r8 phase 2 objectives

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JIP Phase 2 proposal

Objectives Benefits Deliverables Costs Proposed CTRs

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The JIP Phase 2 workscope is intended to continue on from, and extend the work of, the JIP Phase 1, by: 1. extending the low pressure, scale testing in air to a wider range of representative carcass profiles 2. determining the effect of carcass profile on acoustic damping 3. carrying out flow visualisation of singing carcass profiles to fully understand the vortex shedding and acoustic lock-on mechanisms 4. high pressure testing of machined profiles and actual riser sections, both in air and other gases, to recreate the process conditions experienced on offshore facilities 5. determining the effectiveness of discrete acoustic dampers 6. determining the required quality factor for resonance 7. development of a numerical prediction method into a useable engineering tool to aid understanding and avoidance of the phenomenon 8. analysis of additional field data as it becomes available 9. developing an empirical engineering guidance document to help designers minimise the risk of the phenomenon occurring

JIP Phase 2 Objectives 1

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For operators:

Access to a fully developed theoretical understanding of the concern, validated by scale and full scale tests Opportunity to be involved in the development of generic guidelines on how to overcome the problem, and help define the optimum means of minimising the risk of a vibration induced fatigue failure Guidelines for the measurement and assessment of the concern for both topsides and subsea pipework Dialogue with the Flexible Riser vendors, and the opportunity to influence the design of their products to your specifications An international focus for knowledge sharing

JIP Phase 2 Benefits 2

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For vendors:

Knowledge sharing with both operators and other vendors; Dialogue with operators, leading to better understanding of their requirements in the area of flexible risers Guidance on potential long terms modifications to risers

For both operators & vendors:

Leveraged funding - for a relatively small outlay, members will benefit from a full scale research and testing programme Access to all JIP deliverables Facilitated technology transfer into participating companies

JIP Phase 2 Benefits 2

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The major deliverables are proposed as follows:

1. A technical report detailing the results of the low pressure scale testing measurements in air, and specifically the effect of the critical carcass profile parameters that characterise the phenomenon, both at onset and under steady state conditions. 2. A report detailing the results of testing at medium pressures with Natural Gas for comparison with the low pressure results. 3. A report detailing the results of testing at higher pressures, with different gases to reproduce boundary layer thickness and Reynolds number similar to those experienced offshore. 4. A technical report describing the numerical prediction method, and an evaluation of its ability as an engineering design tool. This will be done by comparison of numerical simulation results with scale and actual test results.

JIP Phase 2 Deliverables 3

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5. A technical report describing the results of the acoustic damping testing, for different machined profiles, with varying process parameters. 6. A technical report describing the effect of strong resonators on the mechanism, for a range of process conditions and riser profiles. 7. A technical report covering results of testing of discrete isolators, and their potential for use in actual systems. 8. Subject to availability of offshore data, issue a technical report summarising the measurement results as a function of al riser system i.e. variation of in-line pressure pulsations, pipework vibration, dynamic stress etc as a function of flowrate. 9. A final summary report identifying potential actions or engineering design changes that could be implemented to prevent the onset of the problem, or move it beyond the normal facility operating envelope. To include empirically based guidance notes on the effect of specific riser and process parameters.

JIP Phase 2 Deliverables 3

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Total cost of 385k over a 2-year period

Based on 75k per existing operator participant

37.5k for regulatory organisations (half ticket)

85k for new participants also gives access to Phase 1 deliverables

Riser Vendor fee to be agreed (contribution in kind possible)

4 JIP Phase 2 Proposed Cost

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Activity (CTR) Sheet

Activity no.: 1 Description: Extension of low pressure testing

Objectives: To complete the testing and analysis of the effect of riser profile on the excitation mechanism at atmospheric conditions, and determine the effect of an increase in pressure (up to 4 bar)

Activities: A number of scale test experiments will be carried out (continuing experiments carried out in the JIP Phase 1), and the following parameters will be tested: Impact of cavity depth (3 depths) Impact of edge radius up- and downstream (3 profiles) Effect of change of flow direction (3 profiles) Impact of pressure (1 bar and 4 bar) on the onset of resonance and pulsation amplitudes (relation with shear layer thickness)

Deliverables: A technical report describing the results, their interpretation and their implications for existing and future riser carcass design.

Budget cost: 50,000

Time scale: 4 months

JIP Phase 2 Proposed CTRs 5

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Activity no.: 2 Description: Low/medium pressure testing with Natural Gas

Objectives: To complete the testing and analysis of the effect of riser profile on the excitation mechanism at up to 40 bar, and to validate the scaling laws for acoustic damping at medium pressure natural gas.

Activities: Scale testing of two test profiles and 1 blank reference profile will be carried out (following on from CTR 1), and the following parameters will be evaluated: Impact of pressure (between 8 and 40 bar) on the onset of resonance and pulsation amplitudes in natural gas Impact of pressure (between 8 and 40 bar) on the damping of acoustic waves in a corrugated pipe as a function of pressure, flow and frequency. An external pulsation source is used to excite a corrugated pipe, which is not producing vortex shedding resonances (see also CTR 3) Flow velocity range 0 to 20 m/s

Deliverables: A technical report describing the measurement results, and their comparison with the low pressure air test results for the same profiles, specifically the onset velocity and profile related to the shear layer thickness

Budget cost: 50,000



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Activity no.: 3 Description: Vortex Blob method

Objectives: To develop and validate the vortex blob method as a numerical prediction model for Strouhal number and source strength

Activities: Quantitative comparison of various corrugation geometries on the source strength and source Strouhal number. Fundamental insight in the sensitivity of corrugation geometry and process conditions on the source. Prediction of source strength and source Strouhal number for field cases Comparison of numerical simulation and scale testing

Deliverables: A technical report describing the numerical method used, simulation results and comparison with field data and scale test results.

Budget cost: 30,000

Time scale: 6 months (in parallel with other work packages)


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Activity no.:4 Description: High pressure testing #1

Objectives: To determine the effect of higher pressures on the onset of resonance and source strength, on test specimens and actual riser sections, in air.

Activities: Test 2 machined profiles and 2 actual riser sections in air for a range of static pressures up to 65 bar, over the velocity range 0 to 40 m/s.

Deliverables: A technical report detailing the measurement results, and their comparison with the low pressure test results for the same profiles.

Budget cost: 50,000

Time scale: 3 weeks.


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Objectives: To determine the effect of gases other than air, at pressures up to 65 bar.

Activities: Test 2 machined profiles and 2 actual riser sections for other gases and compositions to give representative Reynolds numbers and boundary layer thicknesses

Deliverables: A technical reports detailing the measurement results, and comparing them with the low pressure, and air at higher pressure results.

Budget cost: 50,000

Time scale: 3 weeks


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Objectives: To determine the impact of using a strong acoustic resonator, and the viability of discrete isolators.

Activities: Test 2 machined profiles and 2 actual riser sections With a strong acoustic resonator upstream or downstream of the test section With an isolator between the riser and resonator

Deliverables: A technical report detailing the measurement results, and the effect of a strong acoustic resonator and a discrete isolator.

Budget cost: 50,000

Time scale: 3 weeks


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Activity no.: 7 Description: Flow visualisation on selected profiles

Objectives: To provide visual understanding of the mechanism

Activities: To carry out flow visualisation on at least 4 singing profiles under representative process conditions.

Deliverables: A report summarising the results of the visualisation. Video files showing visualisation results of interest

Budget cost: 30,000



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Activity no.: 8 Description: Field data analysis

Objectives: To provide analysis and interpretation of additional field data

Activities: To either carry out an offshore measurement survey on a facility experiencing this problem, or purchase already recorded data for analysis. To analyse the data onshore for comparison with other assets, for example, the process conditions for onset, the variation of pressure pulsation levels with gas flow velocity, pipework vibration and stress levels etc.

Deliverables: A technical report detailing the analysis results and their interpretation.

Budget cost: 20,000



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Activity no.: 9 Description: Project administration & management

Objectives: To provide analysis and interpretation of additional field data

Activities: Project launch to include announcements, liaison with current Operators, identify new Operators and possible contractor involvement, help with contractual issues, organise launch meeting etc Secretariat progress reporting, organising and facilitating meetings, managing project documentation, arranging JIP publicity, maintaining JIP website, acting as project focal point.

Budget cost: 51,500

Time scale: 24 months (project duration)


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Activity no.: 10 Description: Empirically based guidance document

Objectives: To provide a guidance document for designers to help them specify a system with a risk of the phenomenon as low as reasonably possible

Activities: Summarize the empirical results of the other major CTRs into a single document that can then be used by operators / designers to make informed decisions on riser choice, process parameters, and topside and subsea pipework design. In this way, the risk of flow induced pulsation in a new design may be minimized.

Budget cost: 10,000

Time scale: 1 month

JIP Phase 2 Proposed CTRs 5 (Additional CTR, following JIP Phase 1 meeting of 20th April 2004)

r8 phase 2 objectives

Documents