Based in the UK and a client has specified that all valve handwheels on a project are to have breakable padlocks with a common key. The environment is high humidity, saliferous.
Unfortunately I have tried many suppliers in the UK but they are not familiar with breakable padlocks.
I can understand for lock-out-tag-out (LOTO) purposes requiring valves that can be "locked."  I'm accustomed to using lengths of chain fed through handwheels and around the pipe the valve is installed in then secured by a padlock.  There are all sorts of strategies that can be applied to the padlocks as far a there being a master key or individual keys but at the end of the day there's nothing unique about the butterfly valve other than the handwheel's ability to take a chain.  I've drilled holes in handles on small, quarter turn valves to run small diamerer cable through for similar locking-out purposes.
I agree, go back to your client for clarification.  Even asking you, as an engineer, to provide chain, cable, or padlocks would be a bit of a stretch.

MORE NEWS