I understand that you can design non Uk standard ring circuit

Probably better to think of a 20A ring as 'non-conventional' rather than 'not standard' - as the latter implies it doesn't comply with standards (in this case BS 7671) - which isn't really the case. BS 7671 simply provides the 20A cable and 30/32A OPD as one arrangement that is 'deemed to comply' - any other arrangement can still comply with BS 7671 as long as it follows the basic principles of circuit design that BS 7671 requires.

This ring got 4 points served. 2x 1 KW wall heater,1 undersinK 10 L water heater( could you not confirm current as no access to) and 1 twin socket.

If it's a domestic sort of environment that may well be fine for a 20A circuit - you'd have to check the particular circumstances but  the water heater will likely only draw power for a few minutes per hour on average so even with both wall heaters on full blast there's likely enough spare capacity for a socket or two. Remember small overloads of short duration aren't prohibited (just think about the diversity rule for cookers - just 30% above the first 10A and 5A for the socket) - that's part of the essence of diversity - conductors and protective devices are co-ordinated to ensure no damage occurs.

   - Andy.

No Sparkingchip.Wiring is single in metallic conduit.

Andy it is on industrial environment. 2 ring circuit installed  1L1 20A, 1L2 32A with less load. Anyway It has been decide to replace them with rcbo. Noone want to put their name to anything in case something bad happens Also To be honest I just want sick to simple rules and not think a lot . Thank you all