ASME BTH-1:2017 pdf free download

ASME BTH-1:2017 pdf free download.Design of Below-the-Hook Lifting Devices.
design: the activity in which a qualified person creates devices, machines, structures, or processes to satisfy a human need (section 1.1).
design factor: the ratio of the limit state stress(es) or strength of an element to the permissible internal stress(es) or forces created by the external force(s) that act upon the element (section 1-2).
fatigue: the process of progressive localized permanent material damage that may result in cracks or complete fracture after a sufficient number of load cycles (para. 1-5.1).
fatigue lie: the number of load cycles of a specific type and magnitude that a member sustains before failure (para. 1-4.5).
hoist: a machinery unit that is used for lifting and lowering (para. 1-5.1).
fting at taclmwnt: a load-supporting device that is bolted or permanently attached to the lifted load, such as lifting lugs, padeyes, trunnions, and similar appurtenances (Nonmandatory Appendix A, section A-2).
limit stah’: a condition in which a structure or component becomes unfit for service, such as brittle fracture, plastic collapse, excessive deformation, durability, fatigue, or instability, and is judged either to be no longer useful for its intended function (serviceability limit state) or to be unsafe (strength limit state) (para. 1-5.1).
load cycle: one sequence of loading defined by a range between minimum and maximum stress (para. 1-5.1).
manufacturer: the person, company, or agency responsible for the design, fabrication, or performance of a below-the-hook lifting device or lifting device component (section 1-1).
maximum stress: highest algebraic stress per load cycle (para. 1-5.1).
mechanical component: a combination of one or more machine elements along with their framework, fastenings, etc., designed, assembled, and arranged to support, modify, or transmit motion, including, hut not limited to, the pillow block, screw jack, coupling, clutch, brake, gear reducer, and adjustable-speed transmission (para. 1-4.3).
minimum stress: lowest algebraic stress per load cycle (para. 1-5.1).
This chapter sets forth design criteria for prismatic structural members and connections of a below-the- hook lifting device.
3-1.2 Loads
Below-the-hook lifting devices shall be designed to nsist the actual applied loads. These loads shall include the rated load, the weights of the individual components of the lifter, and other forces created by the operation of the lifter, such as gripping force or lateral loads. The loads used in the design of the structural and mechanical components of a lifting magnet shall be derived based on the maximum breakaway force of the magnet. Resolution of these loads into member and connection forces shall be performed by an accepted structural analysis method.
3-1.3 Static Design Basis
3-1.3.1 NomInal Design Factors. The static strength design of a below-the-hook lifting device shall be based on the allowable stresses defined in sections 3-2 and 3-3. The minimum values of the nominal design factor, N, in the allowable stress equations shall be as follows:
N4 = 2.00 for Design Category A lifters
= 3.00 for Design Category B lifters
= 6.00 for Design Category C Lifters
31.3.2 Other Design Conditions. Allowable stresses for design conditions not addressed herein shall be based on the following design factors:
(a) Design factors for Design Category A lifting devices shall be not less than 2.00 for limit states of yielding or buckling and 2.40 for limit states of fracture and for connection design.
(b) Design factors for Design Category B lifting devices shall be not less than 3.00 for limit states of yielding or buckling and 3.64) for limit states of fracture and for connection design.
(c) Design factors for Design Category C lifting devices shall be not less than 6.00 for limit states of yielding or buckling and 7.20 for limit states of fracture and for connection design.