In article ,
rrh wrote:
Surely a ring spanner of the right size will not mark the nut under
normal amounts of torque? The force will be distributed more evenly
than with an open ended spanner or wrench-plus-material-between-jaws.

Difficult to use a ring spanner where pipes are involved...

--
*Nothing is foolproof to a sufficiently talented fool.

Dave Plowman London SW
To e-mail, change noise into sound.