Gates, Valves & Hydro-Mechanical
Equipment for Dams
Pakistan's water security sits on a handful of storage dams, a network of barrages on the Indus system and the canal head regulators that feed the largest contiguous irrigation network in the world. Every one of them depends on steel that has to move on demand under head. REW designs, fabricates, installs and refurbishes spillway and sluice gates, hoisting arrangements, trash racks, stoplogs, penstock butterfly valves and reservoir outlet valves — and reverse-engineers spares for gates whose original maker no longer exists.
REF · DAM-2026
Mangla Dam · Jhelum River
Engineering for Head, Silt and Sixty-Year Service
Pakistan stores a very small share of the water it receives. The Indus system delivers the bulk of its annual flow in a short summer window, and the country's usable live storage — principally Tarbela on the Indus, Mangla on the Jhelum and Chashma as a re-regulating reservoir — is measured in weeks of demand, not months. Every acre-foot therefore has to be released through equipment that works the first time it is asked.
The duty is unusually severe. Reservoir sediment inflow makes Indus-system water abrasive; gates and outlet valves operate under heads from a few metres at a canal regulator to well over a hundred metres at a storage dam; and the same components are expected to remain serviceable for fifty to seventy years with periodic maintenance only. A spillway gate that will not lift during a flood peak, or a low-level outlet valve that cavitates itself hollow, is not a spare-parts problem — it is a dam-safety problem.
REW has manufactured heavy fabricated steelwork and flow-control equipment in Lahore since 1948. For dams, barrages, canal head regulators and hydropower projects we supply fabricated gates and embedded parts, hoisting mechanisms, trash racks and stoplogs, large-diameter butterfly and outlet valves, and reverse-engineered replacement parts produced from a sample, an old drawing or a measured sketch — the practical route on structures commissioned in the 1950s and 1960s whose original suppliers are long gone.
Selection is engineered against the real condition on your structure — design head, submergence, sediment concentration, cycling frequency, seismic and flood loading — not against a generic catalogue rating.
Catchment to Canal Head
A dam and reservoir scheme in sequence — what each stage does, what it demands from equipment, and where gates and valves are installed.
Reservoir & Dam Body
Runoff and snowmelt are impounded behind an embankment, rockfill or concrete dam. Reservoir level, sediment delta and drawdown regime set the operating envelope for every mechanical component below.
Intake Structure & Trash Racks
Water enters the intake tower or approach channel through screens that keep debris, weed and floating trash out of the conveyance system.
Spillway & Gates
Surplus flood flow is passed over the crest or through orifices, controlled by radial (tainter) or vertical-lift gates and dissipated in a stilling basin or flip bucket.
Sluices & Outlet Works
Irrigation releases, environmental flow and emergency drawdown pass through low-level conduits fitted with guard and regulating gates or valves under the highest head at the structure.
Penstocks & Power Channel
Water is carried to the machines through steel-lined penstocks, tunnels or an open power channel with surge and air-vent protection.
Powerhouse & Turbines
Francis, Kaplan or Pelton units convert head into shaft power; cooling water, drainage and dewatering systems support them continuously.
Barrage & Head Regulators
On the plains, barrages raise the river to command canal offtakes; undersluices flush sediment and head regulators meter flow into each canal.
Water Supply, Pumping & BOP
Raw water is delivered onward to treatment plants, city supply mains and pumping stations, with valves, pumps and metering on every branch.
What Actually Fails on a Dam
Ten recurring failure modes seen on dams, barrages and reservoir outlet works in Pakistan, and the design response each one requires.
Cavitation damage on high-head outlets
Low-level outlet and regulating gates at a storage dam work under heads of fifty to well over a hundred metres. Partial openings create local pressures below vapour pressure, and the collapsing cavities pit the gate lip, the conduit invert and the downstream liner.
Abrasion by silt-laden Indus flow
Sediment concentration during the flood season is high enough to act as a continuous grinding medium. Seal seats, gate lips, liners and valve trim lose profile far faster than clean-water design charts predict.
Seal extrusion, hardening and leakage
Music-note and bulb rubber seals harden with ultraviolet exposure and age, then extrude under head. A leaking spillway or regulator gate wastes stored water continuously and ices the downstream face in winter at high altitude.
Seized trunnions and lifting failure
A radial gate may sit unmoved for a full year. Corroded trunnion pins, dry bushes and distorted guide rollers raise breakaway load beyond hoist capacity — the gate refuses to lift on the day the flood arrives.
Corrosion at the waterline and in embedded parts
The alternate wet/dry splash zone corrodes fastest, and embedded guides grouted into concrete cannot be replaced without breaking structure. Coating breakdown starts at edges, welds and bolt heads.
Hoist rope, gearing and brake wear
Rope drum hoists carry very high line pull at low duty cycle. Ropes corrode internally, gear teeth pit, and brakes hold less than the rated load — discovered only when a gate is asked to hold at part opening.
Water hammer in penstocks and rising mains
Closing a large butterfly valve too fast, or a pump tripping on a long delivery main, produces a surge that can deform liners, shift supports and split joints.
Trash rack blinding and structural collapse
Weed, timber and plastic debris blind a rack in hours during a flood. The differential head that builds across a blinded panel can exceed its structural design and fold it into the intake.
Vibration and flow-induced instability
Gates operating at small openings, and bottom seals with an unfavourable lip profile, can vibrate strongly enough to damage guides, loosen fasteners and fatigue skin-plate welds.
Obsolete gates and unsupported spares
Much of the country's water infrastructure was commissioned between the 1930s and 1970s — Sukkur Barrage in 1932, Taunsa in 1958, Tarbela in 1976. Original suppliers have often disappeared, and imported spares carry long lead times against a canal closure window that will not move.
Equipment for Dam & Reservoir Duty
Only equipment relevant to dams, barrages, reservoirs and hydropower is listed. Final selection is confirmed against your design head, sediment data, structural drawings and operating regime.
DAM-01Radial (Tainter) Gates
Curved skin-plate gates on trunnion arms for crest and orifice spillways, sized so breakaway load stays inside hoist capacity after a full season standing idle.
DAM-02Vertical Lift & Bay Gates
Fixed-wheel, slide and roller-mounted lift gates for barrage bays, undersluices, canal head regulators and intake guard duty.
DAM-03Sluice & Outlet Gates
Guard and service gates for low-level conduits, sediment flushing and irrigation release, with the wetted zone treated as a wear part.
DAM-04Penstock & Guard Butterfly Valves
Large-diameter butterfly valves for penstock isolation, turbine guard duty, power channel intakes and raw-water transmission mains, manufactured in-house up to 100".
DAM-05Regulating & Energy-Dissipating Valves
Fixed-cone (howell-bunger), hollow-jet and needle-type arrangements plus heavy gate and globe valves for controlled high-head release.
DAM-06Trash Racks, Screens & Stoplogs
Bar screens, rack panels, guide frames, bulkhead gates and stoplog sets for intake dewatering and inspection.
DAM-07Gate Hoists, Winches & Screw Gear
Rope drum hoists, screw and rack-and-pinion gearing, gantries and hydraulic cylinder arrangements with position indication and manual back-up.
DAM-08Pumps, Cooling & Dewatering Sets
Drainage, dewatering, cooling-water, raw-water and fire-water pump sets for powerhouses, intake structures and pump stations, assembled and performance-checked before dispatch.
DAM-09Refurbishment & Reverse-Engineered Spares
Gate re-plating and stiffener renewal, seal and seal-seat replacement, trunnion and bush overhaul, hoist rebuilds, plus parts remade for equipment no longer supported by its maker.
Where Each Product Is Installed
Hover or tap a node on the water-control chain to see the equipment installed at that point in the scheme.
Reservoir
Spillway, guard and bay gates that must move on demand under head.
Service gates, fixed-cone and control valves metering release and canal supply.
Non-return valves, air valves and surge protection on penstocks and rising mains.
Drainage, dewatering, cooling and raw-water pump sets with matched spares.
Water Infrastructure Across Pakistan
The categories of structure our gates, hoists and valves are engineered for — from 1930s barrages on the Indus to new high-head storage dams under construction.
Project names indicate the categories of dam, barrage and reservoir infrastructure our equipment is engineered for. Supply scope, references and project details are confirmed in writing at enquiry stage.
Dams & Reservoirs Specification Sheet
Reference data for design, dam-safety, operations and procurement teams. Project-specific values are confirmed at quotation stage.
Pakistan's Dams & Barrages
Documentary photography of the water infrastructure this equipment is built for. Click any photo to enlarge.
Questions From Dam & Irrigation Engineers
Do you manufacture spillway radial gates in Pakistan?
What is the largest valve you can supply for a penstock or intake?
Can you make spares for gates whose original manufacturer no longer exists?
Which standards do you design gates to?
How do you handle silt-laden Indus water?
What prevents cavitation on high-head outlet gates?
Do you carry out erection and commissioning at site?
Can work be completed inside a canal closure window?
What corrosion protection do you apply?
Which testing is included before dispatch?
Do you supply pumps for powerhouse and intake auxiliaries?
What information do you need for a quotation?
Send Us the Plant Data
Share your line list, valve schedule or a marked-up P&ID and our engineering team will confirm suitable equipment, materials and testing scope. For spare parts, a photograph of the nameplate or the worn component is usually enough to begin.
Direct Lines
Route your enquiry to the right desk and you will get an engineering answer, not a sales script.
Valve and pump selection, material grades, steam and CW duty queries
Budgetary and firm quotations, delivery schedules, documentation scope
Reverse-engineered parts, rebuild kits, planned shutdown support
rewpak@yahoo.com | info@rehmanengg.com
Rehman Plaza, Sanda Khurd, Bund Road, Lahore, Pakistan
Engineers & Contractors since 1948