3P Services Inspects Tesoro Kapolei Refinery Hawaii Sub-Sea Pipelines
03 February 2010
In-line inspection of pipelines using high-resolution, instrumented 'pigs' based on magnetic flux leakage (MFL) or ultra-sonic (UT) technologies is now a necessary diagnostic tool for responsible operators of transportation pipeline networks. Marine loading lines, such as those connecting export or import terminals with SPM/PLEM combinations located some kilometers offshore, have often been constructed before this inspection technique was available and have consequently been considered 'un-piggable'. Alone among the in-line inspection industry, 3P Services have developed over the last several years a technology of bi-directional MFL inspection. The first free-swimming bidirectional inspection was achieved in 2000.
Currently, inspection of marine loading lines is often achieved using tethered tools. However, there are some serious disadvantages associated with the tethered approach including range limitations: drag in bends, potential damage to the inside of the pipeline from the tether, the pipeline must be decommissioned, and possibly incomplete inspection data. Furthermore, cleaning represents a difficulty of its own when no pigs can be applied. 3P's technique is a free-swimming tool that is pumped from the launching position to the PLEM and then back to the launching position.
In early 2008 3P Services was contracted to inspect the shore to offshore marine manifold terminal pipelines of the Tesoro Refinery in Oahu, Hawaii/US. It is a tanker loading / unloading system consisting of a 16in bunker oil loading line, a 20in white oil loading line and a 30in crude oil loading line.
Inspection of the three pipelines presented some unique challenges, including an initial cleaning programme. In addition there were existing 1.5D bends inside the pipeline and we were requested to build a so-called Combo tool accomplishing different inspection technologies like GEO geometric, XYZ inertial mapping and MFL metal loss sensors. Therefore it was necessary to design a new tool to meet all the requirements. The concept of assembling special Combo tools for specific projects is common practice to 3P Services. We have substantial experience of successfully mounting the different sensor systems on the same pig chassis, and special configuration of the on-board data management systems to acquire and store the sensor systems' output.
Besides the technical challenges of this project each marine loading line's particular configuration also obliges a unique solution to pipeline operations during pigging. Tesoro wanted to perform the inspections in fresh water. To develop an optimised pigging procedure we worked closely with them and also shared our experience of inspecting marine lines with them. Cleaning and gauging of the pipelines was performed by Tesoro and Coffman Engineering but also supported by 3P Services equipment and instruction to prepare the pipelines for the inspection tools. When pre-inspection cleaning was finished, inspection operations started.
A special need of bidirectional inspections is to monitor the tool's location during the run. This enables the tool to be stopped at a predetermined location, the so called 'turn-around point'. For this application 3P Services developed special sub-sea antennae to detect the arrival of the pigs. These have been proven in previous projects to be extremely reliable, since they use different independent pig detection technologies at the same time and include redundancies.
Inspection work was completed in the beginning of October 2008. All lines have been successfully inspected and the applied sensor technologies delivered reliable data.
