Provides minimum structural and mechanical design and electrical component selection criteria for ASME B The provisions in this Standard apply to the design or modification of below-the-hook lifting devices. Your Alert Profile lists the documents that will be monitored. If the document is revised or amended, you will be notified by email. You may delete a document from your Alert Profile at any time.
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Jump to Page. Search inside document. This Standard serves as a guide to designers, manufacturers, purchasers, and users of below-the hook lifting devices, Commentary: This Standard has been developed in response to the need to provide clarification of the intont of ASME Com- pliance with requirements and criteria that may be unique to specialized industries and environments is outside of the scope of this Standard, Lifting devices designed to this Standacd shall comply with ASME B ASME The design crite set forth are minimum requirements that may be increased at the discretion of the lifting device manufscturer or a qualified person.
Design Responsibility Lifting devices shall be designed by, or under the direct supervision of, a qualified person, Commentary: Although slways implied, this provi sion now explicitly statos that the dosign of bolow the hook lifting davices is the responsibility of a qualified person.
This requirement has been established in recog: nition of the impact that the performance of a lifting device has on workplace safety, the complexity of the design process, and the level of knowladge and training required to competently design litting devices.
Values are given in US. Customary units as the primary units followed by the International System of Units SI in parentheses as the secondary units. The values stated in US. Customary units are to be regarded as the standard. Customary units Commentary: The requirements of this Standord are presented wherever possible ina manner that is rensionally independent, thus allowing application of these raquirements using either U. Customary units are the primary units used in this Standard.
Resolution of leads into forces and stress values affecting structural members, mechanical compo- nents, and connections shall be performed by an accepted analysis method. Consideration of the effects of stress concentrations is not normally required when determining the static strength of a lifter component see Commentary for para. However, the affects of stress concentra- tons are most important when determining fatigue Ite.
This is particularly true when evaluating static etrangth. While the use of uch methods ie not prohibited, modeling of the device and interpretation of the results demands suitable expertise to assure the requirements of this Standard are met without cresting unnecessarily conservative limits for static strength and, fatigue life, Commentary: Tho dosign provisions in Chapters 3 and 4 are based on practices and research for design Using carbon, high-strength lowralloy, and heattreated constructional alloy steels.
Some of the equations pre- sented ate empirical and ray not be directly applicable to use with other materiale, Bath ferrous and nonferrous materials, including the constructional steels, may be used ia the mechanical components described in Chapter 4 Industry-wide specifications are those from organiza tions such as ASTM International ASTM , the Amarican lron and Stee!
A proprictary specification is one developed by an individual manufacturer. The design strength of welds shall beas defined in para. These considerations may include choosing a material that has better cold-temperatuce or high- temperature properties, limiting the design stresses to a lower percentage of the allowable stresses, or restricting use ofthe lifter until the component tempera- ture falls within the stated limits.
Lifters expected to operate in ambient temperatures beyond this limit shall have elec- trical components designed for the higher ambient temperature, Commentary: The temperature limits stated are based on the following. Flaws in steel plate material were the primary cause of these failures. With tighter produc tion processes, closer metallurgical control, and better quality checks in current practice, the risk of such failure is reduced.
Some materials decline by as much as 4. If the exposure is prolonged and cyclic in nature, the creep rupture strength of the material, which is lower than the simple elevated temperature value, must be used in determining the design rated load and life of the device. A lifter may move briefly through an area of frigid air without the temperature of the steel dropping to the point of concern. Likewise, a lifter that handles very hot items may have some com- ponents that become heated due to contact.
The defined terms are divided into general terms para. Definitions — General ambient tersperature: the temperature of the atmosphere surrounding the lifting device para. Tension stress is considered to have the opposite algebraic sign from compression stress para. Ly bearing life: the basic sating, or specification life of a bearing para. Because ofits slight movement, it ig not termed a running sheave para. Where notation did not exist, unique symbols are defined herein and have been selected to be clear in meaning to the user.
For rolled shapes, this value may be taken as the clear distance between flanges less the fillet or comer radius, in. Nmm para.
However, some areas ere best suited to be covered by reference to established industry standards. Section lists codes, standards, and other documents that are cited within the main body of this Standard and pro- vides the names and addresses of the publishers of those documents.
Each chapter of this Standard is accompanied by a commentary that explains, where necessary, the basis of tho provicions of that chapter. All publications cited in these commentaries are listed below. These refer ences are cited for information only. Cornell, C. STS Duerr, 0. Kulak GL, and Ravindra, M.
ST9 Galambos, T. ST9 Kitipornohai, S. EM2, April Ravindre, M. STS Yura, J. Government Printing Office, Washington, D. Fisher, J. A, and Hobllt,. Wileon, W. Young, W. A quali fied person or manufecturer must assure that the Design Category and Service Clase opecified for a parti.
Ular lifter are appropriate for the intended use so as to provide a design with adequete structural reliability and expected service Ife If not specified by the ownes, purchaser, or user, the Design Category and Service Class shall be designated by the qualified person responsible for the design. Commentary: The purpose of this requirement is to ensure thet the designe, menufacturer, and end user are aware of the assigned Design Category and Service Class.
Typically, documents that require the indicated markings may include top level drawings. Lifter components operating at temperatures outside the range specified in para, I-L7 may requie additional consideration, 2 Commentary: Ambient operating temperature lim- lts are intended only to be guideline.
The component tomporature of each part of the lifter must be consid ered when the device is operating in an environment outside the limits defined in para. The affects of dust, moisture, and corrosive atmospheric substances on the integrity and performance of a lifter cannot be specifically defined. These design considerations must be evaluated and accounted for by the lifting device manufecturer or qualified porson. The design factors are given in para. Lifters shall be designed to Design Category B, unless 4 qualified person determines that Design Category 4 is appropriate.
Commentary: When selecting a Design Category, consideration shall be given to all operations that will affect the lifting device design. The discussions of the Design Categories below and in Commentary for pare. These comments are in no way to be interpreted as permitting 2 lifting device to be used above its rated load under any cireumstances other than for loed tasting in accor.
Typleal characteris tics of the application for this Design Catagery include lifts at slow speeds utilizing a well maintained lifting evice under the contiol of lift supervisor and experi enced crane operator.
Typical char- acteristics of the application for this Design Category include rough usage and lifts in adverse, less controlled conditions.
Design Category B will generally be appro priate for lifters that are to be used in sevara environ ments. However, the Design Category 8 design factor docs not neces! The selacted Service Class establishes allowable stress range values for structural members section and design parameters for mechanical components sections and The intent is to provide the owner with the opportunity for more economical designs for the cases where duty service is less severe.
A choice of five Service Classes is provided. Commentary: The member allowable stresses, defined in Chanter 3 have generally been derived based on the assumption of the members being prismatic. Design of taperad members may require additional considerations.
These loads shall include the rated load, the weights ofthe individual components of the lifter, and other forces created by the operation of the ifter, such as gripping force or lateral loads. Reso- lution of these loads into member and connection forces shall be performed by an accepted structural analysis method.
This provision is not intended to require the use of an arbitrary lateral load in lifter dasign. For most designs, an added impsct allowance ie not required. This issue is discussed further in Commentaries for paras.
The load and strength uncer: tainties are related to a design factor Ny using eq.
Asme Bth-1-2008 Design of Below-The-hook Lifting Devices
Digital products are restricted to one per purchase. Become a member. The provisions in this Standard apply to the design or modification of below-the-hook lifting devices. Compliance with requirements and criteria that may be unique to specialized industries and environments is outside of the scope of this Standard. BTH-1 addresses only design requirements. As such, this Standard should be used in conjunction with B
ASME BTH-1-2008 DESIGN OF BELOW-THE-HOOK LIFTING DEVICES.pdf
Design of Below-the-Hook Lifting Devices