note
A note about using lead pipe. It is as others have noted a wonderful source of pure lead.
You should be cautious about melting it, depending on it's prior use.
A quick tale: I scrounge lead whenever and wherever I can. I have lived in Brooklyn, NY for many years in an area where the homes average 150 years age. Many still have lead plumbing from the 19th century and early 20th.
As these buildings get renovated, the lead gets replaced. I try to pick up the lead pipe when I can.
OK. I had a stock of it (still have some). It all had mineral deposits on the inside of the pipe from decades of use.
Those mineral deposits absorb water from the air. I did not know that. I had some of the stuff for years. I cut some up one day to turn into ingots. I had melted lead in a pot and had cut the pipe into pieces about three inches long. I placed one into the molten lead. It exploded. The pipe acted like a gun barrel and shot a gout of molten lead across the garage - about ten feet. Fortunately, the pipe was pointed away from me - merely by chance. Otherwise, I would have been hurt.
I check pipe now for deposits and preheat them if I find any.
Pete