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AFRICA
GEOSYNTHETICS
AFRICA

GeoStruct™ – HDPE Structured Wall Pipes

GeoStruct™ is a high-performance HDPE structured wall pipe system for gravity sewer, stormwater, culvert and large-diameter drainage applications across Africa. Available in internal diameters from 300 mm to 1500 mm at ring stiffness classes 4 kN/m² and 8 kN/m², GeoStruct™ combines a smooth hydraulic bore with a spirally wound structured wall profile to deliver exceptional ring stiffness at a fraction of the weight of equivalent concrete pipe. Supplied in 6 m and 12 m lengths with a full system of coupling seals, extrusion weld sleeve joints and clamp joints. Approved for installation in dolomite risk areas in accordance with SANS 1936-3.

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Technical Specification of GeoStruct™ – HDPE Structured Wall Pipes

GeoStruct™ is manufactured through a purpose-engineered spiral winding process. A square or rectangular HDPE profile is extruded and wound onto a precision mandrel - the overlapping edge fused homogeneously in the hot plastic state to create a continuous, smooth internal bore. The result is a lightweight engineered pipe with the hydraulic and mechanical performance of a solid-wall HDPE pipe, delivered at substantially reduced weight and with significant handling and transport cost savings.

GeoStruct™ is specified in two ring stiffness classes. The 4 kN/m² class suits standard municipal sewer, stormwater and gravity drainage installations under moderate cover and traffic loading. The 8 kN/m² class is specified where deeper burial, higher traffic loading, or dolomite ground conditions demand greater structural performance. Both classes share identical internal diameters - the choice between them is driven by the structural design of the installation, not the hydraulic design.

The internal bore of GeoStruct™ carries a Manning's roughness coefficient of n = 0.01, delivering flow rates 20–25% greater than equivalent concrete pipes of the same internal diameter. At the largest available sizes - 1000 mm to 1500 mm ID - this hydraulic advantage translates directly into reduced pipe size requirements and lower excavation volumes on large infrastructure projects.

GeoStruct™ HDPE structured wall manholes are prefabricated to the same ID range as the pipe system - 300 mm to 1500 mm - eliminating the dimensional mismatch common with concrete manhole rings. Manholes are factory-fabricated with benching, HDPE ladders and pipe stubs welded in situ, delivered to site ready to lower into the excavation. All weld joints are executed by trained HDPE welders and the complete manhole assembly is pressure-tested before dispatch.

Typical Values for PIPES DRAINAGE DUCTING

Pipe System
HDPE Structured Wall · Smooth Internal Bore
Size Range
ID 300mm – ID 1500mm
Ring Stiffness
4 kN/m² Standard · 8 kN/m² Heavy Duty
Supply Lengths
6m and 12m lengths
Dolomite Approved
SANS 1936-3 D2 & D3 · SANS 10268-1
Compliance
SANS 21138 · Manning's n = 0.01

Properties & Dimensions

PropertyTest MethodUnitGeoStruct 4 kN/m²GeoStruct 8 kN/m²
Material--HDPEHDPE
Ring Stiffness - StandardISO 9969kN/m²48
Nominal Diameter Range (DN)-mm300 – 1500300 – 1500
Outer Diameter Range-mm328 – 1624338 – 1650
Standard Length-m66
Manning's Roughness Coefficient (n)--0.010.01
DensityISO 1183-1g/cm³≥ 0.950≥ 0.950
Flexural ModulusISO 178MPa1 000 – 2 0001 000 – 2 000
Melt Flow Index (190 °C / 5 kg)ISO 1133g/10 min≤ 1.6≤ 1.6
Oxidation Induction Time (200 °C)ISO 11357-6min≥ 20≥ 20
Impact Strength (TIR)ISO 3127%≤ 10≤ 10
Longitudinal ReversionISO 2505%≤ 3≤ 3
Creep Ratio (2-year extrapolation)ISO 9967-≤ 4≤ 4
Min. Weld Tensile StrengthISO 13262N380 – 1 020 (size dependent)380 – 1 020 (size dependent)
Standard Compliance--SANS 21138SANS 21138
Download Full Technical Datasheet for GeoStruct™ – HDPE Structured Wall Pipes (PDF)

Popular Catalogue Items

GeoStruct™ HDPE Structured Wall Pipe

GeoStruct™ HDPE Structured Wall Pipe

Spirally wound HDPE structured wall pipe for gravity sewer, stormwater, culvert and bulk drainage. DN300 to DN1500 in SN4 and SN8, manufactured to SANS 21138. Around 90 % lighter than equivalent concrete pipe, with a smooth bore holding Manning's n = 0.01 across a design life of up to 100 years.
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Three Questions To Ask Before You Order

1.What is the difference between GeoStruct™ KN4 and KN8?
KN4 and KN8 refer to the ring stiffness class of the pipe - 4 kN/m² and 8 kN/m² respectively. Both classes share identical internal diameters, so the hydraulic design of your pipeline is unaffected by which class you specify. The choice between them is driven by the structural design: cover depth, traffic loading, soil conditions and whether the installation is in a dolomite risk area. KN4 is specified for standard municipal sewer and stormwater installations under normal cover and loading. KN8 is specified for deeper burial, heavy traffic loading, road and haul road crossings, and all installations in dolomite risk areas designated D2 and D3 under SANS 1936-3. If you are unsure which class your project requires, our technical team can assist with a structural assessment.
2.Is GeoStruct™ approved for use in dolomite areas?
Yes. GeoStruct™ HDPE structured wall pipe and manholes with hot-gas extrusion weld jointing are approved for installation in dolomite risk areas designated D2 and D3 in accordance with SANS 1936-3 : 2012. The extrusion weld jointing method - executed in accordance with SANS 10268-1 - produces a fully fused, homogeneous joint with no mechanical seal, gasket or joint movement. The result is a 100% leak-proof jointless HDPE system. HDPE pipe and manhole systems are the recommended material for sewer and stormwater infrastructure in dolomite areas precisely because joint leakage is eliminated - joint leakage is the primary mechanism through which dolomite dissolution and sinkhole formation occurs in buried pipe infrastructure.
3.What jointing methods are available for GeoStruct™?
Three jointing methods are available. The coupling and rubber seal joint is a push-fit system for rapid installation without specialist equipment - available sand-tight and water-tight, suitable for standard municipal sewer and stormwater applications. The hot-gas extrusion weld joint uses an HDPE sleeve welded to the first pipe; the second pipe is inserted on site and extrusion welded to form a fully fused leak-proof joint in accordance with SANS 10268-1 - this is the required jointing method for dolomite risk areas and any application where absolute leak-tightness is mandated. The clamp joint is a mechanical connection for plain-ended pipes used in stormwater, pipeline repair and maintenance applications. Your jointing method selection should be confirmed with your project engineer against the applicable design standard and ground conditions.
4.What sizes does GeoStruct™ come in?
GeoStruct™ is available in internal diameters from 300 mm to 1500 mm -covering household connection laterals through to major bulk sewer and stormwater trunk infrastructure. Available sizes are 300, 350, 400, 450, 500, 600, 700, 800, 900, 1000, 1100, 1200 and 1500 mm internal diameter. Each size is available in both 4 kN/m² and 8 kN/m² ring stiffness classes. Note that the 450 mm size is available in 8 kN/m² only. All sizes are supplied in 6 m and 12 m lengths. Minimum order quantities apply per size - contact our technical team for current stock availability and lead times.
5.How does GeoStruct™ compare to concrete pipe?
GeoStruct™ outperforms concrete pipe across most performance criteria relevant to buried gravity drainage infrastructure. It weighs up to 90% less, enabling faster installation with lighter plant. Its smooth HDPE bore delivers Manning's n = 0.01 versus concrete at n = 0.013–0.015, giving 20–25% greater hydraulic capacity at equivalent diameters. It does not crack under differential settlement, root pressure or dynamic loading. It is immune to the hydrogen sulfide corrosion that destroys concrete sewers from the inside. It carries a design service life of 50–100 years versus concrete's 30–50 years in standard conditions. Prefabricated HDPE manholes deliver approximately 40% faster construction than precast concrete manholes. The principal area where concrete retains an advantage is compressive strength under extreme point loading - however for standard buried pipe applications under normal and heavy traffic loading, GeoStruct™ KN8 meets or exceeds the structural requirements that govern concrete pipe selection.
6.What is the minimum order quantity for GeoStruct™?
GeoStruct™ is manufactured to order on a production run basis. The minimum run length is 120 metres per size to ensure an economical production run. Pipes are supplied in 6 m or 12 m lengths as required. Lead time is typically 10–14 working days from order confirmation, subject to current production scheduling and order size. For urgent requirements or project-specific scheduling, contact our technical team directly to confirm availability and lead time for your specific size and ring stiffness class combination.
7.Are GeoStruct™ HDPE manholes available to match the pipe system?
Yes. GeoStruct™ prefabricated HDPE manholes are available from 300 mm to 1500 mm internal diameter in both 4 kN/m² and 8 kN/m² classes - matching the full pipe size range. Each manhole is factory-fabricated with HDPE benching, internal HDPE ladder and pipe stub connections, all extrusion welded and pressure tested before dispatch. Manholes are delivered fully assembled and ready to lower into the excavation. For dolomite risk area projects, the manhole and pipe connection joints are executed using hot-gas extrusion weld jointing to produce a fully jointless, leak-proof system. Custom manhole configurations, shaft heights and stub arrangements can be accommodated - contact our technical team with your project requirements.

Specification For The Design, Installation Of GeoStruct™ – HDPE Structured Wall Pipes

Excavate & Prepare Trench - Excavate to the required depth and grade. Trench width should allow 150 mm clearance each side of the pipe for embedment compaction. Lay a 100 mm compacted sand or gravel bedding layer at the trench bottom to the design gradient before pipe placement.

Place & Joint Pipes - Lower pipes into the trench and align vertically and horizontally. For coupling and seal jointing, clean pipe ends, fit the rubber seal, apply lubricant to the coupling interior and push to insertion depth. For extrusion weld jointing on dolomite projects, the HDPE sleeve is pre-welded to the first pipe - insert the second pipe on site and complete the extrusion weld in accordance with SANS 10268-1.

Haunch & Initial Backfill - Place selected granular embedment material in 75 mm layers up to the crown of the pipe, compacting each layer by hand tamper. Ensure no voids form under the pipe haunches. Leave all joints exposed at this stage for inspection and testing.

Test & Final Backfill - Conduct leak testing with all joints exposed. Once testing is passed, complete backfill in 300 mm compacted layers to the required surface level. The final backfill level should be slightly above natural ground to allow for consolidation.

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