Every hot tapping operation involves a machine, a hole saw, a fitting, and a valve. Of these four components, the valve is the one that stays on the pipeline permanently. It determines what you can do with the new branch connection for years or even decades after the tap is complete. Choosing the right hot tap valve means matching bore size, connection type, and valve mechanism to the medium, the pipeline material, and the long-term purpose of the branch.
This article walks through the key decisions that go into selecting a hot tap venttiili for pressurized pipeline work. We cover the differences between ball valves and gate valves, connection types and their site requirements, medium-specific considerations for gas and water networks, bore sizing, and what happens to the valve once the hot tapping machine is removed.
Why the valve, not the machine, defines the finished tap
A hot tapping machine is a temporary tool. It mounts, it cuts, and it retracts. Once the operation is done, the machine leaves the site. The valve, on the other hand, becomes a permanent part of the pipeline. It is the component that operators will interact with for maintenance, future tie-ins, or isolation work long after the initial hot tapping crew has packed up.
This is why the hot tapping venttiilivalinta deserves careful thought. A valve that does not match the pipeline’s operating conditions or the intended use of the branch can create problems that are expensive to fix on a live system. Replacing a valve on a pressurized pipeline is significantly more involved than selecting the correct one from the start.
The valve also has to work with the hot tapping machine during the cut. The machine mounts on top of the valve, and the cutter passes through it. If the valve bore is too small, the cutter cannot pass. If the connection type does not match the saddle or fitting below, the assembly will not seal. The valve sits at the center of the full hot tapping assembly, linking the machine above to the pipeline below.
Ball valve or gate valve: what each is suited to
The two most common valve types used in hot tapping are ball valves and gate valves. A palloventtiili hot tapping application uses a spherical closure element with a bored-through passage. When open, the ball rotates so that the bore aligns with the flow path, giving a clear and unobstructed opening. A quarter turn of the handle moves the valve from fully open to fully closed.
A gate valve uses a flat or wedge-shaped disc that slides up and down across the flow path. Opening a luistiventtiili kaasu application, for example, requires multiple turns of a handwheel or actuator. Gate valves are widely used in gas networks, where the gas gate valve design provides a full-bore passage and reliable sealing in buried installations that may not be operated for long periods.
The practical difference on a hot tapping site is straightforward. Ball valves are compact, fast to operate, and well suited to above-ground installations where space is limited. Gate valves tend to be longer in body length but are a proven choice in below-ground gas and water applications. The right choice depends on the medium, the installation environment, and the operator’s network standards. Neither type is universally better than the other.
Connection types: threaded, flanged, weldable, and what each demands on site
The hot tap liitostyypit available for connecting a valve to the pipeline fitting fall into three main categories: threaded (or screwed), flanged, and weldable. Each has distinct implications for what equipment and preparation the site crew needs.
Threaded connections
Threaded connections are common on smaller branch sizes. The valve screws directly onto the saddle or fitting. This makes for a relatively quick assembly, but the connection must be properly sealed and torqued. Threaded connections are typically used on branch sizes up to around DN50, depending on the application and the operator’s specifications.
Flanged connections
Flanged connections use bolted flange pairs with a gasket between them. They are easy to disassemble for future maintenance or valve replacement, which makes them popular in above-ground process installations and district heating networks. The trade-off is that flanged assemblies are bulkier and require more vertical clearance above the pipeline, which matters in confined spaces.
Weldable connections
Weldable connections are welded directly to the fitting or saddle. This produces a permanent, compact joint. Weldable valves are common in gas pipeline work, where buried installations benefit from a joint that does not rely on bolts or threads. The requirement, of course, is that the pipeline material must be weldable and that qualified welding personnel are available on site.
Choosing between these hot tap liitostyypit is not purely a technical preference. It also depends on what the network operator’s standards require for the specific medium and location. When special materials or unique requirements are involved, consulting with our sales team ensures the right connection type is specified from the start.
Valves for gas versus valves for water and district heating
The medium flowing through the pipeline influences valve selection in several ways. Gas networks typically follow strict operator and national standards that define which valve types and materials are approved for use. A kaasun luistiventtiili, for example, must meet the gas network operator’s requirements for that specific installation. We do not recommend assuming that a valve approved for water service is automatically suitable for gas, or vice versa.
Water and district heating networks have their own requirements. District heating systems operate with hot water or steam, which places demands on valve body and seal materials. Water networks may require valves with drinking water approvals. In each case, the applicable standard and the network operator’s own procedures govern the selection.
If you are unsure which valve suits your project, we recommend contacting us. Together with our professionals, you can assess your specific requirements and choose the most appropriate solution. You can also explore our range of gate valves for gas applications on our product pages for reference.
Full bore versus reduced bore and the effect on the cutter
A full-bore valve has an internal passage that matches the nominal pipe size of the branch. A reduced-bore valve has a smaller internal passage. This distinction matters for two reasons: flow capacity after the tap is finished, and cutter clearance during the hot tapping operation itself.
During hot tapping, the hole saw and pilot drill must pass through the open valve to reach the pipeline wall. If the valve bore is smaller than the cutter diameter, the operation cannot proceed. This means the valve’s bore size must be confirmed against the cutter size before the equipment is assembled on site. It is a straightforward check, but overlooking it leads to delays.
After the tap is complete, a full-bore valve allows unrestricted flow and unobstructed access for future inline tools or inspections. A reduced-bore valve may be acceptable where the branch is used for a smaller instrument connection or where flow restriction is not a concern. The intended long-term use of the branch should guide this decision.
What the valve has to do after the tap is finished
Once the hot tapping machine is removed, the valve takes on its permanent role. In many installations, the valve is closed and capped, serving as a future access point. In others, it remains open as part of an active branch connection feeding a new section of the network.
Building on the bore size discussion above, the valve’s long-term function determines whether features like locking mechanisms, actuator mounting provisions, or extension spindles for buried installations are needed. A valve buried in a gas network, for instance, needs to be operable from ground level, which requires a compatible extension spindle and surface box.
The valve must also maintain its seal integrity over time. A paineellinen putkisto venttiili that leaks years after installation creates a problem that is far more disruptive to address than specifying the right valve at the outset. This is why valve quality and material compatibility with the medium are not areas where cost savings pay off in the long run.
Questions we get asked
Can any valve be used for hot tapping?
No. A hot tap venttiili must have a bore large enough for the cutter to pass through and a body design that allows the hot tapping machine to mount securely on top. Standard pipeline valves are not designed for this. Purpose-built hot tapping valves are engineered to work with specific machine and fitting combinations.
Is a ball valve or a gate valve better for hot tapping?
Neither is universally better. Ball valves offer compact dimensions and fast operation. Gate valves are widely specified in buried gas and water networks. The choice depends on the medium, the installation environment, and the network operator’s standards. Both types are available as dedicated hot tapping venttiilit.
How do I know which connection type to specify?
The connection type depends on the pipeline material, the branch size, the installation location, and the operator’s requirements. For standard applications, your network’s design standards will typically specify whether threaded, flanged, or weldable connections are required. For special materials or unusual configurations, contact our sales team for guidance.
Hot tap valves from Tonisco
We are a family-owned Finnish company, founded in 1969, and we manufacture hot tapping and line stopping products at our facility in Tampere, Finland. Our hot tap valve range covers sizes from DN20 up to DN600, and our hot tap machines have adapters for Broen, Danfoss, Tonisco, Vexve, and Böhmer valves. We operate in over 20 countries, serving gas and oil, water, HVAC, district heating and cooling, and process industry networks.
Our product range includes dedicated Tonisco hot tap valves designed to work seamlessly with our hot tapping machines, saddles, and fittings. Whether you need a valve for a small instrument tap or a large-diameter branch connection, our team can help you select the right combination of valve type, bore size, and connection type for your specific application.
If you are planning a hot tapping project and want to ensure you specify the right valve, contact us at sales@tonisco.com or call +358 3 2611724. Our professionals will help you assess your requirements and recommend the most appropriate solution.