Section 4 — Structures and Foundations

Structural Steel

IPE Engineering Practice IPE-EP-4-5-1

Document number: IPE-EP-4-5-1 · Section: 4 — Structures and Foundations

SCOPE

This Practice covers material selection and mandatory design requirements for structural steel.
Fabrication and erection requirements for structural steel are covered in EP 4-5-2.
Any deviation to this Practice must be approved by the procedure described in EP 1-1-3.
An asterisk (*) indicates that a decision or approval by the Owner or the Owner's Engineer is required or that additional information is furnished by the Purchaser.
A revision bar indicates all changes made to this Revision.
Documentation required in accordance with this Practice is given in Table 1.

2.0 REFERENCES

The latest edition of the following standards and publications are referred to herein.

STANDARDS AND PUBLICATIONS

IPE Engineering Practices
EP 1-1-3 Deviations to IPE Engineering Practices EP 4-1-1 Design Criteria and Loads for Structures EP 4-5-2 Structural Steel Construction EP 4-5-3 Auxiliary Structures for Operation and Maintenance EP 10-3-8 Galvanized Coatings EP 11-2-1 Fireproofing
ASCE
7-95 Minimum Design Loads for Buildings and Other Structures
AISC Specifications
Specification for the Design Fabrication and Erection of Structural Steel for Buildings Code of Standard Practice for Steel Buildings and Bridges Specification for Structural Joints Using ASTM A 325 or A 490 Bolts
ANSI Standards
B 27.2 Plain Washers B 27.4 Beveled Washers

STANDARDS AND PUBLICATIONS (CONT.)

DEFINITIONS

Contractor - Company or business that agrees to furnish materials or perform specified services at a specified price and/or rate to the Owner.
Inspector - A Inflection Point Engineering, LLC appointed engineer or inspector.
Manufacturer - The recipient of a direct or indirect purchase order for materials and/or equipment. In this context, a direct order is one issued to a manufacturer by a contractor or the Owner. An indirect order is one issued to a manufacturer by a vendor (recipient of a direct order) for materials, fabricated components, or subassemblies.
Owner - Inflection Point Engineering, LLC.
Owner's Engineer - A Inflection Point Engineering, LLC appointed engineer.
Purchaser - The party placing a direct purchase order. The purchaser is the Owner's designated representative.

MATERIALS

General
Materials furnished under this Practice shall be new and of first quality conforming to the applicable specifications referenced herein.
Certified mill test reports shall be submitted to the Inspector for structural steel.
The Manufacturer's certification stating conformity of the welding filler materials with this specification shall be submitted to the Inspector upon request.
The Manufacturer's certification stating conformity of bolts, nuts, and washers with this specification shall be submitted to the Inspector upon request.

(*)No substitution of materials, sizes, or shapes shall be made without the prior written approval of the Purchaser.
Structural Steel
Structural steel shapes and plates shall conform to ASTM A 36 and its general requirements specification ASTM A 6.
Steel pipe for structural applications shall conform to ASTM A 53, Type E or S, Grade B, open hearth or basic oxygen steel.
Structural square and rectangular tubing shall conform to ASTM A 500.
Bolting
(*)Structural bolts shall conform to ASTM A 307 Grade A and high strength bolts shall conform to ASTM A 325 for service temperatures above -20°F. For service temperatures below -20°F, appropriate austenitic bolting material shall be specified in the Order. Structural carbon and alloy steel nuts shall conform to ASTM A 563.
Washers for use with structural bolting shall conform to the following:
Plain washers shall conform to ANSI B27.2.
Beveled washers shall conform to ANSI B27.4.
Hardened washers shall conform to ASTM F 436.
(*)Load indicator washers shall be "Coronet Load Indicator" as manufactured by Cooper and Turner, Pittsburgh, PA, or Owner approved equal.
The Manufacturer shall supply all bolts, nuts and washers necessary for erection purposes and permanent field connections. The Manufacturer shall supply the required number of bolts, nuts, and washers for each length and diameter plus 10% excess.
Floor Plate

Floor plate shall be nonskid checkered plate, raised pattern, made or carbon steel in accordance with ASTM A 36. The plate thickness shall be as indicated on the drawings. The minimum permissible plate thickness is 1/4 inch.

Grating and Stair Treads
(*)Unless otherwise specified by the Owner's Engineer, rectangular open-type welded grating, with 3/16 inch x 1-1/4 inch serrated bearing bars with a 1-3/16 inch center spacing shall be used. Materials for grating shall conform to ASTM A 569.
Banding of open grating shall be performed by the Manufacturer at the following locations:
Open ends of grating at head of ladder approaches to platform.
All hinged sections.
Grating panels with four or less cross bars.
All openings where more than four bars are cut in gratings including field cut openings.

The band bar shall be the same size as the bearing bars, except where a toeplate is specified in place of a banding bar. The band bar shall extend to the first continuous bearing bar on each side of cutout and shall be welded to each cut bearing bar and to each continuous bearing bar with a single full-length 1/8-inch fillet weld.
Stair treads shall be welded steel grating with non-skid type nosing and shall conform to ASTM A 569.
Grating and stair treads shall be hot-dipped galvanized after fabrication in accordance with EP 10-3-8.

DESIGN

General
(*)The criteria, loads, and load combinations for design of structural steel shall be in accordance with EP 4-1-1. In addition, design and detailing of structural steel shall conform to AISC "Manual of Steel Construction", AISC "Specification for the Design, Fabrication and Erection of Structural Steel for Buildings", and the AISC "Code of Standard Practice for Steel Buildings and Bridges". Allowable Stress Design shall be used, unless the Owner's Engineer approves the use of Load & Resistance Factor Design.
For structural elements continuously exposed to heat above 500°F, the allowable design stresses shall be reduced in proportion to reductions in yield strength of the steel at the design temperature.
For structural elements exposed to severe corrosion or wear conditions, special materials, protection, or material thickness allowance shall be employed instead of decreasing allowable stresses.
(*)All designing and detailing by the Manufacturer shall be in accordance with the AISC "Manual of Steel Construction". Allowable Stress Design shall be used, unless the Owner's Engineer approves the use of Load & Resistance Factor Design.
Suitable deductions to provide for draw shall be made in the computed lengths of all diagonal angle bracing longer than 10 feet.
Angle bracing shall have the vertical leg turned down unless specifically shown otherwise.
All structural steel designs, specifications, drawings and calculations shall be approved and signed by a registered professional engineer.
Connections
(*)Except as modified by drawings, connections shall be designed and detailed as follows:
Shop connections shall be welded. Bolts may be used for shop connections only where welding is impractical.
(*)Field connections shall be bolted wherever practical. Exceptions to this requirement shall be approved by the Owner's Engineer.
Bevel washers shall be furnished for structural and high strength bolted connections to sloping flanges, and when required for flanges for diagonal tie rod bracing connections.

Where beam connections are not detailed or described on design drawings, and no reaction value is specified, they shall be detailed by the fabricator or detailer to resist the reactions specified in the sub-paragraph below. Where reaction values are specified on the drawings, they shall be detailed for these values, except that they shall also meet the requirements of the sub-paragraph below.
The connections shall be designed to resist, as a minimum, the reactions caused by the allowable uniform load shown in the beam tables of Part 2 of the AlSC Manual.
Each bolted joint shall have at least two bolts but in no case shall the number of rows of bolts be less than the minimum shown in the table for "Framed Beam Connections, Bolted" of Part 4 of the AlSC Manual.
Unless otherwise indicated on the fabrication drawings, all connections for diagonal bracing and connections at the ends of tension or compression members in trusses shall be designed to develop the force due to the design load. As a minimum, these connections shall also be designed to develop the greater of 50% of the allowable tension capacity of the bracing member or 6 kips, in ASCE 7 Seismic Performance Categories A and B, and the greater of 100% of the allowable tension capacity of the bracing member or 6 kips, in ASCE 7 Seismic Performance Categories C and above. The allowable tension capacity shall be calculated using the gross cross-sectional area of the member. Working points for designing and detailing the connections shall be as shown on the fabrication drawings.
Bolted connections for ladders, handrail posts, stair stringers, purlins, and girts shall be made with structural bolts. All other bolted connections shall be made with high strength bolts. High- strength bolted connections shall be in accordance with the AlSC "Specification for Structural Joints using ASTM A 325 or A 490 Bolts."
Bolt sizes shall be in accordance with the following requirements:
Structural bolts with hex bolt head shall be 5/8-in. minimum diameter unless limited by the size of the connected parts.
(*)High strength bolts with heavy hex bolt head shall be ¾-in. minimum diameter unless otherwise specified on the design drawings.
Heads and nuts of high strength bolts shall bear on hardened steel washers.
Gusset plates and bracing connection plates shall have a minimum thickness of 3/8 inch and a minimum of two bolts per member for bolted connections.
Clips and brackets shall be as follows:
All clips for attaching platform brackets, ladders, davits, etc., to vessels and tanks will be furnished shop-welded to vessel or tank by the vessel fabricator unless otherwise noted.
Where field welding is specified, the structural steel fabricator shall furnish necessary erection clips and bolts.
Auxiliary Structures for Operation and Maintenance

Design requirements for platforms, ladders, stairways and other auxiliary structures for operation and maintenance shall be in accordance with the requirements of this Practice and EP 4-5-3.
Platforms, stairways and handrails shall be shop-assembled in the largest units for handling, shipping and erection, unless otherwise noted on drawings.

FABRICATION DRAWINGS

The Manufacturer shall prepare complete fabrication and erection drawings including shop details and bills of material. Erection drawings shall be cross-referenced to the design drawings and shall show erection marks, and a complete erection bolt schedule for each connection.
(*)The Manufacturer shall submit shop and erection drawings for approval to the Owner, and shall not proceed with fabrication until approval is received in writing. Approval of shop drawings by the Owner shall be construed as approval of general methods only, and shall not constitute verification of proper member sizes, dimensions, details, or quantities. The Manufacturer shall be solely responsible for correctness of the fabrication and erection drawings. Final fabrication and erection drawings shall be reviewed and approved by a registered Professional Engineer.
(*)The Manufacturer shall be responsible for correct interpretation of design drawings, and shall call to the attention of the Owner any discrepancies found on the drawings. The Manufacturer shall be responsible for dimensions of details not shown on design drawings. The Manufacturer shall be solely responsible for detailing and fabrication to insure that erection will be convenient and free from all interferences, drilling, or cutting.
(*)Regardless of the design drawing presentation, the Manufacturer shall be responsible for the erectibility of the structure. If, in order to achieve erectibility, shop detailing that alters the design intent is required, the Owner shall be consulted and his approval shall be obtained before proceeding.

7.0 FIREPROOFING

Fireproofing of structural steel shall be in accordance with EP 11-2-1.

8.0 TABLES

TABLE 1 DOCUMENTATION REQUIREMENTS FOR STRUCTURAL STEEL PER EP 4-5-1

Item	Description	Format	As-Built
1	Certified mill test reports.	Text	N/A
2	Manufacturer's certification of conformity of weld filler materials.	Text	N/A
3	Manufacturer's certification of conformity of bolts nut, and washers.	Text	N/A
4	Shop, fabrication, and erection drawings and details.	See EP 2-5-2	Yes
5	Bill of materials.	See EP 2-5-2	Yes

© 2026 Inflection Point Engineering, LLC. All rights reserved. The content of this page — including calculation methods, reference data, written analysis, interactive tools, and source code — is the intellectual property of Inflection Point Engineering, LLC and is protected under applicable copyright, trademark, and trade secret laws. Unauthorized reproduction, redistribution, modification, or derivative use in whole or in part is prohibited without prior written consent.

Disclaimer. This material is provided for informational and educational purposes only and does not constitute professional engineering advice. Calculations, reference data, and methodologies are based on published standards and accepted engineering practice but are not a substitute for engineering judgment, site-specific analysis, or review by a licensed Professional Engineer. Inflection Point Engineering, LLC makes no warranties, express or implied, regarding the accuracy, completeness, or fitness for a particular purpose of any content presented here, and shall not be liable for any direct, indirect, incidental, or consequential damages arising from its use. Users assume all risk associated with applying this content to real-world design, operations, or decisions.