An apparatus for controlling a weld penetration profile on a workpiece having an outer region, an inner region, and one or two open conduit ends comprising: a welder configured to create a weld joint from the outer region of the workpiece, wherein the weld joint penetrates from the outer region of the workpiece to the inner region of the workpiece; a gas supply in fluid communication with the inner region configured to provide a shielding gas to the inner region of the workpiece, wherein a pressure of the shielding gas provides a force that limits weld penetration; and being characterised by the following: a pressure gauge in communication with the inner region, wherein the pressure gauge is configured to measure the pressure of the shielding gas present in the inner region; a valve in fluid communication with the inner region configured to adjust the shielding gas pressure within the inner region; one or two seals coupled to the one or two open conduit ends to seal the inner region so that the shielding gas only escapes via a pre-welded abutment of the workpiece; and a system electronics in communication with both the pressure gauge and the valve is configured to receive a pressure signal from the pressure gauge and electronically adjust the valve accordingly so as to maintain the pressure within the inner region within a predetermined pressure range while the welder seals the pre-welded abutment of the workpiece, wherein the workpiece comprises at least a part of a flowmeter. a welder configured to create a weld joint from the outer region of the workpiece, wherein the weld joint penetrates from the outer region of the workpiece to the inner region of the workpiece; a gas supply in fluid communication with the inner region configured to provide a shielding gas to the inner region of the workpiece, wherein a pressure of the shielding gas provides a force that limits weld penetration; and being characterised by the following: a pressure gauge in communication with the inner region, wherein the pressure gauge is configured to measure the pressure of the shielding gas present in the inner region; a valve in fluid communication with the inner region configured to adjust the shielding gas pressure within the inner region; one or two seals coupled to the one or two open conduit ends to seal the inner region so that the shielding gas only escapes via a pre-welded abutment of the workpiece; and a system electronics in communication with both the pressure gauge and the valve is configured to receive a pressure signal from the pressure gauge and electronically adjust the valve accordingly so as to maintain the pressure within the inner region within a predetermined pressure range while the welder seals the pre-welded abutment of the workpiece, wherein the workpiece comprises at least a part of a flowmeter. a pressure gauge in communication with the inner region, wherein the pressure gauge is configured to measure the pressure of the shielding gas present in the inner region; a valve in fluid communication with the inner region configured to adjust the shielding gas pressure within the inner region; one or two seals coupled to the one or two open conduit ends to seal the inner region so that the shielding gas only escapes via a pre-welded abutment of the workpiece; and a system electronics in communication with both the pressure gauge and the valve is configured to receive a pressure signal from the pressure gauge and electronically adjust the valve accordingly so as to maintain the pressure within the inner region within a predetermined pressure range while the welder seals the pre-welded abutment of the workpiece, wherein the workpiece comprises at least a part of a flowmeter.