Wind Load Design for Petrochemical and Other Industrial Facilities

The basis and procedures for determining design wind loads for enclosed structures and other conventional structures are well documented in the engineering literature. ASCE 7 provides several methods for calculating design wind loads on the main wind force–resisting system (MWFRS) and on components and cladding. The envelope procedure for a building’s MWFRS was introduced to simplify analysis of typical regularly shaped building structures. The directional procedure for a building’s MWFRS is permitted for structures of any height and without unusual geometric irregularities or unusual response characteristics. The chapter also overviews the book’s key concepts, including the procedures for determining the design wind loads for nonbuilding structures in petrochemical and other industrial facilities. The book reflects various company practices, available research, and committee consensus for the wind load design of petrochemical and other industrial facilities.

This chapter’s background information is intended to assist the user of this book in interpreting and applying the material presented in subsequent chapters. The chapter also discusses fundamental wind engineering concepts and the general aerodynamic characteristics of structure types common to petrochemical and other industrial facilities. Open-frame structures are characterized by regular bays of open structural framing, the presence of equipment housed within the structure envelope, the presence of piping, and other appurtenances such as stairs and handrails. The chapter discusses some general aerodynamic characteristics of partially clad structures and vertical vessels. It concludes with a presentation of other sources of guidance that may be helpful to designers or analysts, a brief summary of research progress since the first edition of this guide, and future research needs.

The 1997 ASCE Task Committee report “Wind Loads and Anchor Bolt Design for Petrochemical Facilities” attempts to address the variability of design practices for industrial structures within the engineering community. The second committee surveyed design engineers and engineering managers from large engineering consulting firms to assess the level of acceptance and effectiveness of the 1997 publication and to identify improvement needs. This chapter presents the results of a survey conducted while preparing the second edition to complement the first committee’s efforts. It discusses design practices for structural types that other industry standards already cover. The chapter also addresses the design practices for calculating the wind loads for tanks, steel stacks, and cooling towers.

This chapter provides guidance for wind load analysis and design of petrochemical and industrial structures and includes topics related to wind effects for these types of facilities. It begins with observations on petrochemical facilities’ historical performance during hurricanes and provides some related general design considerations. The chapter also provides background on alternate methods for determining wind loads, specifically wind tunnel testing and computational fluid dynamics approaches. Information regarding recommended wind load combinations for petrochemical structures is also provided. The chapter presents special wind load provisions related to US Department of Transportation regulations for liquefied natural gas facilities and references to and summaries of current industry guidelines for evaluating wind loads on existing structures and foundations. It concludes with a discussion of the uncertainty associated with determining wind loads.

This chapter presents recommended guidelines and commentary to reflect recent updates to ASCE 7. The basic equation for design wind loading is adopted from ASCE 7 procedures for “Design Wind Loads on Other Structures.” The chapter also presents the calculation of wind on pipe racks and covers wind loads on open frame or lattice structures, with or without equipment, piping, electrical items, stairs, ladders, and handrail. The chapter addresses structures with cladding on fewer than four exterior walls. The forces calculated are intended to be applied to the main wind force–resisting system and are not intended for design of components and cladding. The chapter aims to clarify the wind loads for compressor shelters with a roof and four exterior walls, in which the opening area in each wall is less than 80% but typically more than 20% of the gross area of the wall.

This chapter presents examples of how to apply the recommended guidelines for determining wind loads on various types of structures in petrochemical and other industrial facilities. In some cases the pipe rack longitudinal strut or stringer might fall in the shielding envelope and can thus be deleted from the sum of the projected area of the piping. The guidelines require considering piping or cable tray separately from structural members, and the chapter presents calculations for piping or cable trays without the structural support members for all configurations. It explains how to determine the wind load on an open frame structure and demonstrates the calculation of wind loads for partially clad structures. It also demonstrates application of the recommended guidelines to calculating wind loads on pressure vessels. In this example the vessel is classified as Risk Category III and therefore the basic wind speed is 155 mph.