Plastic pipes are indispensable in modern construction, building services engineering, and industrial infrastructure. They serve as lines for water, wastewater, gases, and media, as protective and empty conduits for cables, and as casing and liner pipes in concrete elements. In new construction they enable lightweight, corrosion-resistant, and installation-friendly solutions; in deconstruction they influence the workflow during controlled demolition, strip-out, and cutting. Especially in combination with hydraulic tools such as concrete demolition shear or hydraulic splitter, a sound understanding of materials, joints, and installation situations of plastic pipes is crucial to work precisely, safely, and in a material-appropriate manner.
Definition: What is meant by plastic pipe
A plastic pipe is a hollow cylindrical line made of thermoplastic or thermoset plastics that convey media, provide protection, or assume construction functions (e.g., penetrations). Common materials are PE-HD (high-density polyethylene), PP (polypropylene), PVC-U (unplasticized PVC), as well as special plastics such as PA (polyamide) or PVDF for chemically demanding applications. Plastic pipes are produced as pressure pipes (e.g., drinking water, gas), gravity lines (e.g., foul and storm water), or conduit/protective conduit systems (e.g., cable protection). Structural parameters such as SDR (wall thickness ratio), PN (pressure rating), and ring stiffness (SN) describe load-bearing capacity and suitability. Joints are made using push-fit sockets with elastomer gaskets, welding methods (butt welding, electrofusion couplers), or adhesive/flanged connections.
Materials, designs, and key parameters of plastic pipes
Plastic pipes differ by raw material, manufacturing, and mechanical design. PE-HD (e.g., PE 100/PE 100-RC) is tough, impact-resistant, and cold-bendable; it is used as a pressure pipe for water, gas, firefighting water, and in tunnel construction for drainage. PP scores with temperature resistance and chemical resistance, often in wastewater and laboratory lines. PVC-U is dimensionally stable and ring-stiff, widely used in gravity sewers and cable protection. Special plastics such as PA or PVDF are employed where pressure, temperature, or chemistry requires it. Ring stiffness (SN classes) describes resistance to earth cover and traffic loads, and the SDR ratio describes wall thickness relative to outside diameter. Multilayer pipes, corrugated designs (smooth inside, structured outside), and composite solutions with protective layers optimize abrasion, UV, and stress-crack resistance. Joints are selected to suit the medium and load case: sealing sockets for gravity pipelines, welded joints for pressure-retaining systems, bonding for PVC-U, and flanges for detachable connections or penetrations in cast-in-place concrete.
Typical applications of plastic pipes in building, civil, and tunnel construction
Plastic pipes cover a wide range of applications from buildings to infrastructure:
- Drinking water and gas supply as pressure-retaining PE-HD pipelines
- Wastewater, storm, and combined water as gravity pipes made of PVC-U or PP
- Drainage, dewatering of subsoil, and tunnel drainage (PE-HD, perforated, with filter wrap)
- Cable protection and conduit systems in foundations, slabs, and corridors
- Media lines in industry and laboratories with increased chemical resistance
- Casing and casing pipe solutions as penetrations in walls, slabs, and bases
In rock demolition and tunnel construction, PE-HD drainage and compressed air line installations secure the construction process; in concrete construction, conduits and casing pipes are embedded for installations or core drilling. In natural stone extraction, robust plastic lines are often used for water conveyance and dust suppression.
Embedding in concrete: conduits, casing pipes, and penetrations
Integrating plastic pipes into concrete elements requires careful planning and execution to ensure watertightness, load-bearing capacity, and subsequent measures (e.g., deconstruction).
Conduits and casing pipes
Conduits (cable protection) and casing pipes (larger diameter for later occupancy) are fixed precisely in plan and elevation. Minimum cover, edge distances, and bending radii must be observed to avoid damage during concreting. For longer runs, thermal expansion and creep of the plastic must be considered; expansion compensation via sockets or sliding support points is advisable.
Penetrations and sealing
Liner pipes and sealing systems separate the element and the line. Sealing against ground moisture, non-pressurized or pressurized water is achieved by sealing flanges or compression seals matched to the pipe geometry. Where fire protection is required, the respective fire stop measures must be planned; details are project-specific and require coordinated execution.
Quality assurance
Leakage tests (e.g., air or water for gravity sewers, pressure tests for pressure pipes), visual inspection of joints, and documentation of the pipeline route ensure functional reliability over the service life.
Deconstruction: plastic pipes in concrete demolition and special demolition
During selective deconstruction, strip-out, and cutting, plastic lines are often connected with concrete, masonry, or steel. They influence the choice of work sequence and tools.
- Survey: Review line plans, locate and expose routes, identify media (water, wastewater, gas, chemicals).
- Shut-down: Safely isolate media, drain and flush lines, relieve residual pressures.
- Exposure: Before demolition, selectively open the pipe surroundings, e.g., with concrete demolition shear for concrete removal or with core drilling as controlled weakening.
- Severing: Cut plastic pipes in a material-appropriate and functionally safe manner, accounting for embrittlement in cold conditions and springback.
- Sorting: Clean separation of plastic, steel (reinforcement, flanges), and concrete debris to optimize recycling routes.
In practice, hydraulic splitter can be helpful for opening components around a line with low stress without generating uncontrolled cracks along a plastic route. Concrete demolition shear allow precise removal of cover concrete to work out embedded conduits or casing pipes.
Impact of plastic pipes on the use of concrete demolition shear and hydraulic splitter
Plastic behaves ductile and can deflect crack propagation or bridge tensile forces. This affects process reliability:
- Crack guidance: Embedded conduits can change the crack path during splitting. Borehole position and splitting direction must be matched to this.
- Grip behavior: Smooth pipe surfaces reduce frictional engagement. When gripping with shears, contact surfaces should be free of sliding layers (moisture, slurry).
- Temperature: PVC-U embrittles in cold conditions; PE/PP become tougher when warm. Cutting and splitting parameters must be adjusted.
- Inserts: Metallic fittings or flanges in the pipe zone require switching to suitable cutting or shear tools.
For clean results, a sequence is advisable: first remove cover concrete, expose the pipe run, then cut in a targeted manner before splitting or breaking larger areas.
Severing and cutting plastic pipes in existing structures
The choice of severing method depends on material, wall thickness, installation situation, and adjacent building materials.
Suitable methods
- Cold-cutting methods with suitable blades or pipe cutters for PE/PP/PVC to avoid thermal damage.
- Guided cuts with controlled chip removal to prevent delamination in composite pipes.
- For composites (pipe in concrete): Pre-cut the plastic, then remove residual concrete with concrete demolition shear or with targeted splitting.
- With steel inserts: Switch to shear or cutter tools; in industrial deconstruction, Multi Cutters or steel shear can be useful when metallic components predominate.
Practical notes
- Fix the pipe and avoid kinking; allow for springback.
- Minimize chip and particle formation; use dust extraction or wetting to reduce microparticles.
- Deburr cut edges if connections will be temporarily re-used.
- Match tool selection to residual media (e.g., avoid spark generation with flammable residues).
Sorting, recycling, and disposal
Material-pure separation improves material recycling. Markings on pipes (material codes, SDR, PN, SN) facilitate identification. PE-HD and PP are well recyclable; PVC-U requires clean fractions and special attention to additives. Composite or fiber-reinforced pipes are often thermally recovered. Disposal must comply with applicable requirements; for contaminated lines (e.g., chemicals, oil), suitable cleaning and disposal routes must be provided.
Resistance, aging, and condition assessment
The service life of plastic pipes is determined by medium, temperature, UV exposure, and mechanical loading. PE can be susceptible to environmental stress cracking (ESC) with certain media and notches; PP is more temperature-stable but more brittle in deep cold. PVC-U exhibits increased impact sensitivity at low temperatures. Regular inspections (visual checks, camera inspection for sewers, pressure/leakage tests) provide proof of condition. For deconstruction planning, documenting year of construction, material, and joints is worthwhile to select suitable cutting and demolition methods.
Marking, standards, and quality assurance
Prints on pipes usually contain information on material, dimension, SDR/PN or SN, and production data. This information is helpful for site supervision, documentation, and later deconstruction. Normative requirements for dimensional accuracy, tightness, ring stiffness, and jointing must be met; the specific application determines the governing standards. Tests and approvals should be documented to make later interventions (e.g., strip-out or special demolition) more plannable.
Interfaces with products and application areas of Darda GmbH
In concrete demolition and special demolition, plastic pipes appear as inserts, media lines, or protective lines. Concrete demolition shear are used to selectively remove concrete and expose lines; hydraulic splitter support low-stress separation cuts and controlled crack guidance near pipe routes. In strip-out and cutting, clean cuts and material-pure streams are important; with mixed composites, Multi Cutters or steel shear help when metallic components predominate. In rock breakout and tunnel construction, PE-HD drainage and supply lines must be protected, rerouted, or dismantled in an orderly manner during advance and support; this includes tunnel drainage and compressed air line systems. In natural stone extraction, plastic lines often secure water conveyance; when removing blocks, the location of these lines must be considered in crack planning. For special demolition (e.g., contaminated media lines), there are increased requirements for occupational safety, cutting technology, and disposal.
Avoiding planning and execution errors
Typical errors include impermissible bending radii, missing fixation before concreting, incompatible sealing systems, unfavorable pipe locations in later separation zones, and insufficient documentation. Future interventions (inspection, repurposing, deconstruction) should be considered already in planning. Good documentation of routes, materials, and jointing techniques makes safe processing with hydraulic tools easier over the life cycle.
Practice-oriented checklist
For new construction
- Define medium, temperature, and pressure; select suitable material (PE, PP, PVC-U) and key parameters (SDR/PN or SN).
- Plan installation conditions: fixation, bending radii, penetrations, sealing.
- Determine jointing technique: push-fit socket, welding, bonding, or flange.
- Create documentation of the pipeline route, material marking, and tests.
For deconstruction/strip-out
- Locate lines, identify media, and safely shut down the system.
- Expose with concrete demolition shear, use controlled splitting in sensitive areas.
- Cut according to the material; with metal content, additionally use shears/cutters.
- Sort cleanly; utilize recycling potential and arrange compliant disposal.