Faygo, a Wanplas factory with 22 years of dedicated experience in plastic pipe and profile extrusion, builds the continuous production lines that turn rigid and flexible PVC compounds into the sealing sections engineers embed in construction joints to keep water out of tunnels, subway stations, and deep underground utility structures. In tunnel and underground engineering, a single leaking joint can compromise an entire segment, so the profile that fills that joint has to be dimensionally stable, chemically durable, and tightly bonded to the surrounding concrete. Co-extrusion makes that possible by forming a rigid carrier body and a soft sealing layer in one pass, eliminating the adhesive line that single-layer strips rely on and that eventually fails under hydrostatic pressure.
Why Continuous PVC Profiles Are the Backbone of Underground Waterproofing
Underground structures face a permanently wet environment where the water table sits above the structure for most of its service life. Concrete alone is porous and develops micro-cracks as it cures and settles, which means the real water barrier is the system of joints, seals, and membranes wrapped around the structure. A water stop strip is a pre-formed profile placed along the center of a construction joint before the second pour of concrete; when the concrete sets around its ribs and bulbs, the strip mechanically locks into both halves of the joint and blocks the capillary path water would otherwise follow. Because the strip runs continuously and is itself homogenous or co-extruded rather than glued, it removes the weakest point that plagues sheet-based barriers: the seam. In long tunnel drives and metro cut-and-cover boxes, kilometers of this profile are installed, so the extrusion line that makes it has to deliver a consistent cross-section, a stable color and filler distribution, and a predictable shore hardness shift-free over thousands of running meters.
The choice of PVC as the base polymer is not accidental. Rigid PVC offers high compressive strength and low creep, so the carrier body holds its shape under the pressures of fresh concrete placement and the later load of surrounding soil. Plasticized PVC, or a co-extruded thermoplastic elastomer layer, supplies the flexibility that lets the soft fins deform and recover as the joint opens and closes with thermal movement and settlement. By co-extruding these two materials through a single die head, the line produces a monolithic strip in which the hard and soft phases share a welded interface rather than a bonded one, which is the difference between a seal that lasts the design life of the tunnel and one that delaminates within a few seasons of saturated service.
How Co-Extrusion Changes the Strip Architecture
A single-layer extruded water stop is limited to one material and therefore one set of properties across the whole cross-section. Co-extrusion breaks that limitation by feeding two or more extruders into a common co-extrusion die, where separate melt streams are brought together at the land of the die so they fuse under heat and pressure into a single unified profile. In a typical water stop strip, a conical twin-screw extruder plasticizes the rigid PVC carrier compound while a single-screw extruder handles the softer sealing compound, and the two melts meet in the die to form a strip with a rigid spine and flexible edge ribs in one continuous piece. Multi-layer co-extrusion can add a third stream, for example a hydrophilic or color-contrast layer that makes inspection easier after installation. The technical advantage is that each layer can be optimized for its function without compromise, so the carrier can be highly filled and stiff while the seal stays soft and resilient.
From a production standpoint, co-extrusion also reduces scrap and simplifies the downstream line. There is no separate lamination step, no adhesive cure oven, and no second calibration pass, which means fewer failure modes and a shorter footprint on the factory floor. The control system only has to manage melt temperature, melt pressure, and haul-off speed consistently across both extruders to hold the layer ratio, and modern servo-driven lines hold that ratio within a narrow band across an entire production run. For a tunnel contractor who needs matched strips from multiple batches, that batch-to-batch consistency is what allows the installed seal to be treated as a single engineered system rather than a series of individually verified pieces.
The Production Line Architecture From Resin to Finished Strip
The complete water stop co-extrusion line follows the same downstream logic as any profile extrusion system, beginning with material preparation and ending with automatic cutting and stacking. Rigid and flexible compounds are first conditioned in drying hoppers if needed, then metered by loss-in-weight feeders into their respective extruders so the layer ratio stays exact. Each extruder uses a barrel divided into feed zone, compression zone, and metering zone, with the screw geometry and L/D ratio selected to give the compound full plasticizing without thermal degradation of the heat-sensitive PVC. The melts are filtered and, where required, passed through a melt pump for steady pressure before entering the co-extrusion die head, where the profile shape is defined.
After the die, the hot profile enters a vacuum calibration sleeve that pulls it to the precise final dimensions against a chilled mold surface, because water stop strips must meet tight width and thickness tolerances to seat correctly in the joint. A multi-belt haul-off then pulls the strip at a constant speed matched to extrusion output, and a planetary or fly-knife cutter sections it to the project length. Throughout the line, touch-screen control with recipe management stores parameter sets per strip type, so switching from a 20 millimeter wide center-bulb strip to a 30 millimeter wide ribbed version is a recipe change rather than a reconfiguration. Faygo, a Wanplas factory, supplies this complete profile extrusion package as a turnkey system, so the buyer receives matched extruders, die, calibration, haul-off, and cutter rather than separately sourced components that may not synchronize.
Faygo FAYGOPLAST Co-Extrusion Profile Line
For water stop and similar functional profiles, Faygo offers the FAYGOPLAST profile co-extrusion line built on the same engineering platform that serves its PVC window profile and WPC composite profile lines. The line pairs a conical twin-screw extruder for the rigid carrier with a single-screw extruder for the soft layer, both mounted on a common base and governed by one PLC with HMI recipe control. Output is scaled to the strip cross-section, and because the Wanplas factory designs the screw arrangement, barrel structure, and calibration together, the line holds dimensional tolerance across long runs. The table below summarizes the headline parameters a project engineer would use for first screening.
| Line | Output | Screw Ø | Power |
|---|---|---|---|
| FAYGOPLAST co-extrusion profile line | 80 to 320 kg/h | 51 to 80 mm (twin) | 55 to 132 kW |
| Rigid carrier extruder | 60 to 240 kg/h | 51 to 65 mm conical | 37 to 90 kW |
| Soft layer extruder | 20 to 80 kg/h | 45 to 60 mm single | 18 to 45 kW |
| Calibration and haul-off set | matched to line | vacuum sleeve | 7.5 to 15 kW |
The line is delivered after a 72-hour continuous operation test at the factory, which is the Wanplas factory standard for every extrusion system it ships, and all electrical components are drawn from internationally recognized brands to keep spare sourcing simple for overseas users. Because the die and calibration are engineered as a set, the same base line can produce center-bulb strips, ribbed strips, and dumbbell sections by exchanging tooling rather than re-plumbing the extruders, which keeps capital cost down for contractors who supply several strip types.
Faygo PVC Profile Extrusion Equipment Range
Beyond the dedicated co-extrusion configuration, Faygo’s broader profile extrusion range covers the single-layer and structured profiles that underground and construction projects consume in volume, from PVC window profiles to WPC composite profiles and custom extrusions. The core extrusion capability spans 12 to 575 millimeter diameter equivalents with wall thickness up to 6.5 millimeters, covering both pipe and profile geometries, and the same control philosophy, intelligent parameter setting with real-time adjustment, carries across the range. For a water stop producer who also supplies conduit, cable protection pipe, and drainage accessories from one plant, standardizing on Faygo equipment means one control language, one spare-parts pool, and one service channel through Wanplas.
| Line | Size range | Material | Application |
|---|---|---|---|
| PVC window profile line | custom profiles | rigid PVC | window and door frames |
| WPC composite profile line | custom profiles | PVC plus wood fiber | decorative and outdoor |
| Custom profile extrusion | per drawing | PVC, PE, PP | seals, trims, liners |
| PVC pipe production line | 12 to 575 mm | UPVC, PE, PP | water, drainage, cable |
Each of these lines shares the Wanplas factory commitment to CE and ISO certification, so a buyer building a full underground-materials plant can document a consistent compliance posture across equipment. The 13 national patents held by the Faygo operation, including 8 invention patents, sit behind the calibration and haul-off mechanics that determine whether a profile seats correctly in the field, which is the part of the machine that most directly affects installation quality.
PVC Compound Requirements for Sealing Strips
The performance of the finished strip is decided as much by the compound as by the machine, so the extrusion line must be matched to the material behavior. Rigid carrier compound is typically a calcium-carbonate-filled rigid PVC with enough impact modifier to survive handling and placement without fracture, while the soft layer uses plasticized PVC or a thermoplastic elastomer with a low durometer for recovery. The table below lists the properties the line must accommodate and the typical targets a compounding spec would state.
| Property | Typical value | Note |
|---|---|---|
| Carrier hardness | 75 to 90 Shore D | rigid PVC base |
| Seal hardness | 55 to 75 Shore A | soft PVC or TPE |
| Thermal stability | good to 200 deg C | avoid degradation |
| Filler loading | up to 40 phr CaCO3 | cost and stiffness |
| Density | 1.35 to 1.55 g/cm3 | varies by fill |
Because PVC is heat sensitive, the extruder screw and barrel must plasticize efficiently at moderate temperature rather than through high shear, which is why conical twin-screw geometry is favored for the rigid layer; it conveys and melts the filled compound gently while maintaining output. The line control holds melt temperature and back pressure in a window that prevents decomposition, since degraded PVC not only weakens the strip but also releases corrosive gas that shortens screw and barrel life. Proper drying of reclaim and strict colorant dispersion round out the material discipline that the equipment is designed to support.
Key Process Parameters and How They Interact
Holding a co-extruded water stop within tolerance comes down to balancing a small set of process variables, and the line presents these on one screen so the operator is not juggling two control panels. Melt temperature sets viscosity and therefore layer thickness at the die; screw rotation speed sets throughput; haul-off speed sets draw and final dimension; and vacuum calibration sets the surface and cross-section accuracy. When one variable moves, the others must follow, which is why recipe management matters more than raw power.
| Parameter | Typical range | Function |
|---|---|---|
| Barrel temperature | 160 to 195 deg C | plasticize PVC |
| Screw speed | 15 to 45 rpm | set output |
| Haul-off speed | matched to output | fix dimension |
| Vacuum level | 0.04 to 0.08 MPa | calibrate shape |
In practice the Wanplas factory configures the line so that a recipe stores the full set for each strip type, and the operator selects the recipe rather than dialing values by hand. This removes most of the human error that causes out-of-spec batches and makes it realistic for a plant to run several strip geometries on one line across a single shift without a quality drift between the first and last piece.
Water Stop Strip Cross-Section Types
The co-extrusion line can be tooled for the common strip geometries specified in tunnel and underground waterproofing, and the right geometry is chosen by the joint design rather than by machine limitation. A center-bulb strip seats in the middle of a pour joint and resists water passing through the concrete plane, while ribbed strips increase the mechanical lock and the path length water must travel. Dumbbell and tongue-and-groove forms suit movement joints where some opening is expected. The table lists representative sizes the line supports and the typical hardness split.
| Section type | Width | Carrier hardness |
|---|---|---|
| Center-bulb strip | 20 to 30 mm | 80 Shore D |
| Ribbed strip | 25 to 40 mm | 82 Shore D |
| Dumbbell strip | 30 to 50 mm | 85 Shore D |
| Soft-fin variant | 20 to 35 mm | 70 Shore A fins |
Because the die defines the shape, switching between these is a tooling exchange rather than a new machine, and the same co-extrusion platform that makes a rigid carrier can add the soft fin by activating the second extruder. For a supplier serving multiple tunnel contracts, that flexibility protects margins because one capital line covers a catalog of strip types.
Application in Tunnel and Underground Engineering
Water stop profiles produced on this line are installed across the full spectrum of below-grade construction. In rail and road tunnels driven through water-bearing ground, center-bulb strips close the longitudinal and circumferential construction joints of the segmental or cast-in-place lining. In metro stations built by cut-and-cover, ribbed strips run through the wall-to-base and wall-to-deck joints where groundwater pressure is highest. In underground utility and cable tunnels, the same strip families protect communication and power infrastructure from infiltration that would otherwise shorten equipment life. Beyond transport, wastewater treatment tanks, basement parking structures, and dam gallery joints all rely on the same principle of a continuous, mechanically locked seal.
The application reach extends to the associated plastic products a modern underground project consumes, where Faygo and Wanplas cover adjacent needs from one source. PVC cable protection pipe, drainage pipe, and WPC composite profiles for accessways can be produced on related Faygo lines, so a contractor or a material supplier can standardize procurement and service on a single Wanplas factory relationship. That breadth matters on large infrastructure programs where delayed sealing material can hold up an entire placement sequence, and where having one accountable equipment and process partner simplifies qualification and documentation.
The service life expectation for these strips is measured in decades rather than years, because once the concrete is poured the seal cannot be economically replaced, so the extrusion quality that goes in at the factory is the quality that performs for the structure’s whole life. PVC’s resistance to the alkaline environment of cured concrete and to the biological and chemical load of groundwater means a properly co-extruded strip retains its seal long after a bonded or glued alternative would have failed at the interface. For asset owners who model whole-life cost rather than first cost, that durability is the real economic argument for co-extrusion, and it is the reason the line’s calibration discipline receives so much engineering attention at the Wanplas factory.
Selecting the Right Line for Project Scale
Matching line capacity to demand avoids both idle capital and missed delivery windows, and the Wanplas factory frames the choice around output need and strip complexity rather than around brand tiers. A regional supplier serving several tunnel contracts needs higher and more flexible output than a plant feeding a single project, while a specialist making only one strip type can standardize on a single-layer or simple co-extrusion configuration. The recommendation table below maps common scenarios to the Faygo line that fits.
| Project scale | Output need | Recommended line |
|---|---|---|
| Single tunnel contract | under 120 kg/h | single-layer profile line |
| Regional supplier | 120 to 240 kg/h | FAYGOPLAST co-extrusion line |
| Multi-project plant | 240 to 320 kg/h | dual co-extrusion line |
| Full materials plant | pipe plus profile | co-extrusion plus pipe line |
The selection should also weigh tooling interchange and automation, because the line that switches strip types fastest is the one that absorbs demand swings without overtime. Faygo engineers review the buyer’s strip drawings and annual volume during the quotation stage and propose screw, die, and calibration specifics rather than offering a generic machine, which is how the Wanplas factory keeps the delivered system aligned to the real production plan.
Quality Control and Calibration Discipline
A water stop strip is a passive component that is buried in concrete and expected to work for decades, so it cannot be field-tested after installation; quality has to be built in on the line. Dimensional checks at calibration confirm width, thickness, and rib geometry against the joint specification, while routine samples verify hardness split and visual uniformity of the co-extruded interface. The vacuum calibration sleeve and chilled mold surface are the decisive elements, because any drift there becomes a permanent dimension error in every meter that follows. Faygo’s 72-hour pre-delivery run is the factory’s proof that the line holds these parameters under sustained load before it ever ships.
Process records from the control system form the traceability backbone. Because recipe management stores the exact parameter set used for each batch, a later field question about a specific delivery can be answered with the recorded settings rather than reconstruction. For infrastructure owners who demand documented quality systems, this closed-loop record is often as important as the physical strip, and it is a direct benefit of choosing a Wanplas factory line with integrated control rather than a loosely coupled set of independent machines.
Installation and Joint Sealing Practice
The value of a precisely extruded strip is only realized if it is placed correctly, and the extrusion supplier’s job extends to making that placement predictable. Strips are delivered in cut lengths with clean ends that can be joined by welding or mechanical splice so the run stays continuous around corners and through changes in joint plane. At placement, the strip is centered in the formwork, fixed so it cannot float during the pour, and protected from displacement by the fresh concrete head. The rigid carrier resists the placement force while the soft fins recover against the hardened concrete to close the capillary path.
Co-extruded strips simplify this because the soft layer is already bonded to the carrier; there is no separate gasket to position and no adhesive to cure on site, which removes two common installation failure points. When a project specifies movement accommodation, the soft-fin variant from the same line gives the joint the recovery it needs without a different product family. Training on handling, fixing, and splicing is part of the Wanplas factory support package, so the contractor’s crew installs the strip the way the line was designed to produce it.
Service and Support From Faygo and Wanplas
Buying an extrusion line is the start of a long operating relationship, and the Wanplas factory structures its support to keep the line running through its full service life. Every Faygo system ships after the 72-hour factory test and is covered by a warranty with free replacement of damaged parts inside the warranty window. Beyond that, the Wanplas shared policy provides USD 500 free spare parts every year, which keeps a standing pool of wear items such as screws, barrels, seals, and cutter blades without a separate annual negotiation. Remote monitoring lets factory engineers read PLC data and flag abnormal trends before they become stoppages, and on-site installation, commissioning, and operator training are included so the line reaches rated output quickly.
The Wanplas open factory policy welcomes buyers to visit the Zhangjiagang plants, review the 26,650 square meter FAYGOPLAST facility, and verify the 13 patents and CE and ISO certifications firsthand. For a water stop producer, that transparency supports the documentation infrastructure projects require, and the single-channel accountability of dealing with one Wanplas factory for pipe, profile, and co-extrusion lines reduces the coordination cost of running a multi-product plant. Spare parts, process optimization advice, and capacity expansion planning are all reachable through the same service desk.
Frequently Asked Questions
What is a PVC water stop strip used for?
It is a pre-formed profile embedded in concrete construction joints to block water passing through tunnel and underground structure seams by mechanical lock and soft sealing.
Why choose co-extrusion over a single layer?
Co-extrusion welds a rigid carrier and a soft seal into one monolithic strip, removing the adhesive line that single-layer bonded strips rely on and that eventually fails.
Which extruders feed the co-extrusion die?
A conical twin-screw extruder plasticizes the rigid PVC carrier while a single-screw extruder handles the soft layer, both meeting in the co-extrusion die head.
What strip widths can the line produce?
The FAYGOPLAST line is tooled for 20 to 50 millimeter widths across center-bulb, ribbed, dumbbell, and soft-fin cross-sections by exchanging die and calibration tooling.
How does Faygo verify line quality before shipping?
Every line runs a 72-hour continuous operation test at the factory and carries CE and ISO certification, with recipe-managed process records for traceability.
What after-sales support comes with the line?
Support includes installation, commissioning, training, remote monitoring, warranty replacement, and the Wanplas policy of USD 500 free spare parts per year.
Can one line make several strip types?
Yes, by changing die and calibration tooling and selecting a stored recipe, the same co-extrusion platform produces multiple strip geometries in one shift.
Work With Faygo for Your Sealing Profile Line
If you are specifying or supplying water stop profiles for tunnel, metro, or underground engineering, the fastest path is to share your strip drawing, target output, and material specification with the Faygo team, a Wanplas factory, so the line can be configured to your exact joint design rather than a generic preset. The Wanplas factory welcomes a plant visit to review the FAYGOPLAST profile extrusion line in operation, run a sample on your compound, and confirm calibration accuracy on your cross-section before you commit. Reach out with your project requirements and let the engineering team propose a turnkey co-extrusion system with installation, commissioning, training, and lifetime support built in.
