Cracks in beam copes after galvanizing

Date 04-02-2005 19:33

Got a batch of A992 beams back this week. Many cracks in copes. Radii good. Finish after oxyfuel cutting and grinding is good. Some have clips welded on end. Some clip fillet welds are within an inch of cracks, others are a few inches away. One beam has holes only for bolt-on clips; no welding. How common is this because I have not seen them before. Am I just blind or is it reasonably rare?

Our engineers will be getting involved, but looking for feedback about cause(s) and how others handle repairs. Obviously will grind zinc off. Also will be using MT to locate and confirm cracks have been removed. D1.1 silent about NDE after repairs, but will MT anyway after cooling to ambient.

Any suggestions or insight welcome. Thanks.

By RBeldyk (**)

Date 04-03-2005 02:35

Last summer I wrote an article in Inspection Trends on Galvanization related Cracking of Structural Steel. The British Steel Construction Insitute is piblishing a guideline on this, might be out now.

Here is a link to the abstract for a paper about galvanized related cracking in a parking garage structure in Germany http://www3.interscience.wiley.com/cgi-bin/abstract/109568368/ABSTRACT Professor Gerhard Sedlacek discusses the tin and bismuth alloying in the galvanizing causing the problem.

Have an analysis done of the galvanizing look at tin, bismuth and lead levels.

Check the galvanizing thickness, the tin and other low melting point elements results in thinner galvanizing.

MT with AC, Yoke, red powder look for fuzzy indications.

By TimGary (****)

Date 04-03-2005 17:57

Check out some of these past discussions on Liquid Metal Embrittlement.

Tim

http://www.aws.org/cgi-bin/mwf/topic_show.pl?id=3767#15260

http://www.aws.org/cgi-bin/mwf/topic_show.pl?id=5177#23771