|Lift beams, spreader bars, container lifting, container casters and connectors for lifting, securing and mobilizing.|
EAD21000A STANDARDS FOR TANDEMLOC SLING & BELOW THE HOOK LIFTING DEVICES MANUFACTURING & TEST SPECIFICATION NOTES
WE DESIGN SERVICE CLASS AND LIFE CATEGORY PER ASME BTH-1-2011
Unless otherwise specified on the product drawing, the design category used is “B" (S.F. 3:1 to yield) and the service life is Class "O" (up to 20,000 load cycles), except that ISO container lift spreaders have a service life Class "1" (up to 100,000 load Cycles). Different design categories and service classes must be defined by the buyer prior to order placement. The lifting product will then be custom engineered to meet the specified requirements.
SERVICE TEMPERATURES OF TANDEMLOC LIFT DEVICES
All lift devices and slings sold by Tandemloc are made in conformance to ASME B30.20 (below the hook lifting Devices) and ASME B30.9 (slings) unless otherwise noted. These specifications require the user to perform a pre-lift equipment inspection and limit the amount of impact and shock loading to minimal. This is of extreme importance especially when the service temperature goes below 35°F, and increasingly important with each degree lower. On this basis, the Tandemloc standard equipment is useable in temperatures of 150°F down to 25°F. (Temperature range per ASME BTH-1).
The user has the option of purchasing ASME B30.20 below the hook lifting devices, made for arctic service (reducing the minimum temperature from 25°F to a range of minus 20°F - minus 50°F.) These devices may be made from special steels which are produced to withstand Charpy impact tests made as low as minus 50°F, however it may not be possible for certain design styles and working load limits, as materials may not be readily available. The user must still avoid impact and shock loading and perform the careful pre-lift inspection noted above, but will have an extra margin of safety. The high temperature limit is 150°F.
Cold Temperature Considerations and Below the Hook Lifting Products.
Operating lifting equipment (under the ASME B30.20 specification for below the hook lifting devices) in cold temperatures (below 25°F) does not in and of itself require the use of cold temperature materials in their manufacture. In fact, as the temperature drops, steels in general will become stronger with respect to their yield strengths. What cold temperature does is tend to make steels become more brittle.
In order for cold temperatures to reduce the safety of a steel lifting product, there must be a sufficiently sudden and substantial impact load applied (or vibration loads), along with a sudden change in material volume in highly stressed areas, through a given piece of lifting equipment. This sudden change of volume is more commonly referred to as a stress riser. These can be in the form of a notch, crack(s), or thin wall attached to a thick wall, for example. ASME B30.20 expressly forbids the end user from applying impact or shock loads to lifting equipment certified under that specification. Without both a suddenly applied load, and a stress riser, cold temperatures will have no effect on the safety of a given lifting product. In fact the safety factor to yield will go up. A stress riser without impact loading (or vibration) will not be more likely to cause failure in cold temperatures, nor will impact loads without a stress riser be more likely to cause failure in cold temperatures. Tandemloc lifting products are designed with at least a 3:1 factor of safety to yield, and that safety factor already considers any stress risers in the system. (all lifting products should be checked for cracks on a regular basis.) Slowly applied forces such as should be encountered during a lift under asme B30.20 will not cause stress risers to lead to failure more readily in cold temperatures. In fact since the yield strength Is increased in cold temperatures, the product will have a greater factor of safety under static or slowly applied loads.
If impact (or substantial vibration) loads are unavoidable in your lift, and the design of the lifting product has stress risers in high stressed areas, cold temperature materials could be part of the solution for your lifting product. However, it should be remembered that impact loading is not covered under the ASME B30.20 specification, and therefore a different specification may be required for your lifter, which should consider dynamic loading.
Tandemloc currently designs all lifters to ASME B30.20 which considers static loading only. We offer cold temperature steels in our designs as a courtesy to our customers, but these lifters are still designed to ASME B30.20 and impact loading will void the warranty as well as be a violation of the specification.
In summary, do not assume that operating your lifts in cold temperatures alone are sufficient reason to incur the substantial additional expense of using cold temperature materials in your lifter. Please talk with your sales representative and Tandemloc engineering to make an informed decision about your lifting requirements.
Pre-lift inspection procedures are noted in ASME B30.20 and ASME B30.9 available from ASME.
Tandemloc recommends that before any low temperature lift or after any accidental damage occurrence that the device is inspected for cracks, gouges and deep scratches in high stress areas. Repair and re-test before using.
ASME B30.9 (2003) defines service temperatures for sling materials as follows:
The above supplementary data is for reference only. Actual service temperatures must be confirmed when purchasing. Sling assemblies will have fittings and other components which will affect service temperatures.
WORK LOAD LIMITS AND NON-UNIFORM LOADING
Products include lifting, mobilizing and securing products for below
the hook and ISO container handling. Tandemloc provides standard
corner fittings, lift beams, spreader bars, pipe end caps, container
lifting devices, lifting attachments, twistlocks, d-rings, heavy
duty casters, container casters, container lifting dollies and more.
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