CN116288370A - Submarine pipeline protection system and method - Google Patents
Submarine pipeline protection system and method Download PDFInfo
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- CN116288370A CN116288370A CN202310301946.0A CN202310301946A CN116288370A CN 116288370 A CN116288370 A CN 116288370A CN 202310301946 A CN202310301946 A CN 202310301946A CN 116288370 A CN116288370 A CN 116288370A
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- 238000000034 method Methods 0.000 title claims abstract description 19
- 238000005260 corrosion Methods 0.000 claims abstract description 40
- 239000010405 anode material Substances 0.000 claims abstract description 37
- 239000011248 coating agent Substances 0.000 claims abstract description 22
- 238000000576 coating method Methods 0.000 claims abstract description 22
- 239000000463 material Substances 0.000 claims abstract description 20
- 239000000945 filler Substances 0.000 claims description 9
- 229910001018 Cast iron Inorganic materials 0.000 claims description 7
- 239000002245 particle Substances 0.000 claims description 7
- 229910052710 silicon Inorganic materials 0.000 claims description 7
- 239000010703 silicon Substances 0.000 claims description 7
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 4
- 239000010426 asphalt Substances 0.000 claims description 3
- 238000005253 cladding Methods 0.000 claims description 3
- 239000011280 coal tar Substances 0.000 claims description 3
- 229910045601 alloy Inorganic materials 0.000 claims 1
- 239000000956 alloy Substances 0.000 claims 1
- 210000003298 dental enamel Anatomy 0.000 claims 1
- 238000003466 welding Methods 0.000 claims 1
- 230000007797 corrosion Effects 0.000 abstract description 25
- 230000002035 prolonged effect Effects 0.000 abstract description 11
- 230000010287 polarization Effects 0.000 abstract description 6
- 238000005536 corrosion prevention Methods 0.000 abstract description 3
- 239000010410 layer Substances 0.000 description 13
- 239000002689 soil Substances 0.000 description 8
- 230000000694 effects Effects 0.000 description 7
- 229910000846 In alloy Inorganic materials 0.000 description 6
- 238000010276 construction Methods 0.000 description 4
- 229910000838 Al alloy Inorganic materials 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- 229910021607 Silver chloride Inorganic materials 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000011651 chromium Substances 0.000 description 2
- 239000000571 coke Substances 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 239000003973 paint Substances 0.000 description 2
- 239000002006 petroleum coke Substances 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000013535 sea water Substances 0.000 description 2
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 210000001367 artery Anatomy 0.000 description 1
- 238000004210 cathodic protection Methods 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
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- 239000003921 oil Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F13/00—Inhibiting corrosion of metals by anodic or cathodic protection
- C23F13/02—Inhibiting corrosion of metals by anodic or cathodic protection cathodic; Selection of conditions, parameters or procedures for cathodic protection, e.g. of electrical conditions
- C23F13/06—Constructional parts, or assemblies of cathodic-protection apparatus
- C23F13/08—Electrodes specially adapted for inhibiting corrosion by cathodic protection; Manufacture thereof; Conducting electric current thereto
- C23F13/16—Electrodes characterised by the combination of the structure and the material
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F13/00—Inhibiting corrosion of metals by anodic or cathodic protection
- C23F13/02—Inhibiting corrosion of metals by anodic or cathodic protection cathodic; Selection of conditions, parameters or procedures for cathodic protection, e.g. of electrical conditions
- C23F13/04—Controlling or regulating desired parameters
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F13/00—Inhibiting corrosion of metals by anodic or cathodic protection
- C23F13/02—Inhibiting corrosion of metals by anodic or cathodic protection cathodic; Selection of conditions, parameters or procedures for cathodic protection, e.g. of electrical conditions
- C23F13/06—Constructional parts, or assemblies of cathodic-protection apparatus
- C23F13/08—Electrodes specially adapted for inhibiting corrosion by cathodic protection; Manufacture thereof; Conducting electric current thereto
- C23F13/20—Conducting electric current to electrodes
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F2213/00—Aspects of inhibiting corrosion of metals by anodic or cathodic protection
- C23F2213/30—Anodic or cathodic protection specially adapted for a specific object
- C23F2213/32—Pipes
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Prevention Of Electric Corrosion (AREA)
Abstract
The invention belongs to the technical field of corrosion prevention of submarine pipeline systems, and particularly relates to a submarine pipeline protection system and a submarine pipeline protection method, wherein the submarine pipeline protection system comprises a sacrificial anode material, an anode bed and a corrosion prevention layer; the outer side of the submarine pipeline is provided with a sacrificial anode material, the sacrificial anode material is provided with two arc-shaped grooves, and an anode land bed is arranged in each arc-shaped groove; the submarine pipeline is electrically connected with the negative electrode of the power supply, and the anode land bed is electrically connected with the positive electrode of the power supply; the corrosion-resistant layer is arranged on the surface of the submarine pipeline, the submarine pipeline is protected by the system, the service life of the submarine pipeline can be prolonged, the operability is good, and the submarine pipeline is subjected to cathodic polarization, sacrificial anode protection on the submarine pipeline and covering coating by using externally applied protection current to reduce the corrosion speed of the material, so that the purpose of effectively controlling the corrosion of the submarine pipeline is achieved.
Description
Technical Field
The invention belongs to the technical field of corrosion prevention of submarine pipeline systems, and particularly relates to a submarine pipeline protection system and a submarine pipeline protection method.
Background
As large arteries for offshore oil and gas transport, subsea pipelines play an increasingly important role. The corrosion seriously affects the service life of submarine pipelines, so that the damage rate of submarine pipelines is increased year by year, and leakage and fracture damage accidents are increased gradually. Submarine pipelines generally adopt steel pipelines, have poor corrosion resistance, great repair difficulty and high cost. Therefore, it is very important to effectively protect submarine pipelines from corrosion and to extend the service life of submarine pipelines.
The corrosion shape of the actual pipeline has certain randomness, and the submarine pipeline is affected by not only the internal and external pressure, the temperature and other working loads, but also the environmental loads such as waves, ocean currents, earthquakes and the like, so that the complicated conditions of the submarine pipeline service often need to be considered, and a plurality of problems still need to be solved.
The single external current method is used for protection, the stability of the system cannot be ensured under the severe ocean environment, and the minimum device cost cannot be reduced when smaller current is required; the sacrificial anode method is used singly for protection, the use is limited in a high-resistance environment, the protection current is not adjustable, the use is limited when the stray current is large, the stray current can cause corrosion of a pipeline, the corrosion rate of the pipeline is monitored, the effect of a cathode protection system is wrongly evaluated, and the accuracy is influenced; the single use of the coating layer has higher quality requirement and higher cost.
Disclosure of Invention
Aiming at the technical problems existing at present, the invention provides a submarine pipeline protection system and a submarine pipeline protection method, the submarine pipeline protection system and the submarine pipeline protection method can prolong the service life of the submarine pipeline, are good in operability, can cope with various severe ocean environments, provide reliable corrosion resistance, and reduce the corrosion speed of materials by utilizing external protection current to enable the submarine pipeline to generate cathode polarization, sacrifice anode to protect the submarine pipeline and cover a coating, so that the purpose of effectively controlling submarine pipeline corrosion is achieved.
The technical scheme of the invention is as follows:
a protection system for submarine pipelines, which comprises a sacrificial anode material, an anode land bed and an anti-corrosion layer; the sacrificial anode material is sleeved on the submarine pipeline, the sacrificial anode material is two arc grooves symmetrically arranged on the pipe wall of the submarine pipeline, and a space is reserved between the two arc grooves; a hole groove is arranged in the arc groove along the direction of the submarine pipeline, and an anode land bed is arranged in the hole groove; the submarine pipeline is electrically connected with the negative electrode of the power supply, and the anode land bed is electrically connected with the positive electrode of the power supply; the surface of the submarine pipeline is provided with an anti-corrosion layer.
Preferably, a space is reserved between two arc-shaped grooves symmetrically arranged on the pipe wall of the submarine pipeline, the symmetrical arrangement of the two arc-shaped grooves is easier to construct relative to the complete tubular sacrificial anode material, the risk of construction technology is small, the required cost is low, and meanwhile the sacrificial anode material is saved.
Preferably, at least two anode beds are provided, and the anode beds are electrically connected.
Preferably, the anode bed is flush with both ends of the arc-shaped tank.
Preferably, filler particles are arranged in the gaps between the arc-shaped grooves and the anode beds, so that the anode beds are prevented from being placed in the holes of the arc-shaped grooves and cannot be perfectly matched, no gaps between the anode beds and the arc-shaped grooves are effectively ensured, the filler particles must be electric conductors, and good electric conductivity between the anode beds and the arc-shaped grooves and between the anode beds and soil (pipelines are buried in soil on the sea bottom) is ensured; the filler should be as low cost as possible, be widely available and have a continuous contact surface, such as petroleum coke or metallurgical coke.
Preferably, the sacrificial anode material is an Al-Zn-In alloy, a high silicon cast iron material.
Preferably, the anticorrosive layer is a asphalt anticorrosive layer and a coal tar tile paint anticorrosive layer.
Preferably, the arc-shaped groove is welded with the submarine pipeline, and the damaged part of the coating at the welded part is repaired by adopting a thermal shrinkage belt cladding mode, so that the submarine pipeline metal is prevented from being in direct contact with external media.
A submarine pipeline protection method utilizes the submarine pipeline protection system to protect submarine pipelines.
Preferably, the number of anode beds in the protection system is calculated as:
wherein the method comprises the steps of
I cm ＝A c ·f cm ·i cm ；
Wherein N is neam Number of anode beds satisfying the average current demand;
m = net weight of total theoretical anode bed (kg);
W anode net weight of anode bed (kg);
t f design lifetime of the line (a);
u=the utilization coefficient of the anode bed;
epsilon = electrochemical capacity of anode bed (Ah/kg);
A c external surface area of the line (m 2 )；
i cm =average current density (a/m 2 )；
f cm =theoretical coating breakage rate;
I cm total average current demand (a);
the maximum distance between two adjacent protection systems should be twice the pipeline length that a single protection system can protect, which can be calculated by the following formula:
where d = line wall thickness (m);
d = line outside diameter (m);
ρ me =pipeline material resistance;
f cf =average coating failure rate;
f′ cf =current breakage rate of coating;
I cf =current demand (a);
L tot length of line (m);
R af resistance of sacrificial anode material (Ω)
l=the length of pipeline that can be protected.
The size of the sacrificial anode material is designed and manufactured according to parameters of an actual submarine pipeline, the size and the number of anode beds, the difficulty degree of construction and the anticorrosive layer, so that the submarine pipeline is better coated, gaps between the submarine pipeline and the sacrificial anode material are reduced as much as possible for more convenient construction, and the size determines the weight, so that the sacrificial anode material meets the requirement of the design service life.
The anti-corrosion coating can effectively prevent the submarine pipeline from being in direct contact with mediums such as seawater, so that the corrosion resistance of the submarine pipeline is enhanced, and the service life of the submarine pipeline is prolonged; the outer layer sacrificial anode material adopts Al-Zn-In alloy, the electricity generation amount of the aluminum alloy is large, the service life is long, and the material is suitable for protecting submarine pipelines; the anode beds are made of high-silicon cast iron materials, the anode beds are electrically connected, then the anode of a power supply is connected, a submarine pipeline is connected with the cathode of the power supply to form a closed loop, so that protection current is sent into soil through the anode beds and flows into a protected pipeline to enable the surface of the pipeline to be subjected to cathodic polarization, the submarine pipeline is in a reducing environment for the cathode in the loop to prevent corrosion, and the anode beds are subjected to oxidation reaction to be corroded, so that the submarine pipeline can be effectively protected from corrosion, and the submarine soil has higher salt content, so that the chromium-containing high-silicon cast iron anode is used; the sacrificial anode material is selected according to the protected pipeline material, the selection is based on the fact that the potential is lower than that of the pipeline material and the price is lower, the Al-Zn-In alloy is selected, the sacrificial anode material is that the anode loses electrons and is corroded, and the submarine pipeline is that the cathode is protected. If one of the protection means is singly used, the service time of the protection system is shorter, the protection effect is poor, the service life of the submarine pipeline is short, the problems of poor stability of the system, larger error of the test result, higher cost and the like exist, the submarine pipeline is protected by adopting the triple protection means, the submarine pipeline is effectively protected, corrosion is prevented, the service time of the protection system is effectively prolonged, the anti-corrosion effect is better, the stability of the system and the accuracy of the test result are ensured, and the cost is low.
The submarine pipeline protection system and the submarine pipeline protection method provided by the invention have the advantages that the service life of the submarine pipeline can be prolonged, the operability is better, the submarine pipeline can be processed in various severe ocean environments, the reliable anti-corrosion capacity is provided, and the submarine pipeline can be subjected to cathodic polarization, sacrificial anode protection on the submarine pipeline and coverage coating by utilizing external protection current, so that the corrosion speed of materials is reduced, and the purpose of effectively controlling submarine pipeline corrosion is achieved; triple protection is carried out on the submarine pipeline, the reliability is high, the operability is good, the cost is good, the time and the labor are saved, the operation period is prolonged, the service life of the submarine pipeline is prolonged, and the method has a good protection effect on the important, expensive and difficult-to-replace submarine pipeline.
Drawings
FIG. 1 is a schematic diagram of a protection system according to the present invention;
FIG. 2 is a front view of the protection system of the present invention;
fig. 3 is a front view of the protection system of the present invention (with a power source);
FIG. 4 is a cross-sectional view of the protection system of the present invention;
in the figure, 1 is a sacrificial anode material, 2 is an anode land bed, 3 is a submarine pipeline, 4 is a power supply, and 5 is an anti-corrosion layer.
Detailed Description
Various embodiments of the present invention will be described more fully with reference to the accompanying drawings. The invention is capable of various embodiments and of being practiced with some modifications and alterations. Accordingly, the present invention will be described in more detail with reference to specific embodiments thereof shown in the drawings. However, it should be understood that: there is no intention to limit the various embodiments of the invention to the specific embodiments of the invention herein, but rather the invention is to be understood to cover all modifications, equivalents, and/or alternatives falling within the spirit and scope of the various embodiments of the invention. Like reference numerals designate like elements throughout the description in connection with the accompanying drawings.
The terminology used in the various embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the various embodiments of the invention. As used herein, the singular is intended to include the plural as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which various embodiments of the invention belong. The terms (such as those defined in commonly used dictionaries) will be interpreted as having a meaning that is the same as the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein in connection with the various embodiments of the invention.
As shown, a protection system for a subsea pipeline 3, the protection system comprising a sacrificial anode material 1, an anode bed 2, a corrosion protection layer 5; the submarine pipeline 3 is sleeved in the sacrificial anode material 1, the sacrificial anode material 1 is provided with two arc grooves which are symmetrically arranged on the pipe wall of the submarine pipeline 3, a space is reserved between the two arc grooves, the two arc grooves are not contacted, the symmetrical arrangement of the two arc grooves is easier to construct relative to the complete tubular sacrificial anode material 1, the risk of construction technology is lower, the required cost is lower, and meanwhile, the space is convenient for the submarine pipeline 3 and the sacrificial anode material 1 to be electrically connected with the power supply 4; the arc-shaped groove is welded with the submarine pipeline 3, and the damaged part of the coating at the welded part is repaired by adopting a thermal shrinkage tape cladding mode to prevent the submarine pipeline 3 from directly contacting with external media; the arc-shaped groove is provided with a hole groove along the direction of the submarine pipeline 3, the hole groove is provided with an anode land bed 2, the anode land bed 2 is flush with two ends of the arc-shaped groove, and meanwhile, the space between the two arc-shaped grooves and the holes on the arc-shaped groove save the cost of the sacrificial anode material 1, and the anode land bed 2 is arranged in the arc-shaped groove, and only the two ends are exposed outside; the submarine pipeline 3 is electrically connected with the negative electrode of the power supply 4, and the anode land bed 2 is electrically connected with the positive electrode of the power supply 4; the surface of the submarine pipeline 3 is provided with an anti-corrosion layer 5.
In another embodiment, filler particles are arranged in the gaps between the arc-shaped grooves and the anode land bed 2, so that in order to prevent the anode land bed 2 from being placed in the holes of the arc-shaped grooves and not being perfectly matched (insufficient contact exists, gaps exist), the anode land bed 2 and the sacrificial anode material 1 (arc-shaped grooves) are effectively ensured to have no gaps; the filler particles used must be electrically conductive in order to ensure good electrical conductivity between the anode bed 2 and the arc-shaped tank and soil (the pipe is buried in the soil at the sea floor); the filler should be as low cost as possible, be widely available and have a continuous contact surface. If there is no gap between the arc-shaped groove and the anode bed 2, no filler particles are provided.
In another embodiment, the sacrificial anode material 1 is an Al-Zn-In alloy, a high-silicon cast iron material and filler particles, the cost of which is as low as possible, the source of which is wide, and the material has a continuous contact surface, such as petroleum coke or metallurgical coke; the anticorrosive coating 5 is a asphalt anticorrosive coating 5 and a coal tar tile paint anticorrosive coating 5.
In another embodiment, the intervals between symmetrical arc grooves on the pipe wall of the submarine pipeline 3 are basically the same as the sizes of the hole grooves arranged on the arc grooves, and the submarine pipeline is designed according to the GB/T4950-2002 standard and combined with practical situations.
A protection method for a submarine pipeline 3, wherein the submarine pipeline 3 is protected by the protection system for the submarine pipeline 3; the number calculation formula of the anode beds 2 in the protection system:
wherein->
I cm ＝A c ·f cm ·i cm ；
Wherein N is neam Anode ground satisfying average current demandThe number of beds;
m = net weight of total theoretical anode bed (kg);
W anode net weight of anode bed (kg);
t f design lifetime of the line (a);
u=the utilization coefficient of the anode bed;
epsilon = electrochemical capacity of anode bed (Ah/kg);
A c external surface area of the line (m 2 )；
i cm =average current density (a/m 2 )；
f cm =theoretical coating breakage rate;
I cm total average current demand (a);
the maximum distance between adjacent protection systems should be twice the pipeline length that a single protection system can protect, which can be calculated by the following formula:
where d = line wall thickness (m);
d = line outside diameter (m);
ρ me =pipeline material resistance;
f cf =average coating failure rate;
f′ cf =current breakage rate of coating;
I cf =current demand (a);
L tot length of line (m);
R af resistance of sacrificial anode material 1 (Ω)
l=the length of pipeline that can be protected.
The coating is an anti-corrosion layer 5, and the pipeline is a submarine pipeline 3.
The specific implementation process is as follows: design parameters of a subsea pipeline (pipeline): the outer diameter of the sacrificial anode material 1 is 350mm; the submarine pipeline has a length of 5km; the service life 10a of the design of the sacrificial anode material 1; the outer diameter of the pipeline is 270mm; the wall thickness of the pipeline is 20mm; the resistance of the pipeline material is 9.7X10 -8 Omega m, resistance of sacrificial anode material 1 is 9.64×10 -8 Ωm。
Design parameters of cathodic protection: the density of the anode bed 2 is 2700kg/m 3 The capacitance of the anode bed 2 is 4470Ah/kg, and the net weight of the anode bed 2 is 21.22kg; the breakage rate of the anticorrosive coating 5 is 5%, and the utilization coefficient of the anode land bed 2 is 0.7; the closing potential of the anode bed 2 is-1V (Ag/AgCl); the open circuit potential (guard potential) was-1.05V (Ag/AgCl) with a minimum current requirement of 0.05A.
The average design current density of the pipeline should be 0.05A/m according to DNV RP F103-2010 standard 2 。
Calculated total average current demand I of the pipeline cm =21.2a; the net weight of the total theoretical anode bed 2 m= 593.6kg; anode bed 2 number N mean =28; the length of the line can be protected l= 247.3m.
The anti-corrosion layer 5 is coated, so that the submarine pipeline 3 can be effectively prevented from being in direct contact with mediums such as seawater, the corrosion resistance of the submarine pipeline is enhanced, and the service life of the submarine pipeline is prolonged; the outer layer sacrificial anode material 1 adopts Al-Zn-In alloy, the electricity generation amount of the aluminum alloy is large, the service life is long, and the material is suitable for protecting the submarine pipeline 3; the anode beds 2 are made of high silicon cast iron materials, the anode beds 2 are electrically connected, then the anode of the power supply 4 is connected, the submarine pipeline 3 is connected with the cathode of the power supply 4 to form a closed loop, so that protection current is sent into soil through the anode beds 2 and flows into protected pipelines to enable the surfaces of the pipelines to be subjected to cathodic polarization, the cathode of the submarine pipeline 3 in the loop is in a reducing environment to prevent corrosion, the anode beds 2 are subjected to oxidation reaction to be corroded, the submarine pipeline 3 can be effectively protected from corrosion, and the submarine soil has high salt content, so that the chromium-containing high silicon cast iron anode is used; the sacrificial anode material 1 is selected according to the protected pipeline material, the selection is based on the fact that the potential is lower than that of the pipeline material and the price is lower, the Al-Zn-In alloy is selected, the sacrificial anode material 1 loses electrons for the anode and is corroded, and the submarine pipeline 3 is protected for the cathode. If one of the protection means is used singly, the service time of the protection system is shorter, the protection effect is poor, the service life of the submarine pipeline 3 is short, the problems of poor system stability, larger test result errors, higher cost and the like exist, the submarine pipeline 3 is protected by adopting the triple protection means, the submarine pipeline 3 is effectively protected, corrosion is prevented, the service time of the protection system is effectively prolonged, the anti-corrosion effect is better, the system stability and the accuracy of the test result are ensured, and the cost is low.
The submarine pipeline protection system and the submarine pipeline protection method provided by the invention have the advantages that the service life of the submarine pipeline can be prolonged, the operability is better, the submarine pipeline can be processed in various severe ocean environments, the reliable anti-corrosion capacity is provided, and the submarine pipeline can be subjected to cathodic polarization, sacrificial anode protection on the submarine pipeline and coverage coating by utilizing external protection current, so that the corrosion speed of materials is reduced, and the purpose of effectively controlling submarine pipeline corrosion is achieved; triple protection is carried out on the submarine pipeline, the reliability is high, the operability is good, the cost is good, the time and the labor are saved, the operation period is prolonged, the service life of the submarine pipeline is prolonged, and the method has a good protection effect on the important, expensive and difficult-to-replace submarine pipeline.
Claims (10)
1. A protection system for submarine pipelines, which is characterized by comprising a sacrificial anode material (1), an anode land bed (2) and an anticorrosive layer (5); the sacrificial anode material (1) is sleeved with the submarine pipeline (3), the sacrificial anode material (1) is provided with two arc grooves which are symmetrically arranged on the pipe wall of the submarine pipeline (3), and a space is reserved between the two arc grooves; a hole groove is arranged in the arc groove along the direction of the submarine pipeline (3), and an anode land bed (2) is arranged in the hole groove; the submarine pipeline (3) is electrically connected with the negative electrode of the power supply (4), and the anode land bed (2) is electrically connected with the positive electrode of the power supply (4); an anti-corrosion layer (5) is arranged on the surface of the submarine pipeline (3).
2. A submarine pipeline protection system according to claim 1, wherein at least two anode beds (2) are provided, the anode beds (2) being electrically connected.
3. A submarine pipeline protection system according to claim 1, characterized in that the gap between the arc-shaped tank and the anode bed (2) is provided with filler particles.
4. A submarine pipeline protection system according to claim 1, wherein the sacrificial anode material (1) is an Al-Zn-In based alloy and the anode bed (2) is a high silicon cast iron material.
5. Protection system for submarine pipelines according to claim 1, characterized in that the anti-corrosion layer (5) is a bitumen anti-corrosion layer (5) or a coal tar enamel anti-corrosion layer (5).
6. A submarine pipeline protection system according to claim 1, wherein the arc-shaped grooves are welded to the submarine pipeline (3).
7. The submarine pipeline protection system according to claim 6, wherein the damaged part of the coating at the welding part of the arc-shaped groove and the submarine pipeline (3) is repaired by adopting a thermal shrinkage belt cladding mode.
8. A method of protecting a subsea pipeline, characterized in that the subsea pipeline is protected by a protection system for a subsea pipeline according to any of the preceding claims 1-7.
9. The method of protecting a submarine pipeline according to claim 8, wherein the number of anode beds in the protection system is calculated by the formula:
Wherein N is neam Number of anode beds satisfying the average current demand;
m = net weight of total theoretical anode bed (kg);
W anode net weight of anode bed (kg);
t f design lifetime of the line (a);
u=the utilization coefficient of the anode bed;
epsilon = electrochemical capacity of anode bed (Ah/kg);
A c external surface area of the line (m 2 )；
i cm =average current density (a/m 2 )；
f cm =theoretical coating breakage rate;
I cm total average current demand (a).
10. A method of protecting a subsea pipeline according to claim 9, characterized in that the maximum distance between two adjacent protection systems is twice the pipeline length that a single protection system can protect, which can be calculated by the following formula:
where d = line wall thickness (m);
d = line outside diameter (m);
ρ me =pipeline material resistance;
f cf =average coating failure rate;
f′ cf =current breakage rate of coating;
I cf =current demand (a);
L tot length of line (m);
R af resistance of sacrificial anode material (Ω)
l=the length of pipeline that can be protected.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1588160A (en) * | 1978-05-26 | 1981-04-15 | Brown John Constr | Riser for offshore oil or gas fields |
| GB8621381D0 (en) * | 1986-09-04 | 1986-10-15 | Mao T D | Protection of metal surfaces |
| US6214203B1 (en) * | 1999-12-06 | 2001-04-10 | United States Pipe Foundry | Anodic encasement corrosion protection system for pipe and appurtenances, and metallic components thereof |
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2023
- 2023-03-27 CN CN202310301946.0A patent/CN116288370A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1588160A (en) * | 1978-05-26 | 1981-04-15 | Brown John Constr | Riser for offshore oil or gas fields |
| GB8621381D0 (en) * | 1986-09-04 | 1986-10-15 | Mao T D | Protection of metal surfaces |
| US6214203B1 (en) * | 1999-12-06 | 2001-04-10 | United States Pipe Foundry | Anodic encasement corrosion protection system for pipe and appurtenances, and metallic components thereof |
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