ASME BTH-1:2017 pdf free download – Design of Below-the-Hook Lifting Devices
A dual unit format is used. Values are given in U.S. Customary units as the primary units followed by the International System of Units (SI) in parentheses as the secondary units. The values stated in U.S. Customary units are to be regarded as the standard. The SI units in the text have been directly (softly) converted from U.S. Customary units.
1-4.3 Design Criteria
All below-the-hook lifting devices shall be designed for specified rated loads, load geometry, Design Category (see section 2-2), and Service Class (see section 2-3). Resolution of loads into forces and stress values affecting structural members, mechanical compo- nents, and connections shall be performed by an accepted analysis method.
1-4.4 Analysis Methods
The allowable stresses and stress ranges defined in this Standard are based on the assumption of analysis by classical strength of material methods (models), although other analysis methods may be used. The anal- ysis techniques and models used by the qualified person shall accurately represent the loads, material properties, and device geometry; stress values resulting from the analysis shall be of suitable form to permit correlation with the allowable stresses defined in this Standard.
1-4.5 Material
The design provisions of this Standard are based on the use of carbon, high-strength low-alloy, or heat- treated constructional alloy steel for structural members and many mechanical components. Other materials may be used, provided the margins of safety and fatigue life are equal to or greater than those required by this Standard.
All welding designs and procedures for lifters fabri- cated from steel, except for the design strength of welds, shall be in accordance with the requirements of AWS D14.1/D14.1M. The design strength of welds shall be as defined in para. 3-3.4. When conflicts exist between AWS D14.1/D14.1M and this Standard, the require- ments of this Standard shall govern. Welding of lifters fabricated from metals other than steel shall be performed in accordance with a suitable welding specification as determined by a qualified per- son, provided the quality and inspection requirements are equal to or greater than those required by this Standard.
The design provisions of this Standard are considered applicable when the temperature of the lifter structural or mechanical component under consideration is within the range of 25°F to 150°F (−4°C to 66°C). When the temperature of the component is beyond these limits, special additional design considerations may be required. These considerations may include choosing a material that has better cold-temperature or high- temperature properties, limiting the design stresses to a lower percentage of the allowable stresses, or restricting use of the lifter until the component tempera- ture falls within the stated limits. The design provisions for electrical components are considered applicable when ambient temperatures do not exceed 104°F (40°C). Lifters expected to operate in ambient temperatures beyond this limit shall have elec- trical components designed for the higher ambient temperature.