Pipeline

Pipelines are the backbone of technical infrastructure: they transport liquids, gases, or solid–liquid mixtures in buildings, industrial plants, tunnels, and open terrain. Planning, construction, operation, rehabilitation, and deconstruction bring together aspects of civil engineering, mechanical engineering, building services, and occupational safety. Especially in the context of concrete demolition and special deconstruction as well as strip-out and cutting, the controlled exposing, separating, and removing of pipelines plays a central role. Tools such as concrete pulverizers or rock and concrete splitters from Darda GmbH are frequently used in combination with hydraulic power packs to open components in a targeted manner and make pipeline runs safely accessible.

Definition: What is meant by pipeline

A pipeline is a self-contained pipeline system consisting of pipes, fittings, connections, valves, seals, supports, and measuring points. It serves the pipeline-based conveyance or distribution of media such as water, wastewater, gas, oil, compressed air, steam, or chemical products. Pipelines can be executed as pressure pipelines or gravity pipelines, run above ground, be integrated into the building structure, or be buried, and are sized according to media, temperatures, pressures, and environmental conditions.

Structure, components, and terms

Pipeline systems are assembled from coordinated components. Precise nomenclature facilitates planning, installation, operation, and deconstruction.

Main components

• Pipes: straight segments with defined nominal size and wall thickness
• Fittings: bends, tees, reducers, branches, caps
• Connections: welds, flanges, threads, adhesive or push-fit sockets, couplings
• Valves: shut-off, control, and check valves, safety valves
• Measuring and testing devices: pressure gauges, thermometers, flow and level meters, sampling points
• Supports: pipe clamps, fixed and sliding supports, slide bearings, vibration dampers
• Expansion joints and expansion elements to accommodate changes in length

Geometry and routing

Routes follow structural, hydraulic, and operational requirements. Changes in direction, slopes, high points (venting), and low points (draining) must be planned so that operation and maintenance are safe and efficient. In buildings, pipelines run in shafts, slabs, or walls; in tunnel construction along the crown or invert with defined support points.

Materials, media, and pressure ranges

Material selection depends on medium, pressure, temperature, corrosion exposure, fire protection, and mechanical loads.

• Metals: unalloyed/alloyed steel, stainless steel, cast iron; high strength, weldable, suitable for pressure and temperature ranges
• Plastics: PE, PP, PVC-U, PVDF; corrosion-resistant, low weight, limited temperature and pressure ranges
• Mineral-based materials: concrete and reinforced-concrete pipes, GRP; often for wastewater and large nominal diameters

Typical media are potable and service water, wastewater, natural gas, process gases, oils, emulsions, hydraulic fluids, compressed air, or slurries. Each medium has specific requirements for tightness, material compatibility, and marking.

Connections, valves, and sealing concepts

The joining technique determines ease of installation, tightness, and deconstructability.

• Welding (steel/stainless steel): permanent and integral; requires qualified execution and testing
• Flanged connections: detachable, maintenance-friendly; select gaskets specific to material and medium
• Threaded and coupling systems: for small to medium nominal sizes, quick installation
• Adhesive socket/push-fit socket (plastics): clean processing and curing are essential

Valves enable shut-off, control, draining, venting, and safeguarding. Expansion joints and sliding supports accommodate thermal expansion; fixed points transfer forces into structures. Pipelines embedded in concrete require coordinated penetrations and sealing systems.

Planning, structural analysis, and hydraulic design

Hydraulics, thermals, and structural analysis interact. Friction losses, flow profiles, and cavitation must be considered, as well as thermal expansion, self-weight, vibrations, and impact loads. For routes in concrete structures, block-outs, penetrations, and embedded components are coordinated early. For later interventions such as strip-out and cutting, documented pipeline routing is advantageous.

Installation, testing, and documentation

Installation sequences follow a structured approach: preassembly, alignment, tack/connection, support installation, tightness and strength testing, and functional testing of valves.

1. Pressure or leak testing by procedures appropriate to the medium and material
2. Flushing and cleaning (particle-free, grease-free, or passivated—depending on the application)
3. Labeling and marking of flow direction and media
4. As-built documentation as a basis for operation, maintenance, and later deconstruction

Operation, inspection, and maintenance

Regular visual inspections, leak monitoring, functional testing of safety valves, and condition assessment of supports ensure availability. Inspection intervals depend on medium, load, and environmental conditions. For sensitive media, a proactive spare-parts and sealing concept is advisable.

Corrosion, aging, and rehabilitation

Corrosion protection combines material selection, coatings, cathodic protection systems, and design measures. Aging mechanisms include wall-thickness reduction, stress corrosion cracking, embrittlement (plastics), erosion, and abrasion. Rehabilitation methods include relining, inlining, CIPP lining, or replacement of pipeline strings. Where load-bearing structures surround pipelines, interventions must be coordinated with structural analysis and fire protection.

Pipelines in concrete and masonry: exposing, opening, deconstruction

During strip-out and concrete demolition, pipelines are often encased by concrete, masonry, or plaster layers. Gentle exposing reduces damage to the pipeline run, enables controlled draining, and minimizes unintended media releases.

Tools and approaches

• Concrete pulverizers: targeted biting of concrete while preserving visibility of built-in pipelines; particularly suitable on beams, wall chases, and shafts
• Rock and concrete splitters: wedge-based splitting technique for low-vibration opening of massive components, e.g., to access bundles of pipelines in plinths or foundations
• Hydraulic power packs: supply splitting and shear tools with the required energy, can be deployed mobile inside buildings

For concealed routing, opening in sections improves control. Reinforcing steel can be cut with Multi Cutters once the concrete is exposed. The coordinated interplay reduces rework and facilitates the safe removal of pipelines.

Cutting and separating steel and cast-iron pipes in deconstruction

In special deconstruction, precise separation of pipe segments is important to reduce loads and separate disposal streams.

• Steel shears: segment-wise cutting of steel and stainless-steel pipes, including in confined shafts
• Combination shears and Multi Cutters: flexible use for pipe, structural steel section, and reinforcement
• Tank cutters: for plant areas with vessels and large-diameter pipelines

The choice of cutting method depends on material, wall thickness, accessibility, spark and heat generation, and emission-reduction requirements. Mechanical–hydraulic methods are advantageous where thermal cutting is to be avoided for fire or explosion protection reasons.

Pipelines in tunnel construction, rock demolition, and natural stone extraction

In tunnel and gallery construction, pipelines for dewatering, compressed air, ventilation, or media supply run along the heading. Route adjustments and recesses in rock or shotcrete are often required at short notice.

• Rock splitting cylinders and rock and concrete splitters: create controlled space in rock or shotcrete for pipeline penetrations or deconstruction openings
• Concrete pulverizers: processing of shotcrete shells, anchor heads, and embedded parts in the area of the pipeline route
• Support installation: mounting of fixed and sliding supports on rails, anchors, or brackets with vibration isolation

In natural stone extraction and special deployments, temporary lines (e.g., water, compressed air) are routed. Safe laying, fixing, and later removal of these pipelines is part of an orderly construction-site workflow.

Safe work on pipelines: draining, inerting, separating

Before interventions on pipelines, media must be safely removed and residual energies dissipated. General principles of occupational safety apply; specific steps depend on the medium, system, and environment.

1. Shut off, tag, and secure affected runs
2. Controlled draining/degassing, if necessary inerting (e.g., with inert gases) with due attention to ventilation
3. Cleaning/flushing to reduce residues
4. Measurement for residual concentrations; only then mechanical opening
5. Separating the pipeline with suitable tools, assessing sparks and ignition sources

In sensitive zones, for example during strip-out and cutting in existing buildings, low-dust and low-vibration methods are advantageous. Concrete pulverizers and splitting techniques can contribute here by enabling controlled openings.

Penetrations, fire stops, and interfaces to the structure

Pipelines penetrate slabs, walls, and base slabs. Sealing against water as well as fire stops must match the medium and the component. In deconstruction, these interfaces are often starting points for exposing: first the surrounding component is opened with concrete pulverizers, then the seal is released and the pipeline is removed in segments.

Environmental and disposal aspects

Deconstruction generates material streams from metal, plastic, concrete, sealing compounds, and possible media residues. Source-separated sorting facilitates recycling and disposal. Pipes made of steel, cast iron, and non-ferrous metals are readily recyclable; plastics are recycled materially or as feedstock depending on quality and additives. Residual media must be properly collected and disposed of; mixing is to be avoided.

Application areas and typical use cases

• Concrete demolition and special deconstruction: exposing and removing embedded pipelines with concrete pulverizers and rock and concrete splitters
• Strip-out and cutting: selective separation of supply pipelines in buildings with Multi Cutters, combination shears, and steel shears
• Rock demolition and tunnel construction: creating openings and niches for pipelines using rock splitting techniques; installation and dismantling of temporary pipeline networks
• Natural stone extraction: safely route and deconstruct media-carrying temporary lines
• Special deployments: work in confined, hard-to-access areas with mobile hydraulic power packs

Practical approach to pipeline deconstruction

A structured sequence increases safety and efficiency.

1. Inventory: drawings, locating, sondages; clarify medium, material, and wall thickness
2. Hazard assessment: medium properties, pressure, explosion protection, structural analysis
3. Draining/cleaning: dissipate residual energy, perform clearance measurement
4. Exposing: open concrete/masonry section by section with concrete pulverizers or splitting techniques
5. Separating: select suitable shears/cutting tools (steel, cast iron, plastic)
6. Removal and material-stream management: collect by type, label, and haul away
7. Restoration of building elements: close penetrations, restore surfaces

Quality, documentation, and traceability

Clean cut edges, undamaged remaining components, and verifiable work steps facilitate inspections and approvals. Photos, measurement records, and material-stream evidence document the process. Clear handovers are helpful for subsequent trades.

Standards, codes of practice, and coordination

Planning, construction, and deconstruction of pipelines are aligned with generally accepted rules of technology. These include material- and medium-specific regulations, safety requirements, and building codes. Coordination with authorities, operators, and specialist planners must be carried out project-specifically. Legal requirements must be reviewed for each application; binding assessments are made by the responsible parties on site.