frightening failure :O

Date 08-23-2005 19:42

A company i contract for asked me to repair some brand new aluminum truss, which has fractures in almost every weld. when i was in the event industry, i used miles of this stuff, and it is manufactured by one of the pioneering truss companies, which shall remain nameless. I have seen only one other weld failure from them in the last ten years. The last time, i called them to let them know, and they blamed our crew for mishandling, however the welds were clearly not penetrated. this time, most of the welds are cratered, and the welds have centerline cracks, but from both ends. plates, laces, every joint. this specific truss was not even loaded when it was used. i have cleaned and TIGed it with no problems, however, it bothers me that such a reputable company could be sending this stuff out. if you heard of the justin timberlake accident, you know how this truss is used, often with serveral tons suspended from it. is this all from poor welds?? how many bad sticks are out there??

By andy

Date 08-24-2005 07:41

Hi superK -

When there are situations like this it is often very very difficult to diagnose by words alone and sometimes pictures dont help either. It sounds like an independent metallurgical investigation is required. It also sounds to me like the company that asked you to repair the trusses needs to instigate the investigation with the original supplier. Now, having read your post while composing this reply it also looks like you've completed the welds. Why didnt the company that asked you to repair just send the trusses back to the original supplier? Now that you've carried out a repair who is liable for the performance of the trusses in service... sounds a bit complicated to me.

Andy

By superK

Date 08-26-2005 23:15

the special events field is very fast paced. This situtation did not allow return and replacement time. It was a rush item, which had to be in place. The last failure i dealt with was the same, with the company shipping out new units while we made do the bad ones. i refused to make the repair the first time, because i wanted the company to see what had happened, but this time, that was not an option.
when i thought more about the problem, it was also poor weld placement, and a design that placed load on the 2 pieces, pulling the weld apart. but all the lacing of the trusses have deep craters and fisheye fracturing. even where craters were welded over, those buttons were cratered.
I told the company that the repairs i made were temporary and i would cover costs of replacement if the manufacturer refused because of the repair. mostly, it bothers me that there is just so much of it out there, because most users would not know a good weld from a compromised one. thanks andy