TECHNICAL SPECIFICATIONS FOR GI Pipe, Fittings And Pumps

 

1. General Administrative and Material Requirements

Definitions and Operational Framework

The technical specifications establish a structured contract framework outlining distinct operational roles for project execution:

·       Purchaser: The Water Supply and Sanitation Division/Subdivision Office (WSSDO) under the Department of Water Supply and Sewerage, Ministry of Physical Planning & Works, Government of Nepal.

·       Manufacturer: A legitimately registered firm or company authorized and approved by the appropriate government agency to fabricate the specified pipes, fittings, or machinery.

·       Supplier: The contracted individual, firm, or company (including the manufacturer) whose tender has been formally accepted by the purchaser for equipment delivery.

Material Standards and Deviations

All engineering goods, raw materials, processed elements, and components incorporated into the works must be entirely new, unused, of the most recent design models, and integrate all current structural improvements.

If alternative materials are proposed during tendering, the supplier must formally draw attention to the deviation, substantiate that the proposed alternative ensures an equal or superior standard of performance, and obtain explicit prior written approval from the purchaser.

Compliance Codes and Standards

All materials, specialized workmanship, and components must strictly comply with current editions or revisions of the relevant national and international standards in effect at the contract closing date. This includes:

·       Nepal Standards (NS): NS: 199-2046 (Galvanized Mild Steel Tubes) and NS 428-2058 (Water Meters).

·       Indian Standards (IS): IS: 1239 (Part I)-1990, IS: 554-1975, IS: 1879-1987 (Malleable Iron Fittings), IS: 781-1984, IS: 779-1994, and IS: 8034 (Submersible Pumps).

·       British Standards (BS): BS 1387: 1967 (Screwed and Socketed Tubes), BS 21, BS 1740, BS 4505, BS 5292, BS 4190, BS 1452 (Cast Iron Properties), and BS 5163 (Valves for Tropical Conditions).

CRITICAL QUALITY ASSURANCE NOTICE The supplier must furnish test certificates in triplicate detailing manufacturing processes, chemical compositions, and physical tests for all items. The purchaser retains the explicit right to perform independent or local tests at any stage, including the guarantee period. Materials failing these independent verifications will be rejected immediately at the supplier's expense and must be distinctively marked to prevent unauthorized deployment.

 

2. Galvanized Mild Steel (GMS) Pipes and Fittings

Structural Fabrication and Tolerances

Pipes designated under Medium and Heavy duties must be fabricated as either seamless or welded sections using tested structural quality steel.

Straight pipeline sections are to be delivered in uniform standard lengths of 6 meters. Each individual section must be supplied with a corresponding size factory-fitted joint socket at one end, and a robust plastic ring cover at the other to shield the threads from transit degradation.

Non-standard pieces, matching specific BOQ criteria, shall be approximately 3 meters in length. Total line length calculations strictly accumulate the clear pipe spans, excluding socket insertion depths.

Hydraulic Mandates and Zinc Galvanization

Prior to post-fabrication finishing, every pipe and matching special fitting must pass an internal hydrostatic proof pressure test of 50 bar (MPa) at the manufacturing plant.

This target pressure must be safely sustained for a minimum duration of three minutes to facilitate a thorough visual leak inspection. Following successful pressure validation, all components must be thoroughly descaled, washed, and completely hot-dip galvanized in a bath of molten zinc containing a minimum of 98.5% zinc by weight.

Threading operations are permitted only after hot galvanization is complete. Quality control mandates that for every batch of 500 pipes, one sample must undergo zinc-coating validation, and two samples must pass rigorous bending and flattening tests.

Fittings, Flanged Joints, and Transit Management

Malleable cast iron specials and fittings must align with IS: 2107 or IS: 2108 structural grades, with threading tolerances meeting IS: 554. All fittings must safely withstand an internal hydraulic baseline pressure of 2.1 MPa, or 1.05 MPa while fully submerged in light oil or water.

Flanges must be boss-screwed types conforming to BS 4505 Table 16/4. Complete flange connection assemblies must arrive with body bolts, nuts, and 3 mm thick medium rubber jointing rings reinforced with two-ply flax fabric complying with BS 5292. Pipes must be color-coded on both ends with 50 mm wide identification bands: Light Class (Brown/Yellow), Medium Class (Blue), and Heavy Class (Red). All pipe threads must be protected with high-grade grease.

3. Valves, Stop Cocks, and Flow Control Devices

Manufacturing and Climate Protections

All flow valves must fulfill recognized international benchmarks, using casting materials free of structural flaws, air blowholes, or plug remedies.

Cast iron components must meet or exceed Grade 14 of BS 1452, while gunmetal and bronze sections must use compositions proven stable in long-term raw and potable water exposures.

Moving parts submerged in water, along with matching guide pins and drive spindles, must be crafted from non-corrodible materials to minimize galvanic bi-metallic degradation.

Cast iron and steel surfaces exposed to climatic extremes must be finished with at least two coats of approved bituminous paint, ensuring strict compliance with BS 5163 tropical climate criteria.

Hydrostatic Testing Standards

Valves must close smoothly in a clockwise direction, with clear directional indicators cast onto the handwheels. They must be rated for continuous water utility across temperatures from 10°C to 70°C and a working pressure of 10 bar (MPa).

 Quality assurance dictates that all sluice and stop valves undergo direct hydrostatic testing at the source, including dual-directional seat tests at 100% of the rated working pressure and open-end body shell tests at 200% of the working pressure.

Leakage-free performance must satisfy the following minimum duration benchmarks:

Nominal Diameter (mm)	Minimum Body Test Duration	Minimum Seat Test Duration
50 mm and under	0.25 minutes	0.25 minutes
65 mm to 150 mm	1.00 minute	1.00 minute
200 mm to 300 mm	2.00 minutes	2.00 minutes

 

4. Specialized Joints, Piping Modules, and Ground Features

For remediation and seamless linking within existing lines, specific components are mandated:

·       Flexible Detachable Couplings: Viking Johnson-type joints without central registers are specified for repairs across nominal diameters ND50 to ND100, engineered to withstand a hydro-head of 250 meters of water.

·       Galvanized Structural Nipples: Fabricated from Medium/Heavy duty GMS pipe stock matching IS: 1239. Length arrangements must strictly follow standard dimensional cutoffs: 100 mm lengths for nominal bores up to 25 mm, 150 mm lengths for 32 mm to 65 mm bores, and 200 mm lengths for 80 mm to 100 mm bores.

·       HDPE to GMS Transition Units: Connections rely on specialized brass expansion units or heavy-duty flange sets. Flange assemblies must include a female threaded flange, a plain unthreaded flange, an HDPE flange adapter, and a heavy-duty matching rubber gasket.

·       Surface Enclosures and Valve Boxes: GI Valve Boxes must be constructed from medium-duty GMS pipe sections conforming to NS: 199-2046. The pipe base must be slotted to secure over the line and locked into place with a 300 mm long plain M.S. bar through 10 mm drilled holes.

·       Mild Steel Manhole Assemblies: Frames must be fabricated from 6 mm thick rolled steel (50 mm wide) anchored into concrete with a 100 cm long, 8 mm mild steel bar. The circular structural cover has a 580 mm outer diameter, 5 mm thickness, and a 6-bar square reinforcing mesh. Assemblies must receive two coats of red oxide metal primer.

5. Water Meters and Fusion Welding Systems

Volumetric Mechanical Water Meters

Flow tracking across service connections allows for semi-positive or inferential volumetric meters complying with IS 779-1994 or NS 428-2058. Structural and performance metrics must adhere to the following framework:

Nominal Size (mm)	Overall Length with Nipple (mm)	Max Width (mm)	Max Height (mm)	Semi-Positive Cap. (lph)	Inferential Cap. (lph)
15	250	130	180	2,000	2,500
20	290	130	180	3,400	3,500
25	380	140	200	5,500	5,500
40	430	230	250	10,000	16,000
50	470	250	300	15,000	23,000

Butt Fusion Welding Machinery

Specialized thermo-fusion machinery for jointing HDPE, PP, and PVDF pipelines must incorporate a machine body with 4 rugged alignment clamps, 2 hydraulic drive cylinders equipped with leak-free fast couplings, an electrical planing milling cutter, and a removable PTFE-coated heating plate.

6. Submersible Pump and Motor Systems

Environmental and Operational Thresholds

Submersible pump-motor assemblies are required to maintain continuous duty cycles ranging from 15 to 22 hours per day within deep tube wells. The system must operate reliably across water temperatures from 2°C to 45°C and exhibit high chemical tolerance against aggressively corrosive agents, specifically managing ammonium spikes up to 120 mg/l and iron concentrations up to 80 mg/l.

Submersible Centrifugal Pump Unit Elements

Pumps must be single or multi-stage radial or mixed-flow centrifugal units exhibiting a minimum standalone hydraulic efficiency of 70% at the specified duty point.

The pump bowls must be manufactured from close-grained cast iron conforming to Grade FG 200 of IS: 210, protected internally with vitreous enamel or baked epoxy coatings to resist abrasion.

Bowls must be hydrostatically tested to twice the rated delivery head or 1.5 times the closed-valve shut-off head, whichever is greater.

Impellers must be made of Bronze, Chrome Steel, Stainless Steel, or Noryl PPO, and dynamically balanced. The main pump shaft must be solid stainless steel (ASTM A276 Type 410) fitted with a secure keyway connection.

Submersible Driving Motor Requirements

. The motor component must achieve a minimum full-load electrical efficiency of 82%, ensuring a combined minimum system overall wire-to-water efficiency of 57.4%. Structural configurations require a star-delta configuration starter, a high-grade stainless steel stator body, and M45 cold-rolled non-grain-oriented low-loss electrical silicon steel stampings with wet-type PVC-insulated winding wires.

Dynamic axial thrust forces must be managed by a Michell-type thrust bearing featuring 5 segments made of ASTM A743 Gr.CA-40A working against a chrome-steel/carbon plate. A rubber expansion diaphragm (EPDM) must be integrated to balance thermal volumetric changes in the internal water volume. Power cables must meet IS: 694 guidelines.

Indoor CRCA Switch and Control Panels

Every pumping system must be controlled by a wall-mounted indoor panel enclosure fabricated from 1.6 mm thick cold-rolled close-annealed (CRCA) steel sheet, treated with industrial powder coating to achieve an IP42 ingress protection rating.

Mandatory components within the control circuit must include an adjustable thermal overload relay, an automatic single-phasing preventer, a phase sequence safety relay, a star-delta starter control unit with an integrated S/D timer, an air-break contactor block, and an ambient-rated voltmeter and ammeter with selector switches.

Circuit protection requires a Triple Pole (TP) MCB for setups up to 15 HP and a heavy-duty Molded Case Circuit Breaker (MCCB) for capacities exceeding 15 HP. Suppliers are required to submit factory-certified performance curves mapping head-discharge behavior, net power absorption, and overall efficiency alongside the official bidding tender.

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