Flexible
A flexible gas pipe run is only as dependable as the fitting that terminates, branches or connects it. Our range brings together fittings and replacement components for TracPipe, AutoFlare, Gastite and Gas Flex Systems installations, covering everything from appliance and manifold connections to copper transitions, tees, couplings and protective tapes.
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A Comprehensive Choice Of Flexible Stainless Steel Gas Pipe Fittings
BES supplies flexible gas pipe fittings from DN12 to DN50, with options for connection to copper tube and for male or female BSP threads. All gas work must be designed, installed, tested and commissioned by a suitably qualified Gas Safe registered engineer.
Tees
Flexible gas pipe tees create a branch from a main Corrugated Stainless Steel Tubing (CSST) run. Our selection includes equal tees for three connections of the same nominal size, as well as reduced configurations for taking a smaller branch or changing pipe size through the fitting. Available arrangements include equal tees, branch-reduced tees, one-end-reduced tees, two-end-reduced tees and end-and-branch-reduced tees. A popular option, the TracPipe Branch Reduced Tee – 28mm x 28mm x 15mm allows a smaller DN15 branch to be taken from a DN28 TracPipe run. GFS tees are available in equal and several reduced configurations for compatible GFS flexible gas pipe.
Compression Fittings
Compression fittings provide a transition between compatible flexible gas pipe and rigid copper tube and are useful where part of an installation is being completed in CSST, and the remaining section continues in copper. The Gastite Copper Compression Fitting – DN25 x 22mm connects compatible DN25 Gastite pipe to 22mm copper tube. Gastite XR2 copper compression fittings and AutoFlare straight compression fittings are also available in several CSST-to-copper combinations.
Trade tip: Note that both dimensions matter: the DN measurement identifies the compatible flexible pipe system size and the millimetre measurement identifies the copper tube size. A DN22 x 15mm fitting is therefore not interchangeable with a DN22 x 22mm fitting. Confirm the flexible pipe series as well as the copper diameter before ordering.
Male Adaptors
Male adaptors terminate compatible flexible gas pipe with a male BSP taper thread. They are commonly used to connect a CSST run to a female-threaded valve, manifold, meter fitting, appliance connection or rigid pipe fitting. The GFS Straight Male Connection – DN15 x 1/2" BSP TM connects DN15 GFS pipe to a 1/2-inch BSP taper female connection. GFS male adaptors are available across DN15, DN20, DN25 and DN32 pipe sizes, with several BSP thread options.
Trade tip: Do not estimate BSP size from the measured outside diameter of the thread. BSP dimensions are based on a nominal pipe bore, so the actual thread diameter is larger than the stated BSP size.
Mechanical Joints
Gastite mechanical joints terminate compatible Gastite CSST with male or female BSP threaded connections. Male adaptors can connect the pipe to suitable manifolds, gas outlets and appliance connections, while female adaptors connect to fittings or valves with male threads. Options include the Gastite XR2 Female Coupler Adaptor – DN20 x 1/2" BSP F and the Gastite XR2 Male Coupler Adaptor – DN20 x 3/4" BSP TM. We also supply Gastite XR2 fittings that use a self-guiding flare arrangement and Jacket-Lock design, which covers the exposed stainless steel at the fitting.
Female Adaptors
Female adaptors connect compatible GFS flexible gas pipe to a male BSP threaded component. They can be used at suitable valves, manifolds, appliance connections and transitions to rigid pipe systems. The GFS Straight Female Connection – DN15 x 3/4" BSP provides a DN15 GFS pipe connection with a 3/4-inch female BSP outlet. Options are available for DN15, DN20, DN25 and DN32 pipe.
Compression Couplings
GFS compression couplings transition from compatible GFS flexible gas pipe to copper tube, allowing the installer to change material without adding a separate threaded adaptor and compression fitting. These fittings are directional in terms of connection type: one side is designed for the specified GFS pipe and the other for copper, and they should not be treated as ordinary copper-to-copper compression fittings. Options range from DN15 x 15mm to DN32 x 35mm, including the GFS Compression Coupling – DN20 x 22mm.
Split Rings
TracPipe and AutoFlare split rings form part of the fitting assembly around the corrugated stainless-steel tube. The two matching half-rings locate in the correct pipe corrugation so that the fitting can form its metal-to-metal seal when tightened. Replacement half split rings are available for TracPipe sizes from 12mm to 40mm, plus an AutoFlare 50mm option. They are supplied in packs, with pack quantities varying according to size.
Taper Fittings
AutoFlare taper fittings terminate TracPipe with a male BSP taper thread. Sizes range from the AutoFlare Gas Straight Fitting 15mm x 1/2" BSP TM to larger 40mm and 50mm fittings for suitably sized installations. The fitting seals to the TracPipe using the AutoFlare connection, while the male BSP end connects to a suitable female threaded component.
Mechanical Couplings
Gastite mechanical couplings join two compatible lengths of Gastite CSST of the same nominal diameter. They can be used when extending a pipe run, carrying out an approved repair or joining separately routed sections. The range includes the Gastite Mechanical Coupling – DN25, together with DN32 and DN50 options. Gastite XR2 mechanical couplings are available in DN15, DN20 and DN40.
Connectors
AutoFlare connectors terminate TracPipe with a female BSP connection and provide a direct transition to a male threaded gas component without adding a separate female socket. A top choice is the AutoFlare Gas Pipe Straight Fitting DN22 x 1/2" BSP F, and other options include DN22 and DN28 fittings with 3/4-inch BSP female connections, plus DN32 x 3/4-inch.
Compression Washers
GFS compression washers are replacement components for compatible GFS fittings. They are available in DN15, DN20, DN25 and DN32 sizes, including the GFS Compression Washer – DN20.
Couplings
AutoFlare couplings join two TracPipe lengths of the same size. They are available across common installation sizes, including the AutoFlare Coupling – DN22.
Silicone Gaskets
GFS silicone gaskets are replacement sealing rings for compatible GFS fittings. Available sizes include DN15, DN20, DN25 and DN32. The GFS Silicone Gasket – DN20 can be used when the original seal has been damaged or when a fitting is being reused where permitted. The gasket is a functional sealing and high-temperature-performance component, not a general-purpose plumbing washer.
Straight Couplings
GFS straight couplings connect two equal-sized lengths of compatible GFS flexible gas pipe. Our selection includes DN15, DN20, DN25 and DN32 options. The GFS Coupling – DN20 uses the GFS Push & Seal fitting arrangement and must be assembled using the components and preparation method specified for the GFS system.
Coupling Fittings
TracPipe coupling fittings cover sizes outside the main AutoFlare coupling group, including DN12, DN40 and DN50. They perform the same basic function of joining equal-sized TracPipe runs. The TracPipe Coupling – DN12 is intended for compact DN12 installations, while DN40 and DN50 couplings serve larger-capacity pipe runs.
Mechanical Tees
Gastite mechanical tees divide a compatible Gastite CSST run into two branches. Equal tees are available in legacy Gastite and XR2 configurations. The Gastite Mechanical Tee – DN25 x DN25 x DN25 provides three equal DN25 connections. Gastite XR2 equal tees are also available in DN15 and DN20.
Reducing Couplings
GFS reducing couplings join two different nominal sizes of compatible GFS flexible gas pipe and they are useful where a correctly sized branch or downstream section reduces from a larger main run. Available options include the GFS Reducing Coupling – DN20 x DN15, DN25 x DN20 and DN32 x DN25.
Silicone Tapes
Used to restore or reinforce the protective covering around specified flexible gas pipe fitting areas, silicone tapes available at BES include 25mm and 50mm widths in different roll lengths.
Elbows
TracPipe-to-copper compression elbows combine a directional change with a transition from flexible gas pipe to rigid copper tube. The TracPipe to Copper Compression Elbow DN22 x 22mm on offer joins DN22 TracPipe to 22mm copper tube at an elbow. We also offer a DN28 x 28mm version.
Self-Amalgamating Tapes
Self-amalgamating tape bonds to itself when stretched and overlapped, creating a continuous protective wrap around compatible CSST terminations and damaged jacket areas where permitted by the system instructions. At BES, we offer 25mm and 50mm widths.
Benefits Of Flexible Stainless Steel Gas Pipe
Corrugated stainless steel tubing can simplify routes that would otherwise require several rigid pipe bends and joints. Depending on the system and installation, its advantages can include forming bends by hand within the permitted radius, routing around structural and mechanical obstacles, reducing the number of intermediate fittings, lower transport and handling weight than equivalent rigid pipe runs, avoiding hot works at CSST fitting connections, supplying long continuous runs from a coil, and easier routing through some restricted spaces.
Choosing The Correct Flexible Gas Pipe Size
Common sizes in this fitting range include DN12, DN15, DN20, DN22, DN25, DN28, DN32, DN40 and DN50. The available sizes vary between manufacturers because each brand uses its own system dimensions and naming conventions. Pipe diameter must be calculated rather than selected by matching an existing appliance connection. Gas pipe sizing depends on things such as the gas type, the appliance heat input and gas rate, the total developed pipe length, the supply pressure and the permitted pressure drop.
Tracpipe, Gastite Or GFS: Which Fittings Do I Need?
CSST fittings are non-interchangeable and cannot be selected by nominal diameter alone. Always match the fitting system directly to the pipe installed on site:
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TracPipe & TracPipeCC: Requires dedicated AutoFlare fittings, including split-ring terminations, couplings, tees, and copper compression transitions
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Gastite: Uses Gastite mechanical or XR2 Jacket-Lock fittings (do not mix XR2 with legacy Gastite fittings unless verified)
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Gas Flex Systems (GFS): Uses brand-specific Push & Seal mechanical fittings, adaptors, tees, and silicone gaskets
Why Buy Flexible Gas Pipe Fittings From BES?
BES stocks fittings and replacement components for three widely used flexible gas pipe systems, helping engineers source the correct termination, branch, transition and sealing parts for new work and maintenance. With more than 50 years serving the gas, plumbing and heating trades, BES provides access to a broad choice of sizes alongside technical product information and customer support.
Next-working-day delivery is available on qualifying products and orders to mainland UK. Customers can also use Click & Collect, while unused products can be returned under the BES 30-day returns policy, subject to the relevant terms and conditions.
FAQs
Are flexible stainless steel fittings suitable for natural gas?
The fittings on this page are intended for specified flexible gas pipe systems, with products available for natural gas and, where stated, LPG applications. Suitability depends on the brand, product series, operating pressure, pipe size and installation conditions. Check the individual fitting and pipe specifications rather than assuming that every product is suitable for every gas.
Can flexible gas pipe fittings be used for a domestic boiler?
A compatible CSST system can be used as part of a domestic boiler gas supply where the system is correctly designed, sized and installed. The pipe must provide the required gas rate within the permitted pressure drop.
Can TracPipe, Gastite and GFS fittings be mixed?
No. Each fitting range is designed for its corresponding pipe system and connection method. A fitting with the same DN marking from another brand is not automatically compatible. Gastite XR2 and earlier Gastite products can also differ, so compatibility must be checked within the same brand.
What is the difference between DN size and BSP size?
DN identifies a nominal pipe-system size. BSP describes the threaded connection used to join the fitting to another component. For example, a fitting may connect DN20 flexible pipe to a 1/2-inch or 3/4-inch BSP thread. Both dimensions must match the installation.
What is the difference between flexible stainless steel pipe and rigid gas pipe?
Flexible CSST can be routed around obstacles and supplied in long coils, often reducing the number of bends and joints. Rigid copper or steel may be preferable where straight, exposed or mechanically vulnerable pipework requires greater rigidity. Many installations use both, joined with an approved copper compression or threaded transition fitting.