Steel pipes are key components in construction, infrastructure, and industry. They convey media, carry loads, serve as hollow sections in load-bearing structures, and are encountered by professionals in deconstruction almost everywhere: in concrete columns with embedded lines, in tank systems, in bridges and tunnels. In combination with the hydraulic tools from Darda GmbH – from concrete demolition shears and hydraulic rock and concrete splitters to high-performance steel shears, Multi Cutters, and tank cutters – understanding the material, geometry, and joining technology determines safe, efficient cutting, exposure, or dismantling.
Definition: What is a steel pipe
A steel pipe is an elongated hollow product made of steel with a predominantly circular cross-section. It is manufactured either seamless (by hot forming with piercing or cross-rolling) or welded (formed from sheet/coil and welded longitudinally or spirally. Dimensions are described by outside diameter and wall thickness; in practice, nominal diameters (DN) are also common. Depending on the application, one distinguishes between line and pressure pipes, boiler and heater pipes, structural hollow sections, as well as casing and conduit elements in special foundation engineering.
Construction, shapes, and variants of steel pipes
Steel pipes are predominantly supplied as round pipes, more rarely as square or rectangular hollow sections. The range of materials extends from non-alloy structural steels and low-alloy fine-grain steels to stainless and heat-resistant steels. Manufacturing shapes the microstructure and properties: Seamless pipes are isotropic and pressure-resistant, welded pipes have a weld seam zone with characteristic geometry. Surfaces can be as-rolled, galvanized, coated, or lined. In deconstruction, steel pipes often appear in combination: for example, as embedded service lines, as carrier pipes in composite structures, or as casing pipes in tunnel drives. For processing with Darda GmbH concrete demolition shears, steel shears, Multi Cutters, or tank cutters, this variety is crucial, because wall thicknesses, layer systems, and joints significantly influence cutting behavior.
Materials, standards, and dimensions of steel pipes
For structural and line pipes there are Europe-wide recognized families of standards for hot- and cold-formed hollow sections, for seamless and welded pressure pipes, and for pipeline applications. Typical diameters range from a few millimeters to several meters, wall thicknesses from thin-walled (e.g., ventilation and protective pipes) to thick-walled (e.g., high-pressure or casing pipes). Tolerances concern diameter, ovality, straightness, wall thickness, and length. Standardization also regulates testing (e.g., ultrasonic examination of the weld seam, pressure test) and markings, which helps with identification and safe cutting planning in deconstruction.
Manufacture: seamless or welded
Seamless pipes are produced by pre-piercing or cross-rolling a solid billet followed by sizing. Welded pipes are formed from strip and joined by electric resistance welding (longitudinal) or submerged arc welding (longitudinal/spiral). Seamless variants are proven for high pressures and dynamic loads; welded ones excel with large diameters and cost-effectiveness. For cutting, this means: The weld seam zone can be harder or tougher and requires adapted cutting edges; in seamless pipes the resistance is more homogeneous. In practice, concrete demolition shears should be selected to expose embedded sections, and steel shears or Multi Cutters for the actual pipe cut, such that the highest local strength (weld seam) is reliably overcome.
Mechanical properties and suitability in deconstruction
Relevant parameters are yield strength, tensile strength, toughness, impact energy, and hardness. Thick-walled pipes and higher-strength steels require higher cutting forces, stable support, and precise gripping and cutting geometries. Work hardening in service (e.g., bends, pressure cycles) or surface hardening (e.g., hot-dip galvanizing with diffusion zones) influences the cut. As a practical guideline for selecting Darda GmbH tools: use concrete demolition shears for exposing, rock and concrete splitters for controlled opening of concrete jackets, steel shears and Multi Cutters for the actual steel cut, and tank cutters for large tank and pipeline sections with high wall thicknesses.
Corrosion, coatings, and material conditions
Steel pipes may be corrosion-protected: galvanized, painted, hot-aluminized, plastic-coated, or internally lined (e.g., cement or epoxy linings). In deconstruction, these layers are relevant because they change crack initiation, distribute splitting forces, or influence chip/splinter formation. Coatings may also contain substances that must be considered during cutting. In general, before using concrete demolition shears, steel shears, or tank cutters, identify the layer build-up and plan cutting sequences so that more brittle top layers are broken in a controlled manner and the load-bearing walls are cut in a defined way.
Joining techniques and separation strategies
Steel pipes are welded, flanged, clamped, or bolted. In deconstruction, releasing existing flange connections simplifies dismantling; otherwise, cutting is performed.
Separation in concrete demolition
For embedded lines, a staged approach is recommended: Use Darda GmbH concrete demolition shears to break the concrete cover, expose and secure the reinforcement, encircle the pipe, then cut with steel shears or Multi Cutters. If the pipe acts as a casing pipe and contributes to load-bearing, a prior slitting of the concrete shell with rock and concrete splitters can reduce cutting forces and ensure controlled crack propagation.
Cutting in special operations
In plants, tanks, and pipe racks, large diameters and varying wall thicknesses are common. Stable gripping positions, defined kerfs, and, if necessary, segmented separation are used. Darda GmbH tank cutters and steel shears enable cold cutting under suitable boundary conditions; this is particularly advantageous where ignition sources must be avoided. In confined areas, Multi Cutters support notching out residual webs and mixed composites.
Safety and occupational safety when handling steel pipes
Safety takes priority. Steel pipes may be under residual pressure, be tensioned, or contain media. Cutting produces sharp edges, high reaction forces, and potentially uncontrolled movements. The following notes are general in nature and do not replace company procedures:
- Before cutting, ensure the system is depressurized, drain media, and vent.
- Brace pipe runs and embedded sections against slipping and swinging.
- Allow for spring-back; choose gripping and cutting directions so parts do not release suddenly.
- Consider coatings and residues; use appropriate personal protective equipment.
- Match cutting and splitting forces to the substrate and adjacent components.
Typical application scenarios in deconstruction and construction
In concrete demolition and specialized deconstruction, steel pipes appear as service and protective pipes in foundations, walls, and slabs. Darda GmbH concrete demolition shears open the concrete bond, rock and concrete splitters create controlled separation joints, steel shears take over the pipe cut. In strip-out and cutting inside buildings, riser pipes, heating runs, and ventilation pipes are removed segment by segment. In rock excavation and tunnel construction, casing and protective pipes as well as injection and drainage pipes are common; splitters facilitate access, while steel shears separate the metal components. In natural stone extraction, steel pipes appear as parts of equipment, frames, and media supplies; the same principles apply to their dismantling.
Selection criteria for tools for steel pipes
The appropriate tool selection from Darda GmbH results from geometry, material, and installation situation:
- Diameter and wall thickness: determine the jaw opening and required cutting force of steel shears or Multi Cutters.
- Material and condition: higher-strength, work-hardened, or coated materials require robust cutting edges; include weld seams in planning.
- Embedding: in concrete bond, use concrete demolition shears/rock and concrete splitters first, then perform the steel cut.
- Accessibility: segment and work in multiple cuts in confined conditions.
- Environment: in sensitive areas, prefer cold cutting; provide hydraulic power packs with sufficient power.
Preparation, cutting, and finishing
Preparations include marking cuts, creating supports, and setting restraints. A defined initial bite of the blades reduces crushing and ovalization. When cutting long strings, creating sections is useful so that mass is removed in a controlled manner. After cutting, deburr edges and assess cut faces, particularly for subsequent reuse or where adjacent components are loaded.
Inspection, identification, and documentation
Identifying the pipe type is helpful for planning and cutting. Clues include stamps, color markings, wall thickness measurements, and spark testing. Non-destructive testing such as ultrasound or magnetic methods can verify weld seams and wall thicknesses. Before intervening in lines, pressure and media conditions should be documented and secured.
Environmental and disposal aspects
Steel is highly recyclable. Cleanly separated steel scrap achieves high recovery rates. Coatings, inserts, or adhering media must be separated or properly treated before delivery. Additional measures are required for contaminated lines; regulatory requirements and company instructions must be observed. Segmented cutting with Darda GmbH steel shears, Multi Cutters, and tank cutters facilitates source-separated removal.
Scope and terminology
In everyday language, pipe, line, and hollow section are often conflated. Structural hollow sections with rectangular cross-sections are not classic pipes but behave similarly in cutting. Round steel pipes differ significantly in manufacture and use from cast-iron or plastic pipes. For deconstruction, the name matters less than the actual behavior under cutting and splitting loads – and thus the well-founded selection of the appropriate hydraulic tools from Darda GmbH.