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Fluid dynamics

1st August 2017

Posted By Paul Boughton


Floating hoses
Hoses connected to CALM buoy configuration
Vertical connection of floating hoses
Submarine line
Installation of a submarine line
Floating hoses connected and ready for final installation

Vincent Lagarrigue and Nicolas Landriere on rethinking oil transfer solution analysis, selection and maintenance

In a market environment that remains characterised by uncertainty, it is essential that suppliers of oil transfer solutions work with their customers to ensure that they are getting maximum value from the equipment they deliver.

It is no longer enough for suppliers to play a passive role – they are increasingly expected to work with customers to provide a collaborative approach. This is a welcome development, yet it brings new challenges and responsibilities.

The onus is now well and truly on suppliers to support customers throughout a project; from the very beginning, understanding the nature of the often-challenging environments in which their products will function, to helping to select the most appropriate option and finally, maintaining the product throughout its lifecycle.

Recent research findings bear out the need for this shift in attitude. In a survey of oil professionals conducted in early 2017 by Trelleborg’s fluid handling solutions operation, ‘quality and durability’ were listed as ‘vital’ over 80% of the time, while ‘price’ was listed as vital only 19% of the time.

The next most ‘vital’ factors were ‘aftersales support and service’ and ‘ease of installation’, at 32% and 28% respectively. In a separate research exercise, from Trelleborg’s offshore operation, 61% of facilities surveyed indicated that they would be willing to spend more on a project upfront to reduce the need for future upgrades and ensure longevity.

There is a growing sense of recognition that as a new way of working is now required, it makes sense to invest in long-term solutions to the challenges of rationalisation – and that an integral part of this is investing in the relationship with suppliers.

Nowhere is this more crucial than in the field of oil transfer, where pressure to work quickly and efficiently is intense.

However, operations must function without endangering the safety of those working on the project or the environment in which transfer occurs.

By ensuring that products and the environments in which they function are properly understood, suppliers can help partners select the right tools for the job, and ensure that hoses operate at their optimum level throughout their service life.

Research, testing and development

In all scenarios, testing is required to qualify each solution according to different standards. Trelleborg’s R&D team routinely becomes involved in the earliest stage of oil & gas projects to co-operate with its customers in defining the most appropriate technical solutions for the targeted application and design life. Traditionally, R&D departments may not have been expected to play such an active role.

However, it is becoming increasingly vital for these teams to consult on each project to ensure truly customised solutions.

In configurations such as conventional buoy mooring (CBM) in water of depths up to 20m, OCIMF tests based on GMPHOM 2009 guidelines will be required – the standard issued by oil companies to provide technical requirements to ensure the satisfactory performance of flexible bonded hoses commonly used at offshore moorings.

Hydrodynamic analysis is conducted as necessary, taking into account how a qualified hose design will function in conjunction with its specific properties, performance expectations and the environment within which it will function.

In more challenging conditions, particularly in deep water, or in use with challenging configurations such as the Chinese Lantern, GMPHOM 2009 guidelines are not always sufficient to guarantee an understanding of the capability of a hose system to withstand the static and dynamic loads that occur on offshore terminals. In this instance, the API Spec 17K (specification for bonded flexible pipe) is used, as it considers requirements regarding design methodology, characterisation of the material, and hydrodynamic and fatigue analysis.

In these instances, high fidelity finite element models (FEM) for each specific hose construction are created, enabling a precise prediction of hose behaviour, including specific characteristics and limitations.

Following this, the fluid properties of the product to be transferred, including temperature, pressure and viscosity – as well as the necessary standards and their specific requirements – are all scrutinised under hydrodynamic analysis (static, dynamic or extreme). This allows for a detailed comparison report on the limitations of each hose to be developed.

As the number of off-loadings will also affect the strain placed on the hose – particularly in more extreme environments – the hoses used in these conditions are also tested against stress and strain databases for fatigue analysis, which is mandatory under API Spec 17K Standard.

Choice: the right tool for the job

Based on this testing and analysis, suppliers will be able to recommend the most suitable option for each task. Hose selection is too important to adopt a ‘one-size-fits-all’ approach, and different options must be carefully considered.

In most cases, the suitable solution for non-harsh, low cost extraction environments will be a single or double carcass nipple hose, such as the Sealine design used by Trelleborg. The manufacture consists in using binding steel wires fixed on the nipple flange to block the hose body structure made with textile layers and reinforced by a steel helix. The standard nature of this design means that this type of hose is the most commonly used in today’s market, in both floating and submarine configurations.

For extremely challenging environments or long service life, more specialised solutions may be required. In this case, nippleless technologies such as Trelleborg’s Trelline or Kleline offerings can be used.

The nippleless technology means that there is no stiff metal connector that would reduce flexibility. These hoses can be used in both submarine and floating situations in which environments would be too challenging for a nipple hose.

Maintenance

Perhaps the most important area that needs collaboration, and something that is vital to upholding the highest safety standards, comes after purchase and installation; maintaining and servicing the equipment.

It is essential that suppliers support projects throughout their execution to ensure that the highest safety standards are upheld, as well as guaranteeing the benefits of proper lifecycle management. This approach includes on-site inspection and testing for requalification, hose maintenance and inspection programmes, and on-site repairs to ensure that hoses are not only performing correctly but are meeting the required standards in safety and quality. This can even extend to undertaking specific investigation programmes. These may include inspections, tests on site or in the factory such as burst tests, or ageing analysis of the components such as adhesion tests and elastomer property analysis. Suppliers can also choose to engage in training and education programmes, disseminating best practices on storage, transportation and maintenance of hoses.

At its most basic level, hose management is risk management. The process of understanding a transfer environment, determining the most suitable solution and making sure that it works in the long term, is a vital part of underpinning safe, efficient working practices. In the face of continued uncertainty, it remains essential to invest in the relationships that underpin these processes, and cementing a collaborative relationship between customer and supplier.

Vincent Lagarrigue & Nicolas Landriere are with Trelleborg’s fluid handling solutions operation. 









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