External Weld Station
Two external weld stations are used to make the two external welds.
Each welding station is equipped with a camera and monitor. The welding process can be followed by the welding operator looking at the monitor. This will prevent the welder from breathing in fumes from the weld operation; this will also
prevent fatigue to the welder and thus produce less weld repairs for double joint welds.
The Elevating Nest Unit allows movement of an Internal Line-Up Clamp. The clamp holds two pipes together during joining at first Weld Station. When the thickness of the concrete coating changes, the nest rack, for the internal line-up clamp, needs to changed as well. Therefore nest rack can be remotely elevated using hydraulic cylinders. Also, the nest can be rotated to keep the internal line-up clamp in an upright position.
The No-Tack Unit (NTU) is used to control and position pipe ends at the beginning of the first weld of the double joint process. The unit allows the first weld pass to be done entirely by submerged arc welding without tack welds to temporarily hold the pipe together.
The external welding equipment is mounted on support structures. The welding operator for the second external weld station is located on the support structure. This provides maximum protection for the operator because he is above the pipe and not between pipes during operation of the barge, this is an important safety advantage. Also, the welding equipment and consumables (flux and welding wire) are located on the support structure; therefore, they can be changed easily during production by the operators.
Internal Weld Station
This station makes the internal weld on the inside diameter of the pipe.
Welding can be done manually or by a controlled weld head with camera and monitor.