Powder Coat on 4130

On Mar 22, 8:29 pm, "Phil" wrote:
Hello
Was watching American Chopper this evening , I see things on that show
that make me cringe but I do enjoy the antics of that family, they always
refer to Pipe if they are building a frame out of Tubing etc. , this evening
they were working on a dragster bike for NAPA and when it came time to paint
the machine they said that powder coat couldn't be used because of the heat
involved would ruin the 4130 tubing , seems like a lot of engine mounts and
other A/C parts will have to be junked , would like to hear some thoughts on
this concept , as an A/C welder it is of interest to me.
Thanks
Phil Lohiser
EAA 12873

The thing about powder coating aircraft structure, is that the places
that do it are not controlled as well as FAA designated shops. Some
might do it right, and some, well.... Also, there is a big difference
in steel vs aluminum, as the temperature involved (~400 F) does not
harm 4130, but might heat treated aluminum, especially if the shop
doesn't pay close attention and gets the temperature much higher
during the process. Most 4130 tube aircraft structures use normalized
4130, so there is no heat treat to worry about. Aluminum is almost
always heat treated, so there is an issue. It is a fact that 10 years
or so ago, a scuba diver had his aluminum tank powder coated when it
started looking bad, and when he was having it filled, it exploded
killing one guy and causing another to have his leg amputated. If the
structure doesn't use heat treated steel, you are probably OK. Powder
coating heat treated aluminum is a definite no no.

Bud