Api rp 752 2009 (american petroleum institute)

www bzfxw com Management of Hazards Associated with Location of Process Plant Permanent Buildings API RECOMMENDED PRACTICE 752 THIRD EDITION, DECEMBER 2009 ` , , ` ` , ` , , ` , , , , , , ` , , , ` `[.]

Management of Hazards

Associated with Location of

Process Plant Permanent Buildings

API RECOMMENDED PRACTICE 752

THIRD EDITION, DECEMBER 2009

Management of Hazards

Associated with Location of

Process Plant Permanent Buildings

Downstream Segment

API RECOMMENDED PRACTICE 752

THIRD EDITION, DECEMBER 2009

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Copyright © 2009 American Petroleum Institute

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

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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, standards@api.org

iii

1 Scope 1

1.1 General 1

1.2 Guiding Principles 1

1.3 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 3

4.1 Buildings Included in the Building Siting Evaluation 3

4.2 Buildings and Structures Excluded from the Building Siting Evaluation 4

4.3 Buildings Evaluated on a Case-by-case Basis for Inclusion 5

5 Building Siting Evaluation Processes 5

5.1 General 5

5.2 Assessment Approach and Scenario Selection 6

5.3 Building Siting Evaluation Criteria 7

5.4 Existing Buildings 9

5.5 Design of New Buildings or Modifications to Existing Buildings 9

5.6 Personnel Performing Building Siting Evaluation 11

5.7 Management of Building Occupancy 11

5.8 Management of Change (MOC) 11

6 Building Siting Evaluation for Explosion 11

6.1 General 11

6.2 Explosions 13

6.3 Determining the VCE Blast Loads on Buildings 14

6.4 Building Analysis and Design Tools 15

6.5 Occupant Vulnerability from Explosions 15

6.6 Blast Evaluation of Existing Buildings 16

6.7 Siting of New Buildings 16

6.8 Design of New Buildings, Additions and Structural Modifications to Existing Buildings 16

7 Building Siting Evaluation for Fire 16

7.1 General 16

7.2 Spacing Table Approach 17

7.3 Factors Influencing Potential and Type of Fires 17

7.4 Determining the Fire Effects at Buildings 18

7.5 Occupant Vulnerability from Fire 18

7.6 Concept Selection for Buildings Exposed to Fire 18

7.7 Determining if Existing Buildings Require Mitigation 19

7.8 Siting and Design of New Buildings 19

8 Building Siting Evaluation for Toxic Material Release 19

8.1 General 19

8.2 Determining the Toxic Effects at Buildings 21

8.3 Occupant Vulnerability from Toxic Material 21

8.4 Concept Selection for Buildings Exposed to Toxic Material Release 21

8.5 Determining if Existing Buildings Require Mitigation 22

8.6 Siting and Design of New Buildings 22

v

Annex A (informative) Examples 23

Bibliography 25

Figures 1 Overall Building Siting Evaluation Flow Chart 8

2 Building Siting Evaluation for Explosions 12

3 Building Siting Evaluation for Fire 17

4 Building Siting Evaluation for Toxic Material Release 20

Tables 1 Hierarchy of Mitigation Measures 10

2 Primary Effects Associated with Fire Type 18

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

3.1

blast load

The load applied to a structure or object from a blast wave, which is described by the combination of overpressure

and either impulse or duration

building 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

3.4

confinement

A 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

3.5

congestion

A 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

The 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

3.8

essential personnel

Personnel 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

3.9

hazard

An 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

3.10

maximum credible event

MCE

A 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

An 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

3.14

quantitative risk assessment

The 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

3.15

risk

A measure of potential injury, environmental damage, or economic loss in terms of both the incident likelihood and the

severity of the loss or injury

3.16

risk-based approach

A 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

3.17

spacing tables approach

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

3.18

toxic material

An 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);

— 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:

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

(Section 4)

STOP

Include building in mitigation plan.

Develop and implement mitigation plan (5.4.2)

YES

NO

NO YES

Are building siting evaluation criteria met? (5.4)

Is it a new building or modification to existing building?

Design building (including extensions and modifications

to existing buildings) to meet building siting evaluation criteria (5.5, Section 6, Section 7, Section 8).

Choose building siting evaluation approach(es) and criteria (5.2 and 5.3).

Is building impacted by explosion, fire or toxics?

(6.1, 7.1, 8.1)

YES NO

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

eliminate hazard substitute with nonhazardous material/process conditions

prevent release

(i.e reduce frequency of scenario)

upgrade metallurgy or design of equipmentreduce leak sources (eliminate flanges, drains, small bore piping, etc.)rate equipment for maximum upset pressure

control size of scenario

minimize confinementminimize congestionutlitize 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 minimizetoxic/flammable gas and smoke ingress

prevent release

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

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

fixed/automatic active fire fighting systems

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

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

prevent release

(i.e reduce frequency of scenario)

mechanical integrity inspectionpermits for hot work, lockout/tagout, line breaking, lifting, etc

sampling to prevent contamination of reactive materialcontrol size of scenario manual active fire fighting systems

mitigate effect to building occupants

emergency 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

STOP

Complete a building damage level assessment (6.4) or

a detailed structural analysis (6.4).

(6.6)

YES

Include building in mitigation plan.

(6.6)

Does building meet building siting 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 modifications

to existing buildings)

to meet building siting evaluation for explosion (6.7, 6.8).