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Welded constructions & machining

Heavy welded steel structures for hydraulic plant — spiral casings, penstock sections, gates and closures — together with turning, boring and milling of the large components that go into them.

Welded constructions

Spiral casings and penstock sections

Spiralgehäuse und Druckrohrleitung · Spiralno kućište i cjevovod

Pressure-retaining welded structures are made from certified fine-grain plate, rolled to shape, assembled on jigs and welded to qualified procedures. Every seam is documented: the weld map, the WPS applied, the welder, and the NDT report belong to the part.

Where the design code requires it, the assembly is stress relieved before final machining of the flanges and sealing surfaces, so that the geometry that leaves the shop is the geometry that arrives on site.

Fabrication data
Scope	Spiral casings, stay rings, draft tube linings, penstock and manifold sections, bifurcations, transition pieces, anchor and embedded parts
Materials	S235JR – S355J2+N; fine-grain S460 / S500 / S690QL to EN 10025-3 and EN 10025-6; stainless steels on request
Plate thickness	up to 80 mm, thicker on request
Welding	Quality requirements to EN ISO 3834-2; procedures qualified to EN ISO 15614-1; welders certified to EN ISO 9606-1
Non-destructive testing	VT, PT, MT, UT and RT to EN ISO 17635, by personnel qualified to EN ISO 9712 level 2/3
Heat treatment	Stress relieving where required by the design code, with recorded temperature curve
Testing	Hydrostatic pressure test, dimensional and geometry check, weld map and test records
Surface protection	Blast cleaning to Sa 2½ (EN ISO 8501-1) and coating systems to EN ISO 12944, categories C3 to C5-M
Execution	EN 1090-2, execution classes EXC2 to EXC4, according to the project specification

Plan schematic of a welded spiral casing — Spiral casing with stay ring, plan view

Gates and closures

Sluice gates — flat, radial and segment

Flach-, Radial- und Segmentschütze · Ravne, radijalne i segmentne zapornice

Gates are supplied as a complete closure: skin plate and stiffening structure, guides and embedded parts, sealing system, and the drive with its controls — designed so that the parts cast into concrete and the moving structure are dimensionally consistent from the start.

Sealing faces are stainless steel and the seal profiles are replaceable without dismantling the structure, which is what determines how much of the plant has to be taken out of service for maintenance.

Fabrication data
Types	Flat (slide) gates, radial gates, segment and sector gates, stoplogs and bulkheads, trash racks and intake screens
Materials	S235JR / S355J2+N structural steel; sealing seats and fasteners in 1.4301, 1.4404 or 1.4571
Seals	Replaceable rubber profiles (note, flat and corner types) to DIN 19704-1
Embedded parts	Guide frames, sill beams, side and top seal seats, anchors and second-stage concrete parts
Drives	Spindle with electric actuator, hydraulic cylinder with power pack, chain or rope hoist, manual emergency operation
Surface protection	Hot-dip galvanising to EN ISO 1461 or coating to EN ISO 12944, categories C4 and C5-M (Im1/Im2 for immersed parts)
Standards	DIN 19704-1/-2/-3, DIN 19705, EN 1993-1, EN 1090-2
Application	Intakes and spillways, bottom outlets, weirs, irrigation and flood control, industrial water systems

Sectional schematic of a radial gate — Radial gate with trunnion and embedded parts

Machining

Machining of large components

Großteilbearbeitung · Mašinska obrada velikih dijelova

Turning, boring, milling and grinding of heavy single pieces and small series — the sealing and bearing surfaces that decide whether a valve is tight and whether it stays tight after a hundred operating cycles.

We work from a drawing, from a sample, or from measurements taken on the installed part when no documentation survives — the usual situation on plants built decades ago.

Machining data
Operations	Vertical and horizontal turning, boring, milling, drilling, threading, keyways, grinding and lapping of sealing faces
Typical parts	Valve bodies and discs, spherical rotors, seat and wear rings, shafts and trunnions, flanges, hubs, covers, turbine components
Working basis	To drawing, to sample, or from measurement and reverse engineering of the installed component
Tolerances and finish	To the drawing; sealing surfaces machined and lapped to the tightness class required by the test specification
Records	Dimensional report, surface roughness measurement and material certificate EN 10204 3.1 supplied with the part
Capacity	Machine list with working envelopes and part weights available on request

Schematic of large part machining on a vertical turning lathe — Vertical turning of a large ring component

Delivered with the part

Documentation package

Materials

Inspection certificates EN 10204 3.1 or 3.2, material traceability and marking.

Welding

Weld map, WPS and WPQR, welder qualifications, welding consumable certificates.

Testing

NDT reports, pressure and tightness test records, dimensional and functional test protocols.

Handover

Coating report, as-built drawings, operation and maintenance manual, spare parts list.

Send us the drawings

Drawings, a specification or photographs of the installed part are enough for us to prepare a technical and commercial proposal.

Request a quotation