ASME has been defining crane safety since 1916.

BTH-1 provides minimum structural and mechanical design and electrical component selection criteria for ASME B30.20 below-the-hook lifting devices. 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. Lifting devices designed to this Standard shall comply with ASME B30.20, Below-the-Hook Lifting Devices. B30.20 includes provisions that apply to the marking, construction, installation, inspection, testing, maintenance, and operation of below-the-hook lifting devices.

BTH-1 addresses only design requirements. As such, this Standard should be used in conjunction with B30.20, which addresses safety requirements. BTH-1 does not replace B30.20. The design criteria set forth are minimum requirements that may be increased at the discretion of the lifting device manufacturer or a qualified person.
Key changes to this revision of BTH-1 include:
• Addition of chapter of requirements for Lifting Magnet Design with additional commentary found in a   corresponding new Nonmandatory Appendix
• Addition of design requirements for new Design Category for specialized application in industries that require lifting designs based on a specified larger Design factor
• Addition of new requirements for Member Properties
• Updated Table 3-2.2-1 Limiting Width-Thickness Ratios for Compression Elements

BTH-1 and B30.20 are to be used in conjunction with equipment described in other volumes of the ASME B30 series of Safety Standards. Careful application of these Safety Standards will help users to comply with applicable regulations within their jurisdictions, while achieving the operational and safety benefits to be gained from the many industry best-practices detailed in these volumes.
Intended for manufacturers, owners, employers, users and others concerned with the specification, buying, maintenance, training and safe use of below-the-hook lifting devices with B30 equipment, plus all potential governing entities.