Marine and Offshore

Bore 20–1000 mm, working pressure up to 500 bar, stroke 6 000 mm and beyond, total length up to 16 000 mm, operating temperature from -50 °C to +200 °C; double-acting, single-acting, telescopic and plunger designs, with position and pressure sensors built in where the control system needs them. We choose the coating by where the cylinder works. On a cylinder under cover the rod gets 25–50 µm of hard chrome. For deck machinery and offshore duty we plate a triplex Ni-Cr layer of 30+30 µm, a nickel underplate with dense chrome and a micro-crack chrome top, which stops chloride reaching the steel through the crack network. Subsea actuators get 150–250 µm of HVOF ceramic (Cr3C2 or WC-Co) sprayed onto the rod. The rod steel depends on the same question. C45 or 42CrMo4 with induction hardening is used for covered positions, 1.4404 (316L) for light marine duty and 1.4462 duplex for offshore and heavy chloride exposure. After plating we grind the rod to Ra 0.2 µm, and where seal life is critical we superfinish it to Ra ≤ 0.1 µm. Every cylinder is pressure tested at 1.5× working pressure for at least five minutes, chrome and paint thickness go into the DFT record, and marine-grade cylinders are built with offshore corrosion protection and the documentation needed for DNV/ABS certification.

Typical parts

• Steering cylinders and rudder actuators
• Anchor windlass, hatch cover and ramp cylinders
• Luffing and hoist cylinders for deck and offshore cranes
• Subsea actuators with ceramic-coated duplex rods

Gear, planetary, axial-piston and radial-piston motors with displacement from 0.25 to 8000 cc/rev, working pressure up to 450 bar, speed from 0.5 to 12000 rpm and operating temperature from -40 °C to +120 °C. A winch drum or a windlass pulls hard at low speed, and a radial-piston motor gives its highest torque in exactly that range, so it is the usual choice for winches and deck drives. Mounting flanges follow SAE and DIN and the dimensions match the common equipment platforms; a motor of ours fits the original winch mount. Before dispatch each unit gets a functional test, a pressure test and a performance check against the catalogue values, and leaves with its documentation package. Motors already in service can be sent in for refurbishment between dockings.

Typical applications

• Radial-piston motors for winches, windlasses and capstans
• Slewing and hoist motors for deck cranes
• Pumps and motors for steering systems
• Drive motors for hatch cover and ramp systems

Our Schiess lathes take shafts up to 2 m in diameter and 16 m long, enough for propeller shafts, intermediate shafts and long piston rods. We hold ±0.05 mm and IT6–IT7 fits and keep straightness inside 0.1 mm/m over the full length. Long shafts do not fit on a CMM table, so we measure them with laser trackers and 3D scanners. Gearing for winches, windlasses, cranes and capstans is cut and ground on the same floor to ISO 1328, with grade 7 as the usual requirement for a loaded reducer stage, and carburised to a case depth of 1 to 3 mm at 56–62 HRC over a core of 240–300 HB. Where a drive sits in a wet or wash-down position we cut the gears in stainless steel or bronze. We machine a pinion shaft from one billet; a windlass gearbox that stands idle for weeks then has no keyed joint to work loose. When there is no drawing we measure the worn wheel and make the replacement from that.

Typical parts

• Propeller shafts and intermediate shafts up to 16 m
• Winch, windlass and capstan gearing, in stainless steel or bronze for wet positions
• Rudder stock components, tiller pins and bushings
• Cylinder bodies, glands and flanges for deck hydraulics

Control boxes, sensor housings and light fittings on deck are cast in aluminium to ±0.1–0.3 mm with Ra 1.6–6.3 µm, and most surfaces need no machining afterwards. Wall thickness can go down to 0.5–1.5 mm. For exposed surfaces we offer anodising, powder coating and painting, and T6 heat treatment where the housing carries load. Castings that have to hold pressure are X-rayed for porosity. Before the series starts, the tool is validated with a first article report.

Typical applications

• Enclosures for deck controls and junction boxes
• Sensor and instrument housings
• Housings for LED light fittings
• Brackets, covers and pump housings

Small gears, levers and pistons in control valves and remote-control units go into a vessel in quantities where sintering costs less than cutting each one from bar, and saves up to 30% of the material on top. We press and sinter stainless steel among other materials, and that matters for a part that sits in a wet cabinet. Compaction pressure goes up to 800 MPa and density to 97%; tolerance is ±0.05 mm as sintered and ±0.02 mm for MIM parts. The same line makes sintered porous filters in bronze or 316L. We check every lot for density, hardness and dimensions.

Typical applications

• Sintered gears and sprockets for pump and control drives
• Small pistons, levers and latches for control blocks
• MIM parts in stainless steel for valves and couplings
• Sintered porous filters in bronze or 316L

In acidic or chloride media a standard WC-Co part fails chemically. The cobalt binder is attacked before the tungsten carbide grains are touched, and no amount of hardness helps against that. For sea-water positions we sinter WC-Ni grades with 9–13% nickel binder at 1 400–1 600 HV; the hardness stays, and the binder is no longer the weak point. We press and sinter in-house at 1 350–1 500 °C, grade to ISO 513, add HIP where the part has to be fully dense, and diamond grind to ±0.01 mm with Ra 0.1–0.4 µm on seal faces. Parts run from 0.001 to 300 kg and from Ø 3 to 500 mm. A choke insert or a flow restrictor works only as long as its bore stays at size. For that reason we specify the ground bore, the braze alloy and the press-fit interference together with the insert.

Typical applications

• Seal rings and mechanical seal faces for sea-water and ballast pumps
• Choke and flow-restriction inserts for offshore process lines
• Nozzle bushings and valve seats in WC-Ni
• Plunger inserts and wear sleeves for high-pressure pumps