Addressing High Flow Rates For Optimal Cleaning Results

The natural gas transportation system includes some large pipeline segments that operate at high pressures and high flow rates. These pipeline segments are growing and becoming increasingly important for the energy supply chain for cities and industrial and manufacturing companies. Therefore, reducing natural gas flow rates for pipeline cleaning and in-line inspections may cause disruptions in the supply chain for natural gas and other products and services. What types of final users or sectors might be affected by a disruption of the natural gas supply chain?

• Steel manufacturing
• Pipe manufacturing companies
• Factories (even beer factories!)
• Car manufacturing
• Cities
• Maybe even our homes

Let us remember one of the most important requirements for achieving a successful in-line inspection: accurate data. To get it, the ILI tool – just like a cleaning tool – must travel within the acceptable velocity range for that specific tool to be effective (1.5 m/s to 5 m/s depending on the specific ILI technology and tool). These natural gas pipelines typically transport gas at velocities that could range from 8 m/s to 20 m/s. When pipeline operators inspect one of these lines, they typically have two options. The most common one, so far, has been to reduce flow rates to the level that is acceptable for the ILI tool, and the second and most recent one is to select a tool with speed-control-reduction technology in order to not reduce the flow rate or reduce it at a lower volume.

What scenarios could actually happen if there really was a supply disruption in the natural gas market?

• Internal storage capacities for energy producers – how long could they stop producing and still not disrupt the supply chain to our customers?
• Production halts – end users require this energy to transform it to other services or products
• Consequences for final users if this energy is not available when needed (less energy than needed or no energy at all)
• Consequences for gas producers if this energy is not available to the final user
• Contractual agreements between gas producers and end users and/or customers cannot be upheld

Every final customer and consumer in the supply chain for natural gas or LNG will have their specific needs and will require specific commitments from their suppliers. The actual disruption for these supply chains will become more difficult to handle with every passing year. This year, with demand already high, it is becoming clearly visible for some gas operators in the US, and North America in general, that work with this type of assets and have high demand for their production.

What to do?

What are the options available on the market to solve the existing need to inspect and clean pipelines without reducing flow rates and disrupting the supply chain? There are a few options offered by highly experienced ILI and pipeline cleaning vendors that try to solve this operational need.

Some pipeline operators run one cleaning run and then move directly into inspecting the pipelines without reducing the much-needed high flow rates. Acceptable velocities for the cleaning and ILI range from under 5 m/s to 7 m/s versus high gas-flow rate lines operating at 8 m/s to 20 m/s. This can result in a variety of issues, including an inefficient cleaning performance and, subsequently, poor data collection from the smart ILI tool due to too much debris or a travel velocity that is too high for proper sensor coverage.

Other options include basic technologies that allow for an un-adjustable level of bypass. Bypass systems on ILI tools allow for product to quite literally bypass, or flow through the tool itself, thereby reducing the differential pressure pulling the tool forwards and allowing it to slow down. Un-adjustable levels of bypass in one run can potentially cause stationary tools. This is a worst-case scenario because the emergency response required is to cut out the tool from the pipeline, ultimately causing a major production and supply chain disruption.

Other types of solutions offer adjustment and flexibility while at the same time offering some peace of mind to pipeline operators. They enable risk mitigation of a stuck pig; an adjustable bypass system will act as programmed to mitigate that risk, like some solutions already offered by ROSEN: Speed Control Units (SCU) on ILI tools and cleaning tools (CLP). Eco-Speed, for example, is a mechanically controlled bypass valve specially designed for a specific pipeline segment.

Although some of these operational options reduce the risk, they may still require small flow rate reductions, and they do not eliminate the potential for disruption. The reaction may not be the one the pipeline operator needed in pipeline A, C, and C, therefore still creating a concern for the supply chain. There are other options focused on maximizing the flow reduction for the CLP or ILI pigs but not mitigating the risks of resulting stationary pigs or lodged pigs while attempting to traverse less traditional fittings that may be present in these pipelines.

But there must be a solution? The ROSEN Group has recently developed and is testing an approach that allows for optimal speed control in high-velocity pipelines; it works specifically with the parameters of each operator's unique pipeline. For this solution, ROSEN experts work closely with operators to identify process-flexible speed control units that are targeted based on specific project requirements. Some of the factors our integrity experts take into account include pipeline production commitments, project-risk mitigation plans and expected tool wear. They also apply heavy-duty tools with self-optimizing variable speed control systems. Dedicated solutions rather than off-the-shelf products would eliminate the need to reduce flow rates and still ensure effective speed control for optimal cleaning performance as well as ILI data collection for future integrity assessments.