Is it very common for the main natural gas pipe in a house to be black and to have an outside diameter of 1.5"

Question

Is it very common for the main natural gas pipe in a house to be black and to have an outside diameter of 1.5"

Answer 1

Yes. The normal pipe size for gas main lines is 1-1/4". They are usually black steel pipe. (called black iron pipe)

Answer 2

In my area 1 1/2 inch pipe isn't used much residentially but is black iron.  You must have many gas appliances.