Replacing seacocks

[pvb]

How long does a through hull fitting last.When do you know is time to change them and the seacocks.What is said by the surveyors and insurances.Thanks

I think the important thing is always to go for bronze through-hulls, which should last almost for ever. For ballvalves, DZR is OK I reckon, because they're quite meaty castings and because they're likely to need replacing for other reasons (leaks, etc) within about 20 years.