Corrosion on fire sprinkler pipe

[hefy_jefy]

Hi all,
I have a sprinkler system in my house, the feed comes directly from the mains water supply via its own meter. I see a large (2 1/2") pipe coming into the house. My worry is corrosion of this pipe. I am wondering whether this large pipe is in fact the outside of the actual pipe or if it is just frost protection for a smaller pipe inside. The sprinkler pipework in the house is only 2" and the pipe at the meter looks to be 1". The pressure in the system is 75psi so a failure of this pipe could be a major problem.
It seems odd that the pipe is so large, is this typical? Also the pressure seems high?
Any thoughts are most welcome!
Geoff

 

[Snoonyb]

Welcome.

The pressure is pretty standard and is dictated by you local fire authority.

The corrosion you see in the #2 photo is typical for black Iron pipe.

You could clean it and then wrap with Fletcher Coat.

 

[hefy_jefy]

OK thanks, the house is about thirty years old, I will do as you suggest. I guess there is a lifetime for these buried pipes and at some point they will have to be replaced? The corrosion is worse of course right at the point where the pipe breaks through the soil level. Will need to keep an eye on it!