Delivering Complex Line Stopping Solutions on Critical Infrastructure
The Flow Control Solutions team recently completed another major large diameter line stopping project involving 1524 mm (60") and 1372 mm (54") single line stops on live carbon steel transmission mains operating under pressure.
Projects of this size require far more than installing fittings and deploying stopping heads. Successful execution depends on detailed engineering, qualified in-service welding procedures, precision hot tapping operations, and continuous monitoring throughout the isolation process.
The work was completed safely, under pressure, and without disrupting downstream operations.
Understanding Line Stopping Technology
Line stopping is a specialized method used to temporarily isolate a section of an active pipeline while allowing the remainder of the system to continue operating normally.
This technique allows maintenance, repairs, tie-ins, inspections, and system upgrades to be performed without requiring a complete shutdown of the pipeline.
A typical line stopping operation includes:
• Installation of a line stop fitting
• Pressure testing of the fitting and valve assembly
• Hot tapping through a full-port valve
• Deployment of a mechanical stopping head
• Verification of isolation performance
• Installation of completion equipment and removal of temporary tooling
By isolating only the required section of pipe, operators can maintain service while essential work is carried out safely.
How Large Diameter Line Stops Are Performed
Large transmission pipelines require a disciplined and highly controlled approach from planning through completion.
Engineered Fitting Installation
For carbon steel transmission systems, fittings are installed using qualified in-service welding procedures that meet applicable industry standards and project requirements.
Prior to welding, technicians verify:
• Pipe condition and integrity
• Outside diameter measurements
• Surface preparation requirements
• Adequate wall thickness
Once installed, welds are inspected and tested before any cutting activities begin.
Assembly Testing Prior to Hot Tapping
Before the hot tapping process starts, the fitting and valve assembly must demonstrate complete integrity. Testing may include:
• CO₂ leak testing for smaller assemblies
• Hydrostatic pressure testing for larger nozzle configurations
These procedures verify that the assembly is secure and capable of safely supporting the hot tapping operation.
Precision Hot Tapping
Hot tapping on 54" and 60" transmission mains requires careful planning and accurate calculations. Prior to cutting, technicians verify:
• Internal pipe dimensions
• Valve clearance requirements
• Cutter travel distances
• Machine positioning
• Retraction distances
• Equipment tolerances
Every measurement is confirmed before cutting begins to ensure safe execution and reliable coupon recovery.
Following completion of the hot tap, measurements are verified to assist with stopping head configuration and seal preparation.
Isolation and Seal Verification
Once the hot tap is complete, the line stop head is assembled according to the confirmed pipeline dimensions and installed into the line.
Isolation effectiveness is then verified through equalization and monitoring procedures. Any bypass flow is measured and documented before downstream work is permitted to proceed.
Pressure and Flow Monitoring
Large diameter line stopping projects require continuous monitoring throughout the isolation period.
Flow Control Solutions implements detailed pressure and flow monitoring procedures that may include:
• Establishing a controlled pressure zone
• Monitoring upstream operating pressure
• Measuring controlled zone pressure
• Calculating blow-by flow rates
• Recording system data at scheduled intervals
This structured approach provides an additional layer of operational control and safety throughout the project.
Benefits of Line Stopping
Line stopping provides significant advantages for municipalities, utilities, and industrial operators.
These advantages include:
• Eliminating full system shutdowns
• Reducing service interruptions
• Maintaining system stability
• Creating controlled isolation zones
• Improving worker safety
• Minimizing operational impacts
For critical transmission infrastructure, these benefits can significantly reduce project costs and operational risk.
Large Diameter Line Stops You Can Trust
Flow Control Solutions specializes in complex live pipeline services and large diameter isolation projects.
Projects involving transmission mains of this size require:
• Experienced senior technicians
• Specialized tapping and stopping equipment
• Engineered procedures
• Quality control documentation
• Comprehensive safety management
Our team routinely performs critical infrastructure work where precision, planning, and procedural discipline are essential to project success.
Our Services
Flow Control Solutions provides turnkey live pipeline services, including:
• Hot tapping
• Line stopping
• Valve insertion
• Pipe freezing
• Hydrant services
• Emergency pipeline support
We work with municipalities, engineers, contractors, utilities, and industrial operators to deliver safe, efficient, and reliable solutions for critical infrastructure projects.
Where We Operate
Flow Control Solutions provides specialized pipeline services to municipalities, industrial operations, and commercial facilities throughout Ontario. Our service area includes Milton, Oakville, Burlington, Pickering, Ajax, Whitby, Oshawa, Newmarket, Aurora, Barrie, Guelph, Cambridge, Brantford, St. Catharines, Niagara Falls, and neighbouring communities.
Our team regularly supports projects at wastewater treatment facilities, manufacturing plants, power generation facilities, hospitals, educational institutions, and other essential infrastructure throughout the Greater Toronto Area (GTA), Southern Ontario, and surrounding regions.
To learn more about our services or discuss an upcoming project, contact Flow Control Solutions.