When you need to modify or repair a pipeline, shutting down the entire system can be extremely expensive and disruptive. Fortunately, there are two better alternatives: hot tapping and line stopping. Both techniques let you work on pressurised systems without full shutdown. However, they serve different purposes and work best in different situations.
What Is Hot Tapping?
Hot tapping, also known as pressure tapping, lets you create new connections on live, pressurised pipelines. This method is used when you need to add branch lines, install new valves, or attach monitoring equipment without stopping service.
The process involves welding a fitting onto the pipe, installing a valve, and then using specialised drilling equipment to cut through the pipe wall. The system stays pressurised the whole time. The cut section (called a coupon) is safely removed, leaving a new opening for connections.
Hot tapping works on pipes of all sizes and is widely used in oil and gas, water distribution, and industrial processing sectors.
When to Choose Hot Tapping
Choose hot tapping when you need permanent system modifications. This includes adding new branch connections, installing permanent isolation valves, or adding monitoring equipment.
The technique works brilliantly when maintaining continuous flow is absolutely critical. Think about refineries where shutdown costs can reach hundreds of thousands of pounds per day, or municipal water systems where service interruption affects thousands of residents.
Hot tapping works best on relatively new pipelines in good condition with adequate wall thickness.
Advantages of Hot Tapping
The biggest advantage is continuity of service. Your pipeline continues operating normally throughout the procedure, eliminating revenue loss from shutdowns.
Hot tapping also improves safety by eliminating risks from depressurisation and repressurisation cycles. There’s no need to drain or purge the system. This reduces environmental concerns and minimises worker exposure to hazardous substances.
Speed is another major benefit. Once preparations are complete, the actual drilling operation takes just hours rather than days. This means direct cost savings and shorter project timelines.
Limitations of Hot Tapping
Hot tapping isn’t suitable for every situation. The technique requires adequate pipe wall thickness to safely accommodate drilling. Severely corroded pipes aren’t good candidates.
Importantly, hot tapping creates a permanent opening. It’s designed for situations where you’re adding something permanent. If you need temporary isolation for maintenance work, hot tapping alone won’t achieve that goal.
What Is Line Stopping?
Line stopping serves a different purpose. This technique provides temporary isolation of a pipeline section, creating a zero-leak seal that allows maintenance, repairs, or modifications on isolated segments whilst the rest of the system stays operational.
The process typically starts with hot tapping to install the necessary fittings and valves. Then a specially designed plugging head is inserted through the valve into the flowing pipeline. This head contains a sealing mechanism that expands to completely block flow.
With the line stopped, the isolated section can be drained, depressurised, and opened for work. Once repairs are complete, the pipeline section is restored, pressure-tested, and the plugging device is removed.
When to Choose Line Stopping
Choose line stopping when you need to work inside the pipeline with complete isolation. This includes replacing valve internals, removing obstructions, installing pig launchers, or cutting out damaged pipe sections.
Emergency repairs often demand line stopping capabilities. When a critical pipeline develops issues that can’t wait for scheduled shutdowns, line stopping allows immediate response whilst maintaining service to unaffected areas.
The technique is also ideal for major tie-in projects where new pipeline segments must be welded to existing infrastructure.
Advantages of Line Stopping
Line stopping excels when work must be performed inside the pipeline. It’s particularly valuable for tie-in operations, allowing welding and integration work without shutting down the entire system.
For urgent repairs, line stopping enables rapid response without waiting for scheduled shutdowns. This can prevent small problems from becoming major incidents.
The technique offers precise control. Multiple line stops can be deployed simultaneously to isolate exactly the working area needed. This is particularly valuable in complex pipeline networks.
Limitations of Line Stopping
Line stopping is temporary, not permanent. The plugging devices must be removed once work is complete.
The technique requires sufficient straight pipeline length both upstream and downstream for proper sealing. Line stopping is also more challenging in systems with high flow velocities or debris that might interfere with sealing.
Combining Both Techniques
In practice, hot tapping and line stopping often work together. Many projects require both methods. Hot tapping installs the fittings and valves needed for access, then line stopping creates the isolation necessary for internal work.
For example, to replace a failing valve in an operational pipeline, hot tapping installs temporary bypass connections around the valve. Then line stopping isolates the valve from both directions, allowing safe removal and replacement whilst the bypass maintains system flow.
Making the Right Choice
Selecting between hot tapping and line stopping requires careful evaluation. Start by clearly defining your project objective. Are you adding something permanently or temporarily isolating for maintenance? Assess your pipeline condition, including wall thickness and corrosion levels.
The UK’s Health and Safety Executive provides comprehensive guidance on safe isolation of plant and equipment, helping ensure your chosen method meets regulatory requirements whilst maintaining the highest safety standards.
RDS Pipeline: Your Partner for Pipeline Isolation Solutions
At RDS Pipeline, we specialise in both hot tapping and line stopping with state-of-the-art equipment and extensively trained personnel. We can recommend the best solution for your specific situation or design integrated approaches that use both techniques.
We’ve completed countless projects across diverse industries, always prioritising safety, efficiency, and minimal disruption. Our expertise extends beyond hot tapping and line stopping to include pipe freezing, mechanical pipework, and comprehensive pipeline repair services.
Contact RDS Pipeline today to discuss your pipeline isolation needs and discover the right solution for your project.
