Engineered For
Head, Flow &
From intake trash racks to tailrace outfall, REW builds the isolation, regulation and dewatering equipment that keeps Pakistan's turbines spinning — designed around real net head, silt loading and water hammer, not catalogue averages.
REF · HYD-2026
Turbine Inlet Isolation
Unit Isolation Without Dewatering
Butterfly and spherical turbine inlet valves with counterweight closure, two-stage closing law and drop-tight seating — so one machine can come offline for overhaul while the station keeps generating.
Surge, Silt & Cavitation Designed Out
13Cr-4Ni trim, stellite hard-facing and profiled seat geometry for Indus-basin sediment that peaks beyond 3,000 ppm in monsoon — because erosion, not pressure, is what usually kills hydropower valves.
Reverse-Engineered Spares, Locally
Obsolete imported components rebuilt from sample or drawing — seats, discs, stems, wear rings, impellers and shafts — with material certification and dimensional reports, in weeks rather than shipping seasons.
Pakistan's Water-To-Watt Backbone
Hydropower supplies roughly a quarter of Pakistan's installed generation capacity and the overwhelming majority of its low-marginal-cost energy. The fleet spans Tarbela and Mangla-scale storage schemes on the Indus and Jhelum, cascade run-of-river plants in Khyber Pakhtunkhwa and Gilgit-Baltistan, and hundreds of micro and mini units feeding isolated valley grids.
What unites them is a punishing duty envelope: high net head, glacier-fed sediment, seasonal flow swings of an order of magnitude, and machinery that must respond to grid load rejection in seconds.
REW has supplied flow-control and pumping hardware into this environment for decades — the same castings, the same test bay, the same engineers who understand that a valve in a powerhouse is a safety device before it is a plumbing fitting.
Seven Stages From Reservoir To Grid
Every stage imposes a different loading on the equipment. REW specifies against the stage, not against a generic pressure class.
Intake
Trash racks, stop logs and intake gates screen debris and permit waterway isolation.
Desilting
Settling basins and flushing gates remove abrasive sediment before it reaches the runner.
Headrace
Tunnel or canal conveys flow at low gradient; drainage pumps keep the invert dry.
Surge Tank
Absorbs pressure transients from load rejection and protects the penstock from hammer.
Penstock
Static head converts to velocity head; branch valves isolate individual units.
Powerhouse
Turbine, generator and auxiliaries — cooling water, lube oil, drainage and fire lines.
Tailrace
Draft tube discharges to river; draft tube gates allow unit dewatering for overhaul.
Ten Ways Hydropower Equipment Fails
Each of these is a real failure mode logged across the region's plants. Each has a specification answer.
Silt Erosion Of Trim
Glacier-fed flow carries quartz-rich sediment that abrades seat faces and disc edges, opening leakage paths within a single monsoon season.
Water Hammer On Load Rejection
Sudden turbine load loss sends a pressure wave up the penstock at close to 1,000 m/s, overstressing shells, anchors and valve bodies.
Cavitation Damage
Local pressure dropping below vapour pressure downstream of a partially open valve collapses bubbles against metal, pitting it into a sponge.
Seat Leakage At Static Head
A valve that passes water while a unit is opened turns an eight-hour inspection into a flooded pit and a lost week of generation.
Stem Seizure & Gland Failure
Infrequently operated gates corrode in place; when an emergency close is finally called, the actuator stalls against a frozen stem.
Pump Wear In Drainage Sumps
Dewatering pumps handle silt-laden water; impeller and wear-ring clearances open, capacity collapses and the sump floods during overhaul.
Obsolete Imported Spares
Plants commissioned decades ago rely on OEMs that no longer support the model; a single seat ring can idle a unit for a full season.
Trash Rack Blockage
Monsoon debris blinds racks, head loss climbs, and differential pressure can deform the rack into the intake tunnel.
Cooling Water Fouling
Generator bearing and transformer coolers foul with silt and biological growth, driving up winding temperatures and derating the unit.
Seismic & Anchor Loading
Plants sit in active seismic zones; unsupported valve masses transmit loads into penstock shells and concrete anchors.
Equipment Built For The Waterway
Every item below is manufactured, assembled and hydro-tested at REW Lahore.
Turbine Inlet Butterfly Valve
Double-flanged or wafer body with offset disc, sized for full penstock bore and closed against flow under emergency conditions.
Spherical / Rotary Valve
Full-bore spherical valve for medium and high head stations where zero head loss at full open and drop-tight closure are both mandatory.
Sluice & Intake Gates
Rising and non-rising stem sluice gates, stop logs and draft tube gates with cast or fabricated frames for embedment in concrete.
Drainage & Dewatering Pumps
Vertical and horizontal centrifugal sets for powerhouse sumps, draft tube dewatering and seepage collection in silt-bearing water.
Cooling Water Valve Sets
Gate, globe, check and strainer assemblies for generator bearing coolers, transformer oil coolers and fire water headers.
Pressure Relief & Air Valves
Surge relief valves, vacuum breakers and combination air valves that protect penstock and headrace from transient over- and under-pressure.
Reverse-Engineered Spares
Discs, seats, stems, bushes, wear rings, impellers, shafts and gland assemblies rebuilt to match obsolete imported equipment.
Where REW Equipment Sits In The Scheme
A schematic run-of-river plant. Hover any node to identify the equipment supplied at that point.
Intake Gates
Intake, flushing and draft tube gates with embedded frames for civil coordination.
Relief, air and vacuum valves plus dewatering pump sets in silt-bearing water.
Inlet valves, cooling water sets and strainers at the turbine and generator.
The Engineering Ledger
Switch tabs for valves, gates, pumps and materials.
| Valve Type | Size Range | Rating | Primary Duty | Governing Standard |
|---|---|---|---|---|
| Butterfly (inlet) | DN 200 – 2400 | PN 10 – 40 | Unit isolation, penstock branch | AWWA C504 / BS EN 593 |
| Spherical / rotary | DN 300 – 1600 | Up to 600 m head | High-head unit isolation | IEC 60193 reference |
| Gate (auxiliary) | DN 15 – 600 | 150 – 300 lb | Cooling & service water isolation | API 600 / BS 1873 |
| Globe (regulating) | DN 15 – 300 | 150 – 300 lb | Throttling, bypass, filling lines | BS 1873 / ASME B16.34 |
| Swing / dual-plate check | DN 50 – 900 | 150 – 300 lb | Pump discharge, reverse-flow block | API 594 / API 6D |
| Pressure relief | DN 50 – 600 | Project set pressure | Surge and hammer protection | Per transient study |
| Air / vacuum | DN 50 – 300 | PN 10 – 25 | Filling, draining, column separation | AWWA C512 |
| Gate Type | Max Opening | Head Condition | Frame / Slide | Operation |
|---|---|---|---|---|
| Intake sluice gate | 3000 × 3000 mm | Seating & unseating | Cast iron / fabricated SS304 | Handwheel, gear or electric hoist |
| Flushing / desilting gate | 2000 × 2000 mm | Seating | Fabricated steel, SS seat faces | Electric hoist |
| Draft tube gate | 4000 × 3000 mm | Unseating | Fabricated steel | Gantry / monorail hoist |
| Stop logs | Modular bays | Static | Fabricated steel with rubber seals | Lifting beam |
| Trash rack panels | Bay width to suit | Design differential head | Structural steel, coated | Manual / raking machine |
| Pump Duty | Capacity | Head | Wetted Materials | Configuration |
|---|---|---|---|---|
| Powerhouse drainage | 50 – 1500 m³/h | 20 – 120 m | High-Cr iron / duplex | Vertical sump, duty + standby |
| Draft tube dewatering | 500 – 3000 m³/h | 10 – 40 m | CI / bronze / SS316 | Horizontal split case |
| Cooling water | 100 – 1200 m³/h | 20 – 60 m | Bronze / SS316 | End suction, 2×100% |
| Seepage collection | 20 – 300 m³/h | 15 – 60 m | High-Cr iron | Submersible / vertical |
| Fire water | Per NFPA sizing | Per system | CI / bronze trim | Jockey + main set |
| Component | Material | Specification | Why It Is Chosen |
|---|---|---|---|
| Valve / pump body | Carbon steel | ASTM A216 WCB | Standard pressure-retaining casting for water service |
| High-erosion body | 13Cr-4Ni martensitic SS | ASTM A743 CA6NM | Cavitation and silt erosion resistance in hydro duty |
| Disc / seat facing | Stellite 6 overlay | Weld deposit, 2 mm min | Hard face survives abrasive sediment cycling |
| Stems | SS410 / SS431 | ASTM A276 | Corrosion resistance with adequate yield for torque |
| Wear rings / bushes | Aluminium bronze | ASTM B148 | Galling resistance against stainless mating faces |
| Seals | EPDM / NBR / graphite | Per service temperature | Drop-tight sealing with predictable ageing |
| External coating | Epoxy + PU topcoat | 300 µm DFT typical | Humidity and spray exposure in powerhouse pits |
Cast, Machined And Tested In Lahore
One roof, one traceable route — pattern to packing list. No brokered imports rebadged as local supply.
Foundry & Casting
Sand casting in WCB, CA6NM and bronze with spectrographic verification on every heat before machining release.
CNC Machining
Vertical turret and horizontal boring capacity for bodies to 2400 mm bore, with seat-face geometry held to drawing tolerance.
Hydrostatic Test Bay
Shell and seat testing at 1.5 × and 1.1 × rated pressure, held for standard duration with witnessed certificates on request.
Commissioning Support
Site supervision for installation, stroking, closing-law setting and integration with plant SCADA and unit protection logic.
Nothing Leaves Untested
Hydropower equipment is inspected as a safety item. Documentation travels with the hardware.
Shell Test
Every pressure-retaining body hydrostatically tested at one-and-a-half times rated pressure.
Seat Test
Closure verified drop-tight at one-point-one times rated pressure in both directions where applicable.
Material Certs
EN 10204 3.1 certification issued with chemistry and mechanical properties per heat.
Volumetric Checks
Dye penetrant, magnetic particle, ultrasonic and radiographic examination per project ITP.
Hydropower In Context
Storage dams, run-of-river headworks, penstocks, powerhouses and the shop floor behind them.
How We Approach A Scheme
Specify the valve against the transient, not the static head. A body that survives 40 bar standing pressure can still split when a 900-metre column stops in two seconds.
In the Indus basin, sediment writes the maintenance schedule. Choose trim for abrasion first, then confirm it satisfies pressure — the reverse order costs a season of generation.
A spare that arrives in fourteen weeks and fits is worth more than one quoted in six and shimmed on site. Matched-fit machining against the actual mating component is not optional.
Every valve leaves the bay with its own test record. If a unit trips at three in the morning, the plant should be able to open a file, not start an argument.
Seven Decades On The Same Rivers
Since 1948
Three generations of continuous manufacturing in Lahore, with pattern libraries and process knowledge that cannot be bought in.
Duty-Led Specification
Selection driven by measured head, flow, sediment and transient behaviour rather than a catalogue pressure class.
Short Lead Times
Local casting and machining removes shipping, customs and OEM queue time from the critical path of an outage.
Single-Roof Traceability
Foundry, machine shop, assembly and test bay under one management system, so accountability never crosses a supplier boundary.
Certified Systems
ISO 9001:2015 quality, ISO 14001:2015 environmental and ISO 45001:2018 occupational health and safety.
Reverse Engineering
Obsolete imported parts reproduced from sample with verified chemistry, hardness and dimensional reporting.
Commissioning Support
Site engineers for installation, stroking, closing-law adjustment and integration with unit protection.
Lifecycle Partnership
Spares planning, condition review and refurbishment scoping across the asset life, not just at order stage.
Hydropower Engineering Questions
Send Us The Head And The Flow
Give our engineering office the duty data and we will return a specification, not a price list. Sample parts welcome.
What You Get Back
One enquiry, answered by engineers who have stood in the same powerhouse pits.
Technical selection returned within five working days
From sample or drawing, with verified chemistry and hardness
Witnessed hydrostatic testing available at our Lahore works
Outage-driven expediting for critical spares
Lahore, Pakistan · Manufacturing since 1948