Anti-Scour Frond Mattress

When a solid object, typically a pipeline, offshore platform structure or bridge pier is put in place on a loose sedimentary sea or river bed the flow of water around this under certain conditions can cause erosion of the bed; this is called scour. It may be gradual or rapid but it is cumulative and the end result may be unsafe spans on pipelines or an unsafe structure generally.

Natural seaweed reduces water velocity locally and correspondingly reduces scour; the SPS Frond Mattress replicates this natural phenomenon. Over 1000 buoyant fronds per square metre at nominally one metre high are built into the Mattress and properly deployed (either directly onto the seabed or attached to an SPS Fleximat) they will stop scour rapidly.

Concrete Mattresses and Mats

Concrete Mattresses provide a recognised engineering solution to several of the challenges faced in subsea pipeline construction, umbilical deployment and seabed and soil protection/stabilisation. They are cost effective and may be readily deployed using standard handling systems. Typically Concrete Mattresses may be used to provide:-

• Protection from dropped objects
• Added weight and stabilisation
• Protection from Trawl Boards
• Scour prevention
• Crossover support and separation for Pipelines and Umbilicals
• Supports or Foundations for other Subsea Activities
• Riverbank erosion control

SPS manufacture a range of Standard Mattresses but will also design and manufacture Mattresses to a client’s specific requirement. Quality and Safety are the key issues in all SPS designs and appropriate safety factors are applied to address lifting and handling in an offshore environment.

Some Concrete Matresses Options

Concrete Density

The density of Concrete used in the manufacture of Standard Mattresses is generally between 2.3 and 2.5 Tonnes per Cubic Metre. Under certain conditions where there may be a requirement for additional or less weight in a Mattress (or other SPS Product). SPS can design and supply a concrete mix with a higher or lower density than the standard.

Protection Pads

Under certain operating conditions SPS clients require a low friction or anti abrasion material between the Concrete Mattress and the asset that it may be stabilising or protecting. SPS can provide this by affixing a range of materials to its Mattress Segments.

Fronded Concrete Mattresses

The Anti Scour Frond Mattress (shown below) may be deployed directly into its location or alternatively attached to and deployed together with a Concrete Mattress. This latter method simplifies deployment and provides additional protection and stabilisation.

General Options

SPS Engineering and Experience is available to address any particular requirements that clients may have for special Mattress designs and modifications.

Crossing Bridges

SPS Crossing Bridges are an ideal solution for crossing an existing pipeline with an pipeline cable in a single unit installation. SPS can manufacture these to its standard designs, clients own designs or can work with clients to develop and design a Bridge for a particular application. As for all SPS products, due consideration is given to all of the issues around handling, installation and certification.

Fabric Formworks

Fabric formwork is constructed from a flexible woven fabric into purpose built bags for injecting subsea with a grout/cement mixture, to form a permanent shape for:

• Pipeline and cable crossing support
• Stabilization and protection for various subsea structures
• Anti-scour protection

Fleximats

The Fleximat is a standard SPS product. It provides a high degree of flexibility, allowing it to closely follow the contours of a pipeline / umbilical and seabed. It is constructed using high strength concrete profiled blocks and U.V. stabilised polypropylene rope. The Fleximat brick pattern matrix reduces the open line effect thus offering additional protection and stability. Once installed the Fleximat may scour into the seabed to effect and increase in stability and overtrawlability

Tapered (Wedged) Fleximats

Extreme seabed, current and wave conditions may determine that additional stability is required beyond that provided by the standard Fleximat. In this case SPS can provide Fleximats with enlarged tapered (wedged) edge elements. This tapered (wedged) element also offers an improved overtrawlability profile.

Grout, sand and Gravel bags

Grout, Sand or Gravel may be supplies in 25kg sealed bags then packed into 1 tonne certified FIBCmultiple trip bags. Special 1 and 1.5Tonne bags may also be supplied for ROV release subsea. The materials are used for filling voids and general support to the other SPS Products; grout bags will cure after deployment to provide a permanent stable support. Sand and gravel can also be supplied loose in FIBC Bags.

Handling and Installation Equipment

As set out in the description of its Products, SPS pays due consideration to issues around their handling and deployment and the corresponding certification of handling equipment. SPS can design and supply handling and deployment systems for all of its products, for purchase or hire.

Deployment Systems may be operated by: -

• Diver Subsea
• ROV Subsea
• From deck of Installation vessel

Log Mats

The Logmat is a standard SPS product, and is flexible in only one plane. This provides an engineering solution to two particular challenges.

Load bearing

Where soft soil conditions exist a logmat may provide a foundation base for supporting a pipeline or other subsea construction.

Stabilisation

In conditions of extreme environmental loadings, buoyancy forces, or loss of weight coat, Subsea Pipelines may require additional weight beyond that provided by the Fleximat. Logmats have a greater overall density and are ideal for this.

Logmats are constructed using high strength, reinforced concrete logs and U.V. stabilised polypropylene rope. Logmats can be quickly and accurately deployed using standard SPS lifting equipment. Log mat lengths are supplied to meet a client’s individual requirement.

Pipeline Supports

Single or multiple reinforced concrete Pipeline Supports are installed to provide a crossing for a new pipeline over an existing pipeline, umbilical or other asset on the seabed. SPS can manufacture these to its standard designs, clients own designs or can work with clients to develop and design a Support or Support system for a particular application. Design issues will typically include, review of seabed conditions, seabed settlement and Support footprint, restraining the pipeline on Support, pipeline bearing surface on Support (e.g. low friction/high friction/low impact etc), pipelay tolerances, handling and installation of Supports, and design life requirements. Full documentation and certification is provides as part of the SPS Package.

Protection Covers

SPS Covers protect pipelines, umbilicals and other subsea assets from dropped objects or trawl board impact without transfer of load to the asset. SPS can manufacture these to its standard designs, clients own designs or can work with clients to develop and design a Cover for a particular application. As for all SPS products, due consideration is given to all of the issues around handling, installation and certification.

Revetment mats

The Revetment Mattress is a fleximat used for protection against river and sea embankment erosion. Its flexible construction ensures the flexiform revetment mattress can be laid to cope with variations in the embankment profile maintaining maximum protection against erosion.

Revetment mats are suitable for various environments including:

• Harbours
• Docks
• Lakes
• River banks
• Break waters
• Weirs
• Sea defences
• Slipways
• Outfalls
• Reclamation applications
• Environmental applications
• Slope stabilisation
• Roads

Rock Filter Bags

Rock Filter Bags can be used for Scour Protection, Span Correction, Cable Protection & Flowline Protection. The Rock Filter  bags are an environmentally friendly solution as these are made from 99% recyled materials.

Due to high flexibility of the Rock Filter Bags it is possible to fill    spans by using multiple bags.

Using SPS handling equipment it is possible to install many  Rock Filter Bags at a time.

 

 

Special Products

The flexibility in design permitted by the use of cast concrete and reinforced concrete, its comparative cost effect and corrosion resistant properties make it an ideal material for use in a range of subsea construction aids and applications.

Here are some of the special products we have provided to our clients: -

• Stabilisation Weights – for retaining umbilical cables and other assets when concrete mattresses are not ablebe applied.
• Pipelay Counteracts - for pipeline ‘snake-lay’ operations
• Weight Collars – for adding additional weight to pipelines or spools or to repair/replace damaged weigh coat.
• Gravity Anchors – for use in confined spaces where traditional anchors are not permitted.
• Artificial Reef Units – to replace or establish reefs and promote marine life

 

 SPS can manufacture these to its standard designs, clients own designs or can work with clients to develop and design a system for a particular application. As for all SPS products, due consideration is given to all of the issues around handling, installation and certification.

 

Speedloaders

SPS we work hard to find the best solutions possible for our customers. In order to improve efficiency during vessel mobilisations and offshore, we have designed and manufactured a range of Concrete Mattress Speedloaders to allow customers to mobilise / deploy multiple Concrete Mattresses in one simple lift rather than multiple individual lifts.

• Save up to 80% vessel loading time.
• Each Speedloader is rated to 25Te SWL & Designed to DNV 2.7-1
• Certified for use offshore - ideal for wet storing mats in minimal duration
• Data Sheet / Design Report available upon request.
• Lift 5 off 6x3x0.15m mats in one simple lift instead of 5 lifts using 16 slings
• Lift 3 off 6x3x0.3m mats in one simple lift instead of 3 lifts using 16 slings