If paint is used it should not be oil base end it should be reapplied every 35 years. Fiberglass, Urethane and Isocyanurate. These types of insulation can be bought in preformed halves. They must be protected from the weather by a watertight PVC or metallic jacket. The slits in the jacket should be positioned on the downward side of the pipes and taped over with water proof, weather resistant tape.
Pressure tests the plumbing before insulating.
The water heater tanks should be insulated to at least R11. Check manufacturer literature to see if the tank is already insulated to this level. If not, it is necessary to add an insulating jacket. R11 fiberglass batts, wrapped around the tank and secured with duct tape, work well. Many Oregon utilities provide free water heater wrap services.