FSWbot - Innovation UK Project

Friction Stir Welding Crawler for Internal Repair and Refurbishment of Pipelines

Abstract

"Steel pipelines corrode due to of the nature of the liquids they contain. Also, cracks can form over time leading to failure and leakage of the contents, resulting in severe economic losses and environmental pollution. To avoid this, inspection, evaluation, and repair activities are performed periodically. Internal cracks and areas of corrosion and metal loss are monitored by the use of intelligent inspection devices (PIGs) which carry special sensors. Sections of pipeline that are found to be likely to fail are reinforced using an externally applied bolt-on clamp which is both costly and is difficult and dangerous to install.

The FSWBot project will see the development of a radical new solution to internal corrosion and cracks that form inside pipelines. Meeting the objective will result in a much cheaper, safer repair process that will enable pipeline asset owners and their service providers to produce very high- quality welds in steel pipelines without shutting down and purging petroleum pipelines and without the use of divers and surface vessels. This is of enormous importance especially in respect to inaccessible pipelines and those which are installed in parallel groups where space around pipes is restricted.

The objective of the project is to develop a robotic platform with a payload consisting of unique hydraulic friction stir welding equipment which produces no sparks. Data obtained by prior high-resolution mapping of anomalies that are produced by metal loss and corrosion will be used to provide information for mission planning. Repair will be carried out in-situ using no external power and no welding consumables. The robot will generate electricity from the liquid flow in the pipeline via a variable pitch turbine diving a generator, which will supply power to a hydraulic pump and a battery which drives the magnetic tracks.

FSWBot will bring about a step change in the competitiveness and growth for 3 UK business -- namely Forth Engineering, Proserv and Innvotek."

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We have recently begun work on a collaborative project, FSWBot, which aims to develop a repair technique for sub-sea pipelines.

The project, sponsored by UKTI, seeks to integrate several state-of-the-art technologies including friction stir welding, and ultrasonic NDT onto a robotic system that can be deployed to conduct repairs on pipelines without the need for the pipeline to be closed down for the duration of the repair. If successful, it is envisaged that the system could be further developed to carry out a range of sub-sea repair and fabrication tasks.

The consortium would be interested in hearing from companies that might have an interest in such a system, in order to consider their potential needs and applications, thus helping to ensure that its benefits can be brought to as many industry sectors as possible.

With many Oil pipelines being kept in service beyond their original design life, and others being used to transport corrosive crude oil, the requirement to monitor and, if possible, repair internal corrosion defects is becoming more significant.

Internal defects are difficult and costly to repair, especially for sub-sea pipelines, yet even these costs are small in comparison with the loss of revenue that ensues if it is necessary to close a pipeline whilst a repair procedure is performed.

Modern PIG systems are capable of detecting the onset of corrosion and monitoring its spread, providing valuable data on the location and potential consequences of the problem. However, once the presence of a defect is known there is a requirement on the operator to assess and mitigate against any effects it may have.

Being able to intervene early and repair any internal corrosion damage discovered before it necessitates a reduction in operating pressure or line closure is desirable, but ideally this requires a repair technique that is deploy-able inside the pipe, and which does not require the pipe to be drained for the repair to be made. Conventional welding techniques, for example arc or laser welding, cannot be used in an operational pipeline, and the use of epoxy grout and internal liners requires that the pipe be clean and warm when the repair patch is applied.

The Background

  • Develop a spark-less, remote operated, online maintenance solution to repair internal corrosion and cracks in oil pipelines prior to failure.

  • Carry out Friction Stir Welding to repair internal flaws.

  • Power will be harvested from the pipeline flow via an on-board turbine.

The Challenge

The objective of the project is to develop a robotic platform with a payload consisting of unique hydraulic friction stir welding equipment which produces no sparks. Data obtained by prior high-resolution mapping of anomalies that are produced by metal loss and corrosion will be used to provide information for mission planning. Repair will be carried out in-situ using no external power and no welding consumables. The robot will generate electricity from the liquid flow in the pipeline via a variable pitch turbine diving a generator, which will supply power to a hydraulic pump and a battery which drives the magnetic tracks.

The Solution

Benefits

  • Improve the flexibility of oil pipeline repair with respect to inaccessible pipelines and those pipelines which are installed in parallel groups where space around the pipes is restricted.

  • Allow pipeline asset owners and their service providers to produce high quality welds in steel pipelines without shutting down and purging petroleum products.

  • Repair will be achieved without using divers or surface vessels which will dramatically improve safety.

  • Petrochemical pipeline operators and their service providers are the target market. Diver or ROV repairs cost in the region of £200k. Use of the FSWBot could save a typical operator in the region of £10M per year. Furthermore, the large cost of unplanned maintenance can be avoided plus the reputational damage caused by downtime and hazardous incidents.

  • International markets: The partners have a good chance to access the sector globally because they are international leaders in the Friction Stir Welding and robotics.

Market

  • At present, the project is ongoing and is aiming to be complete by 2021.

The Result