GB2153962A - Riser shroud - Google Patents

Riser shroud Download PDF

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Publication number
GB2153962A
GB2153962A GB08502448A GB8502448A GB2153962A GB 2153962 A GB2153962 A GB 2153962A GB 08502448 A GB08502448 A GB 08502448A GB 8502448 A GB8502448 A GB 8502448A GB 2153962 A GB2153962 A GB 2153962A
Authority
GB
United Kingdom
Prior art keywords
riser
shroud
spoiler
vortex
external diameter
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB08502448A
Other versions
GB8502448D0 (en
Inventor
Trevor Peter Jee
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BP PLC
Original Assignee
BP PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB848402994A external-priority patent/GB8402994D0/en
Application filed by BP PLC filed Critical BP PLC
Priority to GB08502448A priority Critical patent/GB2153962A/en
Publication of GB8502448D0 publication Critical patent/GB8502448D0/en
Publication of GB2153962A publication Critical patent/GB2153962A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02B—HYDRAULIC ENGINEERING
    • E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
    • E02B17/0017—Means for protecting offshore constructions
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
    • E21B17/01—Risers

Abstract

A vortex spoiler for a riser 2 comprises a perforated shroud 1 adapted to surround and be spaced apart from the riser. Vortex shedding around a riser can lead to high and low pressure variations on the riser which can set up damaging vibrations. The spoiler reduces the formation of such vortices and thus protects the riser, and is preferably installed at mid-span of the riser. It may be of plastics, and may incorporate anti-fouling mesh. <IMAGE>

Description

SPECIFICATION Riser shroud This invention relates to an improved vortex spoiler for use on an offshore platform riser.
A riser is a pipe running between the sea bed and deck level on a platform. It generally passes through a number of guides set at various levels between the deck and the sea bed to limit its movement. The distance between any two successive guides is known as a span. A riser is subjected to a number of stresses caused by movement of the sea. One particular stress is caused by strong currents which create vortices around the riser. Vortex shedding leads to high and low pressure variations on the riser. This can set up potentially damaging vibrations in the structure. The effect is particularly marked at midspan positions where the riser has greatest freedom of movement.
We have now devised a vortex spoiler for a riser which reduces the formation of powerful vortices.
Thus according to the present invention there is provided a vortex spoiler for a riser which spoiler comprises a perforated shroud adapted to surround and be spaced apart from the riser. The spoiler disrupts the synchronisation of vortex shedding and thus reduces vibration.
The shroud is preferably constructed from a plastics material. Suitable plastics include polyethylene, polypropylene and glass fibre reinforced polyester.
The perforations should be sharp-edged holes and may be of any shape, e.g. circular of square.
Preferably from 8 to 1 2 holes are cut around the circumference.
The ratio of the area of the holes to the total area of the shroud is preferably in the range 30 to 50%.
Anti fouling mesh may be incorporated in the surface of the shroud to prevent it from becoming clogged with marine growth.
The shroud may be made in one or more horizontal sections along the riser axis. It, or each half-section, is preferably made in two half-shells.
According to another aspect of the invention there is provided an offshore platform riser fitted with a vortex spoiler comprising a perforated shroud surrounding and spaced apart from the riser.
The shroud is preferably spaced apart from the riser by spacers at its extremities between the shroud and the riser.
It is preferably located about midspan position(s) of the riser. The shroud may be attached to the riser by means of a clamp or clamps.
The length of the shroud is preferably from 10 to 30% of the length of the span.
The external diameter of the shroud is preferably in the range 1.1 to 1.3 times the external diameter of the riser.
Antifouling mesh may also be incorporated in the riser coating under the shroud. The preferred coating in this area is neoprene which in addition to providing a surface in which to embed the mesh also protects the riser from corrosion.
The invention is illustrated with reference to the accompanying drawing.
A perforated shroud 1 is fitted around a platform riser 2 at midspan by means of clamps 3. Neoprene or plastics material spacers 4 keep it apart from the riser.
The length of the shroud 157.5 cm which is 20% of the riser span and its external diameter is 21.34 cm which is 1.2 times the external diameter of the riser.
8 holes are cut around the circumference and the ratio of the area of the holes to the total area is 40%.
1. A vortex spoiler for a riser which spoiler comprises a perforated shroud adapted to surround and be spaced apart from the riser.
2. A vortex spoiler according to claim 1 wherein the shroud is constructed from a plastics material.
3. A vortex spoiler according to either of the preceding claims wherein the ratio of the perforations to the total area of the shroud is in the range 30% to 50%.
4. An offshore platform riser fitted with a vortex spoiler according to any of the preceding claims.
5. An offshore platform riser according to claim 4 wherein the vortex spoiler is located about the midspan position(s).
6. An offshore platform riser according to either of claims 4 or 5 wherein the length of the shroud of the vortex spoiler is in the range from 10% to 30% of the length of the span.
7. An offshore platform riser according to any of claims 4 to 6 wherein the external diameter of the shroud is in the range 1.1 to 1.3 times the external diameter of the riser.
8. A vortex spoiler as herein before described with reference to the accompanying drawing.
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (1)

  1. **WARNING** start of CLMS field may overlap end of DESC **.
    SPECIFICATION Riser shroud This invention relates to an improved vortex spoiler for use on an offshore platform riser.
    A riser is a pipe running between the sea bed and deck level on a platform. It generally passes through a number of guides set at various levels between the deck and the sea bed to limit its movement. The distance between any two successive guides is known as a span. A riser is subjected to a number of stresses caused by movement of the sea. One particular stress is caused by strong currents which create vortices around the riser. Vortex shedding leads to high and low pressure variations on the riser. This can set up potentially damaging vibrations in the structure. The effect is particularly marked at midspan positions where the riser has greatest freedom of movement.
    We have now devised a vortex spoiler for a riser which reduces the formation of powerful vortices.
    Thus according to the present invention there is provided a vortex spoiler for a riser which spoiler comprises a perforated shroud adapted to surround and be spaced apart from the riser. The spoiler disrupts the synchronisation of vortex shedding and thus reduces vibration.
    The shroud is preferably constructed from a plastics material. Suitable plastics include polyethylene, polypropylene and glass fibre reinforced polyester.
    The perforations should be sharp-edged holes and may be of any shape, e.g. circular of square.
    Preferably from 8 to 1 2 holes are cut around the circumference.
    The ratio of the area of the holes to the total area of the shroud is preferably in the range 30 to 50%.
    Anti fouling mesh may be incorporated in the surface of the shroud to prevent it from becoming clogged with marine growth.
    The shroud may be made in one or more horizontal sections along the riser axis. It, or each half-section, is preferably made in two half-shells.
    According to another aspect of the invention there is provided an offshore platform riser fitted with a vortex spoiler comprising a perforated shroud surrounding and spaced apart from the riser.
    The shroud is preferably spaced apart from the riser by spacers at its extremities between the shroud and the riser.
    It is preferably located about midspan position(s) of the riser. The shroud may be attached to the riser by means of a clamp or clamps.
    The length of the shroud is preferably from 10 to 30% of the length of the span.
    The external diameter of the shroud is preferably in the range 1.1 to 1.3 times the external diameter of the riser.
    Antifouling mesh may also be incorporated in the riser coating under the shroud. The preferred coating in this area is neoprene which in addition to providing a surface in which to embed the mesh also protects the riser from corrosion.
    The invention is illustrated with reference to the accompanying drawing.
    A perforated shroud 1 is fitted around a platform riser 2 at midspan by means of clamps 3. Neoprene or plastics material spacers 4 keep it apart from the riser.
    The length of the shroud 157.5 cm which is 20% of the riser span and its external diameter is 21.34 cm which is 1.2 times the external diameter of the riser.
    8 holes are cut around the circumference and the ratio of the area of the holes to the total area is 40%.
    1. A vortex spoiler for a riser which spoiler comprises a perforated shroud adapted to surround and be spaced apart from the riser.
    2. A vortex spoiler according to claim 1 wherein the shroud is constructed from a plastics material.
    3. A vortex spoiler according to either of the preceding claims wherein the ratio of the perforations to the total area of the shroud is in the range 30% to 50%.
    4. An offshore platform riser fitted with a vortex spoiler according to any of the preceding claims.
    5. An offshore platform riser according to claim 4 wherein the vortex spoiler is located about the midspan position(s).
    6. An offshore platform riser according to either of claims 4 or 5 wherein the length of the shroud of the vortex spoiler is in the range from 10% to 30% of the length of the span.
    7. An offshore platform riser according to any of claims 4 to 6 wherein the external diameter of the shroud is in the range 1.1 to 1.3 times the external diameter of the riser.
    8. A vortex spoiler as herein before described with reference to the accompanying drawing.
GB08502448A 1984-02-04 1985-01-31 Riser shroud Withdrawn GB2153962A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08502448A GB2153962A (en) 1984-02-04 1985-01-31 Riser shroud

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB848402994A GB8402994D0 (en) 1984-02-04 1984-02-04 Riser shroud
GB08502448A GB2153962A (en) 1984-02-04 1985-01-31 Riser shroud

Publications (2)

Publication Number Publication Date
GB8502448D0 GB8502448D0 (en) 1985-03-06
GB2153962A true GB2153962A (en) 1985-08-29

Family

ID=26287287

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08502448A Withdrawn GB2153962A (en) 1984-02-04 1985-01-31 Riser shroud

Country Status (1)

Country Link
GB (1) GB2153962A (en)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995026294A1 (en) * 1994-03-28 1995-10-05 Shell Internationale Research Maatschappij B.V. Spar platform
GB2377237A (en) * 2001-06-08 2003-01-08 Balmoral Group Riser impact protection
GB2385648B (en) * 2000-08-30 2003-12-03 Crp Group Ltd Protection of underwater elongate members
NL1021347C2 (en) * 2002-08-28 2004-03-02 Lankhorst Special Mouldings B Suppression element for vortex vibrations, kit, suppression system, mineral extraction device and a mold.
FR2870287A1 (en) * 2004-05-13 2005-11-18 Inst Francais Du Petrole System for limiting the vibrations induced by vortex on a rising column suspended by one end from a support and subject to external lateral fluid flows
CN101949404A (en) * 2010-08-27 2011-01-19 中国计量学院 Subduction method for cylindrical wave current load
CN105253275A (en) * 2015-11-13 2016-01-20 中国船舶重工集团公司第七二六研究所 Underwater hoisting equipment and stabilizing device thereof
CN107237797A (en) * 2017-07-17 2017-10-10 中国计量大学 A kind of method for reducing of tandem arranged cylinders body vortex-induced vibration
WO2018215653A1 (en) * 2017-05-26 2018-11-29 Universitat Rovira I Virgili Device for passive suppression of vortex-induced vibrations (viv) in structures
EP4096038A1 (en) 2021-05-27 2022-11-30 Nexans Cable protection system
WO2023040170A1 (en) * 2021-09-16 2023-03-23 中国华能集团清洁能源技术研究院有限公司 Offshore wind power foundation

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1492456A (en) * 1974-05-16 1977-11-23 Texaco Development Corp Vessel for drilling or producing fluids from submerged wells
GB1580910A (en) * 1977-02-24 1980-12-10 Nat Res Dev Stabilising of structures
GB2061452A (en) * 1979-10-12 1981-05-13 Miller D S Improvements in or Relating to Stabilising Bluff Structures against Oscillation

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1492456A (en) * 1974-05-16 1977-11-23 Texaco Development Corp Vessel for drilling or producing fluids from submerged wells
GB1580910A (en) * 1977-02-24 1980-12-10 Nat Res Dev Stabilising of structures
GB2061452A (en) * 1979-10-12 1981-05-13 Miller D S Improvements in or Relating to Stabilising Bluff Structures against Oscillation

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2301648A (en) * 1994-03-28 1996-12-11 Shell Int Research Spar platform
GB2301648B (en) * 1994-03-28 1998-07-15 Shell Int Research Spar platform
WO1995026294A1 (en) * 1994-03-28 1995-10-05 Shell Internationale Research Maatschappij B.V. Spar platform
GB2385648B (en) * 2000-08-30 2003-12-03 Crp Group Ltd Protection of underwater elongate members
GB2377237A (en) * 2001-06-08 2003-01-08 Balmoral Group Riser impact protection
GB2377237B (en) * 2001-06-08 2003-06-18 Balmoral Group Riser impact protection
US7458752B2 (en) 2002-08-28 2008-12-02 Lankhorst Special Mouldings B.V. Suppression element for vortex-induced vibrations
NL1021347C2 (en) * 2002-08-28 2004-03-02 Lankhorst Special Mouldings B Suppression element for vortex vibrations, kit, suppression system, mineral extraction device and a mold.
WO2004020777A1 (en) * 2002-08-28 2004-03-11 Lankhorst Special Mouldings B.V. Suppression element for vortex-induced vibrations, construction kit, apparatus for extracting minerals, and mold
FR2870287A1 (en) * 2004-05-13 2005-11-18 Inst Francais Du Petrole System for limiting the vibrations induced by vortex on a rising column suspended by one end from a support and subject to external lateral fluid flows
CN101949404A (en) * 2010-08-27 2011-01-19 中国计量学院 Subduction method for cylindrical wave current load
CN101949404B (en) * 2010-08-27 2012-11-21 中国计量学院 Subduction method for cylindrical wave current load
CN105253275A (en) * 2015-11-13 2016-01-20 中国船舶重工集团公司第七二六研究所 Underwater hoisting equipment and stabilizing device thereof
WO2018215653A1 (en) * 2017-05-26 2018-11-29 Universitat Rovira I Virgili Device for passive suppression of vortex-induced vibrations (viv) in structures
CN107237797A (en) * 2017-07-17 2017-10-10 中国计量大学 A kind of method for reducing of tandem arranged cylinders body vortex-induced vibration
CN107237797B (en) * 2017-07-17 2018-12-21 中国计量大学 A kind of method for reducing of tandem arranged cylinders body vortex-induced vibration
EP4096038A1 (en) 2021-05-27 2022-11-30 Nexans Cable protection system
WO2023040170A1 (en) * 2021-09-16 2023-03-23 中国华能集团清洁能源技术研究院有限公司 Offshore wind power foundation

Also Published As

Publication number Publication date
GB8502448D0 (en) 1985-03-06

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