Tri Tool was contracted to perform video inspection and laser weld profile measurement as a mission critical part of welding quality control for petroleum transmission pipelines. This required a stroke length beyond the scope of standard non-rotating cylinders. The weld inspection was to be performed under demanding conditions on highly specialized corrosion resistant alloy lined pipe, a process that had not previously been attempted. Accordingly, a unique vendor was needed for a custom cylinder such as this.
Mechanical Requirements of the Cylinder
Tri Tool needed a cylinder manufactured to provide an extra long (2 meter) stroke length. In addition, the cylinder needed to provide an aligned, non-rotating stroke to accurately position both video and laser optical components located by the cylinder rod in an ID bore as small as 111 mm. Beyond basic specifications and function, the extreme nature of industrial pipeline production required that an increased performance and durability level of the cylinder was crucial.
Custom Cylinder Application
The cylinder was an outsourced component used in a custom configured Tri Tool Internal Line-Up Clamp (ILUC) clamp that provided weld fit-up alignment, gas purging, and both 2D imaging and 3D surface measurements of the ID weld root.
These operational capabilities were needed as part of the on-shore fabrication of oil transmission pipelines that would be deployed on the ocean floor to transmit oil from wellheads to a surface platform.
In the first stage of the application, 40ft lengths of corrosion resistant pipe were welded to create mile long interim pipe sections. In the second stage, the mile long sections were joined into a single continuous pipeline. The resulting pipeline (over seven miles long) was placed on a large spool located on a pipe lay vessel docked alongside the pipe fabrication yard.
Performing critical weld inspection down-hole in long pipe sections required that precision weld alignment clamps be capable of operating reliably at the end of an extremely long umbilical that can transfer Ethernet control inputs and inspection data over fiber optic lines.
Pipe inspection was performed using Tri Tool’s ILUC with integral SMC cylinder that located the ID weld root 2D video and 3D laser dimensional inspection system, connected to a 40ft umbilical going to the inspection system controller.
The purpose of the custom cylinder was to provide a (plus or minus) 1 meter variable offset due to the large tolerance of the overall pipe lengths. A large tolerance was required because the operator needed to align and use the ILUC at one end of the pipe while also aligning and using the inspection system at the other end of the pipe.
In the second stage of the application, operators performed similar inspections but with the ILUC connected to a 5200ft umbilical and large umbilical winch system.
Field Results of the Custom Cylinder
Despite the harsh and physically demanding operational environment, the SMC designed and built cylinder proved to perform magnificently. Experienced, on-site service personnel described the utilization level of the cylinder as “abusive.” The torsional forces applied to the cylinders caused a 90º rotational displacement at some points. Even with this extreme flexural distortion, the cylinders consistently did not leak and performed beyond reasonable expectations.
It is through the successful application of proven custom engineering and quality manufacturing that novel and previously untried field procedures are introduced to the offshore petroleum development industry. New quality inspection processes such as this are a welcome development to the offshore industry that is under more and more expectations to perform oil production and transmission with increased safety and attention to environmental concerns.
Tri Tool thanks SMC for their design and manufacturing assistance in ensuring that this project was an engineering success.