Subsea Protection: Mattresses & Grout Bags
Local manufacture and supply of subsea concrete mattresses and grout bags.
Afrishore manufactures and supplies subsea protection products – articulated concrete mattresses and grout bags – for the protection and stabilisation of pipelines, flowlines, umbilicals, cables and subsea structures on the seabed. Where most of the industry imports these products, Afrishore has manufactured them locally in Southern Africa to international specification, beside the offshore load-out.
Subsea concrete mattresses
An articulated mattress is an array of high-strength concrete blocks linked by a UV-stabilised polypropylene rope matrix. It conforms to the seabed while adding the weight to hold subsea lines in place and resist scour – the recognised solution for protecting and stabilising pipelines, flowlines, umbilicals and cables. For SBM Offshore's Project Ikhwezi, Afrishore cast 1,480 mattresses (nominally 6 m × 3 m) on the Mossel Bay quayside to DNV-type specification – locally fabricated moulds, locally supplied high-strength ready-mix and a 100% local workforce.
Subsea grout bags
Flexible polypropylene units charged with high-strength grout and lowered onto the seabed where rigid mattresses cannot follow the topography. They conform to the contours of the seabed and harden into a load-bearing support – filling scour holes, free spans and voids, and bedding and stabilising pipelines, manifolds, jumpers and structures. Afrishore has batched and bagged subsea grout in bulk (4,000 t for Project Ikhwezi) and manufactured, certified and exported grout bags by the consignment (200 units to offshore Angola for Oceaneering).
Manufactured locally, certified to spec
Each unit is made to international (DNV-type) specification using locally sourced materials and crews, and every lift runs to a documented safe system of work – trained banksman slinging, competent-person beam inspection and proof-load-tested, ROV-operable deployment spreader bars. The result is certified subsea product to the same standard as imported equivalents – without the import freight, lead time or handling damage, and with the skills retained in the Southern African supply chain.
What we provide
- Subsea concrete mattress manufacture (articulated, rope-matrix)
- Subsea grout bag manufacture, filling & certification
- Bulk subsea grout batching
- Local mould fabrication to international (DNV-type) spec
- ROV-operable deployment spreader bars (proof-load tested)
- Lifting, rigging & quayside load-out
- Sea-freight export & consignment handling
- Documented safe systems of work (QHSE)
