ARE YOU SEEKING SURETY IN BEND STIFFENER DESIGN, MANUFACTURE AND DELIVERY?

Bend stiffeners are used to support flexible pipe, umbilicals and cables when connected to rigid structures or a floating production system where there is a requirement to control the minimum bend radius of the pipe. They are usually attached at either the topside or seabed connection.

Balmoral bend stiffeners are fully accredited by Bureau Veritas to API 17L standards and, using specifically formulated polyurethane materials, are designed to suit engineered operational parameters including fluid temperature variance, project specific flowline, umbilical or cable stiffness and minimum bend radius (MBR) requirements.

In dynamic applications bend stiffeners require to have sufficient fatigue resistance to control the in-service bend radii and sustain the cyclic loads to the end of the specified life whereas in static applications they protect against gross over-bending.

Stiffeners are typically conically shaped polyurethane mouldings with a cylindrical bore that slips over the pipe, umbilical or cable.

Balmoral uses the proprietary package ‘Orcabend’, an industry standard for many years, to generate a profile for the active conical section of the stiffener.

Information that is critical to bend stiffener design includes:

• Tension and angle data from the riser analysis
• Temperature
• Interface detail
• Riser end-fitting profile
• Diameter and stiffness
• Minimum bend radius
• Riser analysis fatigue data

Balmoral’s FEA package is used to verify the Orcabend design and analyse the end-fitting structure and can also provide thermal analysis if required.

Balmoral bend stiffeners are comprehensively flex-fatigue tested and Type Approved by Bureau Veritas.

A combination of Orcabend and FEA technologies allows split stiffeners to be designed for retro fitting.

Balmoral has invested heavily in the technology and infrastructure to produce what are thought to be the largest bend stiffeners available to the industry. The market-leading facility allows the company to produce one-piece stiffeners exceeding 15m in length.

A key aspect of the Balmoral bend stiffener/restrictor development program was to negate the significant health and safety issues associated in traditional elastomer stiffener supply. The material systems used in Balmoral products meet the increasing demand for minimum hazard at all stages of manufacture and use.

Balmoral does not use carcinogenic aromatic amine cross-linkers and uses only ‘stripped’ prepolymers, ie, materials that are essentially free of volatile and toxic toluene diisocyanate (TDI). Additionally, Balmoral bend stiffeners comply with Norwegian Product Regulation 2.3 which bans the use of toxic mercury catalysts.

Dynamic bend stiffeners

Dynamic bend stiffeners provide localised stiffening for umbilicals and flowlines in demanding applications. They are designed to protect the MBR inflicted by flexing while under axial loads and also to prevent fatigue failure.

The end steelwork on dynamic stiffeners is custom-designed and fully encapsulated to connect with the matching project hardware.

• API 17L Type Approved
• Tailored to optimise performance for bend protection and fatigue resistance for the desired service life and environmental conditions accounting for fluid temps, environment, client-specific riser, flowline or umbilical stiffness and MBR requirements
• Prevents overbending and adds localised stiffness
• Steel and alloy 625 integrated steelworks tailored to match client end fittings and specifications
• FBE or nickel based coatings for corrosion protection
• Several flex fatigue tests performed
• Multiple grades of PU enables Balmoral to provide the most cost-effective solution to meet performance requirements
• Black or yellow pigmentation
• Extensive track record
• 10m³ one-shot pumping capacity means all product sizes are readily accommodated

Balmoral’s unique manufacturing capability means that stiffeners of virtually any size can be produced.

Intermediate bend stiffeners

Typically used for mid-line connection where dynamic loads are at a minimum. They are usually a simplified dynamic bend stiffener with a metallic interface measuring between 0.5-2m in length.

Static bend stiffeners

Balmoral static stiffeners provide overbend protection during installation and overboarding procedures. They support and control the MBR on flexible pipe and cable at the end fitting and mid-line joints.

A standardised Orcabend design and modular tooling means that static stiffeners can be offered on a very quick turnaround.

Split bend stiffeners

These Orcabend-designed products are generally produced for retrofitting to umbilicals, cables and flowlines already in service and are analysed in all orientations to ensure performance meets project requirements.

Split stiffeners can be used on a number of end fittings and are usually strapped or bolted in place.

A smooth transition is required between the rigid flange and the flexible cone of the stiffener. Balmoral’s design achieves this by creating both rigidly bonded and un-bonded areas that provide deflection and minimum stress in these localised areas.

The vast majority of offshore elastomer products are used subsea where UV degradation is not an issue.

However, a limited number of moulded products are deployed above the surface and by far the most critical in terms of performance and consequences of failure are bend stiffeners.

To overcome this issue, Balmoral developed its unique SOLGUARD^® UV protection system which effectively creates an overcoat layer preventing UV penetration to the stiffener.

Balmoral boasts an unmatched reputation in clamping solutions for the distributed buoyancy market and has developed this capability for use in its bend stiffener range.

The DBM clamp design was altered by adding a funnel to provide load distribution along the body of the bend stiffener. This bridges over the vulnerable tip of the stiffener to prevent damage at this critical region of the stiffener.

This evolution was introduced following client requests and is used for two applications in particular:

• Pull in Allows fitting of the bend stiffener to the pipeline on deck prior to deployment. The clamp is installed a set distance from the end fitting to prevent the bend stiffener from sliding along the flexible line simplifying the recovery and pull in process
• In service Freak loads unforeseen by global analysis or metocean data can lead to damage and the stiffener becoming detached. The clamp can be fitted prior to deployment or retrospectively to prevent a damaged stiffener being lost at sea or adversely affecting the performance of the flexible at an undesired location

Using the design parameters of the flexible line the same clamping performance as the DBM clamp range provides confidence that the bend stiffener will not travel further than desired should damage and potential failure occur.