[ RadSafe ] Fw: [OEM] TIG Welding and Titanium face implants

[Richard L. Hess]

Please do not rely on what I am about to say as 
this is just some preliminary thoughts for 
further research. I am a broadcast engineer not a CHP nor MD.

It appears that the bulk of TIG welding is done 
with mains-operated AC arcs. There appears to be 
benefits to using AC over DC in the welding process.

http://www.twi.co.uk/j32k/protected/band_3/ksgbm001.html

Indicates that the HF energy introduced into the 
arc for starting the arc (and perhaps for 
stabilization during the process). One reference 
indicates that this is 50,000 Hz and above. 0.05 
MHz. A microwave oven operates at about 2,450 MHz 
(near the 802.11 b/g spectrum-joy). 
http://www.ccohs.ca/oshanswers/phys_agents/microwave_ovens.html

I don't see a lot of energy being available for facial heating.

The biggest risk I see is aiming a lot of energy 
in the direction of the person's face when that 
energy would be of such a frequency as to 
resonate with the metal implants.  In that case 
there could be heating of the implants. Let's 
assume the implants are less than six inches long 
and little power will be transferred to them if 
they are less than 1/8 of a wavelength (both 
conservative numbers driving the frequency 
lower). So what is the frequency of to be 
conservative again a 2 m wave in space? It's about 150 MHz.

Would we expect to see substantial energy at 150 
MHz from this arc plus the HF ignitor? I could 
find any spectrum plots, but my first guess would be no.

Now there may be other techniques that I am not 
aware of using microwave energy to heat the 
metal, but TIG looks like a conventional arc with 
a shielding gas and a non-sacrificial tungsten electrode.

More research required. Hope this out-loud 
thinking was at least slightly helpful.

Cheers,

Richard

At 04:31 PM 1/14/2006, John_Rich at fpl.com wrote:
>Radsafers,
>
>Just to get the conversation started - - Isn't TIG welding low voltage,
>high current, with a small arc.  If so, how would significant microwave
>energy be generated?   In addition, if this is an issue, couldn't the
>welding mask be lined with a copper screen to shield the workers face
>(half a Faraday Cage)??
>
>
> > A third  year journeyman welder has titanium implants in his face due to
> > facial fractures from his youth.
> >
> > His technical college welding instructor told him that TIG welding is
>like
> > putting his face in a microwave.  Now he is worried and wants the
>titanium
> > implants removed.
> >
> > Would welding cause any problem with titanium face implants?
> >
> > I could not find anything relevant to this subject.
> >
> > Harold E. Hoffman, MD, FRCPC, FACOEM
> > Occupational & Environmental Medicine
> > #402 College Plaza, 8215-112 Street
> > Edmonton, Alberta, Canada  T6G 2C8
> > Telephone (780) 439-9491
> > Fax (780) 439-9091
> > Email:  occmed at telus.net
> >
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Richard L. Hess                   richard at richardhess.com
Aurora, Ontario, Canada       http://www.richardhess.com/
Detailed contact information: http://www.richardhess.com/tape/contact.htm