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TECHNICAL CORRECTION September 2007

Process Industry Practices

Structural

PIP STC01015Structural Design Criteria

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PURPOSE AND USE OF PROCESS INDUSTRY PRACTICES

In an effort to minimize the cost of process industry facilities, this Practice has

been prepared from the technical requirements in the existing standards of majorindustrial users, contractors, or standards organizations. By harmonizing these technicalrequirements into a single set of Practices, administrative, application, and engineering

costs to both the purchaser and the manufacturer should be reduced. While this Practiceis expected to incorporate the majority of requirements of most users, individualapplications may involve requirements that will be appended to and take precedenceover this Practice. Determinations concerning fitness for purpose and particular mattersor application of the Practice to particular project or engineering situations should not

be made solely on information contained in these materials. The use of trade namesfrom time to time should not be viewed as an expression of preference but ratherrecognized as normal usage in the trade. Other brands having the same specificationsare equally correct and may be substituted for those named. All Practices or guidelinesare intended to be consistent with applicable laws and regulations including OSHA

requirements. To the extent these Practices or guidelines should conflict with OSHA orother applicable laws or regulations, such laws or regulations must be followed.Consult an appropriate professional before applying or acting on any material

contained in or suggested by the Practice.

This Practice is subject to revision at any time.

© Process Industry Practices (PIP), Construction Industry Institute, The

University of Texas at Austin, 3925 West Braker Lane (R4500), Austin,Texas 78759. PIP member companies and subscribers may copy this Practice

for their internal use. Changes, overlays, addenda, or modifications of anykind are not permitted within any PIP Practice without the express written

authorization of PIP.

PRINTING HISTORY

December 1998 Issued August 2004 Complete Revision

February 2002 Technical Revision February 2006 Technical Correction

April 2002 Editorial Revision September 2007 Technical Correction

Not printed with State funds

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Process Industry Practices Page 1 of 30

Process Industry Practices

Structural

PIP STC01015Structural Design Criteria

Table of Contents

1. Introduction ................................. 2 1.1 Purpose ............................................ 2 1.2 Scope ............................................... 2

2. References .................................. 2 2.1 Process Industry Practices .............. 2 2.2 Industry Codes and Standards ........ 2 2.3 Government Regulations ................. 4

3. Definitions ................................... 5

4. Requirements.............................. 5 4.1 Design Loads ................................... 5 4.2 Load Combinations ........................ 14 4.3 Structural Design ........................... 23 4.4 Existing Structures ......................... 30

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PIP STC01015 TECHNICAL CORRECTIONStructural Design Criteria September 2007

Page 2 of 30 Process Industry Practices

1. Introduction

1.1 Purpose

This Practice provides structural engineering design criteria for the processindustries.

1.2 Scope

This Practice describes the minimum requirements for the structural design of process industry facilities at onshore U.S. sites. This Practice is intended to be used in

conjunction with PIP ARC01015, PIP ARC01016 , PIP CVC01015, PIP CVC01017 , and PIP CVC01018, as applicable.

2. References

Applicable parts of the following Practices, industry codes and standards, and references shall

be considered an integral part of this Practice. The edition in effect on the date of contractaward shall be used, except as otherwise noted. Short titles will be used herein whereappropriate.

2.1 Process Industry Practices (PIP)

– PIP ARC01015 - Architectural and Building Utilities Design Criteria

– PIP ARC01016 - Building Data Sheets

– PIP CVC01015 - Civil Design Criteria

– PIP CVC01017 - Plant Site Data Sheet

– PIP CVC01018 - Project Data Sheet

– PIP PCCWE001 - Weighing Systems Criteria

– PIP PCEWE001 - Weighing Systems Guidelines

– PIP REIE686/API 686 - Recommended Practices for Machinery Installationand Installation Design

– PIP STC01018 - Blast Resistant Building Design Criteria

– PIP STE05121 - Anchor Bolt Design Guide

– PIP STE03360 - Heat Exchanger and Horizontal Vessel Foundation DesignGuide

– PIP STS02360 - Driven Piles Specification

2.2 Industry Codes and Standards

American Association of State Highway and Transportation Officials (AASHTO)

– AASHTO Standard Specifications for Highway Bridges

American Concrete Institute (ACI)

– ACI 318/318R - Building Code Requirements for Structural Concrete and

Commentary

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– ACI 350/350R – Code Requirements for Environmental Engineering ConcreteStructures and Commentary

– ACI 530/ASCE 5/TMS 402 - Building Code Requirements for Masonry

Structures

American Institute of Steel Construction (AISC)

– AISC Steel Construction Manual - Allowable Stress Design (ASD) and Loadand Resistance Factor Design (LRFD)

– Specification for Structural Joints Using ASTM A325 or A490 Bolts

American Iron and Steel Institute (AISI)

– AISI SG 673, Part I - Specification for the Design for Cold-Formed Steel

Structural Members

– AISI SG 673, Part II - Commentary on the Specification for the Design forCold-Formed Steel Structural Members

– AISI SG 913, Part I - Load and Resistance Factor Design Specification forCold-Formed Steel Structural Members

– AISI SG 913, Part II - Commentary on the Load and Resistance Factor DesignSpecification for Cold-Formed Steel Structural Members

American Petroleum Institute (API)

– API Standard 650 - Welded Steel Tanks for Oil Storage

American Society of Civil Engineers (ASCE)

– ASCE/SEI 7-05 - Minimum Design Loads for Buildings and Other Structures

– SEI/ASCE 37-02 - Design Loads on Structures During Construction

– ASCE Guidelines for Seismic Evaluation and Design of Petrochemical Facilities

– ASCE Guidelines for Wind Loads and Anchor Bolt Design for Petrochemical Facilities

– ASCE Design of Blast Resistant Buildings in Petrochemical Facilities

American Society of Mechanical Engineers (ASME)

– ASME A17.1 - Safety Code for Elevators and Escalators

ASTM International (ASTM)

– ASTM A36/A36M - Standard Specification for Carbon Structural Steel

– ASTM A82/A82M - Standard Specification for Steel Wire, Plain, for Concrete

Reinforcement

– ASTM A185/A185M - Standard Specification for Steel Welded Wire Reinforcement, Plain, for Concrete

– ASTM A193/A193M - Standard Specification for Alloy-Steel and StainlessSteel Bolting Materials for High Temperature or High Pressure Service andOther Special Purpose Applications

– ASTM A307 - Standard Specification for Carbon Steel Bolts and Studs,

60 000 PSI Tensile Strength

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– ASTM A325 - Standard Specification for Structural Bolts, Steel, Heat Treated,120/105 ksi Minimum Tensile Strength

– ASTM A354 - Standard Specification for Quenched and Tempered Alloy Steel Bolts, Studs, and Other Externally Threaded Fasteners

– ASTM A490 - Standard Specification for Structural Bolts, Alloy Steel, HeatTreated,150 ksi Minimum Tensile Strength

– ASTM A615/A615M - Standard Specification for Deformed and PlainCarbon-Steel Bars for Concrete Reinforcement

– ASTM A706/A706M - Standard Specification for Low-Alloy Steel Deformedand Plain Bars for Concrete Reinforcement

– ASTM A992/A992M - Standard Specification for Structural Steel Shapes

– ASTM F1554 - Standard Specification for Anchor Bolts, Steel, 36, 55, and105-ksi Yield Strength

American Welding Society (AWS)

– AWS D1.1/D1.1M - Structural Welding Code - Steel

American Forest and Paper Association

– National Design Specification for Wood Construction (NDS)

– NDS Supplement - Design Values for Wood Construction

Crane Manufacturers Association of America (CMAA)

– CMAA No. 70 - Specifications for Top Running Bridge and Gantry Type Multiple Girder Overhead Electric Traveling Cranes

– CMAA No. 74 - Specifications for Top Running and Under Running SingleGirder Overhead Electric Traveling Cranes Utilizing Under Running Trolley

Hoist

Precast/Prestressed Concrete Institute (PCI)

– PCI MNL 120 - Design Handbook - Precast and Prestressed Concrete

Steel Joist Institute (SJI)

– SJI Standard Specifications, Load Tables and Weight Tables for Steel Joistsand Joist Girders

2.3 Government Regulations

Federal Standards and Instructions of the Occupational Safety and HealthAdministration (OSHA), including any additional requirements by state or local

agencies that have jurisdiction in the state where the project is to be constructed, shallapply.

U.S. Department of Labor, Occupational Safety and Health Administration(OSHA)

– OSHA 29 CFR 1910 - Occupational Safety and Health Standards

– OSHA 29 CFR 1926 - Safety and Health Regulations for Construction

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3. Definitions

engineer of record: Purchaser’s authorized representative with overall authority andresponsibility for the engineering design, quality, and performance of the civil works,structure, foundations, materials, and appurtenances described in the contract documents.

The engineer of record shall be licensed as defined by the laws of the locality in which the

work is to be constructed, and be qualified to practice in the specialty discipline required forthe work described in the contract documents.

owner: The party who has authority through ownership, lease, or other legal agreement overthe structures to be designed

4. Requirements

4.1 Design Loads

4.1.1 General

4.1.1.1 New facilities, buildings, and other structures, including floor slabsand foundations, shall be designed to resist the minimum loadsdefined in ASCE/SEI 7 , local building codes, this section and theloads defined in PIP CVC01017 and CVC01018.

4.1.1.2 In addition to the loads in this section, other loads shall beconsidered as appropriate. These loads shall include, but are notlimited to, snow, ice, rain, hydrostatic, dynamic, upset conditions,

earth pressure, vehicles, buoyancy, and erection.

4.1.1.3 Future loads shall be considered if specified by the owner.

4.1.1.4 For existing facilities, actual loads may be used in lieu of theminimum specified loads.

4.1.1.5 Eccentric loads (piping, platforms, etc.), particularly on horizontaland vertical vessels and exchangers, shall be considered. Foradditional information regarding eccentric loads on horizontal

vessels and exchangers, see PIP STE03360.

4.1.1.6 The owner shall be consulted to determine the classification ofOccupancy Categories for buildings and other structures for the

purpose of applying wind, earthquake, snow, and ice load provisionsin accordance with Section 1.5 of ASCE/SEI 7-05.

Comment: For process industry facilities, ASCE/SEI 7 Category III is the most likely classification becauseof the presence of toxic or explosive substances.

Category II may be used if the owner candemonstrate that release of the toxic or explosive

substances does not pose a threat to the public. See ASCE/SEI 7-05, Section 1.5.2 and Table 1-1, forspecific details. In some cases, it may be appropriateto select Category IV.

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4.1.2 Dead Loads (D)

4.1.2.1 Dead loads are the actual weight of materials forming the building,

structure, foundation, and all permanently attached appurtenances.

4.1.2.2 Weights of fixed process equipment and machinery, piping, valves,

electrical cable trays, and the contents of these items shall beconsidered as dead loads.

4.1.2.3 For this Practice, dead loads are designated by the followingnomenclature:

Ds, Df , De, Do, and Dt, where

Ds = Structure dead load is the weight of materials forming thestructure (not the empty weight of process equipment,

vessels, tanks, piping, nor cable trays), foundation, soilabove the foundation resisting uplift, and all permanentlyattached appurtenances (e.g., lighting, instrumentation,

HVAC, sprinkler and deluge systems, fireproofing, andinsulation, etc.).

Df = Erection dead load is the fabricated weight of processequipment or vessels (as further defined in Section 4.1.2.4).

De = Empty dead load is the empty weight of process equipment,

vessels, tanks, piping, and cable trays (as further defined inSections 4.1.2.4 through 4.1.2.6).

Do = Operating dead load is the empty weight of processequipment, vessels, tanks, piping, and cable trays plus themaximum weight of contents (fluid load) during normaloperation (as further defined in Sections 4.1.2.4

through 4.1.2.7).

Dt = Test dead load is the empty weight of process equipment,vessels, tanks, and/or piping plus the weight of the testmedium contained in the system (as further defined in

Section 4.1.2.4).

4.1.2.4 Process Equipment and Vessel Dead Loads

1. Erection dead load (Df ) for process equipment and vessels is

normally the fabricated weight of the equipment or vessel and isgenerally taken from the certified equipment or vessel drawing.

2. Empty dead load (De) for process equipment and vessels is the

empty weight of the equipment or vessels, including allattachments, trays, internals, insulation, fireproofing, agitators,

piping, ladders, platforms, etc. Empty dead load also includesweight of machinery (e.g., pumps, compressors, turbines, and

packaged units).

3. Operating dead load (Do) for process equipment and vessels isthe empty dead load plus the maximum weight of contents(including packing/catalyst) during normal operation.

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4. Test dead load (Dt) for process equipment and vessels is theempty dead load plus the weight of test medium contained in

the system. The test medium shall be as specified in the contractdocuments or as specified by the owner. Unless otherwisespecified, a minimum specific gravity of 1.0 shall be used forthe test medium. Equipment and pipes that may be

simultaneously tested shall be included. Cleaning load shall beused for test dead load if the cleaning fluid is heavier than thetest medium.

4.1.2.5 Pipe Rack Piping Loads

1. Dead loads for piping on pipe racks shall be estimated as

follows, unless actual load information is available and requiresotherwise:

a. Operating dead load (Do): A uniformly distributed load of40 psf (1.9 kPa) for piping, product, and insulation

Comment: This is equivalent to 8-inch (203-mm)

diameter, Schedule 40 pipes, full of water, at15-inch (381-mm) spacing.

b. Empty dead load (De): For checking uplift and componentscontrolled by minimum loading, 60% of the estimated

piping operating loads shall be used if combined with windor earthquake unless the actual conditions require adifferent percentage.

c. Test dead load (Dt) is the empty weight of the pipe plus theweight of test medium contained in a set of simultaneously

tested piping systems. The test medium shall be as specifiedin the contract documents or as specified by the owner.

Unless otherwise specified, a minimum specific gravity of1.0 shall be used for the test medium.

2. For any pipe larger than 12-inch (304-mm) nominal diameter,

a concentrated load, including the weight of piping, product,valves, fittings, and insulation shall be used in lieu of the 40 psf(1.9 kPa). This load shall be uniformly distributed over the

pipe’s associated area.

3. Pipe racks and their foundations shall be designed to support

loads associated with full utilization of the available rack spaceand any specified future expansion.

4.1.2.6 Pipe Rack Cable Tray Loads

Dead loads for cable trays on pipe racks shall be estimated asfollows, unless actual load information is available and requiresotherwise:

a. Operating dead load (Do): A uniformly distributed dead load of20 psf (1.0 kPa) for a single level of cable trays and 40 psf(1.9 kPa) for a double level of cable trays.

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Comment: These values estimate the full (maximum)level of cables in the trays.

b. Empty dead load (De): For checking uplift and componentscontrolled by minimum loading, a reduced level of cable tray

load (i.e., the actual configuration) should be considered as theempty dead load. Engineering judgement shall be exercised in

defining the dead load for uplift conditions.

4.1.2.7 Ground-Supported Storage Tank Loads

Dead loads for ground-supported storage tanks are shown in Table 9with the same nomenclature as other dead loads in this Practice for

consistency. The individual load components making up the deadloads may have to be separated for actual use in design, discussed asfollows:

a. Operating dead load (Do): Operating dead load for a ground-supported storage tank is made up of the metal load from the

tank shell and roof, vertically applied through the wall of thetank, in addition to the fluid load from the stored product. Thefluid load acts through the bottom of the tank and does not act

vertically through the wall of the tank. Therefore, the metaldead load and the fluid load must be used separately in design.

b. Empty dead load (De): For checking uplift and componentscontrolled by minimum loading, the corroded metal weight (if acorrosion allowance is specified) should be considered as the

empty dead load.

c. Test dead load (Dt): Test dead load for a ground-supported

storage tank is made up of the metal load from the tank shell

and roof, vertically applied through the wall of the tank, inaddition to the fluid load from the test medium. The fluid load

acts through the bottom of the tank and does not act verticallythrough the wall of the tank. Therefore, the metal dead load and

the fluid load must be used separately in design. The testmedium shall be as specified in the contract documents or as

specified by the owner. Unless otherwise specified, a minimumspecific gravity of 1.0 shall be used for the test medium.

4.1.3 Live Loads (L)

4.1.3.1 Live loads are gravity loads produced by the use and occupancy ofthe building or structure. These include the weight of all movable

loads, such as personnel, tools, miscellaneous equipment, movable partitions, wheel loads, parts of dismantled equipment, storedmaterial, etc.

4.1.3.2 Areas specified for maintenance (e.g., heat exchanger tube bundleservicing) shall be designed to support the live loads.

4.1.3.3 Minimum live loads shall be in accordance with ASCE/SEI 7 ,applicable codes and standards, and, unless otherwise specified, inTable 1:

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TABLE 1. MINIMUM LIVE LOADS

Uniform** Concentrated**

Stairs and Exitways 100 psf (4.8 kN/m2) 1,000 lb (4.5 kN)

Operating, AccessPlatforms, and

Walkways

75 psf(3.6 kN/m2)

1,000 lb (4.5 kN)

Control, I/O,HVAC Room Floors

100 psf (4.8 kN/m2) 1,000 lb (4.5 kN)

Manufacturing Floorsand Storage Areas:

Light125 psf(6.0 kN/m2)

2,000 lb(9.0 kN)

Heavy 250 psf(12.0 kN/m2)*

3,000 lb(13.5 kN)

Ground-SupportedStorage Tank Roof

25 psf(1.2 kN/m2)

NA

*This 250 psf (12.0 kN/m2

) live load includes small equipment.**The loads provided in this table are to be used unless noted otherwise

on the owner’s data sheet.

4.1.3.4 Uniform and concentrated live loads listed in Table 1 shall not be

applied simultaneously.

4.1.3.5 According to ASCE/SEI 7 , concentrated loads equal to or greaterthan 1,000 lb (4.5 kN) may be assumed to be uniformly distributed

over an area of 2.5 ft (750 mm) by 2.5 ft (750 mm) and shall belocated to produce the maximum load effects in the structural

members.

4.1.3.6 Stair treads shall be designed according to OSHA regulations or building code as applicable.

4.1.3.7 Live load reductions shall be in accordance with ASCE/SEI 7 .

4.1.3.8 For manufacturing floor areas not used for storage, the live load

reduction specified by ASCE/SEI 7 for lower live loads may be used.

4.1.3.9 The loadings on handrails and guardrails for process equipmentstructures shall be in accordance with OSHA 1910.

4.1.3.10 The loadings on handrails and guardrails for buildings and structuresunder the jurisdiction of a building code shall be in accordance with

the building code.

4.1.4 Wind Loads (W)

4.1.4.1 Unless otherwise specified, wind loads shall be computed andapplied in accordance with ASCE/SEI 7 and the recommendedguidelines for open frame structures, pressure vessels, and pipe racks

in ASCE Guidelines for Wind Loads and Anchor Bolt Design for Petrochemical Facilities.

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4.1.4.2 Site specific design parameters shall be in accordance with PIP CVC01017 .

4.1.4.3 The full design wind load shall be used when calculating wind drift(see Section 4.3.6).

4.1.4.4 A solid width of 1.5 ft (450 mm) shall be assumed when calculatingthe wind load on ladder cages.

4.1.4.5 Partial wind load (WP) shall be based on the requirements ofSEI/ASCE 37-02, Section 6.2.1, for the specified test or erectionduration. The design wind speed shall be 68 mph (109 kph) (which is

0.75 x 90 mph [145 kph] according to SEI/ASCE 37 for test orerection periods of less than 6 weeks).

4.1.4.6 For test or erection periods of 6 weeks or more or if the test orerection is in a hurricane-prone area and is planned during the peakhurricane season (from August 1 to October 31 in the U.S.A), see

SEI/ASCE 37-02, Section 6.2.1.

4.1.5 Earthquake Loads (E)

4.1.5.1 Except for API Standard 650 ground-supported storage tanks,earthquake loads shall be computed and applied in accordance with

ASCE/SEI 7 , unless otherwise specified.

Comment: The earthquake loads in ASCE/SEI 7 are limit stateearthquake loads, and this should be taken into

account if using allowable stress design methods orapplying load factors from other codes. Earthquakeloads for API Standard 650 storage tanks are

allowable stress design loads.

4.1.5.2 Site specific design parameters shall conform to PIP CVC01017 .

4.1.5.3 ASCE Guidelines for Seismic Evaluation and Design of Petrochemical Facilities may also be used as a general reference forearthquake design.

4.1.5.4 Earthquake loading shall be determined using ASCE/SEI 7-05,Chapter 15, if ASCE/SEI 7 is used for the earthquake design of

nonbuilding structures as defined in ASCE/SEI 7-05, Section 15.1.1and Tables 15.4-1 and 15.4-2.

Comment: Nonbuilding structures include but are not limited toelevated tanks or vessels, stacks, pipe racks, andcooling towers.

4.1.5.5 The importance factor “I” for nonbuilding structures shall bedetermined from ASCE/SEI 7-05, Section 15.4.1.1.

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Comment: In general, for nonbuilding structures in petrochemical process units, use an importance

factor “I” of 1.25 in conjunction with OccupancyCategory III; however, in some cases, it may beappropriate to use an importance factor “I” of 1.0 or1.5 in conjunction with Occupancy Category II or IV

respectively.

4.1.5.6 For the load combinations in Section 4.2, the following designationsare used:

Eo = Earthquake load considering the unfactored operating deadload and the applicable portion of the unfactored structuredead load

Ee = Earthquake load considering the unfactored empty dead loadand the applicable portion of the unfactored structure dead

load

4.1.6 Impact Loads

4.1.6.1 Impact loads shall be in accordance with ASCE/SEI 7 .

4.1.6.2 Impact loads for davits shall be the same as those for monorailcranes (powered).

4.1.6.3 Lifting lugs or pad eyes and internal members (included both endconnections) framing into the joint where the lifting lug or pad eye is

located shall be designed for 100% impact.

4.1.6.4 All other structural members transmitting lifting forces shall bedesigned for 15% impact.

4.1.6.5 Allowable stresses shall not be increased when combining impactwith dead load.

4.1.7 Thermal Loads

4.1.7.1 For this Practice, thermal loads are designated by the followingnomenclature:

T p, T, Af , and Ff , where

T p = Forces on vertical vessels, horizontal vessels, or heatexchangers caused by the thermal expansion of the pipeattached to the vessel

T = Self-straining thermal forces caused by the restrained

expansion of horizontal vessels, heat exchangers, andstructural members in pipe racks or in structures

Af = Pipe anchor and guide forces

Ff = Pipe rack friction forces caused by the sliding of pipes orfriction forces caused by the sliding of horizontal vessels or

heat exchangers on their supports, in response to thermalexpansion

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4.1.7.2 All support structures and elements thereof shall be designed toaccommodate the loads or effects produced by thermal expansionand contraction of equipment and piping.

4.1.7.3 Thermal loads shall be included with operating loads in the

appropriate load combinations. Thermal load shall have the sameload factor as dead load.

4.1.7.4 Thermal loads and displacements shall be calculated on the basis ofthe difference between ambient or equipment design temperature andinstalled temperature. To account for the significant increase in

temperatures of steel exposed to sunlight, 35oF (20oC) shall be addedto the maximum ambient temperature.

4.1.7.5 Friction loads caused by thermal expansion shall be determinedusing the appropriate static coefficient of friction. Coefficients offriction shall be in accordance with Table 2:

TABLE 2. COEFFICIENTS OF FRICTION

Steel to Steel 0.4

Steel to Concrete 0.6

Proprietary Sliding Surfaces orCoatings (e.g., “Teflon”)

According to Manufacturer’sInstructions

4.1.7.6 Friction loads shall be considered temporary and shall not becombined with wind or earthquake loads. However, anchor and

guide loads (excluding their friction component) shall be combinedwith wind or earthquake loads.

4.1.7.7 For pipe racks supporting multiple pipes, 10% of the total pipingweight shall be used as an estimated horizontal friction load appliedonly to local supporting beams. However, an estimated friction load

equal to 5% of the total piping weight shall be accumulated andcarried into pipe rack struts, columns, braced anchor frames, and

foundations.

Comment: Under normal loading conditions with multiple pipes, torsional effects on the local beam need not beconsidered because the pipes supported by the beamlimit the rotation of the beam to the extent that the

torsional stresses are minimal. Under certaincircumstances, engineering judgement shall be

applied to determine whether a higher friction loadand/or torsional effects should be used.

4.1.7.8 Pipe anchor and guide loads shall have the same load factor as dead

loads.

4.1.7.9 Internal pressure and surge shall be considered for pipe anchor andguide loads.

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4.1.7.10 Beams, struts, columns, braced anchor frames, and foundations shall be designed to resist actual pipe anchor and guide loads.

4.1.7.11 For local beam design, only the top flange shall be consideredeffective for horizontal bending unless the pipe anchor engages both

flanges of the beam.

4.1.8 Bundle Pull Load (Bp)

4.1.8.1 Structures and foundations supporting heat exchangers subject to bundle pulling shall be designed for a horizontal load equal to1.0 times the weight of the removable tube bundle but not less than

2,000 lb (9.0 kN). If the total weight of the exchanger is less than2,000 lb (9.0 kN), the bundle pull design load need not exceed thetotal weight of the exchanger.

4.1.8.2 Bundle pull load shall be applied at the center of the bundle.

Comment: If it can be assured that the bundles will be removed

strictly by the use of a bundle extractor attachingdirectly to the exchanger (such that the bundle pullforce is not transferred to the structure orfoundation), the structure or foundation need not bedesigned for the bundle pull force. Such assurance

would typically require the addition of a sign postedon the exchanger to indicate bundle removal by anextractor only.

4.1.8.3 The portion of the bundle pull load at the sliding end support shallequal the friction force or half the total bundle pull load, whichever

is less. The remainder of the bundle pull load shall be resisted at theanchor end support.

4.1.9 Traffic Loads

4.1.9.1 Buildings, trenches, and underground installations accessible to truckloading shall be designed to withstand HS20 load as defined by

AASHTO Standard Specifications for Highway Bridges.

4.1.9.2 Maintenance or construction crane loads shall also be considered

where applicable.

4.1.9.3 Truck or crane loads shall have the same load factor as live load.

4.1.10 Blast Load

4.1.10.1 Blast load is the load on a structure caused by overpressureresulting from the ignition and explosion of flammable material or

by overpressure resulting from a vessel burst.4.1.10.2 Control houses or other buildings housing personnel and control

equipment near processing plants may need to be designed for blast

resistance.

4.1.10.3 Blast load shall be computed and applied in accordance with

PIP STC01018 and the ASCE Design of Blast Resistant Buildings in Petrochemical Facilities.

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4.1.11 Pressure Loads (Ground-Supported Tanks Only)

For this Practice, pressure loads for ground-supported tanks are designated

by the following nomenclature:

Pi, Pe, and Pt, where

Pi = design internal pressure

Pe = external pressure

Pt = test internal pressure

4.1.12 Snow Loads (S)

4.1.12.1 Unless otherwise specified, snow loads shall be computed and

applied in accordance with ASCE/SEI 7 .

4.1.12.2 Site specific design parameters shall be in accordance with

PIP CVC01017.

4.2 Load Combinations

4.2.1 General

Buildings, structures, equipment, vessels, tanks, and foundations shall be

designed for the following:

a. Appropriate load combinations from ASCE/SEI 7 except as otherwise

specified in this Practice

b. Local building codes

c. Any other applicable design codes and standards

d. Any other probable and realistic combination of loads

4.2.2 Typical Load Combinations (for Structures and Foundations)

4.2.2.1 General

Load combinations are provided in Sections 4.2.2.2 through 4.2.2.6for specific types of structures in both allowable stress design (ASD)and strength design format.

a. Allowable Stress Design

1. The noncomprehensive list of typical load combinations for

each type of structure provided in Sections 4.2.2.2through 4.2.2.6 shall be considered and used as applicable.

Comment: The dead load factor used for the earthquake

uplift ASD load combinations is generally takenas 0.9. This factor is greater than the 0.6 dead

load factor used in the ASD load combinationsof ASCE/SEI 7-05, Section 2, because the deadloads of nonbuilding structures are known to ahigher degree of accuracy than are thecorresponding dead loads of buildings. A dead

load factor of 0.9 instead of 1.0 is used to

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account for the effect of vertical seismic forces.The use of this reduction is necessary because

foundations sized using ASD loads, except forfoundations for ground-supported storage tanks,are generally not required to consider the effectof vertical seismic uplift forces if a dead load

factor of 0.6 is used. A dead load factor of 1.0 isused for the wind uplift ASD load combinations

because of the higher accuracy of dead loads ofnonbuilding structures

2. Engineering judgment shall be used in establishing allappropriate load combinations.

3. The use of a one-third stress increase for load combinationsincluding wind or earthquake loads shall not be allowed for

designs using AISC ASD.

b. Strength Design

1. The noncomprehensive list of typical factored loadcombinations for each type of structure provided inSections 4.2.2.2 through 4.2.2.6 shall be considered andused as applicable.

2. Engineering judgment shall be used in establishing allappropriate load combinations.

3. The following load combinations are appropriate for usewith the strength design provisions of either AISC LRFD

(third edition or later) or ACI 318 (2002 edition or later).

4.2.2.2 General Plant Structures

Load combinations for buildings and open frame structures shall bein accordance with ASCE/SEI 7-05, Section 2.

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4.2.2.3 Vertical Vessels

TABLE 3. LOADING COMBINATIONS - ALLOWABLE STRESSDESIGN (SERVICE LOADS)

Load

Comb.No. Load Combination

Allowable

StressMultiplier Description

1 Ds + Do + L 1.00 Operating Weight +Live Load

2 Ds + Do +(W or 0.7 Eoa)

1.00 Operating Weight +Wind or Earthquake

3 Ds + De + W 1.00 Empty Weight +Wind

(Wind Uplift Case)

4a 0.9 (Ds + Do) + 0.7 Eoa 1.00 Operating Weight +Earthquake

(Earthquake UpliftCase)

4b 0.9 (Ds + De) + 0.7 Eea 1.00 Empty Weight +Earthquake


5 Ds + Df + Wp 1.00 Erection Weight +Partial Windb

(Wind Uplift Case)

6 Ds + Dt + Wp 1.20 Test Weight +Partial Wind

Notes:

a. For skirt-supported vertical vessels and skirt-supported elevatedtanks classified as Occupancy Category IV in accordance with

ASCE/SEI 7-05 , Section 1.5 and Table 1-1, the critical earthquakeprovisions and implied load combination of ASCE/SEI 7-05 ,Section 15.7.10.5, shall be followed.

b. Erection weight + partial wind is required only if the erection weight ofthe vessel is significantly less than the empty weight of the vessel.

c. Thrust forces caused by thermal expansion of piping shall be includedin the calculations for operating load combinations, if deemedadvisable. The pipe stress engineer shall be consulted for anythermal loads that are to be considered.

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TABLE 4. LOADING COMBINATIONS AND LOAD FACTORS – STRENGTH DESIGN

LoadComb.

No. Load Combination Description

1 1.4 (Ds + Do) Operating Weight

2 1.2 (Ds + Do) + 1.6 L Operating Weight + Live Load

3 1.2 (Ds + Do) +(1.6 W or 1.0 Eoa)

Operating Weight + Wind orEarthquake

4 0.9 (Ds + De) + 1.6 W Empty Weight + Wind(Wind Uplift Case)

5a 0.9 (Ds + Do) + 1.0 Eoa Operating Weight + Earthquake(Earthquake Uplift Case)

5b 0.9 (Ds + De) + 1.0 Eea Empty Weight + Earthquake(Earthquake Uplift Case)

6 0.9 (Ds + Df ) + 1.6 Wp Erection Weight + Partial Windb

(Wind Uplift Case)

7 1.4 (Ds + Dt) Test Weight

8 1.2 (Ds + Dt) + 1.6 Wp Test Weight + Partial Wind

Notes:

a. For skirt-supported vertical vessels and skirt-supported elevated tanksclassified as Occupancy Category IV in accordance with ASCE/SEI7-05 , Section 1.5 and Table 1-1, the critical earthquake provisions andimplied load combination of ASCE/SEI 7-05 , Section 15.7.10.5, shallbe followed.

b. Erection weight + partial wind is required only if the erection weight ofthe vessel is significantly less than the empty weight of the vessel.

c. Thrust forces caused by thermal expansion of piping shall be includedin the calculations for operating load combinations, if deemedadvisable. The pipe stress engineer shall be consulted for any thermalloads that are to be considered. The same load factor as used for deadload shall be used.

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4.2.2.4 Horizontal Vessels and Heat Exchangers


Load

Comb.No.

Load Combination

Allowable

StressMultiplier Description

1 Ds + Do +(T or Ff )b

1.00 Operating Weight +Thermal Expansion or

Friction Force

2 Ds + Do + L +(T or Ff )b

1.00 Operating Weight +Live Load +

Thermal Expansion orFriction Force

3 Ds + Do +(W or 0.7 Eo)

1.00 Operating Weight +Wind or Earthquake

4 Ds + De + W 1.00 Empty Weight + Wind

(Wind Uplift Case)

5a 0.9 (Ds + Do) +0.7 Eo

1.00 Operating Weight +Earthquake

(Earthquake Uplift Case)

5b 0.9 (Ds + De) +0.7 Ee

1.00 Empty Weight +Earthquake


6 Ds + Df + Wp 1.00 Erection Weight +Partial Windc

(Wind Uplift Case)

7 Ds + Dt + Wp 1.20 Test Weight +Partial Wind

(For Horizontal VesselsOnly)

8 Ds + Ded + Bp 1.00 Empty Weight +Bundle Pull

(For Heat ExchangersOnly)

Notes:

a. Wind and earthquake forces shall be applied in both transverse andlongitudinal directions, but shall not necessarily be appliedsimultaneously.

b. The design thermal force for horizontal vessels and heat exchangersshall be the lesser of T or F f .

c. Erection weight + partial wind is required only if the erection weight ofthe vessel or exchanger is significantly less than the empty weight ofthe vessel or exchanger.

d. Heat exchanger empty dead load will be reduced during bundle pullbecause of the removal of the exchanger head.

e. Sustained thermal loads not relieved by sliding caused by vessel orexchanger expansion shall be considered in operating loadcombinations with wind or earthquake.

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f. Thrust forces caused by thermal expansion of piping shall be included in thecalculations for operating load combinations if deemed advisable. The pipestress engineer shall be consulted for any thermal loads that are to beconsidered.

TABLE 6. LOADING COMBINATIONS AND LOAD FACTORS – STRENGTH DESIGN

LoadComb.


1 1.4 (Ds + Do) + 1.4 (T or F f )b Operating Weight +Thermal Expansion or Friction Force

2 1.2 (Ds + Do) + 1.6 L +1.2 (T or Ff )b

Operating Weight + Live Load +Thermal Expansion or Friction Force

3 1.2 (Ds + Do) +(1.6 W or 1.0 Eo)

Operating Weight +Wind or Earthquake

4 0.9 (Ds + De) + 1.6 W Empty Weight + Wind(Wind Uplift Case)

5a 0.9 (Ds + Do) + 1.0 Eo Operating Weight + Earthquake(Earthquake Uplift Case)

5b 0.9 (Ds + De) + 1.0 Ee Empty Weight + Earthquake(Earthquake Uplift Case)

6 0.9 (Ds + Df ) + 1.6 Wp Erection Weight + Partial Windc

(Wind Uplift Case)

7 1.4 (Ds + Dt) Test Weight(For Horizontal Vessels Only)

8 1.2 (Ds + Dt) + 1.6 Wp Test Weight + Partial Wind(For Horizontal Vessels Only)

9 1.2 (Ds + Ded) + 1.6 Bp Empty Weight + Bundle Pull(For Heat Exchangers Only)

10 0.9 (Ds + Ded) + 1.6 Bp Empty Weight + Bundle Pull(For Heat Exchangers Only)

(Bundle Pull Uplift Case)

Notes:

a. Wind and earthquake forces shall be applied in both transverse and longitudinaldirections, but shall not necessarily be applied simultaneously.

b. The design thermal force for horizontal vessels and heat exchangers shall bethe lesser of T or Ff.

c. Erection weight + partial wind is required only if the erection weight of the vesselor exchanger is significantly less than the empty weight of the vessel orexchanger.

d. Heat exchanger empty dead load will be reduced during bundle pull because ofthe removal of the exchanger head.

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e. Sustained thermal loads not relieved by sliding from vessel orexchanger expansion shall be considered in operating loadcombinations with wind or earthquake.

f. Thrust forces caused by thermal expansion of piping shall be includedin the calculations for operating load combinations, if deemed

advisable. The pipe stress engineer shall be consulted for anythermal loads that are to be considered. The same load factor asused for dead load shall be used.

4.2.2.5 Pipe Rack and Pipe Bridge Design


LoadComb.

No. Load Combination

AllowableStress

Multiplier Description

1 Ds + Do + Ff + T + Af 1.00 Operating Weight +

Friction Force +Thermal Expansion +

Anchor Force

2 Ds + Do + Af +(W or 0.7 Eo)

1.00 Operating Weight + Anchor + Wind or

Earthquake

3 Ds + Dec + W 1.00 Empty Weight + Wind(Wind Uplift Case)

4a 0.9 (Ds) + 0.6 (Do) + Af + 0.7 Eod

1.00 Operating Weight +Earthquake


4b 0.9 (Ds + Dec) +0.7 Ee

1.00 Empty Weight +Earthquake


5 Ds + Dt + Wp 1.20 Test Weight +Partial Winde

Notes:

a. Considerations of wind forces are normally not necessary in thelongitudinal direction because friction and anchor loads will normallygovern.

b. Earthquake forces shall be applied in both transverse and longitudinaldirections, but shall not necessarily be applied simultaneously.

c. 0.6Do is used as a close approximation of the empty pipe condition

De.

d. Full Ds + Do value shall be used for the calculation of Eo in loadcombination 4a.

e. Test weight + partial wind normally is required only for local memberdesign because test is not typically performed on all pipessimultaneously.

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TABLE 8. LOADING COMBINATIONS ANDLOAD FACTORS STRENGTH DESIGN

LoadComb.


1 1.4 (Ds + Do + Ff + T + Af )Operating Weight +Friction Force +

Thermal Expansion + Anchor

2 1.2 (Ds + Do + Af ) +(1.6 W or 1.0 Eo)

Operating Weight + Anchor + Wind or

Earthquake

3 0.9 (Ds + Dec) + 1.6 W Empty Weight + Wind(Wind Uplift Case)

4a 0.9 (Ds + Do) + 1.2 (Af ) +

1.0 Eo

Operating Weight +Earthquake


4b 0.9 (Ds + Dec) + 1.0 Ee Empty Weight + Earthquake


5 1.4 (Ds + Dt) Test Weight

6 1.2 (Ds + Dt) + 1.6 Wp Test Weight + Partial Windd

Notes:

a. Considerations of wind forces are normally not necessary in thelongitudinal direction because friction and anchor loads will normallygovern.

b. Earthquake forces shall be applied in both transverse and longitudinaldirections, but shall not necessarily be applied simultaneously.

c. 0.6Do is used as a close approximation of the empty pipe condition De.

d. Test weight + partial wind normally is required only for local member

design because test is not typically performed on all pipessimultaneously.

4.2.2.6 Ground-Supported Storage Tank Load Combinations

Load combinations for ground-supported storage tanks shall be takenfrom API Standard 650. Load combinations from API Standard 650

and modified for use with ASCE/SEI 7 loads and PIP nomenclatureare shown in Table 9.

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LoadComb.


1 Ds + Do + Pi Operating Weight +Internal Pressurea

2 Ds + Dt + Pt Test Weight +Test Pressure

3 Ds + (De or Do) + W + 0.4 Pib Empty or OperatingWeight + Wind +

Internal Pressurea

4 Ds + (De or Do) + W + 0.4 Peb Empty or OperatingWeight + Wind +External Pressure

5 Ds + Do + (L or S) + 0.4 Peb Operating Weight +Live or Snow +

External Pressure

6 Ds + (De or Do) + 0.4 (L or S) + Pe Empty or OperatingWeight +

Live or Snow +External Pressure

7 Ds + Do + 0.1 S + Eoc + 0.4 Pib Operating Weight +Snow + Earthquake +

Internal Pressurea


8 Ds + Do + 0.1 S + Eoc Operating Weight +Snow + Earthquake

Notes:a. For internal pressures sufficient to lift the tank shell according to the

rules of API Standard 650 , tank, anchor bolts, and foundation shall bedesigned to the additional requirements of API Standard 650

Appendix F.7.

b. If the ratio of operating pressure to design pressure exceeds 0.4, theowner shall consider specifying a higher factor on design pressure inload combinations 3, 4, 5, and 7 of Table 9.

c. Earthquake loads for API Standard 650 tanks taken from ASCE/SEI 7 “bridging equations” or from API Standard 650 already include the0.7 ASD seismic load factor.

4.2.2.7 Load Combinations for Static Machinery, Skid and Modular

Equipment, Filters, and Other Equipment

Load combinations for static machinery, skid and modularequipment, filters, etc., shall be similar to the load combinations forvertical vessels.

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4.2.3 Test Combinations

4.2.3.1 Engineering judgment shall be used in establishing the appropriate

application of test load combinations to adequately address actualtest conditions in accordance with project and code requirements

while avoiding overly conservative design.

4.2.3.2 Consideration shall be given to the sequence and combination oftesting for various equipment, vessels, tanks, and/or piping systems

supported on common structures, pipe racks, or foundations.

4.2.3.3 Full wind and earthquake loads are typically not combined with test

loads unless an unusually long test duration is planned (i.e., if asignificant probability exists that the “partial wind velocity” will beexceeded or an earthquake event may occur).

4.2.3.4 Additional loading shall be included with test if specified in thecontract documents.

4.2.3.5 For allowable stress design, a 20% allowable stress increase shall be permitted for any test load combination.

4.2.3.6 For ultimate strength/limit states design, no load factor reductionshall be permitted for any test load combination.

4.3 Structural Design

4.3.1 Steel

4.3.1.1 Steel design shall be in accordance with AISC ASD or AISC LRFDspecifications.

4.3.1.2 For cold-formed shapes, design shall be in accordance with AISIspecifications.

4.3.1.3 Steel joists shall be designed in accordance with SJI standards.Comment: Supplement number 1 to the AISC ASD

specification deleted the one-third stress increase

for use with load combinations including wind orearthquake loads. Because of the deletion of theone-third stress increase, designs made to the AISC

LRFD specifications should be considered foreconomy.

4.3.1.4 Steel design, including steel joists and metal decking, shall bedesigned in accordance with OSHA 29 CFR 1926 , Subpart R, to

provide structural stability during erection and to protect employeesfrom the hazards associated with steel erection activities.

Comment: Common requirements that affect steel design areas

follow (this is not an all inclusive list):

a. All column base plates shall be designed with a minimum of

four anchor bolts. Posts (which weigh less than 300 lb [136 kg])are distinguished from columns and are excluded from the four-anchor bolt requirement.

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b. Columns, column base plates, and their foundations shall bedesigned to resist a minimum eccentric gravity load of 300 lb(136 kg) located 18 inches (450 mm) from the extreme outerface of the column in each direction at the top of the column

shaft. Column splices shall be designed to meet the same load-resisting characteristics as those of the columns.

c. Double connections through column webs or at beams thatframe over the tops of columns shall be designed so that at leastone installed bolt remains in place to support the first beamwhile the second beam is being erected. The fabricator may alsosupply a seat or equivalent device with a means of positive

attachment to support the first beam while the second beam is being erected.

d. Perimeter columns shall extend 48 inches (1,200 mm) above the

finished floor (unless constructability does not allow) to allowthe installation of perimeter safety cables. Provision shall be

made for the attachment of safety cables.

e. Structural members of framed metal deck openings shall beturned down to allow continuous decking, except where not

allowed by design constraints or constructability. The openingsin the metal deck shall not be cut until the hole is needed.

f. Shear stud connectors that will project vertically from orhorizontally across the top flange of the member shall not beattached to the top flanges of beams, joists, or beam attachmentsuntil after the metal decking or other walking/working surfacehas been installed.

4.3.1.5 All welded structural connections shall use weld filler materialconforming to AWS D1.1/D1.1M , Section 3.3 (including Table 3.1),and have an electrode strength of 58 ksi (400 MPa) minimum yield

strength and 70 ksi (480 MPa) tensile strength, unless otherwiserequired.

4.3.1.6 Structural steel wide-flange shapes, including WT shapes, shall be inaccordance with ASTM A992/A992M , unless otherwise specified.

4.3.1.7 All other structural shapes, plates, and bars shall be in accordancewith ASTM A36/A36M , unless otherwise specified.

4.3.1.8 Preference in design shall be given to shop-welded, field-bolted

connections.

4.3.1.9 Compression flanges of floor beams, not supporting equipment, may

be considered braced by decking (concrete or floor plate) if positively connected thereto.

4.3.1.10 Grating shall not be considered as lateral bracing for support beams.

4.3.1.11 Except as specified in Section 4.3.1.12 or if slip-critical connectionsare required by the AISC Specification for Structural Joints Using

ASTM A325 or A490 Bolts, all bolts 3/4 inches (19 mm) and larger

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(except anchor bolts) shall be type-N (bearing-type with threadsincluded in the shear plane) high-strength ASTM A325 bolts.

4.3.1.12 Bolt size shall be as follows:

a. Structural members - 3/4 inch (19 mm) minimum

b. Railings, ladders, purlins, and girts - 5/8 inch, (16 mm) ASTM A307

4.3.1.13 Minimum thickness of bracing gusset plates shall be 3/8 inch

(10 mm).

4.3.2 Concrete

4.3.2.1 Concrete design shall be in accordance with ACI 318/318R.

4.3.2.2 Concrete design for liquid-containing structures shall also bedesigned in accordance with ACI 350/350R.

4.3.2.3 Unless otherwise specified, all reinforcing steel shall be inaccordance with ASTM A615/A615M Grade 60 deformed.

4.3.2.4 ASTM A615/A615M Grade 60 plain wire conforming to ASTM A82/A82M may be used for spiral reinforcement.

4.3.2.5 Welded wire fabric shall conform to ASTM A185/A185M .

4.3.2.6 Reinforcement designed to resist earthquake-induced flexural andaxial forces in frame members and in wall boundary elements shall

be in accordance with ASTM A706/A706M . ASTM A615/A615M Grade 60 reinforcement is acceptable for these members under the

following conditions:

a. The actual yield strength based on mill tests does not exceed thespecified yield strength by more than 18,000 psi (124 MPa).

Retests shall not exceed this value by more than an additional3,000 psi (20.7 MPa).

b. The ratio of the actual ultimate tensile strength to the actualtensile yield strength is not less than 1.25.

4.3.2.7 Precast and prestressed concrete shall be in accordance with the

PCI Design Handbook.

4.3.3 Masonry

Masonry design shall be in accordance with ACI 530/ASCE 5/TMS 402.

4.3.4 Elevator Supports

Elevator support design shall be in accordance with ASME A17.1.

4.3.5 Crane Supports

4.3.5.1 Vertical deflection of support runway girders shall not exceed the

following limits given in Table 10 if loaded with the maximumwheel load(s), without impact (where L = the span length).

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TABLE 10. MAXIMUM ALLOWABLE GIRDERDEFLECTIONS

Top-Running CMAA Class A, B, and C Cranes L/600

Top-Running CMAA Class D Cranes L/800

Top-Running CMAA Class E and F Cranes L/1000

Under-Running CMAA Class A, B, and C Cranes L/450

Monorails L/450

4.3.5.2 Vertical deflection of jib crane support beams shall not exceed L/225(where L = the maximum distance from the support column to load

location along the length of the jib beam) if loaded with themaximum lifted plus hoist load(s), without impact.

4.3.5.3 Lateral deflection of support runway girders for cranes with lateral

moving trolleys shall not exceed L/400 (where L = the span length)

if loaded with a total crane lateral force not less than 20% of the sumof the weights of the lifted load (without impact) and the cranetrolley. The lateral force shall be distributed to each runway girderwith consideration for the lateral stiffness of the runway girders and

the structure supporting the runway girders.

4.3.5.4 Crane stops shall be designed in accordance with the crane

manufacturer ’s requirements or, if not specified, for the followingload:

F = W V2/(2gTn)

where:

F = Design force on crane stop, kips (kN)W = 50% of bridge weight + 90% of trolley weight,

excluding the lifted load, kips (kN)

V = Rated crane speed, ft/sec (m/sec)

g = Acceleration of gravity, 32.2 ft/sec2 (9.8 m/sec2)

T = Length of travel (ft) of spring or plunger required tostop crane, from crane manufacturer, typically0.15 ft (0.05 m)

n = Bumper efficiency factor (0.5 for helical springs.Consult crane manufacturer for hydraulic plunger.)

4.3.6 Allowable Drift Limits

4.3.6.1 Allowable wind drift limits for pipe racks shall not exceed H/100(where H = pipe rack height).

4.3.6.2 Except as indicated in the following subsections, the allowable wind

story drift limits for occupied buildings shall not exceed H/200(where H = story height).

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4.3.6.3 Allowable wind drift limits for pre-engineered metal buildings shallnot exceed H/80 (where H = building height).

4.3.6.4 Allowable wind drift limits for a building with a bridge crane that isrequired to be in service even during hurricanes shall not exceed

H/400 or 2 inches (50 mm), whichever is less (where H = the height

from the base of the crane support structure to the top of the runwaygirder).

4.3.6.5 Allowable wind drift limits for buildings with bridge cranes that willnot be in service during hurricanes shall not exceed H/140 or

2 inches (50 mm), whichever is less (see Section 4.3.6.4 fordefinition of H).

4.3.6.6 Allowable wind drift limits for process structures and personnel

access platforms shall not exceed H/200 (where H = structure heightat elevation of drift consideration).

4.3.6.7 Allowable seismic drift limits shall be in accordance with ASCE/SEI 7 .

4.3.7 Foundations

4.3.7.1 Foundation design shall be based on the results of a geotechnicalengineering investigation.

4.3.7.2 The minimum overturning “stability ratio” for service loads otherthan earthquake shall be 1.5 (see Section 4.3.7.4 for the minimum

overturning “stability ratio” for earthquake loads). For foundationdesign of buildings and open frame structures, if the dead load factoris 0.6 in accordance with ASCE/SEI 7-05, Section 2, the minimumoverturning “stability ratio” shall be 1.0.

Comment: This requirement is consistent with ASCE/SEI 7

provisions, in which the “factor of safety” is builtinto the 0.6 “dead load factor” in the loadcombinations.

4.3.7.3 The minimum factor of safety against sliding for service loads otherthan earthquake shall be 1.5 (see Section 4.3.7.4 for the minimum

sliding factor of safety for earthquake loads). For foundation designof buildings and open frame structures, if the dead load factor is 0.6in accordance with ASCE/SEI 7-05, Section 2, the minimum factor of

safety against sliding shall be 1.0.

Comment : This requirement is consistent with ASCE/SEI 7

provisions, in which the “factor of safety” is built

into the 0.6 “dead load factor” in the loadcombinations.

4.3.7.4 Overturning and sliding caused by earthquake loads shall be checkedin accordance with ASCE/SEI 7-05, Chapter 12. The minimum

overturning “stability ratio” and the minimum factor of safety againstsliding for earthquake service loads shall be 1.0. In addition, the

minimum overturning “stability ratio” for the anchorage andfoundations of skirt-supported vertical vessels and skirt-supportedelevated tanks classified as Occupancy Category IV in accordance

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with ASCE/SEI 7-05, Section 1.5 and Table 1-1, shall be 1.2 for thecritical earthquake loads specified in ASCE/SEI 7-05, Section15.7.10.5.

4.3.7.5 For earthquake loads calculated by the “Equivalent Lateral Force

Procedure” in ASCE/SEI 7 , additional stability checks shall be performed in accordance with ASCE/SEI 7-05, Section 12.8.5,

“Overturning.” For foundations designed using seismic loadcombinations from Tables 3, 5, and 7 of this Practice, the reductionin overturning effects at the soil-foundation interface permitted in

ASCE/SEI 7-05, Section 12.13.4, shall not be used.

4.3.7.6 The minimum factor of safety against buoyancy shall be 1.2 if usingactual unfactored service loads.

4.3.7.7 Long-term and differential settlement shall be considered ifdesigning foundations supporting interconnected, settlement-

sensitive equipment or piping systems.

4.3.7.8 Because OSHA requires shoring or the equivalent for excavations5 ft (1,525 mm) deep or greater and because it is costly to shoreexcavations, minimizing the depth of spread footings shall beconsidered in the design.

4.3.7.9 Unless otherwise specified, the top of grout (bottom of base plate) of pedestals and ringwalls shall be 1 ft (300 mm) above the high point

of finished grade.

4.3.7.10 Except for foundations supporting ground-supported storage tanks,uplift load combinations containing earthquake loads do not need to

include the vertical components of the seismic load effect, E, if usedto size foundations.

4.3.7.11 Foundations for ground-supported storage tanks that have sufficientinternal pressure to lift the shell shall be designed for therequirements of API Standard 650 Appendix F.7.5.

4.3.8 Supports for Vibrating Machinery

4.3.8.1 Machinery foundations shall be designed in accordance with PIP REIE686 , Chapter 4, equipment manufacturer’srecommendations, and published design procedures and criteria for

dynamic analysis.

4.3.8.2 If equipment manufacturer ’s vibration criteria are not available, themaximum velocity of movement during steady-state normal

operation shall be limited to 0.12 inch (3.0 mm) per second forcentrifugal machines and to 0.15 inch (3.8 mm) per second for

reciprocating machines.

4.3.8.3 Support structures or foundations for centrifugal machinery greaterthan 500 horsepower shall be designed for the expected dynamic

forces using dynamic analysis procedures.

4.3.8.4 For centrifugal machinery less than 500 horsepower, in the absence

of a detailed dynamic analysis, the foundation weight shall be

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designed to be at least three times the total machinery weight, unlessspecified otherwise by the equipment manufacturer.

4.3.8.5 For reciprocating machinery less than 200 horsepower, in theabsence of a detailed dynamic analysis, the foundation weight shall

be designed to be at least five times the total machinery weight,

unless specified otherwise by the manufacturer.4.3.8.6 The allowable soil-bearing or allowable pile capacity for foundations

for equipment designed for dynamic loads shall be a maximum ofhalf of the normal allowable for static loads.

4.3.8.7 The maximum eccentricity between the center of gravity of thecombined weight of the foundation and machinery and the bearingsurface shall be 5% in each direction.

4.3.8.8 Structures and foundations that support vibrating equipment shallhave a natural frequency that is outside the range of 0.80 to1.20 times the exciting frequency.

4.3.9 Anchor Bolts

4.3.9.1 Anchor bolts shall be headed type or threaded rods with compatiblenuts using ASTM A36 / A36M , A307, F1554 Grade 36, F1554 Grade 55, F1554 Grade 105, A193 / A193M Grade B7, A354

Grade BC, or A354 Grade BD material.

4.3.9.2 All ASTM A36/A36M , A307 , and F1554 Grade 36 anchor bolts shall

be hot dip galvanized.

4.3.9.3 Anchor bolt design shall be in accordance with PIP STE05121.

4.3.10 Wood

Wood design shall be in accordance with the American Forest and Paper

Association National Design Specification for Wood Construction and withthe NDS Supplement - Design Values for Wood Construction.

4.3.11 Design of Drilled Shafts

4.3.11.1 Minimum vertical reinforcement shall be 0.50% of the pier gross

area or as required to resist axial loads and bending moments.

4.3.11.2 The minimum clear spacing of vertical bars shall not be less thanthree times the maximum coarse aggregate size nor less than threetimes the bar diameter.

4.3.11.3 Reinforcing steel shall allow a minimum of 3 inches (75 mm) of

concrete cover on piers without casing and 4 inches (100 mm) ofconcrete cover on piers in which the casing will be withdrawn.

4.3.12 Design of Driven Piles

4.3.12.1 Unless otherwise specified or approved, the pile types specified in PIP STS02360 shall be used.

4.3.12.2 In addition to in-place conditions, piles shall be designed to resisthandling, transportation, and installation stresses.

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4.3.12.3 Unless otherwise specified, the exposure condition shall beevaluated to establish the corrosion allowances for steel piles.

4.3.12.4 The top of piles shall penetrate a minimum of 4 inches (100 mm)into the pile cap.

4.3.13 Vessel Load Cell Supports

Supports for vessel load cells shall be designed in accordance with PIP PCCWE001 and PIP PCEWE001.

4.4 Existing Structures

If the owner and the engineer of record agree that the integrity of the existingstructure is 100% of the original capacity based on the design code in effect at thetime of original design, structural designs shall be performed in accordance with thefollowing:

4.4.1 If additions or alterations to an existing structure do not increase the force in

any structural element or connection by more than 5%, no further analysis isrequired.

4.4.2 If the increased forces on the element or connection are greater than 5%, theelement or connection shall be analyzed to show that it is in compliance withthe applicable design code for new construction.

4.4.3 The strength of any structural element or connection shall not be decreased toless than that required by the applicable design code or standard for new

construction for the structure in question.

STC01015 Sample

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Transcript of STC01015 Sample