TIG (GTAW) welding of copper-nickel

By janke Date 11-19-2005 23:32

Hi, I'm a new poster here.

My hobby is building Live Steam locomotives in 1:8 scale, and I'm contemplating buying a 160 amp DC TIG welder for assembling the engine frame (HRS and SS) and for making the boiler, which will be of 1/8" copper-nickel (10% Ni, 1.6% Fe, 1% Mn, balance Cu).

Can any of you point me to some source of info, or give me some hints?

Specifically, will 160 amps give enough penetration for 1/8" Cu-Ni ? The boiler is some 8" in diameter, internal pressure 100 psi. I want to play safe... ;-)

Thank you!

Jan-Eric Nystrom, Helsinki, Finland
my Live Steam website: http://www.saunalahti.fi/animato/steam

By MBSims

Date 11-20-2005 01:59

Jan,

160 amps DC is fine for welding this thickness of CuNi. I would recommend a machine with foot control to allow you to taper the current down on the end of the beads. CuNi is prone to crater pits and crater cracks if you pull the arc out too quickly. These will affect pressure integrity of your vessel.

Speaking of pressure integrity, I assume you will follow the applicable laws and regulations in your country regarding pressure vessel fabrication and safety. Here in the U.S., a steam vessel operating at 100 psig would be required to be manufactured by an ASME certificate holder following the rules of the ASME Boiler & Pressure Vessel Code, with qualified welding procedures and welders, applicable NDE and pressure testing, and review by an Authorized Inspector. What rules or laws would apply in Finland?

By janke Date 11-20-2005 10:08

- What rules or laws would apply in Finland?

As I see it, the European Union's rules apply: when a pressure vessel is less than 50 bar-liters (total volume times pressure, approx 150 psi-gallons), no official testing is required. Of course, I'll make a 2.5 x hydro test myself, that goes without saying.

There are no specific rules for building model boilers in Europe that I know of, but there are in Australia, published by the Australian Miniature Boiler Safety Committee, and I've followed those on my previous two projects, where the boilers are silver-soldered. Also, I re-test my boilers to 1.5 x working pressure every year.

- CuNi is prone to crater pits and crater cracks if you pull the arc out too quickly.

The TIG welder I'm looking at (GYS 160 HF, made in France) has an automatic, adjustable ramp-down of the current. That should be adequate... ;-)

Thanks for your replies, any and all further comments are appreciated.

regards,
Jan-Eric

By billvanderhoof (****)

Date 11-20-2005 07:31

That's just too cool for words.
Bill

By ssbn727 (*****)

Date 11-20-2005 10:32

Heck!
You Ca'nt even sell sugar!!!

Respectfully,
SSBN727
Run Silent... Run Deep!!!