Provided are metal structures and methods of forming such structures for use in oil, gas and/or petrochemical applications that are joined with non-ferrous weld metal compositions or a high alloy weld metal compositions. The welded metal structures include two or more segments of ferrous or non-ferrous components, and fusion welds, friction stir welds or a combination thereof bonding adjacent segments of the components together, wherein the welds comprise a non-ferrous weld metal composition or a high alloy weld metal composition that is substantially different from the metal composition of the two or more components. The resultant welded structures exhibit improvements in fatigue resistance, toughness, strain capacity, strength, stress corrosion cracking resistance, and hydrogen embrittlement resistance compared to traditional iron-based weld compositions. The structures and methods of forming such structures are advantageous in joining metal components in applications for natural gas transportation and storage, oil and gas well completion and production, and oil and gas refinery and chemical plants.