Below the Hook Hoist Attachment Capacity?
I have several customers that are machine shops. All have very skilled craftsmen including machinists and tool & die makers. Most of the smaller companies do not have large engineering departments loaded with BSMEs. They may have people on staff that are incredibly talented and experienced in mechanics, materials, and forces, but not degreed. These customers machine steel, iron, or aluminum castings that can weigh a few ounces to several hundred pounds. These castings are in all kinds of shapes and sizes. If the castings weigh > 25-pounds the employees lift these castings into the machining centers using hoists. These hoists most often have below the hook attachments made in house. Being a former tool & die apprentice myself, I am amazed at the craftsmanship and design on these dedicated attachments. However, how does the company comply with 1910.179(n)(2)(ii) to set a capacity limit on the devices they make themselves?
In a cursory review ASME 30.20 – 2018 Below the Hook Attachments talks more about inspection and training. ASME BTH-1-2017 Below the Hook Attachments talks more about construction. However, I got to page 22 and holy smokes! I have not seen that much math since I barely got through my first term of calculus, and knew there was no way I could get through another entire year to be a BSME myself! Is there some practical simpler way that a small company can certify their hoist attachments, without all that engineering and expense? I know employers have been cited for hook attachments without capacity ratings.
One of my customers has talked about buying a Finite Analysis software package. This software might do some of the math. Anyone else have any experience with this and certification of their own attachments?
Comments (8)
We ran into this all the time at my last employer (a machine and fab shop) where they needed to engineer/design various "in-house" lifting attachments/devices, whether they were used on forklifts, overhead cranes, or anything else. At the end of the day, there is no "shortcut", per se. Any lifting device has to have the proper rating listed on it, which has to be calculated by a "qualified person" (often an engineer, but it doesn't necessarily "HAVE" to be).
If you look at ASME B30.20 (2018 edition), it states the following in their "Structural and Mechanical Lifting Devices" section (on page 5 of the standard if you have a copy of it):
"Structural and mechanical lifting devices shall be marked with, but not limited to, the following information:
(1) manufacturer’s name and contact information
(2) serial number (unique unit identifier)
(3) lifter weight, if over 100 lb (45 kg)
(4) cold current (amps) (when applicable)
(5) rated voltage (when applicable)
(6) rated load [as described in (a)]
(7) ASME BTH-1 Design Category
(8) ASME BTH-1 Service Class"
If you refer to ASME BTH-1 (2017 edition), it states that "Lifting devices shall be designed by, or under the direct supervision of, a qualified person." Similar to OSHA's definition, ASME's definition of a qualified person is "a person who, by possession of a recognized degree in an applicable field or certificate of professional standing, or who, by extensive knowledge, training, and experience, has successfully demonstrated the ability to solve or resolve problems relating to the subject matter and work".
Even if you used the software to do the math (such as the FEA software you mentioned your customer may buy), you would still need someone to "sign off" on it saying that the data/calculations provided by the software is truly accurate. There's too much risk of human error, even with software, to not have a qualified person do the proper calculations.