Run 150 feet natural gas line to garage what size and type of pipe.?

The size of the piping depends on the amount of gas needed for the appliance in the garage. But lets assume that you need to operate a 160,000 Btuh appliance.

1 inch diameter schedule 40 metallic pipe can be used for Natural Gas,@ 1/2 psi pressure, with a specific Gravity of .60

3/8 inch diameter semi-rigid copper tubing can be used for Natural Gas if your delivery pressure is 2 psi and a regulator is installed at the appliance