Did You Know? Below-the-Hook Standards
Important to Understand BTH Standards
So, what are BTH devices? They are structural and mechanical lifting devices (spreader beams, lifting beams, C-hooks, plate clamps, pallet lifters, coil grabs, etc.), vacuum lifters, lifting magnets, scrap and material-handling grapples.
Fulcrum Lifting Companies follow the guidelines set forth in the ASME B30.20 standards. Below are highlights of the standard, however, the full ASME B30.20 standard can be downloaded here.
The ASME Documents
- Two ASME publications cover BTH devices: ASME B30.20 covers marking, construction, installation, inspection, testing, maintenance and operation of BTH lifting devices. ASME BTH-1 covers the design criteria for ASME B30.20, which sets up design guidelines.
- This provides the design category (A or B) that establish the stress limits used in the BTH lifter’s design.
- Design Category A is for loads, use & working conditions which are accurately defined, predictable and not severe.
- Design Category B is used for loads and variations which are severe and not accurately defined. MOST OF FULCRUM LIFTING SUPPLIED DEVICES ARE CAT B AS STANDARD.
- Establishes load cycles (service life) of a BTH device. Service Class is determined by the specified fatigue life of the lifter
- Service Class 0 is 0 to 20,000 load cycles.
- Service Class 1 is 20,001 to 100,000 load cycles.
- Service Class 2 is 100,001 to 500,000 load cycles.
- Service Class 3 is 500,001 to 2,000,000 load cycles.
- Service Class 4 is over 2,000,000 load cycles
- All new devices must be identified with manufacturer’s name and address, serial number, lifter weight (if over 100 Ilbs.), rated load, design category, service class, and the following when applicable: model number, electrical power requirements, pressure and volume of compressed air requirements, duty cycle and operating hydraulic pressure.
- ASME B30.20 details the required Inspection criteria (Initial, Every Lift, Frequent, Periodic, Repairs). Dated inspection records shall be made on critical lifters and for each periodic inspection.
- Depending on the type of BTH device, mandates on load testing can vary. Structural and mechanical devices “should” be load tested, which means they aren’t required to be load tested, but it’s recommended. The other devices (vacuum lifters, magnetic lifters, grapples) are all written as “shall” be tested. If you’re concerned about the load testing of a specific device, we suggest that you ask specifically about this criteria when selecting a BTH device. Opinions on the merits of load testing vary among manufacturers. We at Fulcrum Lifting are happy to help you decipher this.
Please note that this is simply a summary of the ASME B30.20 and ASME BTH-1 standards. We encourage you to read through the complete standards on your own as well. If you have any questions, Fulcrum Lifting is here for you.