Steel in the News
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Posted by Geoff Weisenberger on February 4, 2008 at 11:56 AM.
Questions first arose a few months ago about the mechanical properties of imported HSS, as well as the credibility and reliability of the documentation provided when the imported products entered the U.S. and Canada. At that time, AISC advised that it was premature to draw any conclusions until information could be assembled and independently reviewed.
Since then, we have collected the available data, which represents a limited number of tests on mechanical and chemical properties. AISC staff and industry materials consultants have reviewed this data and noted the following:
Many of the tests were performed to different procedures and protocols than are required for HSS in ASTM A500, and therefore lacked uniformity for analysis.
Testing speeds varied significantly among the tests that were reported to us.
There was no control or tracking of the location of test specimens as to what position they came from in the width and length of the coil.
Despite these factors, each of which will induce significant variations in the testing results, the mean of the independent test results was similar to the mean of the material test report (MTR) values. As should be expected, these factors did result in a higher standard of deviation. Accordingly, it is AISC’s conclusion that this does not represent a building code issue.
“Perhaps the most important recommendation is that the buyer should know and evaluate their material supply chain,” stated Roger Ferch, P.E., AISC’s president. “As with any other purchase, don’t just look at the quoted price, but also consider the quality, reputation, and experience of the supplier.” Also, it is important to verify that the material and its documentation meet ASTM A500 requirements when they are received. A few MTRs AISC received with the information submitted to us were for material that had been accepted by the purchaser with metric values reported on the MTRs that did not meet the minimum ASTM requirements. Such deviations can be avoided with simple receiving inspection of the material to ensure it is as it was ordered.
In addition, AISC has received reports of seam weld quality concerns with imported HSS. The seam weld deficiencies that led to these concerns can be seen on the California Division of the State Architect website (www.dsa.dgs.ca.gov/labs/hss_pictures.htm), based upon their discovery of weld seam problems in some imported HSS. As can be seen in the photographs on the site, the defective material is such that the defects are identifiable through visual inspection.
The limited information that is available to date on this topic and the anecdotal nature of reports of weld seam defects leads us to believe there is no crisis in HSS supply, and no dramatic response is necessary. “Producer quality control is an essential part of the supply chain, and we believe that North American producers are routinely exercising good QC processes,” explained Louis F. Geschwindner, Ph.D., P.E., vice president of engineering and research at AISC. “Receiving inspection at various levels is a routine method to evaluate supplier quality control, and we believe that steel service centers and fabricators are properly performing this function. Where a supplier is new or unknown, these reports may be cause to increase vigilance to ensure that the material they supply is acceptable.”
AISC will continue to monitor these situations and keep the design community and construction industry informed of any changes. If additional information is needed, please contact AISC’s chief structural engineer, Charles Carter, P.E., S.E., at firstname.lastname@example.org or contact the AISC Steel Solutions Center at email@example.com.