ABSTRACT

An analytical model for a fibre reinforced hose has been developed as part of the "Umbilicals - the Future" joint Industry research programme. The model, which is an extension of wire reinforced hose theory, has been used to develop a design for a 1035 bar (15,000 PSI) working pressure, 41 safety factor hose suitable for use in subsea control umbilicals. Experimental hoses were manufactured and tested, and good agreement was demonstrated between computed and actual burst pressures.

INTRODUCTION

The use of fibre-reinforced thermoplastic hoses In subsea umbilicals is now established practice These hoses are relatively low-weight, corrosion resistant, flexible, and can be produced in very long continuous lengths thereby avoiding the need for any in-line joints In most instances, the more traditional rubber hose manufacture has over the years been reasonably well supported by analytical work at universities and in industry, and the performance of steel reinforced hoses in particular can be accurately predicted The manufacture of fibre-reinforced thermoplastic hoses, however, owes much to empirical design techniques To date very little analytical work has been carried out on thermoplastic hoses This is due very largely to the less well defined properties and geometry of the constructional materials, and their susceptibility to variations in the manufacturing process

The strength and modulus of the fibre reinforcement materials available for thermoplastic hose construction have increased considerably over the past 15-20 years, and nowadays the armd fibre is commonly used by most manufacturers of umbilical hose At the time of writing the maximum working pressure for commercially available thermoplastic hoses is around 760 bar (with a 4 1 safety factor) Many new developments of high pressure oil/gas reservoirs, however, are dictating down hole safety valve hydraulic pressures of up to 1000 bar

This paper describes a programme of work under the "Umbilicals - the Future" joint industry programme to produce designs for a 1035 bar (15,000 psi) working pressure. 4140 bar (60,000 psi) burst pressure fibre-reinforced hose The model developed has drawn together some of the relevant strands of research which have been carried out in a number of countries, plus parallel work in the field of composite materials. Where necessary, the lack of available information was addressed by laboratory experiment, both at the Mechanical Engineering Centre, and where manufacturing machinery was necessary, on the premises of a participating hose manufacturer.

LITERATURE REVIEW

The work commenced with a literature search to determine the current state-of-the-art In hose design The industry-wide search covered all types of hose construction, and Included relevant hose design patents and candidate reinforcement materials. Papers were obtained on analytical and finite element methods applied to hose design and a variety of related subjects, eg filament wound cylinders, composites and analysis of textiles.

Some of the earliest hose design analyses were based upon equilibrium considerations of inextensible reinforcement.

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