Hot tapping is a method of creating a new connection or access point on a pressurised pipeline while the system remains in operation. Instead of shutting down, draining and refilling the pipeline, technicians install a fitting and valve before cutting through the pipe wall with a sealed hot tapping machine.
Also known as line tapping or pressure tapping, hot tapping is widely used when an interruption would be costly or disruptive. Typical applications include expanding district heating networks, connecting new buildings, installing instruments and preparing access points for line stopping.
The word “hot” refers primarily to working on a live system. It does not necessarily mean that the pipeline itself carries a hot medium, although the method is particularly valuable in district heating and cooling networks.
At Tonisco, we manufacture hot tapping equipment and provide professional services for pressurised pipelines. Whether you need equipment for your own technicians or a turnkey operation, we can help you select a solution for your pipeline, operating conditions and required connection.
How does hot tapping work?
A hot tapping operation creates a controlled opening through a valve attached to the live pipeline. The fitting, valve and tapping machine form a pressure-containing assembly throughout the cutting process.
A typical operation follows these stages:
- Assess the pipeline and operating conditions. The pipe material, diameter, wall thickness, condition, design limits, operating pressure and temperature are confirmed before equipment is selected.
- Install the fitting. Depending on the pipe material and application, a welded fitting, fusion-welded saddle or mechanical clamp is attached to the main pipeline.
- Install the valve. A suitable hot tap valve or shut-off valve is mounted on the fitting. The valve must provide sufficient clearance for the cutter and be rated for the operating conditions.
- Attach the hot tapping machine. The machine is connected to the valve, creating a sealed path between the machine and the pipeline.
- Open the valve and make the cut. The pilot drill and cutter advance through the open valve and cut through the pipe wall while the main pipeline remains pressurised.
- Retrieve the coupon. The removed section of pipe wall, known as the coupon, is retained by the cutting assembly and withdrawn into the machine.
- Close the valve and remove the machine. Once the cutter has been retracted, the valve is closed. The tapping machine can then be depressurised and removed, leaving a controlled connection ready for the next stage of the project.
The exact procedure varies according to the pipeline material, medium, connection size, pressure, temperature and site conditions. Every operation therefore requires project-specific planning.
What equipment is needed for hot tapping?
A complete hot tapping setup normally includes five essential elements:
- A fitting or saddle that provides the structural connection to the main pipeline
- A compatible valve through which the cutting equipment can pass
- A hot tapping machine that controls the cutting movement while containing pipeline pressure
- A cutter and pilot drill selected for the required opening and pipe material
- Suitable adapters and a drive unit for the valve, connection type and worksite conditions
The complete assembly must be compatible. Selecting a machine solely by branch diameter is not enough. The valve bore, fitting, cutter, machine travel, adapters, seals and drive method must all be suitable for the application.
Tonisco’s product range includes hot tapping machines, valves, cutters, pilot drills, adapters, drive units, saddles and repair clamps. This allows us to configure equipment for different connection types and operating environments.
TONISCO B30 for DN40 to DN200 connections
For medium-sized connections, the TONISCO B30 Hot Tap Machine – E is designed for making connections to pipelines, tanks and plant piping without stopping the main system.
Its published specifications include:
- Hot tap sizes from DN40 to DN200
- Maximum pressure of 60 bar
- Maximum temperature of 200 °C
- PN40 standard
- Threaded, weldable or flanged connections when used with suitable adapters
- Applications in heating and cooling, water, HVAC and process-industry systems
Maximum pressure and maximum temperature values must not automatically be treated as a simultaneous operating point. The permitted configuration depends on the complete equipment assembly, valve, fitting, medium and project conditions. Our technical team can confirm the appropriate setup before use.
What is hot tapping used for?
Hot tapping is most valuable when a pipeline must be modified without interrupting service. Common uses include:
- Creating branch connections for new buildings or network sections
- Extending district heating and cooling networks
- Connecting new process equipment to an operating pipeline
- Installing pressure, temperature or other measuring points
- Adding vents, drains or sampling connections
- Installing a new branch valve
- Creating access points for line stopping equipment
- Preparing temporary bypass connections for maintenance work
Hot tapping itself creates the opening or branch connection. More extensive operations, such as replacing an inline valve or removing a damaged pipe section, may also require line stopping, bypass arrangements or another isolation method.
Why is hot tapping valuable in district heating networks?
District heating networks serve homes, commercial properties, public buildings and critical facilities. A conventional connection may require the affected pipeline section to be isolated, depressurised, drained, modified, refilled and returned to operating temperature.
Hot tapping allows the main network to remain operational during the connection work, provided the pipeline and operating conditions are suitable. This makes it particularly useful for network expansion and maintenance during periods when a heating interruption would be difficult to arrange.
For example, a new residential or commercial development can be connected to an existing district heating main without first draining the main pipeline. Existing customers continue receiving heat while the new branch connection is created.
Tonisco Service commonly uses the following connection methods in heating and cooling networks:
- Steel pipelines: a welded reinforcement plate or weldolet combined with a hot tap valve
- PE pipelines: a fusion-welded hot tap saddle with a gate or ball valve
- Other pipeline materials: a mechanical hot tap clamp with a suitable gate or ball valve
The correct method is selected after the pipe material, condition and operating parameters have been confirmed.
What are the benefits of hot tapping?
The business case for hot tapping depends on the pipeline and the consequences of an outage. When the method is technically suitable, it can offer several advantages.
Continuous service
The main pipeline remains in operation while the opening is created. In a district heating network, this can prevent an outage affecting multiple buildings or an entire service area.
No need to drain and refill the main pipeline
Avoiding drainage preserves treated network water or other process media. It also reduces the work associated with disposal, refilling, venting and returning the system to its normal operating state.
Reduced heat and energy losses
A district heating network does not need to be cooled and reheated solely to make the connection. The actual savings depend on the size and configuration of the affected network.
More flexible project scheduling
Work does not always need to be limited to a narrow shutdown window. This can make it easier to coordinate network extensions, new customer connections and planned maintenance.
Potential cost savings
Hot tapping can reduce costs associated with shutdown preparation, customer notifications, temporary services, system drainage, replacement water, reheating and recommissioning. It is important to compare the complete hot tapping cost with the real operational cost of the alternative shutdown.
| Project consideration | Hot tapping | Conventional shutdown connection |
|---|---|---|
| Main pipeline operation | Normally remains in service | Affected section must be isolated |
| Draining and refilling | Normally not required for the main | Commonly required |
| Customer interruption | Can often be avoided | Usually requires an outage |
| Treated medium and heat loss | Limited | Can be considerable |
| Scheduling | More flexible | Depends on an agreed shutdown window |
| Engineering | Requires a specialist live-line assessment | Requires an isolation and restart plan |
Hot tapping is not automatically the lowest-cost solution for every connection. Its value is greatest when the avoided interruption, drainage, energy loss or production downtime carries a significant cost.
Is hot tapping safe?
Hot tapping is an established pipeline technique, but working on a live pressurised system involves inherent hazards. Safe execution depends on proper engineering, correctly rated equipment, suitable pipeline conditions and trained personnel.
Before approving a hot tap, the project team should assess:
- Pipe material and actual wall thickness
- Corrosion, damage and the general condition of the pipe
- Design pressure and temperature
- Current and expected operating pressure and temperature
- Pipeline medium and its relevant hazards
- Compatibility of the fitting and joining method
- Valve bore, pressure class and cutter clearance
- Hot tapping machine capacity and travel
- Site access and available working space
- Permits, local regulations and applicable standards
- Worksite restrictions, including whether electric tools are allowed
- Contingency arrangements for abnormal conditions
The fitting, valve, adapters and tapping machine must be considered as one pressure-containing system. The machine’s maximum rating alone does not establish that the complete setup is suitable.
Hot tapping should not proceed if the pipe condition is uncertain, the remaining wall thickness is inadequate, the material or medium is incompatible with the proposed method, or a safe pressure-containing assembly cannot be established. In these situations, another repair or isolation method should be selected.
When should hot tapping and line stopping be used together?
Hot tapping and line stopping perform different but complementary functions.
Hot tapping creates a controlled opening in the live pipeline. Line stopping uses that opening to insert a temporary stopping head and isolate part of the pipeline.
The methods may be combined when a project involves:
- Replacing an inline valve
- Removing or repairing a pipe section
- Installing inline equipment
- Modifying a section that cannot remain pressurised during the work
- Establishing a temporary bypass around an isolated section
Depending on the network configuration, one or more line stops may be used. A temporary bypass can also be installed when flow must continue around the isolated work area. Our team can assess whether your project requires hot tapping alone or a combination of hot tapping and line stopping services.
Tonisco hot tapping services
Tonisco is a Finnish family-owned company founded in 1969. We manufacture equipment for under-pressure pipeline work and provide professional hot tapping and line stopping services in more than 20 countries.
Our Heating & Cooling Hot Tapping Service can cover everything from initial assessment and component selection to turnkey on-site execution. We can recommend suitable valves and fittings or work with approved components supplied by the customer.
The published operating parameters for our Basic Service Package include:
- Hot tap sizes from DN10 to DN1600
- Maximum operational pressure of 60 bar at 40 °C
- Maximum operational temperature of 200 °C at 16 bar
- Compatibility with ASME and DIN standards
These are service capability limits, not universal limits for every pipeline or equipment configuration. Final feasibility is always determined from the project data.
Customers can choose the level of support that suits their organisation:
- Equipment and components for an experienced in-house team
- Technical guidance and equipment selection
- Cooperation with the customer’s contractors
- Specialist installation support
- Complete planning and turnkey execution
Planning a hot tapping project
To assess your application and prepare a budgetary quotation, we normally need the following information:
- Main pipeline size and material
- Main pipeline wall thickness
- Design pressure and design temperature
- Current operating pressure and temperature
- Required hot tap size and pressure class
- Preferred fitting and valve arrangement, if already specified
- Site location, access and available working space
- Whether electric tools are permitted at the worksite
- Desired project schedule
Providing accurate operating and pipeline data helps us recommend the correct valve, fitting, machine, cutter and working method from the beginning.
Contact Tonisco to discuss your connection. We can help you determine whether hot tapping is suitable and provide the equipment, technical support or complete service required to carry out the work.
Frequently asked questions about hot tapping
Does hot tapping stop the flow in the main pipeline?
Normally, no. The purpose of hot tapping is to create a connection while the main remains pressurised and operational. Any temporary operating adjustments required during the work are determined during project planning.
Can hot tapping be performed on every pipeline?
No. Suitability depends on pipe material, wall thickness, condition, medium, pressure, temperature and the available connection method. A project-specific assessment is required before work begins.
How long does hot tapping take?
The duration depends on the connection size, material, wall thickness, operating conditions, fitting method, site access and preparation requirements. Cutting the opening is only one stage of the project, so an accurate schedule should be based on the complete scope.
What does hot tapping cost?
Cost is influenced by pipe diameter, material, pressure, temperature, connection size, location, accessibility and project complexity. The correct comparison should also account for the costs that hot tapping can avoid, including outages, drainage, replacement medium, reheating and recommissioning.
What pipe sizes can Tonisco hot tap?
Our Basic Service Package covers hot tap sizes from DN10 to DN1600, subject to the pipeline, operating conditions and selected equipment. Individual Tonisco machines have their own ranges. For example, the TONISCO B30 covers DN40 to DN200.
Can hot tapping be performed during winter?
It can be planned for winter operation when the pipeline, worksite and environmental conditions support safe execution. One of its main benefits in district heating is the ability to carry out necessary connections without arranging a heating shutdown.
What materials can be hot tapped?
Tonisco Service works with the materials used in district heating and cooling systems. Common methods include welded fittings on steel, fusion-welded saddles on PE and mechanical clamps on other materials. The pipe and joining method must always be assessed for the individual project.
Is hot tapping the same as line stopping?
No. Hot tapping creates an opening or branch connection. Line stopping inserts temporary isolation equipment through a hot-tapped opening so work can be performed on a selected pipe section. Many complex pipeline modifications use both methods.