a containment case for a gas turbine including : a cylindrical outer casing extending about an axis and having a radially outer and a radially inner surface ; a coaxially arranged cylindrical inner skin formed of a harder material than the outer casing joined to the inner surface of the cylindrical outer casing ; and an array of ribs extending radially from the inner skin towards the axis . the case for can have the coaxially arranged cylindrical inner skin formed of a harder material than the outer casing joined to the inner surface of the cylindrical outer casing by a galvanic isolation layer .