Kitchen Gas Appliances - gas piping codes

Last week, a neighbor installed some gas piping for two new appliances in our home. He is a plumber by trade, and led me to believe this was within his area of expertise. Crawling under the house today, I saw that he had done half of the job with threaded steel pipe, and half with copper tubes and sweat-fittings (soldered).
The latter worries me...
I'm wondering if anyone can tell me if this is up to code?

Hi:mr.jones

I could stand to be corrected here but there isn't anyplace in this country I am aware of where copper is legal or up to code inside or under a house.

The reason is the natural sulphurous and other inert chemicals in all natural gas corrode copper from the inside outwards.

Check with your local building and safety office regarding the codes in your area.

Good Luck,
TomBartco

Copper piping is okay to carry natural gas and propane, at least where I am ( western Canada). There are some consideration though: The soldier used on the copper must be a high temperature soldier ( if I remember right- 1000 deg. F ) basically silfous or silver soldier. Secondly pipe strapping: 4ft. intervals on the copper for strapping. Although I don't personally agree with all the uses of copper in gas piping they are allowing these days, by the code they are allowed.