There have been many formal requests for interpretation of the limited structural design criteriastated within ASME B30 .20 , Below-the-Hook Lifting Devices, a safety standard . As a consequence,industry has for quite some time expressed a need for a comprehensive design standard forbelow-the-hook lifting devices that would comp lement the safety requirements of ASME B30 .20 .All editions of ASME B30 .20 have included structural design criteria oriented toward the industrialmanufacturing community requiring a minimum design factor of 3 , based on the yield strengthof the material; recent editions have also included design criteria for the fatigue failure mode .However, members of the construction community expressed the need for design criteria moresuitab le to their operating conditions, including a lower design factor, and the necessity to addressother failure modes such as fracture, shear, and buckling, and design top ics such as impact andfasteners .A Design Task Group was created in 1 997 to begin work on a design standard as a companiondocument to ASME B30 .20 . The ASME BTH Standards Committee on the Design of Below-theHook Lifting Devices was formed out of the Design Task Group and held its organizationalmeeting on December 5 , 1 999 .ASME BTH-1 –2005 , Design of Below-the-Hook Lifting Devices, contained five chapters : Scopeand De finit ions , L ifter C las s ifica t ions , S truc tu ra l Des ign , Me chanica l Des ign , and E lec tr ica lComponents . This Standard, intended for general industry and construction, set forth two designcategories for lifters based on the magnitude and variation of loading, and operating and environmental conditions . The two design categories provided different design factors for determiningallowab le static stress limits . Five Service Classes based on load cycles were provided . The ServiceClass estab lishes allowab le stress range values for lifter structural members and design parametersfor mechanical components . ASME BTH-1 –2005 was approved by the American National Standards Institute (ANSI) on October 1 8 , 2005 .ASME BTH-1 –2008 incorporated editorial revisions and two new mechanical design sectionsfor grip ratio and vacuum lifting device design. ASME BTH-1 –2008 was approved by ANSI onSep tember 1 7, 2008 .ASME BTH-1 –201 1 incorporated revisions throughout the Standard and the addition of a newmechanical design section for fluid power systems . ASME BTH-1 –201 1 was approved by ANSIon September 23 , 201 1 .ASME BTH-1 –201 4 incorporated into Chapter 4 a section on lifting magnets . Other technicalrevisions included new requirements for fluid pressure control and electrical system guarding.Along with these technical changes, the nonmandatory Commentary for each chapter was movedto its own respective Nonmandatory Appendix. ASME BTH-1 –201 4 was approved by ANSI onJune 24, 201 4 .This revision of ASME BTH-1 includes the addition of Chapter 6 : Lifting Magnet Design, anaccompanying Nonmandatory Appendix with commentary for the new chap ter, and other revisions . Following the approval by the ASME BTH Standards Committee, ANSI approved thisedition as an American National Standard, with the new designation ASME BTH-1 –201 7, onJanuary 6, 201 7.

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