On Sun, 15 Mar 2015 14:48:22 -0500, dpb wrote:

On 03/15/2015 1:46 PM, wrote:
On Sun, 15 Mar 2015 10:01:04 -0500, wrote:
On 03/15/2015 9:36 AM, trader_4 wrote:
...

I don't know what size pipe he's talking about where it was welded.
I've seen welding done to join large gas mains, eg 12" diameter, but
never the typical small lines to a residence. Those are just black
pipe using couplings/fittings. They are supposed to be covered in a tar type
compound to protect them from corrosion. ...

I also was puzzled; I'd surely think never do such a thing on smaller
diameter than 6", either......
...
4 inch and up MUST be welded. 2 inch and up are commonly welded
lines.

Not sure where that's coming from...from the PSEG manual I quoted earlier...

"Steel piping up to and including 1-1/4 inches shall be of the threaded
construction with line pipe couplings. Steel pipe larger than 1-1/4
inches may be of threaded, welded or compression coupled construction."

And that disagrees with what I said how??? You may find in some areas
1 1/4 to 4 inch pipe MAY be threaded - while in other areas all of
those, or most of them, will be welded.

I think if you look farther you will find 4" and up are never
threaded. However, very unlikely you will find large pipe on the
customer side of the meter, so your quote is irrelevent in the case of
the feeder line to the house IN MOST CASES, because, at least here,
the meter is at the house.

The above is from the section applying to the customer side of the meter
for residential and similar installations.

I'm sure some industrial facilities have more stringent requirements as
I'm sure other jurisdictions may as well but considering it "common" for
lines as small as 2" to be welded for such an application strikes me as
"not likely" at least anywhere around here.

Of course, now anything new underground would be plastic.

High pressure gas lines of any size are virtually ALWAYS welded.

Sure, but that's another animal entirely.