October 1999

Process Industry PracticesStructural

PIP STF05535Vessel Circular Platform Details

PURPOSE AND USE OF PROCESS INDUSTRY PRACTICES

In an effort to minimize the cost of process industry facilities, this Practice hasbeen 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 engineeringcosts 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 precedence overthis Practice. Determinations concerning fitness for purpose and particular matters orapplication of the Practice to particular project or engineering situations should not bemade solely on information contained in these materials. The use of trade names fromtime to time should not be viewed as an expression of preference but rather recognizedas normal usage in the trade. Other brands having the same specifications are equallycorrect and may be substituted for those named. All practices or guidelines are intendedto be consistent with applicable laws and regulations including OSHA requirements. Tothe extent these practices or guidelines should conflict with OSHA or other applicablelaws or regulations, such laws or regulations must be followed. Consult an appropriateprofessional before applying or acting on any material contained in or suggested by thePractice.

©Process Industry Practices (PIP), Construction Industry Institute, TheUniversity of Texas at Austin, 3208 Red River Street, Suite 300, Austin,Texas 78705. PIP member companies may copy this practice for their internaluse.

Not printed with State funds

October 1999

Process Industry Practices Page 1 of 13

Process Industry PracticesStructural

PIP STF05535Vessel Circular Platform Details

Table of Contents

1. Introduction ...............................21.1 Purpose ........................................... 21.2 Scope .............................................. 2

2. References.................................22.1 Process Industry Practices (PIP) ...... 22.2 Industry Codes and Standards ......... 22.3 Government Regulations ................. 3

3. Definitions..................................3

4. General.......................................34.1 Responsibility................................... 34.2 Safety .............................................. 34.3 Pre-Assembly................................... 34.4 Platform Design Loads..................... 3

5. Materials.....................................4

List of DetailsFigure 1 - Typical Plan for Ladders and

Platforms Attached to Vessel............... 5Figure 2 - Typical Grating Layout for

Circular Platforms................................ 6Figure 3 - Typical Splice Detail for

Circular Platforms................................ 7Figure 4 - Typical Bracket Details for

Circular Platforms................................ 8Figure 5 - Typical Vessel Clip Details for

Circular Platforms................................ 8Figure 6 - Typical Angle Railing Post

Connection Details for CircularPlatforms............................................. 9

Figure 7 - Typical Pipe Railing PostConnection Details for CircularPlatforms........................................... 10

Figure 8 - Ladder Exit Detail for CircularPlatforms........................................... 11

Figure 9 - Typical Pipe Railing End PostConnection Details for CircularPlatforms........................................... 12

Figure 10 - Typical Angle Railing EndPost Connection Details for CircularPlatforms........................................... 13

PIP STF05535 October 1999Vessel Circular Platform Details

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1. Introduction

1.1 Purpose

The purpose of this Practice is to provide design engineers and Fabricators with astandard circular platform design to be used on the vertical vessels in process industryfacilities.

1.2 Scope

1.2.1 This Practice describes the requirements of the design details for fabrication oftypical circular vessel platforms and is intended to be issued to Fabricatorssupplying these platforms.

1.2.2 Any conflicts or inconsistencies between this Practice and other ContractDocuments shall be brought to the attention of the Buyer for resolution.

2. References

Applicable requirements in the following PIP practices, codes and standards, and governmentregulations shall be considered an integral part of this Practice. The latest edition in effect onthe date of contract award shall be used, except as otherwise noted. Short titles will be usedherein when appropriate.

2.1 Process Industry Practices (PIP)

– PIP STC01015 - Structural Design Criteria

– PIP STF05501 - Fixed Metal Ladders and Cages Details

– PIP STF05520 - Pipe Railing for Walking and Working Surfaces Details

– PIP STF05521 - Angle Railing for Walking and Working Surfaces Details

– PIP STS05120 - Fabrication of Structural and Miscellaneous SteelSpecification

2.2 Industry Codes and Standards

• American Society of Testing and Materials (ASTM)

– ASTM A36 - Carbon Structural Steel

– ASTM A307 - Carbon Bolts and Studs, 60 000 PSI Tensile Strength

– ASTM A325 - Structural Bolts, Steel, Heat Treated, 120/105 ksi MinimumTensile Strength

– ASTM A569 - Steel, Carbon (0.15 Maximum Percent), Hot-Rolled Sheetand Strip Commercial Quality

October 1999 PIP STF05535Vessel Circular Platform Details

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2.3 Government Regulations

Federal Standards and Instructions of the Occupational Safety and HealthAdministration (OSHA), including any additional requirements by state or localagencies that have jurisdiction where the vessel platform is to be erected, shall apply.

3. Definitions

Buyer: The party who awards the contract to the Fabricator. The Buyer may be the Owner orthe Owner’s authorized agent.

Contract Documents: Any and all documents, including design drawings, that the Buyer hastransmitted or otherwise communicated, either by incorporation or by reference, and made partof the legal contract agreement or purchase order agreement between the Buyer and theFabricator

4. General

4.1 Responsibility

The Fabricator shall furnish all equipment, materials, labor, and supervision and shallperform all operations necessary for the fabrication of vessel platforms, as indicatedby the Contract Documents. Fabrication shall be in accordance withPIP STS05120.

4.2 Safety

The Fabricator shall comply with all safety requirements specified in the ContractDocuments.

4.3 Pre-Assembly

The platforms shall be pre-assembled in the shop, up to the maximum size permittedfor shipping.

4.4 Platform Design Loads

The loads given in the following table are based on 6 feet arc length of outsideplatform perimeter between the supporting brackets. The design loads are based uponthe criteria specified in PIP STC01015, that is, a live load of 75 psf and the dead loadof actual material weight. A concentrated load of 1000 pounds on 2'-6" x 2'-6" areawill normally not govern the clip design and is not used for these standards. However,the engineer shall consider specific cases to verify the governing case.

The beam, bolt, and haunch design shall be checked if there is additional loading dueto pipe support, etc., or for strength reduction due to high vessel temperatures(connection bolts and bracket steel temperature above 350° F). Modification of thedesign may be required and/or personnel protection shall be provided for thesecircumstances.

PIP STF05535 October 1999Vessel Circular Platform Details

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Platform Width V (kips) M1 (Kip-Feet) M2 (Kip-Feet)

up to 3'-0" 1.77 1.87 2.97

3'-6" 2.03 2.66 3.92

4'-0" 2.30 3.58 5.01

4'-6" 2.56 4.63 6.23

5'-0" 2.83 5.82 7.58

5'-6" 3.09 7.13 9.06

6'-0" 3.35 8.58 10.68

Notes: V: Shear at centerline of boltsM1: Moment at face of haunch for beam designM2: Moment at centerline of bolts for bolt and bracket design (The bracket refers to

the section of the combined beam channel and gusset plate.)Note: Moment for vessel clip design is equal to M2 + (V) (X), where X is the distance

from the centerline of bolts to the face of the vessel.

5. Materials

5.1 All structural material shall be ASTM A36 steel unless otherwise noted.

5.2 Welded Steel Bar Grating shall be used on all platforms with 1-1/4" x 3/16" plainbearing bars on 1-3/16" spacing and cross bars on 4" spacing. The material shall beper ASTM A569. If the serrated grating is used in lieu of plain grating, the serratedgrating capacity shall be verified for platform width.

5.3 All bolting material shall be 3/4" diameter ASTM A325 bearing type with threadsincluded in the shear plane, unless otherwise noted. Bolt holes shall be 1/16" greaterthan bolt diameter except as noted.

5.4 Railing type shall be as specified in the Contract Documents.

5.5 Unless otherwise shown in the Contract Documents, all steel platform components andfasteners shall be galvanized in accordance with PIP STS05120.