PE100 has taken over most small and medium water networks, but steel pipe is still the right answer for many large-diameter and high-stress applications. Engineers designing trunk mains, pump-station manifolds or river crossings in Georgia need to know where steel pipes — especially spiral-welded pipe — outperform plastic, and how to specify them so they last.
Types of steel pipe for engineering networks
| Type | How it is made | Typical diameters | Typical use |
|---|---|---|---|
| Seamless | Pierced and rolled from a solid billet | Small–medium (up to ~426 mm) | High pressure, industrial, risers |
| Longitudinally welded (ERW) | Plate formed and welded along its length | 21–530 mm | Distribution, structural, risers |
| Spiral-welded (SSAW) | Steel strip wound helically and welded | 219–2500+ mm | Large water trunk mains, outfalls, piling, culverts |
Spiral-welded pipe is the economical way to get very large diameters with consistent wall thickness, which is why it dominates large transmission mains.
When steel beats PE
- Very large diameters at high pressure (DN 800+ at PN 16+), where PE walls become very thick and heavy.
- Above-ground and exposed sections: bridges, river crossings, pipe racks and pump stations. Steel is UV-stable and rigid.
- High external loads: shallow cover under heavy traffic, railway crossings and casing pipes for trenchless crossings.
- Pump-station and reservoir manifolds with many flanged outlets for gate valves, dismantling joints, flow meters and air valves.
- Fire-water ring mains in industrial plants, where codes may require metallic pipe.
Specification checklist
- Standard and grade: for example EN 10224 / EN 10217 for water, or API 5L for line pipe, with the steel grade defined.
- Wall thickness: designed for internal pressure, vacuum, external load and corrosion allowance.
- Internal lining: cement-mortar lining or food-grade epoxy for potable water.
- External coating: three-layer polyethylene (3LPE) or polyurethane for buried pipe, plus cathodic protection on long mains.
- Ends: bevelled for welding, or flanged for valves and fittings.
- Testing: hydrostatic test certificates and weld inspection (NDT) reports.
Steel + PE: a combined design
Many modern networks use both materials. A steel trunk main and pump-station pipework feed PE100 distribution pipes, connected through flange adaptors or PE-to-steel transitions. It is the kind of mixed steel-and-PE supply GON delivered for the Banoja water supply project.
What to write in the BOQ
*"Spiral-welded steel pipe DN 1000, wall [x] mm, grade [x], to EN 10224 / EN 10217, internal cement-mortar lining for potable water, external 3LPE coating, bevelled ends for butt welding; hydrostatic test certificates and NDT weld reports with delivery."* Add flanged spools for valves and a dismantling joint at every pump and meter.
Quick selector
- River crossing on a bridge, DN 400 → steel, epoxy-lined, coated, with expansion joints.
- Trunk main DN 1000 from a reservoir → spiral-welded steel, cement-lined, 3LPE coated.
- Village distribution DN 63–200 → PE100 is usually better and cheaper.
- Trenchless road crossing → steel casing pipe with the carrier pipe inside.
GON project experience
GON supplied steel pipes together with PE100 pressure pipes, fittings, armature and fire hydrants for the Banoja village water supply, and supplies steel pipe for engineering networks across Georgia.
Related products: Steel / iron pipes · Dismantling joints · Gate valves · PE100 pressure pipes
Further reading: Gate or butterfly valve on distribution mains?
Is spiral-welded pipe suitable for drinking water?
Yes, when it is made to a water standard and lined with cement mortar or approved epoxy.
Why use a dismantling joint on steel pipework?
Steel pipework is rigid. A dismantling joint lets you remove a valve, pump or meter without cutting the pipe.
Steel or ductile-iron pipe?
Both are used for large mains. Steel is common for the largest diameters and welded systems. Ductile iron is used for push-fit jointed mains.
Get a project quote
Send pipe schedules, diameters and lengths to sales@gon.ge or call +995 595 818 800.
GON supplies drainage, water, gas and road-infrastructure products to contractors, utilities and IFI-funded programmes across Georgia.