Boldogs, Gothmogs and Sauron's New Clothes

[Neithan]

There are some who hold that Gorbag's reference, in his conversation with Shagrat, to the "bad old times" and the "Great Siege" derives from first hand experience, suggesting an extraordinary longetivity.

Does Tolkien say anywhere what the normal life span of an Orc is?

Whether this applies to Melkor alone, or also to lesser fallen Ainu, is not clear.

I think it only applied to Morgoth (and maybe Sauron since he became a lot like Morgoth in the end). After all, Ungoliant had offspring.