Definition(s)
Partial Overlay Equipment
Equipment where some, but not all, retained fluid-wetted surfaces are either weld overlaid or weld clad with a corrosion-resistant alloy or an austenitic stainless steel to resist metal-loss corrosion.
Source: API SPEC 6A, Specification for Wellhead and Christmas Tree Equipment, Twentieth Edition, October 2010 (Addendum November 2012). Global Standards