A welding head for a welding apparatus, the head comprising an outer face attachable to a welding device such as an electron beam gun or laser, an inner face sealable to a workpiece, and an outer sealing ring and an inner sealing ring situated within the inner face and disposed on either side of an evacuatable region, wherein the inner face has a teardrop-shaped profile. Outer and inner sealing rings can be inflatable or formed from different materials, the outer sealing ring being formed from a material with a Shore hardness of between 50 to 70 and the inner sealing ring being formed from a material with a Shore hardness of 20 to 40. A bridging seal can extend from within the inner sealing ring to the outer sealing ring.