These get driven over, fall off, turned into Frisbees and generally mangled. However
the lid is a VITAL safety feature as it keeps water out of the bitumen and acts as
a fire snuffer in the event of an overheat. It is part of the boiler and must be
in good and serviceable condition.
Simply measure the diameter and let us know what it is ....
If you don't have the lid any more, just measure the diameter over the pan walls