Replacing a ball valve: how to seal the threads?

[VicMallows]

Eventually I have used sikaflex 291 because I thought that any thread lock like loctite would be overkill for the job and would have made it very difficult to remove the ball valve next time if needed be.

I just hope that you DO find it easy next time. I was dreading changing a ballvalve between tides on the mud mooring recently in case I broke the hull seal on the skin fitting. Fortunately I had used PTFE tape originally and the valve unscrewed easily. On domestic plumbing these days I always use liquid sealant because it is so easy, but it certainly needs quite some torque to undo if necessary in the future.

 

[superheat6k]

Surely you jest?

Don't understand your concern. Works for me.

 

[vyv_cox]

Don't understand your concern. Works for me.

Just that it contradicts the advice given by every expert on installing olives in compression fittings. Probably doesn't do much harm in large bore water fittings but definitely will in fuel.

 

[nigelmercier]

Just that [PTFE tape] contradicts the advice given by every expert on installing olives in compression fittings...

Quite so. PTFE is a thread sealer.