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Process Industry PracticesStructural

PIP STC01015Structural Design Criteria

COMPLETE REVISIONAugust 2004


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PURPOSE AND USE OF PROCESS INDUSTRY PRACTICESIn 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 thesetechnical requirements into a single set of Practices, administrative, application, andengineering costs to both the purchaser and the manufacturer should be reduced. Whilethis Practice is expected to incorporate the majority of requirements of most users,individual applications may involve requirements that will be appended to and takeprecedence over this Practice. Determinations concerning fitness for purpose andparticular matters or application of the Practice to particular project or engineeringsituations should not be made solely on information contained in these materials. Theuse of trade names from time to time should not be viewed as an expression ofpreference but rather recognized as normal usage in the trade. Other brands having thesame specifications are equally correct and may be substituted for those named. AllPractices or guidelines are intended to be consistent with applicable laws andregulations including OSHA requirements. To the extent these Practices or guidelinesshould conflict with OSHA or other applicable laws or regulations, such laws orregulations must be followed. Consult an appropriate professional before applying oracting on any material contained in or suggested by the Practice ..

This Practice is subject to revision at any time by the responsible Function Team andwill be reviewed every 5 years. This Practice will be revised, reaffirmed, or withdrawn.Information on whether this Practice has been revised may be found at www ..pip.org.

Process Industry Practices (PIP), Construction Industry Institute, TheUniversity of Texas at Austin, 3925 West Braker Lane (R4500), Austin,Texas 78759. PIP member companies and subscribers may copy this Practicefor their internal use. Changes, overlays, addenda, or modifications of anykind are not permitted within any PIP Practice without the express writtenauthorization of PIP.

PIP will not consider requests for interpretations (inquiries) for this Practice.PRINTING HISTORYDecember 1998February 2002

IssuedTechnical Revision

April 2002 Editorial RevisionAugust 2004 Complete Revision

Not printed with State funds


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PIP STC01015Structural Design Criteria COMPLETE REVISIONAugust 2004

1. Introduction1.1 Purpose

This Practice provides structural engineering design criteria for the processindustries.

1.2 ScopeThis Practice describes the minimum requirements for the structural design ofprocess industry facilities at onshore U.S. sites. This Practice is intended to be usedin conjunction with PIP ARC0101.5, PIP ARC01 016, PIP CVC0101.5,PIP CVC01017, and PIP CVC010I8, as applicable

2. ReferencesApplicable parts of the following Practices, industry codes and standards, and referencesshall be considered an integral part of this Practice. The edition in effect on the date ofcontract award shall be used, except as otherwise noted. Short titles will be used hereinwhere appropriate ..2.1 Process Industry Practices (PIP)

- PIP ARCO 10 15 - Architectural and Building Utilities Design Criteria- PIP ARCOl016 - Building Data Sheets- PIP CVCOI015 - Civil Design Criteria- PIP CVCOI017 - Plant Site Data Sheet- PIP CVCOI018 - Project Data Sheet- PIP REIE686/API 686 - Recommended Practices for Machinery Installation

and Installation Design- PIP STCOI018 - Blast Resistant Building Design Criteria

PIP STE05121 -Anchor Bolt Design Guide- PIP STS02360 - Driven Piles Specification

2.2 IndustryCodes 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 Requirementsfor Structural Concrete and

Commentary- ACI 350R - Environmental Engineering Concrete Structures- ACI 5301ASCE 5 - Building Code Requirements for Masonry Structures

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COMPLETE REVISIONAugust 2004 PIP STC01 015Structural Design Criteria

American Institute of Steel Construction (AISC)AISC Manual of Steel Construction - Allowable Stress Design (ASD)

- AISC Manual of Steel Construction - Load and Resistance FactorDesign (LRFD)Specificationfor Structural Joints Using ASTM A32.5 orA490 Bolts

- ANSIIAISC 341-02 - Seismic Provisionsfor Structural Steel Buildings American Iron and Steel Institute (AISI)

- AISI SG 673, Part I - Specification for the Designfor Cold-Formed SteelStructural MembersAISI SG 673, Part II - Commentary on the Specificationfor the DesignforCold-Formed Steel Structural Members

- AISI SG 913, Part I - Load and Resistance Factor Design SpecificationforCold-Formed Steel Structural Members- AISI SG 913, Part II - Commentary on the Load and Resistance Factor DesignSpecificationfor Cold-Formed Steel Structural Members

American Petroleum Institute (API)- API Standard 650 - Welded Steel Tanks for Oil Storage

American Society of Civil Engineers (ASCE)- SEI/ASCE 7-02 -Minimum Design Loadsfor Buildings and Other Structures

SEI/ASCE 37-02 - Design Loads on Structures during Construction- ASCE Guidelinesfor Seismic Evaluation and Design of PetrochemicalFacilities- ASCE Guidelines for WindLoads and Anchor Bolt Designfor PetrochemicalFacilitiesASCE Design of Blast Resistant Buildings in Petrochemical Facilities

American Society of Mechanical Engineers (ASME)- ASME AI7.I - Safety Codefor Elevators and Escalators

American Society for Testing and Materials (ASTM)ASTM A36/A36M - Standard Specification for Carbon Structural Steel

- ASTM A82 - Standard Specificationfor Steel Wire, Plain, for ConcreteReinforcement- ASTM AI85 - Standard Specification for Steel Welded Wire Fabric, Plain, forConcrete Reinforcement

ASTM AI93/AI93M - Standard Specification for Alloy-Steel and StainlessSteel Bolting Materials for High-Temperature Service- ASTM A307 - Standard Specification for Carbon Steel Bolts and Studs,60,000 psi Tensile Strength

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- ASTM A325 - Standard Specificationfor Structural Bolts, Steel, HeatTreated, 1201105 ksi Minimum Tensile Strength

- ASTM A325M - Standard Specification for High-Strength Boltsfor StructuralSteel Joints [Metric]

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

- ASTM 490/490M - Standard Specification for Heat- Treated Steel StructuralBolts, 150 ksi Minimum Tensile Strength

- ASTM A615/A615M - Standard Specificationfor Deformed and Plain Billet-Steel Bars for Concrete Reinforcement

- ASTM A 706/ A 706M - Standard Specification for Low-Alloy Steel DeformedBars for Concrete Reinforcement

- ASTM A992/ A992M - Standard Specification for Steelfor Structural Shapesfor Use in Building Framing

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

American Welding Society (AWS)- AWS D 1..1 - Structural Welding Code - Steel

American Forest and Paper Association- National Design Specification for Wood Construction (NDS)- NDS Supplement - Design Valuesfor Wood Construction

Crane Manufacturers Association of America (CMAA)- CMAA No ..70 - Specificationsfor Top Running Bridge and Gantry TypeMultiple Girder Overhead Electric Traveling CranesCMAA No ..74 - Specificationsfor Top Running and Under Running SingleGirder Overhead Electric Traveling Cranes Utilizing Under Running TrolleyHoist

PrecastlPrestressed Concrete Institute (PCI)- PCI MNL 120 - Design Handbook - Precast and Prestressed Concrete

Steel Joist Institute (SJI)- SJI Standard Specifications and Load Tables

2.3 Government RegulationsFederal Standards and Instructions of the Occupational Safety and HealthAdministration (OSHA), including any additional requirements by state or localagencies that have jurisdiction in the state where the project is to be constructed,shall apply.



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COMPLETE REVISIONAugust 2004 PIP STC01015Structural Design Criteria

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 Regulationsfor Construction

3. Definitionsengineer of record: The owner's authorized representative with overall authority andresponsibility for the structural designowner: The party who owns the facility wherein structure will be used

4. Requirements4.1 DesignLoads

4.1.1 General4.1.1.1 New facilities, buildings, and other structures, including floor slabs

and foundations, shall be designed to resist the minimum loadsdefined in SEIIASCE 7, local building codes, this section and theloads defined in PIP CVC01 017 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 when specified by the owner.4.1.1.4 For existing facilities, actual loads may be used in lieu of the

minimum specified loads.4.1.1 ..5 Eccentric loads (piping, platforms, etc ..), particularly on horizontal

and vertical vessels and exchangers, shall be considered ..4.1.2 Dead Loads (D)

4.12 ..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:

D, = Structure dead load is the weight of materials forming thestructure (not the empty weight of process equipment,vessels, tanks, piping, nor cable trays), foundation, soil

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above the foundation resisting uplift, and all permanentlyattached appurtenances (e. .g .., lighting, instrumentation,HV AC, sprinkler and deluge systems, fireproofing, andinsulation, etc ..).

Dr = 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 4.1.2.4through 4.1.2 ..7).

D,=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 inSection 4 ..1..2..4)..

4.1.2.4 Process Equipment and Vessel Dead Loads1. Erection dead load (D!) for process equipment and vessels is

normally the fabricated weight of the equipment or vessel andis generally taken from the certified equipment or vesseldrawing.

2. Empty dead load (De) for process equipment and vessels is theempty 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, andpackaged 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.

4. Test dead load (Dt) for process equipment and vessels is theempty dead load plus the weight of test medium contained inthe system ..The test medium shall be as specified in thecontract documents or as specified by the owner. Unlessotherwise specified, a minimum specific gravity of 1..0 shall beused for the test medium. Equipment and pipes that may besimultaneously tested shall be included. Cleaning load shall beused for test dead load if the cleaning fluid is heavier than thetest medium.

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COMPLETE REVISIONAugust 2004 PIPSTC01015Structural Design Criteria

4.1.2.5 Pipe Rack Piping Loads1. 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 insulationComment. This is equivalent to 8-inch (203-mm)

diameter, Schedule 40 pipes, full of water,at I5-inch (38I-mm) spacing.

b. Empty dead load (De): For checking uplift and componentscontrolled by minimum loading, 60% of the estimated pipingoperating loads shall be used if combined with wind orearthquake unless the actual conditions require a differentpercentage.

c. Test dead load (Dt) is the empty weight of the pipe plus theweight of test medium contained in a set of simultaneouslytested 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 I2-inch (304-mm) nominal diameter, aconcentrated 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 thepipe's associated area.

3. Pipe racks and their foundations shall be designed to supportloads associated with full utilization of the available rack spaceand any specified future expansion.

4.1.2.6 Pipe Rack Cable Tray LoadsDead 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.

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 trayload (i.e., the actual configuration) should be considered as theempty dead load. Engineering judgement shall be exercised indefining the dead load for uplift conditions.

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4.1.2.7 Ground-Supported Storage Tank LoadsDead loads for ground-supported storage tanks are shown in Table 9with the same nomenclature as other dead loads in this Practice forconsistency ..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 thetank 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 actvertically 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(when a corrosion allowance is specified) should be consideredas the empty dead load.

c. Test dead load (Dj): Test dead load for a ground-supportedstorage tank is made up of the metal load from the tank shelland roof, vertically applied through the wall of the tank, inaddition to the fluid load from the test medium. The fluid loadacts through the bottom of the tank and does not act verticallythrough the wall of the tank. Therefore, the metal dead load andthe fluid load must be used separately in design ..The testmedium shall be as specified in the contract documents or asspecified 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 of

the building or structure. These include the weight of all movableloads, such as personnel, tools, miscellaneous equipment, movablepartitions, 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 SEJIASCE 7,applicable codes and standards, and, unless otherwise specified, inTable 1:

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COMPLETE REVISIONAugust 2004 PIP STC01 015Structural Design Criteria

TABLE 1. MINIMUM LIVE LOADSUniform** Concentrated**

Stairs and Exitways 100 psf (4.8 kN/m2) 1,000 Ib (4.5 kN)Operating, Access 75 psf 1,000 Ib (4..5 kN)Platforms, and (3.6 kN/m2)WalkwaysControl, 11O, 100 psf (4.8 kN/m2) 1,000 Ib (4.5 kN)HVAC Room FloorsManufacturing Floorsand Storage Areas:Light 125 psf 2,0001b(60 kN/m2) (9.0 kN)Heavy 250 psf 3,0001b

(12..0 kN/m2), (13..5kN)Ground-Supported 25 psf NAStorage Tank Roof (1.2 kN/m2)'This 250 psf (12..0 kN/m2)live load includes small equipment"The loads provided inthis table are to be used unless notedotherwise on the owner's data sheet

4.1.3.4 Uniform and concentrated live loads listed in Table 1 shall not beapplied simultaneously,

4.1.3.5 According to SEIIASCE 7, concentrated loads equal to or greaterthan 1,000 lb (4.5 kN) may be assumed to be uniformly distributedover 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 structuralmembers.

4.1.3.6 Stair treads shall be designed according to OSHA regulations orbuilding code as applicable"

4.1.3.7 Live load reductions shall be in accordance with SEIIASCE 7..4.1.3.8 For manufacturing floor areas not used for storage, the live load

reduction specified by SEIIASCE 7 for lower live loads may be used.4.,1..3.9 The loadings on handrails and guardrails for process equipment

structures shall be in accordance with OSHA 1910.4.13,,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 SEIIASCE 7 and the recommendedguidelines for open frame structures, pressure vessels, and pipe racksin ASCE Guidelines for Wind Loads and Anchor Bolt Design forPetrochemical Facilities.

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4.1.4.2 Site specific design parameters shall be in accordance withPIP CVCOI017.

4.1.4.3 The owner shall be consulted for the determination of theclassification category.

Comment: For process industry facilities, SEIIASCE 7Category III is the most likely classification becauseof the presence of hazardous materials. Category IImay be used if the owner can demonstrate thatrelease of the hazardous material does not pose athreat to the public ..Refer to SEIIASCE 7-02,Section 1.5.2 and Table 1-1, for specific details ..Insome cases, it may be appropriate to selectCategory IV.

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

4.1.4.5 A solid width of 1.5 ft (350 rum) shall be assumed when calculatingthe wind load on ladder cages ..

4.1.4.6 Partial wind load (Wp) shall be based on the requirements ofSEIIASCE 37-02, Section 6.2.1, for the specified test or erectionduration. The design wind speed shall be 68 mph (109 kph) (whichis 0.75 x 90 mph [145 kph] according to SEIIASCE 37 for test orerection periods of less than 6 weeks).

4.1.4.7 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), referto SEIIASCE 37-02, Section 6.2.1..

4.1.5 EarthquakeLoads(E)4.1.5.1 Except for API Standard 650 ground-supported storage tanks,

earthquake loads shall be computed and applied in accordance withSEIIASCE 7, unless otherwise specified.

Comment The earthquake loads in SEIIASCE 7 are limit stateearthquake loads, and this should be taken intoaccount if using allowable stress design methods orapplying load factors from other codes. Earthquakeloads for API Standard 650 storage tanks areallowable stress design loads ..

4.1.5.2 Site specific design parameters shall conform to PIP CVCOI017.4 ..1 .. 5 . . 3 ASCE Guidelines for Seismic Evaluation and Design of

Petrochemical Facilities may also be used as a general reference forearthquake design.

Comment: Buildings and building-like structures, designed forearthquakes according to SEIIASCE 7, are typically



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COMPLETE REVISION PIP STC01015August 2004 Structural Design Criteria

classified as Category III. In some cases, it may beappropriate to select Category IV,

4.1.5.4 Earthquake loading shall be determined using SEIIASCE 7-02,Section 9.14, if SEIIASCE 7 is used for the earthquake design ofnonbui1ding structures as defined in SEIIASCE 7-02,Section 9.14 ..1 . . 1 and Table 9.14,,5.1.1.

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 fromSEIIASCE 7-02, Table 9.14.5.1.2.

Comment: In general, for nonbuilding structures inpetrochemical process units, select seismic usegroup II, giving an importance factor "I" of 1.25;however, in some cases, it may be appropriate toselect seismic use group I or III.

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 deadload

4.1.6 Impact Loads4.1.6.1 Impact loads shall be in accordance with SEIIASCE 7.4..1,,6..2 Impact loads for davits shall be the same as those for monorail

cranes (powered).4.1.6.3 Lifting lugs or pad eyes and internal members (included both end

connections) framing into the joint where the lifting lug or pad eye islocated 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 ThermalLoads4.1.7.1 For this Practice, thermal loads are designated by the following

nomenclature:

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PIP STC01015Structural Design CriteriaCOMPLETE REVISIONAugust 2004

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

T= Self-straining forces caused by the restrained thermalexpansion of structural steel in pipe racks or horizontalvessels and heat exchangers

Ai = Pipe anchor and guide forcesFr = Pipe rack friction forces caused by the sliding of pipes or

friction forces caused by the sliding of horizontal vessels orheat exchangers on their supports, in response to thermalexpansion

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 theappropriate 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 temperatureand installed temperature ..To account for the significant increase intemperatures of steel exposed to sunlight, 35D F ( 2 0 D C ) 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 FRICTIONSteel to Steel 04Steel to Concrete 0..6Proprietary Sliding Surfaces or According to Manufacturer'sCoatings (e.q., "Teflon") Instructions

4.1.7.6 Friction loads shall be considered temporary and shall not becombined with wind or earthquake loads. However, anchor andguide loads (excluding their friction component) shall be combinedwith wind or earthquake loads.

4.1.7.7 For pipe racks supporting multiple pipes, 10% ofthe total pipingweight shall be used as an estimated horizontal friction load appliedonly to local supporting beams. However, an estimated friction loadequal to 5% of the total piping weight shall be accumulated andcarried into pipe rack struts, columns, braced anchor frames, andfoundations.

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COMPLETE REVISION PIPSTC01015August 2004 Structural Design Criteria

Comment Under nonnalloading conditions with multiplepipes, torsional effects on the local beam need notbe considered because the pipes supported by thebeam limit the rotation of the beam to the extent thatthe torsional stresses are minimal. Under certaincircumstances, engineering judgement shall beapplied 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 deadloads.

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

4.1.7.10 Beams, struts, columns, braced anchor frames, and foundations shallbe designed to resist actual pipe anchor and guide loads.4.1.7.11 For local beam design, only the top flange shall be considered

effective for horizontal bending unless the pipe anchor engages bothflanges 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 than2,000 lb (9 . .0 kN). If the total weight of the exchanger is less than2,000 lb (9.0 kN), the bundle pull load is permitted to be taken as 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 assurancewould typically require the addition of a sign postedon the exchanger to indicate bundle removal by anextractor only.

4 ..1.83 The portion of the bundle pull load at the sliding end support shallequal the friction force or half the total bundle pull load, whicheveris less. The remainder of the bundle pull load shall be resisted at theanchor end support.

4.1.9 Traffic Loads4 ..1..9. .1 Buildings, trenches, and underground installations accessible to

truck loading shall be designed to withstand HS20 load as definedby AASHTO Standard Specificationsfor Highway Bridges.

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4.1.9.2 Maintenance or construction crane loads shall also be consideredwhere 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 orby overpressure resulting from a vessel burst.

4.1.10.2 Control houses or other buildings housing personnel and controlequipment near processing plants may need to be designed for blastresistance.

4.1,10.3 Blast load shall be computed and applied in accordance withPIP STCOl018 and the ASCE Design of Blast Resistant Buildingsin Petrochemical Facilities.

4.1.11 Pressure Loads (Ground-Supported Tanks Only)For this Practice, pressure loads for ground-supported tanks are designatedby the following nomenclature:

Pi, Pe, and r,wherePi= design internal pressureP e = external pressurePI= test internal pressure

4.1.12 Snow Loads (5)4. .L 12,.1 Unless otherwise specified, snow loads shall be computed andapplied in accordance with SEIIASCE 7 .,

4.1.12.2 Site specific design parameters shall be in accordance withPIP CVCOl017

4.2 Load Combinations4.2.1 General

Buildings, structures, equipment, vessels, tanks, and foundations shall bedesigned for the following:a. Appropriate load combinations from SEIIASCE 7 except as otherwise

specified in this Practice ..b. Local building codesc. Any other applicable design codes and standardsd. Any other probable and realistic combination ofloads



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3. The following load combinations are appropriate for usewith the strength design provisions of either AISC LRFD(third edition or later) orACI318 (2002 edition or later).

4.2.2.2 General Plant StructuresLoad combinations for buildings and open frame structures shall bein accordance with SEIIASCE 7-02, Section 2..

4.2.2.3 Vertical VesselsTABLE 3. LOADING COMBINATIONS - ALLOWABLE STRESS

DESIGN (SERVICE LOADS)Load AllowableComb. StressNo. Load Combination Multiplier Description

1 D, + Do + L 1,00 Operating Weight +Live Load2 Ds+ Do+ 1,00 Operating Weight +(W or 0,7 Eoa) Wind or Earthquake3 Ds+ De+W 1,00 Empty Weight +Wind(Wind Uplift Case)4a 0,,9(D, + Do)+ 0,7 Eoa 1,00 Operating Weight +Earthquake(Earthquake UpliftCase)4b 0,9 (D, + De)+ 0,.7Eea 1,,00 Empty Weight +Earthquake

(Earthquake UpliftCase)5 Os + Df + Wp 1,00 Erection Weight +Partial Windb(Wind Uplift Case)6 D, + Dt +Wp 1,.20 Test Weight +Partial Wind

Notes:a For skirt-supported vertical vessels and skirt-supported elevatedtanks classified as SUG III in accordance with SEIIASCE 7-02,Section 9, the critical earthquake provisions and implied loadcombination of SEIIASCE 7-02, Section 9,,14,7,3,10,,5,shall befollowed,b Erection weight + partial wind is required only if the erection weight ofthe vessel is signif icantly less than the empty weight of the vesselc Thrust forces caused by thermal expansion of piping shall beincluded in the calculations for operating load combinations, ifdeemed advisable, The pipe stress engineer shall be consulted forany thermal loads that are to be considered



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COMPLETE REVISIONAugust 2004 PIPSTC01015Structural Design Criteria

TABLE 4. LOADING COMBINATIONS AND LOAD FACTORS -STRENGTH DESIGN

LoadComb.No. Load Combination Description

1 14(Ds+Do) Operating Weight2 1.2 (D, + Do)+ 1..6L Operating Weight + Live Load3 1..2 (D, + Do) + Operating Weight + Wind or(1.6 W or 1..0E03) Earthquake4 0.9 (Ds + De) + 1.6 W Empty Weight + Wind(Wind uplift case)5a 0..9 (D, + Do)+ 1.0 Eo3 Operating Weight + Earthquake

(Earthquake Uplift Case)5b 0.9 (D, + De)+ 1..0 Ee3 Empty Weight + Earthquake(Earthquake Uplift Case)6 0..9 (D, + Df) + 1.6Wp Erection Weight + Partial Windb(Wind Uplift Case)7 14 (D, + Dt) Test Weight8 1.2 (D, + Dt) + 1.6 Wp Test Weight + Partial Wind

Notes:a For skirt-supported vertical vessels and skirt-supported elevated tanksclassified as SUG III in accordance with SEIIASCE 7-02, Section 9,the critical earthquake provisions and implied load combination of

SEIIASCE 7-02, Section 9..14..7.3..10.5, shall be followedb Erection weight + partial wind is required only when the erectionweight of the vessel is signif icantly less than the empty weight of thevessel.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 fordead load shall be used



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4.2.2.4 Horizontal Vessels and Heat ExchangersTABLE 5. LOADING COMBINATIONS - ALLOWABLE STRESSDESIGN (SERVICE LOADS)Load AllowableComb. Load StressNo. Combination Multiplier Description1 Os+ Do+ 1.00 Operating Weight +(T or Ff)b Thermal Expansion orFriction Force2 Os+ Do + L + 1.00 Operating Weight +(T or Ff)b Live Load +Thermal Expansion orFriction Force3 Os+ Do+ 1.00 Operating Weight +(W orO.7 Eo) Wind or Earthquake4 D, + De+W 1.00 Empty Weight + Wind(Wind Uplift Case)5a 0.9 (D, + Do)+ 1..00 Operating Weight +0..7 Eo Earthquake(Earthquake Uplift Case)5b 0..9 (D, + De) + 1.00 Empty Weight +0.7 s, Earthquake(Earthquake Uplift Case)6 Os+ Df+Wp 1.00 Erection Weight +Partial Windc(Wind Uplift Case)7 Os+ Dt +Wp 1..20 Test Weight +Partial Wind(For Horizontal VesselsOnly)8 Os+ Oed+ 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 exchangers

shall be the lesser of T or Ffc. Erection weight + partial wind is required only when the erectionweight of the vessel or exchanger is significantly less than the emptyweight of the vessel or exchangerd 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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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 DESIGNloadComb.No. load Combination Description1 14 (D, + Do)+ 14 (T or Ff)b Operating Weight +Thermal Expansion or Friction Force2 1..2(D, + Do) + 1.6 l + 1.2 Operating Weight + live load +(T or Ff)b Thermal Expansion or Friction Force3 1..2(Ds + Do) + Operating Weight +(1.6 W or 1.0 Eo) Wind or Earthquake4 0.9 (D, + 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 (D, + De)+ 1..0 Ee Empty Weight + Earthquake(Earthquake Uplift Case)6 0..9 (D, + De)+ 1.6 Wp Erection Weight + Partial Windc(Wind Uplift Case)7 14 (Ds+ Dt) Test Weight(For Horizontal Vessels Only)8 1..2 (D, + Dt)+ 1..6 Wp Test Weight + Partial Wind(For Horizontal Vessels Only)9 1..2ro , + Ded) + 1 6 Bp Empty Weight + Bundle Pull(For Heat Exchangers Only)10 0..9 (D, + Ded) + 1..6Bp Empty Weight + Bundle Pull(For Heat Exchangers Only)(Bundle Pull Uplift Case)

Notes:8. Wind and earthquake forces shall be applied in both transverse andlongitudinal directions, but shall not necessarily be applied simultaneouslyb 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 when the erection weight of thevessel or exchanger is signif icantly less than the empty weight of the vessel orexchangerd Heat exchanger empty dead load wil l be reduced during bundle pull because ofthe removal of the exchanger head



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PIP STC01015 COMPLETE REVISIONStructural Design Criteria August 2004

e. Sustained thermal loads not relieved by sl iding from vessel orexchanger expansion shall be considered in operating loadcombinations with wind or earthquake.Thrust forces caused by thermal expansion of piping shall beincluded in the calculations for operating load combinations, ifdeemed advisable. The pipe stress engineer shall be consulted forany thermal 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

TABLE 7. LOADING COMBINATIONS - ALLOWABLE STRESSDESIGN (SERVICE LOADS)

Load AllowableComb. StressNo. Load Combination Multiplier Description

1 Ds+ Do+ FI + T + AI 1.00 Operating Weight +Friction Force +Thermal Expansion +Anchor Force2 Ds+ Do+ AI+ 1.00 Operating Weight +(W or 0.7 Eo) Anchor + Wind orEarthquake3 Ds+ DeC+ W 1.00 Empty Weight + Wind(Wind Uplift Case)4a 0.9 (Ds) + 0..6 (Do)+ 1.00 Operating Weight +0..7 Eo d Earthquake

(Earthquake UpliftCase)4b 0..9 (D, + De")+ 1.00 Empty Weight +0.7 s, Earthquake(Earthquake UpliftCase)5 Ds+Dt+ 1.20 Test Weight +Wp Partial Winde

Notes:8. Considerations of wind forces are normally not necessary in thelongitudinal direction because friction and anchor loads will normallygovernb. Earthquake forces shall be applied in both transverse andlongitudinal directions, but shall not necessarily be appliedsimultaneouslyc. 06Do is used as a close approximation of the empty pipe conditionDed. Full Ds+ Dovalue shall be used for the calculation of Eo in loadcombination 4ae Test weight + partial wind normally is required only for local memberdesign because test is not typically performed on all pipessimultaneously



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PIPSTC01015Structural Design Criteria

TABLE 8. LOADING COMBINATIONS ANDLOAD FACTORS STRENGTH DESIGN

LoadComb.No. Load Combination Description1 14 (D, + Do+ FI + T + AI) Operating Weight +Friction Force +Thermal Expansion +Anchor2 1..2 (D, + Do+A I) + Operating Weight +(1.6 W or 1..0 Eo) Anchor + Wind orEarthquake3 0.9 (Os+ Dec)+ 1..6W Empty Weight + Wind(Wind Uplift Case)4a 0.9 (Os) + 0.6 (00)+ 1..0Eo d Operating weight +Earthquake(Earthquake Uplift Case)4b 0..9 (Ds+ Dec)+1.0Ee Empty weight + Earthquake(Earthquake Uplift Case)5 14 (D, + Dt) Test Weight6 1..2 (D, + Dt) + 1.6 Wp Test Weight + Partial Winde

Notes:a Considerations of wind forces are normally not necessary in thelongitudinal direction because friction and anchor loads will normallygovernb Earthquake forces shall be appl ied in both transverse andlongitudinal directions, but shall not necessarily be appliedsimultaneously ..c. 0600 is used as a close approximation of the empty pipe condit ionDed Full Os+ Dovalue shall be used for the calculation of Eo in loadcombination 4ae Test weight + partial wind normally is required only for local memberdesign because test is not typically performed on all pipessimultaneously.

4.2.2.6 Ground-Supported Storage Tank Load CombinationsLoad combinations for ground-supported storage tanks shall betaken from API Standard 650. Load combinations fromAPI Standard 650 and modified for use with SEIIASCE 7 loads andPIP nomenclature are shown in Table 9 ..

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TABLE 9. LOADING COMBINATIONS - ALLOWABLE STRESSDESIGN (SERVICE LOADS)

LoadComb.No. Load Combination Description1 Ds+ Do+ Pj Operating Weight +Internal Pressure"2 D, + Dt + Pt Test Weight +Test Pressure3 Ds+ (Deor Do)+ W + 0.4 pjb Empty or OperatingWeight + Wind +Internal Pressure"4 Ds+ (Deor Do)+ W + 0.4 Peb Empty or OperatingWeight + Wind +External Pressure5 Ds+ Do+ (L or S) + 0.4 Peb Operating Weight +Live or Snow +External Pressure6 Ds+ (De or Do) + 0.4 (L or S) + Pe Empty or OperatingWeight +Live or Snow +External Pressure7 Ds+ Do+ 0 ..1 S + Eo C + 0.4 pjb Operating Weight +Snow + Earthquake +Internal Pressure"(Earthquake Uplift

Case)8 Ds+ Do+ 0.1 S + EoC Operating Weight +Snow + Earthquake

Notes:a For internal pressures sufficient to li ft the tank shell according to therules ofAPI Standard 650, tank, anchor bolts, and foundation shallbe designed to the additional requirements ofAPI Standard 650Appendix F.7..b If the ratio of operating pressure to design pressure exceeds 0.4,the owner shall consider specifying a higher factor on designpressure in load combinations 3, 4, 5, and 7 of Table 9c Earthquake loads for API Standard 650 tanks taken fromSEIIASCE 7 "bridging equations" or from API Standard 650 already

include the 0..7 ASD seismic load factor4.2.2.7 Load Combinations for Static Machinery, Skid and Modular

Equipment, Filters, and Other EquipmentLoad combinations for static machinery, skid and modularequipment, filters, etc., shall be similar to the load combinations forvertical vessels.



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COMPLETE REVISION PIP STC01015August 2004 Structural Design Criteria

4.2.3 Test Combinations4.2.3.1 Engineering judgment shall be used in establishing the appropriateapplication 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 of

testing for various equipment, vessels, tanks ..and/or piping systemssupported on common structures, pipe racks, or foundations ..4.2.3.3 Full wind and earthquake loads are typically not combined with testloads unless an unusually long test duration is planned (i.e., if asignificant probability exists that the "partial wind velocity" will be

exceeded or an earthquake event may occur),4.2.3.4 Additional loading shall be included with test if specified in the

contract documents.4.2..3..5 For allowable stress design, a 20% allowable stress increase shall bepermitted for any test load combination.4.2.3.6 For ultimate strength/limit states design, no load factor reduction

shall be permitted for any test load combination.4.3 Structural Design

4.3.1 Steel4..3.1.1 Steel design shall be in accordance with AISC ASD or AISC LRFD

specifications.4..3..1..2 For cold-formed shapes, design shall be in accordance with AISIspecifications.4.3.1.3 Steeljoists shall be designed in accordance with SJI standards ..

Comment Supplement number 1 to the AISC ASDspecification deleted the one-third stress increasefor use with load combinations including wind orearthquake loads..Because of the deletion of theone-third stress increase, designs made to the AISCLRFD specifications should be considered foreconomy.

4.3.14 Steel design, including steeljoists and metal decking, shall bedesigned in accordance with OSHA 29 CFR 1926, Subpart R, toprovide structural stability during erection and to protect employeesfrom the hazards associated with steel erection activities.Comment: Common requirements that affect steel design areasfollow (this is not an all inclusive list):

a. All column base plates shall be designed with a minimum offour anchor bolts. Posts (which weigh less than 300 lb



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[136 kg]) are distinguished from columns and are excludedfrom the four-anchor bolt requirement.

b. Columns, column base plates, and their foundations shall bedesigned to resist a minimum eccentric gravity load of300 lb(136 kg) located 18 inches (450 mm) from the extreme outerface of the column in each direction at the top of the columnshaft. 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 mayalso supply a seat or equivalent device with a means of positiveattachment to support the first beam while the second beam isbeing erected.

d. Perimeter columns shall extend 48 inches (1,200 mm) abovethe finished floor (unless constructability does not allow) toallow the installation of perimeter safety cables ..Provision shallbe made for the attachment of safety cables.

e. Structural members of framed metal deck openings shall beturned down to allow continuous decking, except where notallowed 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 beamattachments until after the metal decking or otherwalking/working surface has been installed.

4.3.1.5 All welded structural connections shall use weld filler materialconforming toAWS D 1.1, Section 3.3 (including Table 3.1), andhave an electrode strength of 58 ksi (400 MPa) minimum yieldstrength 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 A 992/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-boltedconnections ..

4.3J.9 Compression flanges of floor beams, not supporting equipment, maybe considered braced by decking (concrete or floor plate) ifpositively connected thereto.

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

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PIP STC01015 COMPLETE REVISIONStructural Design Criteria August 2004

4.3.5 Crane Supports4.3.5.1 Vertical deflection of support runway girders shall not exceed the

following limits given in Table 10 ifloaded with the maximumwheelload(s), without impact (where L=the span length).

TABLE 10. MAXIMUM ALLOWABLE GIRDERDEFLECTIONSTop-Running CMAA Class A, B, and C Cranes Ll600Top-Running CMAA Class D Cranes Ll800Top-Running CMAA Class E and F Cranes Ll1000Under-Running CMAA Class A, B, and C Cranes Ll450Monorails Ll450

4..3.5.2 Vertical deflection of jib crane support beams shall not exceedLl225 (where L=the maximum distance from the support column toload location along the length of the jib beam) ifloaded with themaximum lifted plus hoist load(s), without impact.

4..3..5.3 Lateral deflection of support runway girders for cranes with lateralmoving trolleys shall not exceed Ll400 (where L =the span length)when loaded with a total crane lateral force not less than 20% of thesum of 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 andthe structure supporting the runway girders.

4..3..5.4 Crane stops shall be designed in accordance with the cranemanufacturer's requirements or, ifnot specified, for the followingload:

where:F =WV =g =T =

n =

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Design force on crane stop, kips (kN)50% of bridge weight + 90% of trol ley weight,excluding the lifted load, kips (kN)Rated crane speed, ftlsec (m/sec)Acceleration of gravity, 322 ft/sec'' (9 . .8 rn/sec")Length of travel (ft) of spring or plunger required tostop crane, from crane manufacturer, typical ly 0. .15 ft(0..05 m)Bumper efficiency factor (0. .5 for helical springs;consult crane manufacturer for hydraul ic plunger.)



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Comment: This requirement is consistent with SEIIASCE 7provisions, in which the "factor of safety" is builtinto the 0..6 "dead load factor" in the loadcombinations ..

43.7.4 Overturning and sliding caused by earthquake loads shall be checkedin accordance with SEIIASCE 7-02, Section 9..The minimumoverturning "stability ratio" and the minimum factor of safetyagainst sliding 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 SUG III in accordance withSEIIASCE 7-02, Section 9, shall be 1.2 for the critical earthquakeloads specified in SEIIASCE 7-02, Section 9.14.7.3..10..5..

4.3.7.5 For earthquake loads calculated by the "Equivalent Lateral ForceProcedure" in SEIIASCE 7, additional stability checks shall be donein accordance with SEIIASCE 7-02, Section 9, Section 9.5.5.6,"Overturning." For foundations designed using seismic loadcombination from Tables 3, 5, and 7 of this Practice, the reduction inthe foundation overturning moment permitted in SEIIASCE 7-02,Section 9, Section 9.5.5.6, "Overturning," shall not be used..

4.3.7.6 The minimum factor of safety against buoyancy shall be 1.2 ifusingactual 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.

43.7.9 Unless otherwise specified, the top ofgrout (bottom of base plate) ofpedestals and ringwalls shall be 1 ft (300 mm) above the high pointof finished grade.

4.3.710 Except for foundations supporting ground-supported storage tanks,uplift load combinations containing earthquake loads do not need toinclude vertical earthquake forces if used to 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 ofAPI Standard 650 Appendix F.7.5.

4.3.8 Supports for Vibrating Machinery43.8.1 Machinery foundations shall be designed in accordance with

PIP REIE686, Chapter 4, equipment manufacturer'srecommendations, and published design procedures and criteria fordynamic analysis.

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4.3.8.2 If equipment manufacturer's vibration criteria are not available, themaximum velocity of movement during steady-state normaloperation shall be limited to 0.12 inch (3.0 mm) per second forcentrifugal machines and to 0..15 inch (3.8 mm) per second forreciprocating machines.

4.3.8.3 Support structures or foundations for centrifugal machinery greaterthan 500 horsepower shall be designed for the expected dynamicforces using dynamic analysis procedures.

4.3.8.4 For centrifugal machinery less than 500 horsepower, in the absenceof a detailed dynamic analysis, the foundation weight shall bedesigned 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 shallbe 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 forfoundations for equipment designed for dynamic loads shall be amaximum of half 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 Bolts4.3.9.1 Anchor bolts shall be headed type or threaded rods with compatible

nuts usingASTMA36IA36M,A307, F1554 Grade 36, F1554Grade 55, F1554 Grade 105,A1931A193MGrade B7,A354Grade Be, or A354 Grade BDmaterial.

4.3 ..92 All ASTM A36/A36M, A307, and F1554 Grade 36 anchor bolts shallbe hot dip galvanized.

4.3.9.3 Anchor bolt design shall be in accordance with PIP STE051214.3.10 Wood

Wood design shall be in accordance with the American Forest and PaperAssociation National Design Specification for Wood Construction and withthe NDS Supplement - Design Valuesfor Wood Construction.

4.3.11 Design of Drilled Shafts4.3 ..1 Ll Minimum vertical reinforcement shall be 0.50% of the pier gross

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



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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) ofconcrete 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 Piles4.3.12.1 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 resist

handling, transportation, and installation stresses.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.

4.4 Existing StructuresIf 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%, the

element 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

to less than that required by the applicable design code or standard for newconstruction for the structure in question..


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