problem: A number of structural solutions have been proposed to replace a local control building. The replacement building will be permanent and will house personnel from an existing building. One option is to use a blast resistant portable building which will be fabricated offsite and transported by road to the proposed location. Should the building siting evaluation be in accordance with API 752 or API 753?

Response: The proposed local control building is intended for permanent use in a fixed location and is specifically designed for significant blast loading. The building siting evaluation is performed in accordance with API 752.

A.3 Examples on Selection of Buildings for Siting Evaluation—Section 5

A.3.1 Field Laboratory

Problem: A field laboratory is used by operators who process samples on an intermittent basis related to chemical analysis. These operators are assigned to a nearby processing unit. No personnel are assigned to this building. Should this building be included in the building siting evaluation?

Response: The field laboratory may be excluded from the building siting evaluation because no personnel are assigned and operators perform the testing on an intermittent basis.

A.3.2 Central Laboratory

Problem: A central laboratory houses an assigned laboratory worker who processes samples related to chemical analysis, quality assurance, and filling out related paperwork. Should this building be included in the building siting evaluation?

Response: Since the central laboratory houses personnel who are assigned to the laboratory, it is a building intended for occupancy and is included in the building siting evaluation.

A.3.3 Warehouse—Example 1

Problem: A warehouse is used to store finished product and to serve as a staging point for moving that product onto transport vehicles for removal from the plant. The workforce assigned to work in the warehouse includes an attendant and forklift operators. Is this an occupied building?

Response: This warehouse is intended for occupancy. A warehouse with personnel assigned is specifically identified in 4.1 as intended for occupancy.

1 The following examples are merely examples for illustration purposes only. (Each company should develop its own approach.) They are not to be considered exclusive or exhaustive in nature. API makes no warranties, express or implied for reliance on or any omissions from the information contained in this document.Where applicable, authorities having jurisdiction should be consulted.



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---


A.3.4 Warehouse—Example 2

Problem: A warehouse is used to store material. There is no office inside the building and no personnel are assigned to perform regular work duties inside the building. Personnel do visit the building intermittently to place or remove items. Should this warehouse be included in a building siting evaluation?

Response: This building:

a) does not have personnel assigned,

b) primarily houses materials, and

c) requires at most only intermittent access.

It does not need to be included in a building siting evaluation.

A.3.5 Building Within a Building

Problem: It is decided to add an enclosed office to the corner of the warehouse discussed in A.3.4. The office is to be used by personnel as their assigned workstation. The other activities in the warehouse remain unchanged. Should the warehouse be included in the building siting evaluation?

Response: The office is a “building within a building.” An office is defined as intended for occupancy because it has personnel assigned as described in 4.1. The remaining portion of the warehouse is not intended for occupancy. Building siting evaluation is applied to the office. The structural response of the warehouse surrounding the office is evaluated since it may impact the office.

A.3.6 Motor Control Center (MCC) Occupancy Status

Problem: An MCC building which is not intended for occupancy has an electrical upgrade project scheduled that requires several electricians to work in the building. Does this change the occupancy status of this building to “intended for occupancy”? Is a building siting evaluation required?

Response: This is an intermittent activity and does not change the occupancy status of the building. A revision to the building siting evaluation is not required. However, as the number of personnel inside the building is increasing for a defined period of time, interim mitigation measures may be appropriate.

A.3.7 Operator Shelter Building

Problem: The facility has a small building used as an operator shelter to fill out paperwork, take breaks, and to generally spend time in when they are not out in the plant. Is this building considered intended for occupancy and should it be included in the building siting evaluation?

Response: The building is intended for occupancy and should be included in the building siting evaluation.

A.3.8 Operator Shelter Building—Routine Occupancy

Problem: The facility has a small building used as an operator shelter. Personnel routinely use the building to fill out work permits particularly on days with inclement weather. When not in the field, these personnel are assigned to and reside in the central control room. Is the operator shelter considered intended for occupancy and should it be included in the building siting evaluation?

Response: This operator shelter has routine occupancy (to write permits) and needs to be included in the building siting evaluation.



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---

25

Bibliography

The following documents are directly referenced in this document.

[1] OSHA, Title 29 Code of Federal Regulations (CFR) Part 1910.119, Process Safety Management of Highly Hazardous Chemicals

[2] Guidelines for Facility Siting and Layout, Center for Chemical Process Safety (CCPS), Wiley-American Institute of Chemical Engineers (AIChE), August 15, 2003

[3] Dow’s Fire & Explosion Index Hazard Classification Guide, Wiley-American Institute of Chemical Engineers (AIChE)

[4] Imperial Chemical Industries, “The Mond Index,” ICI PLC, Explosion Hazards Section, Technical Department, Winnington, UK, 1985

[5] Design of Blast Resistant Buildings in Petrochemical Facilities, American Society of Civil Engineers (ASCE)

[6] PIP STC01018, Process Industry Practice, Blast Resistant Building Design Criteria, 2006

[7] PDC Technical Report 06-08, Single Degree of Freedom Structural Response Limits for Antiterrorism Design, U.S. Army Corps of Engineers Protective Design Center, October 2006

Further Reading—The following documents are not directly referenced in this document but may provide a useful source of information.

General—References Not Specific to Particular Subject Area

[8] Guidelines for Postrelease Mitigation in the Chemical Process Industry, Center for Chemical Process Safety (CCPS)

[9] Lees’ Loss Prevention in the Process Industries: Hazard Identification, Assessment and Control, Third Edition, 2004

Building Siting Evaluation Process

[10] M. H. Goose, “Location and design of occupied buildings at chemical plants—assessment step by step,” Hazards XV, The Process, its Safety, and the Environment, Getting it Right, April 4 to 6, 2000, Manchester, (IChem E Symposium Series No. 147, pp. 461 to 476)

[11] Guidance for the Location and Design of Occupied Buildings on Chemical Manufacturing Sites, Chemical Industries Association (CIA)

[12] Guidelines for Evaluating Process Plant Buildings for External Explosions, Fires and Toxics, Second Edition, Center for Chemical Process Safety (CCPS) (work in progress)

Risk and Risk Criteria

[13] “Approved methods and algorithms for DOD explosives siting,” Department of Defense Explosives Safety Board Technical Paper No. 14, Alexandria, Virginia, November 2008



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---


[14] Guidelines for Developing Quantitative Safety Risk Tolerance Criteria, Center for Chemical Process Safety (CCPS), 2009

[15] PGS 3: Guidelines for quantitative risk assessment, TNO (the “Purple Book”), formerly CPR 18 (3.5 MB PDF) IN ENGLISH

[16] PGS 4: Methods for determining and processing probabilities, TNO (the “Red Book”), formerly CPR 12E, (1.4 MB PDF) IN ENGLISH

[17] Guidelines for Chemical Process Quantitative Risk Analysis—Second Edition, Center for Chemical Process Safety (CCPS), Wiley-American Institute of Chemical Engineers (AIChE), 1999

[18] M. Moosemiller, “Avoiding Pitfalls in Assembling and Equipment Failure Rate Database for Risk Assessments,” Journal of Hazardous Materials, 130 (2006) pp. 128 to 132

[19] Spouge, J., “New Generic Leak Frequencies for Process Equipment”, Process Safety Progress, December 2005

Occupant Vulnerability

[20] Methods for the Determination of Possible Damage to People and Objects Resulting from Releases of Hazardous Materials, TNO “Green Book,” CPR 16E, The Hague, Netherlands, 1992

[21] “Derivation of Fatality Probability Functions for Occupants of Buildings Subjected to Blast Loads, Phases 1 to 4,” prepared by W. S. Atkins Science and Technology for the Health and Safety Executive, 1997

[22] C. J. Oswald and Q. A. Baker, “Vulnerability Model for Occupants of Blast Damaged Buildings,” 34th Annual Loss Prevention Symposium March 6 to 8, 2000

Fire and Explosion

[23] PGS 2: Methods for the calculation of physical effects, due to releases of hazardous materials (liquids and gases), TNO (the “Yellow book”), formerly CPR 14E (3.3 MB PDF)

[24] Guidelines for Evaluating the Characteristics of Vapor Cloud Explosions, Flash Fires, and BLEVES, Center for Chemical Process Safety (CCPS), Wiley-American Institute of Chemical Engineers (AIChE)

[25] Harris and Wickens, Understanding Vapour Cloud Explosions—An Experimental Study, British Gas PLC, Communication 1408, 1989

[26] Baker, W. E., Cox, P. A., Westine, P. S., Kulesz, J. J., and Strehlow, R. A., Explosion Hazards and Evaluation, Fundamental Studies in Engineering 5, Elsevier Scientific Publishing Company, 1983

[27] Estimating the flammable mass of a vapor cloud, Center for Chemical Process Safety (CCPS), Wiley-American Institute of Chemical Engineers (AIChE), New York, 1998

[28] Guidelines for Consequence Analysis of Chemical Releases, Center for Chemical Process Safety (CCPS),Wiley-American Institute of Chemical Engineers (AIChE), New York, Copyright 1999 (with errata sheet)

[29] “The Prediction of Blast and Fragment Loadings on Structures,” prepared for U. S. Department of Energy, by Southwest Research Institute, under contract with Mason & Hanger, and Battelle Pantex, Report No. DOE/TIC 11268, July 1992



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---


Spacing Tables for Fire

[30] GAP.2.5.2, Oil and Chemical Plant Layout and Spacing (9/3/01)

[31] GAP.2.5.2.A, Hazard Classification of Process Operations for Spacing Requirements (9/3/01)

Structural Design and Analysis

[32] UFC 3-340-02, Structures to Resist the Effects of Accidental Explosion, December 5, 2008 (replaces TM 5-1300), United Facilities Criteria (UFC)

[33] Biggs, J. D., Introduction to Structural Dynamics, McGraw-Hill Publishing Company, New York, New York, 1964

[34] SBEDS v. 3.1, “Single-Degree-of-Freedom Blast Effects Design Spreadsheets,” U.S. Army Corps of Engineers Protective Design Center, September 12, 2006

[35] FEMA 74, Reducing the Risk of Nonstructural Earthquake Damage, Federal Emergency Management Agency (FEMA), September 1994

Toxics

[36] FEMA 453, Risk Management Series: Design Guidance for Shelters and Safe Rooms, Providing Protection to People and Buildings against Terrorist Attacks, Federal Emergency Management Agency (FEMA), May 2006

[37] AIHA, Emergency Response Planning Guidelines (ERPG)

[38] Temporary Emergency Exposure Limits for Chemicals: Methods and Practice, U.S. Department of Energy Washington, DC 20585

[39] ASHRAE Standard 62.1:2007, Ventilation for Acceptable Indoor Air Quality



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---

Invoice To (❏ Check here if same as “Ship To”)

Name:

Title:

Company:

Department:

Address:

City: State/Province:

Zip/Postal Code: Country:

Telephone:

Fax:

Email:

❏ Payment Enclosed ❏ P.O. No. (Enclose Copy)

❏ Charge My IHS Account No.

❏ VISA ❏ MasterCard ❏ American Express❏ Diners Club ❏ Discover

Credit Card No.:

Print Name (As It Appears on Card):

Expiration Date:

Signature:

Quantity Title Total

Subtotal

Applicable Sales Tax (see below)

Rush Shipping Fee (see below)

Shipping and Handling (see below)

Total (in U.S. Dollars)

★ To be placed on Standing Order for future editions of thispublication, place a check mark in the SO column and sign here:

Pricing and availability subject to change without notice.

Date:

SO★ Unit Price

❏ API Member (Check if Yes)

Ship To (UPS will not deliver to a P.O. Box)

Name:

Title:

Company:

Department:

Address:

City: State/Province:

Zip/Postal Code: Country:

Telephone:

Fax:

Email:

Mail Orders – Payment by check or money order in U.S. dollars is required except for established accounts. State and local taxes, $10 processing fee, and 5% shipping must be added.Send mail orders to: API Publications, IHS, 15 Inverness Way East, c/o Retail Sales, Englewood, CO 80112-5776, USA.Purchase Orders – Purchase orders are accepted from established accounts. Invoice will include actual freight cost, a $10 processing fee, plus state and local taxes.Telephone Orders – If ordering by telephone, a $10 processing fee and actual freight costs will be added to the order.Sales Tax – All U.S. purchases must include applicable state and local sales tax. Customers claiming tax-exempt status must provide IHS with a copy of their exemption certificate.Shipping (U.S. Orders) – Orders shipped within the U.S. are sent via traceable means. Most orders are shipped the same day. Subscription updates are sent by First-Class Mail.Other options, including next-day service, air service, and fax transmission are available at additional cost. Call 1-800-854-7179 for more information.Shipping (International Orders) – Standard international shipping is by air express courier service. Subscription updates are sent by World Mail. Normal delivery is 3-4 days fromshipping date.Rush Shipping Fee – Next Day Delivery orders charge is $20 in addition to the carrier charges. Next Day Delivery orders must be placed by 2:00 p.m. MST to ensure overnight delivery.Returns – All returns must be pre-approved by calling the IHS Customer Service Department at 1-800-624-3974 for information and assistance. There may be a 15% restocking fee.Special order items, electronic documents, and age-dated materials are non-returnable.

Effective January 1, 2009.API Members receive a 30% discount where applicable.The member discount does not apply to purchases made for the purpose of resaleor for incorporation into commercial products, training courses, workshops, or othercommercial enterprises.

Available through IHS:Phone Orders: 1-800-854-7179 (Toll-free in the U.S. and Canada)

303-397-7956 (Local and International)Fax Orders: 303-397-2740Online Orders: global.ihs.com

2009PublicationsOrder Form

Std 521, Guide for Pressure-relieving and Depressuring Systems

RP 753, Management of Hazards Associated with Location of Process Plant Portable Buildings

$212.00

$136.00



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---

API provides additional resources and programs to the oil and natural gas industry which arebased on API Standards. For more information, contact:

API MONOGRAM® LICENSINGPROGRAMPhone: 202-962-4791Fax: 202-682-8070Email: [email protected]

API QUALITY REGISTRAR(APIQR®)> ISO 9001 Registration> ISO/TS 29001 Registration> ISO 14001 Registration> API Spec Q1® RegistrationPhone: 202-962-4791Fax: 202-682-8070Email: [email protected]

API PERFORATOR DESIGNREGISTRATION PROGRAMPhone: 202-682-8490Fax: 202-682-8070Email: [email protected]

API TRAINING PROVIDERCERTIFICATION PROGRAM(API TPCPTM)Phone: 202-682-8490Fax: 202-682-8070Email: [email protected]

API INDIVIDUAL CERTIFICATIONPROGRAMS (ICP®)Phone: 202-682-8064Fax: 202-682-8348Email: [email protected]

API ENGINE OIL LICENSING ANDCERTIFICATION SYSTEM (EOLCS)Phone: 202-682-8516Fax: 202-962-4739Email: [email protected]

API PETROTEAM (TRAINING,EDUCATION AND MEETINGS)Phone: 202-682-8195Fax: 202-682-8222Email: [email protected]

API UNIVERSITYTM

Phone: 202-682-8195Fax: 202-682-8222Email: [email protected]

Check out the API Publications, Programs,and Services Catalog online at www.api.org.

Copyright 2008 – API, all rights reserved. API, API monogram, APIQR, API Spec Q1,API TPCP, ICP, API University and the API logo are either trademarks or registeredtrademarks of API in the United States and/or other countries.

THERE’S MOREWHERE THIS CAME FROM.



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---



--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---

Additional copies are available through IHSPhone Orders: 1-800-854-7179 (Toll-free in the U.S. and Canada)

303-397-7956 (Local and International)Fax Orders: 303-397-2740Online Orders: global.ihs.com

Information about API Publications, Programs and Servicesis available on the web at www.api.org

1220 L Street, NWWashington, DC 20005-4070USA

202.682.8000

Product No. K75203Copyright American Petroleum Institute Provided by IHS under license with API Licensee=BP International/5928366101


--``,,,,`,`,`,`,,``,,,,`,`,`,,,,-`-`,,`,,`,`,,`---

api 752 management of hazards

Documents