Marine & Desalination
Large-diameter seawater intake and brine discharge lines.
Overview
Seawater intake mains, brine outfalls and offshore discharge lines for desalination plants and coastal power stations.
Specification
- Product range: QFlow Solid-Wall HDPE
- Standard: IS 4984
- Desalination Sizes: Up to 315 mm OD
- Pressure Rating: PN 10 / PN 16 rating
- Standard Code: IS 4984 / ISO 4427
Why HDPE here
- Salt, brine and chlorinated seawater do not attack it
- Floats when the ends are capped, which is how a sea line is towed out and then sunk into place
- Sections are welded together on shore into one long continuous string
Typical deployments
- Desalination seawater intakes
- Brine outfall lines
- Submarine sewage outfalls
- Coastal cooling loops
Specification and site notes
Why HDPE goes to sea
Salt water and chlorine destroy ferrous pipe and attack concrete. HDPE is unaffected by both, and it is slightly less dense than water, which is the property the marine laying method is built around.
Float, position, sink
The standard technique is to butt-fuse long strings ashore, float them out capped, position them over the line and flood them under control so they sink onto the seabed. Every metre of that depends on the string being one continuous fused pipe with no joint to fail.
Ballast and anchoring
Concrete collar weights hold the line down against buoyancy and current. Weight spacing comes from the marine engineering design for the site's current, wave climate and seabed, not from the pipe specification.
Weather window
The float-and-sink operation is a single continuous sequence that cannot be paused mid-way. The programme is governed by the weather window, so pre-fabrication ashore has to be complete and tested before it opens.
FAQ
Why is HDPE used for seawater intake and brine outfalls?
Salt water and chlorine destroy ferrous pipe and attack concrete, while HDPE is unaffected by both. It is also slightly less dense than water, which is the property the standard marine float-and-sink laying method depends on.
How is a marine HDPE pipeline installed?
Long strings are butt-fused ashore, floated out capped, positioned over the line, then flooded under control so they sink onto the seabed. The whole method relies on the string being one continuous fused pipe with no joint to fail mid-operation.
What holds a floating HDPE pipeline on the seabed?
Concrete collar weights, spaced by the marine engineering design for the site's current, wave climate and seabed conditions. That spacing is a project-specific calculation, not a property of the pipe.
What sizes does ALOM supply for marine duty?
Up to 315 mm OD in QFlow solid-wall HDPE at PN 10 or PN 16. Larger diameters for major intake mains are outside the current production range.
Commonly specified sizes
Related applications
See also
For CAD drawings, compliance certificates and B2B pricing estimates, contact mktg@alom.in.
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