Re: [PSUBS-MAILIST] weld testing

[William Alford <walford@dbtech.net>]

At 06:43 AM 4/11/2002 -0400, you wrote: 
>
> for my understanding the first sign for hull failure are some local ruptures
> in a welding only some micrometers large..... if you sprinkle some color
> powder or simply flour from the kitchen or talcum or foot powder over all
> weldings and seals


I found this quite interesting--

Magnetic Particle Testing or MAG Testing - This is a method of testing
metal for
cracks. The operator uses an electromagnet to send an electric charge through a
piece of metal while sprinkling a fine iron powder over the test area. A crack
in the metal will cause a positive and negative charge to form on either side
of the void attracting the iron powder which will line up with the crack.
http://www.iets.com/testing/mt.htm , http://www.fema.gov/library/353appf.pdf ,
http://www.cnde.iastate.edu/ncce/MT_CC/History.html - this last site is the
best
explaination of technique- click "next" at top-L to proceed thru contents.

William Alford
walford@dbtech.net

Tout comprendre c'est tout pardonner