ASME B30.20-2003 pdf download

ASME B30.20-2003 pdf download.BELOW-THE-HOOK LIFTING DEVICES.
Interpretation: 20-12 Subject: ASME B30.20-1993, Below-The-Hook Lifting Devices Date Issued: June 11, 1999 Question: Paragraph 20-1.2.2 states: “A lifter shall be designed to withstand the forces imposed by its rated load, with a minimum design factor of 3, based on yield strength for load-bearing structural components.” Paragraph 20-1.4.2(a) states: “Prior to initial use, all new, altered, modified, or repaired lifting devices should be tested and inspected by or under the direction of a qualified person and a written report be furnished by such a person, confirming the load rating of the lifter. The load rating should not be more than 80% of the maximum load sustained during the test. Test loads shall not be more than 125% ofthe rated load unless otherwise recommended by the manufacturer. Test reports should be available.” Was the minimum design factor of 3 (based on yield) strength selected so that the dynamic loading (which could double the static stresses) would leave at least 50% margin before the device components would be exposed to their yield strength? Reply: No. A minimum design factor of 3, based on yield strength, was chosen to minimize the probability of lifter failure due to normal variability and uncertainty arising from design manufacturing and use of below-the-hook lifters. Interpretation: 20-13 Subject: ASME B30.20c-1998, Below-The-Hook Lifting Devices, Para. 20-1.2.2 Date Issued: May 23, 2000 Question (1): In interpretation 20-3, the lastline states: “This standard is nota design standard…” Paragraph 20-1.2.2 states: “A lifter shall be designed to…” This seems to be a direct contradiction. What is the intention of para. 20-1.2.2 if it is not a design standard? Reply (1): As stated in interpretation 20-3, “The intent of Section 20-1.2.2 is that the load suspension parts of a lifter shall be designed so that the static stress calculation of the rated load shall not exceed 33% of the yield strength.” Question (2): Is the intent of para. 20-1.2.2 to apply the 3 to 1 minimum design factor based on yield strength after considering stress concentration factors, laboratory testing and/or FEA (finite element analysis) software to determine the actual maximum stress? Reply (2): Please see Reply (1). Question (3): In para. 20-1.2.2 does it seem reasonable to apply a minimum design factor of 3, based on yield strength of the steel, to any part with no regard to the ultimate strength of the steel? Reply (3): Subjects not covered within the B30.20 Volume cannot be interpreted. The ASME B30 Standards Committee is presently developing the standardization ofdesign criteria for below- the-hook lifting devices, which will address this subject.
Interpretation: 20-14 Subject: ASME B30.20-1999, Below-The-Hook Lifting Devices, paras. 20-1.6.2(a) and (b), 20-1.6.3, and 20-1.6.4(e) Date Issued: September 26, 2000 Question (1): If a pressure gripping type lifting device is to be attached by another designated person and is not attached, or mechanically operated, by the person who operates the crane that hoists the lifting device, are paras. 20-1.6.2(a) and (b) intended to apply to the crane operator? Reply (1): No. Question (2): Do any of the recommendations or requirements defined in para. 20-1.6.3 apply to a crane operator: who does not attach or mechanically operate the pressure gripping lifting device; who is not the designated operator of the below-the-hook lifting device; whose sole function is to operate the crane that hoists the lifting device and its attached load? Reply (2): No. Question (3): If there are recommendations or requirements that are defined in para. 20-1.6.3 that are intended to apply to the crane operator as defined in Question (2) above, in which subparagraphs of 20-1.6.3 are they found? Reply (3): ASME B30.20 does not address crane operators as defined in Question (2). Question (4): What does the phrase “the load is correctly distributed for the lifter being used” mean as used in para. 20-1.6.4(e)? Reply (4): The phrase means as described in the lifting device manufacturer’s operating instruc- tions.