Design of Below-the-Hook Lifting Devices ASME BTH-1-2017

There have been many formal requests for interpretation of the limited structural design criteria stated 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 for below-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 industrial manufacturing community requiring a minimum design factor of 3 , based on the yield strength of 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 more suitab le to their operating conditions, including a lower design factor, and the necessity to address other failure modes such as fracture, shear, and buckling, and design top ics such as impact and fasteners . A Design Task Group was created in 1 997 to begin work on a design standard as a companion document 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 organizational meeting on December 5 , 1 999 . ASME BTH-1 –2005 , Design of Below-the-Hook Lifting Devices, contained five chapters : Scope and 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 l Components . This Standard, intended for general industry and construction, set forth two design categories for lifters based on the magnitude and variation of loading, and operating and environmental conditions . The two design categories provided different design factors for determining allowab le static stress limits . Five Service Classes based on load cycles were provided . The Service Class estab lishes allowab le stress range values for lifter structural members and design parameters for 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 sections for grip ratio and vacuum lifting device design. ASME BTH-1 –2008 was approved by ANSI on Sep tember 1 7, 2008 . ASME BTH-1 –201 1 incorporated revisions throughout the Standard and the addition of a new mechanical design section for fluid power systems . ASME BTH-1 –201 1 was approved by ANSI on September 23 , 201 1 . ASME BTH-1 –201 4 incorporated into Chapter 4 a section on lifting magnets . Other technical revisions included new requirements for fluid pressure control and electrical system guarding. Along with these technical changes, the nonmandatory Commentary for each chapter was moved to its own respective Nonmandatory Appendix. ASME BTH-1 –201 4 was approved by ANSI on June 24, 201 4 . This revision of ASME BTH-1 includes the addition of Chapter 6 : Lifting Magnet Design, an accompanying Nonmandatory Appendix with commentary for the new chap ter, and other revisions . Following the approval by the ASME BTH Standards Committee, ANSI approved this edition as an American National Standard, with the new designation ASME BTH-1 –201 7, on January 6, 201 7.