液化天然氣16萬立方米儲罐海水試壓期間陰極保護(hù)方案

1、第98頁 共98頁GUANGDONG ZHUHAI LNG PROJECT- PHASE 1Project:8521Code: ZHLNG-7A-TK-FCC-MS-0027Rev:ASheet PAGE 1 of NUMPAGES 119儲罐海水試壓階段陰極保護(hù)工程設(shè)計方案Cathodic Protection of LNG Storage Tanks at Seawater Hydrotest StageMethod Statement廣東珠海金灣液化天然氣一期工程 液化天然氣儲罐海水試壓階段陰極保護(hù)工程設(shè)計方案Guangdong Zhuhai Golden Bay LNG Project

2、 Phase ICathodic Protection of LNG Storage Tanks at Seawater Hydrotest StageMethod StatementA2013/01/26Issue for revision郭明旭陳仁興費良REV.版本.DATE日期PURPOSE OF THE EDITION發(fā)文目的PREPARED BY編制REVIEWED BY審核APPROVRD BY批準(zhǔn)目錄 Contents TOC o 2-3 h z u t 標(biāo)題 1,1 HYPERLINK l _Toc345488558 一、臨時陰極保護(hù)工程概況Project Basic Data

3、 for Cathodic Protection PAGEREF _Toc345488558 h 3 HYPERLINK l _Toc345488559 二、臨時陰極保護(hù)工程實施前的測試與實驗 Tests prior to Cathodic Protestion PAGEREF _Toc345488559 h 3 HYPERLINK l _Toc345488560 二、設(shè)計依據(jù) Design Reference PAGEREF _Toc345488560 h 3 HYPERLINK l _Toc345488561 三、采用標(biāo)準(zhǔn) Applicable Standards PAGEREF _Toc

4、345488561 h 3 HYPERLINK l _Toc345488562 四、技術(shù)指標(biāo) Technical Parameters PAGEREF _Toc345488562 h 3 HYPERLINK l _Toc345488563 五、被保護(hù)體參數(shù) Data of the Protected Structures PAGEREF _Toc345488563 h 3 HYPERLINK l _Toc345488564 六、陰極保護(hù)設(shè)計 Cathodic Protection Design PAGEREF _Toc345488564 h 3 HYPERLINK l _Toc34548856

5、5 6.1設(shè)計應(yīng)考慮的實際因素Actual Factors to be Considered in the Design PAGEREF _Toc345488565 h 3 HYPERLINK l _Toc345488566 6.2陰極保護(hù)設(shè)計方案的選用 Design of Cathodic Protection Methods PAGEREF _Toc345488566 h 3 HYPERLINK l _Toc345488567 6.3罐底板及1.5米高罐壁犧牲陽極陰極保護(hù)設(shè)計 Design of Galvanic Anode Cathodic Protection for Inner Ta

6、nk Bottom and Shell Paltes up to 1.5m Elevation PAGEREF _Toc345488567 h 3 HYPERLINK l _Toc345488568 6.3.1保護(hù)電流密度的選取 Selection of Protection Current Density PAGEREF _Toc345488568 h 3 HYPERLINK l _Toc345488569 6.3.2保護(hù)電流計算 Calculation of Protection Current PAGEREF _Toc345488569 h 3 HYPERLINK l _Toc34548

7、8570 6.3.3犧牲陽極材料的選取 Selection of Sacrificial Anode Material PAGEREF _Toc345488570 h 3 HYPERLINK l _Toc345488571 6.3.4犧牲陽極發(fā)生電流量的計算 Calculation of Sacrificial Anode Generated Current Volume PAGEREF _Toc345488571 h 3 HYPERLINK l _Toc345488572 6.3.5犧牲陽極的壽命核算 Calculation of the Service Life of Sacrifical

8、 Anodes PAGEREF _Toc345488572 h 3 HYPERLINK l _Toc345488573 6.3.6陽極量計算 Calculation of Required Quantity of Anodes PAGEREF _Toc345488573 h 3 HYPERLINK l _Toc345488574 6.3.7陽極安裝圖 Anodes Installation Plan PAGEREF _Toc345488574 h 3 HYPERLINK l _Toc345488575 6.4罐壁及不銹鋼管道等結(jié)構(gòu)物的外加電流陰極保護(hù)設(shè)計 Design of Impressed

9、 Current Cathodic Protection (ICCP) of Inner Tank Tank Shell, Stainless Steel Piping and other Structure PAGEREF _Toc345488575 h 3 HYPERLINK l _Toc345488576 6.4.1外加電流陰極保護(hù)輔助陽極的選用 Selection of AuxiliaryAnodes for Impressed Current Cathodic Protection (ICCP) PAGEREF _Toc345488576 h 3 HYPERLINK l _Toc34

10、5488577 6.4.2MMO陽極的發(fā)生電流量計算 Calculation of MMO Anode Generated Current Volume PAGEREF _Toc345488577 h 3 HYPERLINK l _Toc345488578 6.4.3罐壁和管道外壁陰極保護(hù)電流量計算 Calculation of Cathodic Protection Current Volume on Inner Shell and Piping External Surface PAGEREF _Toc345488578 h 3 HYPERLINK l _Toc345488579 6.4.

11、4陽極數(shù)量的計算 Calculation of Required Quantity of Anodes PAGEREF _Toc345488579 h 3 HYPERLINK l _Toc345488580 6.4.5恒電位儀的選取 Selection of Constant-Potential Potentiometer PAGEREF _Toc345488580 h 3 HYPERLINK l _Toc345488581 6.4.6參比電極 Reference Electrode PAGEREF _Toc345488581 h 3 HYPERLINK l _Toc345488582 6.4

12、.7罐內(nèi)測試片 Testing Slips inside the Tank PAGEREF _Toc345488582 h 3 HYPERLINK l _Toc345488583 七、臨時陰極保護(hù)材料清單 Temporary Cathodic Protection Materials List PAGEREF _Toc345488583 h 3 HYPERLINK l _Toc345488584 八、臨時陰極保護(hù)主材數(shù)據(jù)單 Datasheets of Main Materials/Equipments for Temporary Cathodic Protection PAGEREF _Toc

13、345488584 h 3 HYPERLINK l _Toc345488585 8.1恒電位儀 Constant-Potential Potentiometer PAGEREF _Toc345488585 h 3 HYPERLINK l _Toc345488586 8.2MMO管裝陽極數(shù)據(jù)單 Datasheet of MMO Tubular Anodes PAGEREF _Toc345488586 h 3 HYPERLINK l _Toc345488587 8.3參比電極數(shù)據(jù)單 Datasheet of ReferenceElectrode PAGEREF _Toc345488587 h 3

14、HYPERLINK l _Toc345488588 8.4犧牲陽極帶數(shù)據(jù)單 Datasheet of Ribbon Sacrificial Anode PAGEREF _Toc345488588 h 3 HYPERLINK l _Toc345488589 8.5陰極保護(hù)電纜數(shù)據(jù)單 Datasheet of Cathodic Protection Cable PAGEREF _Toc345488589 h 3 HYPERLINK l _Toc345488590 九、施工圖紙 Construction Drawings PAGEREF _Toc345488590 h 3 HYPERLINK l _

15、Toc345488591 十、外加電流陰極保護(hù)系統(tǒng)的調(diào)試 Commissioning of ICCP System PAGEREF _Toc345488591 h 3 HYPERLINK l _Toc345488592 十一、保護(hù)期內(nèi)的管理與服務(wù) Management and Services during the Protection Period PAGEREF _Toc345488592 h 3 HYPERLINK l _Toc345488593 十一、施工組設(shè)計 Constution Planning PAGEREF _Toc345488593 h 3一、臨時陰極保護(hù)工程概況 Proj

16、ect Basic Data for Cathodic Protection廣東珠海金灣液化天氣一期一程3臺儲罐位廣東省珠海市金灣區(qū)高欄港庫區(qū)，儲罐自身有如下特點：Guangdong Zhuhai Goden Bay LNG Project Phase I is located in Gaolan Port area, Jinwan District, Zhuhai, Guangdong, and have three tanks with the following characteristics:罐內(nèi)結(jié)構(gòu)復(fù)雜；2）罐內(nèi)結(jié)構(gòu)物材質(zhì)差異很大，罐壁及罐底材料為X7Ni9鋼、罐內(nèi)管道為304L不銹

17、鋼、管道支架為A240鋼、罐內(nèi)梯子為304L鋼；3）罐內(nèi)焊縫材質(zhì)也不同于X7Ni9鋼；4）經(jīng)試片海水試驗，各材質(zhì)的電位相差較大；5）經(jīng)試片試驗、不同材質(zhì)的鋼板電性連接時，高電位材質(zhì)在海水中的腐蝕速度較快，5天的時間，X7Ni9鋼表面出現(xiàn)了明顯的點蝕現(xiàn)象；6）鋼質(zhì)儲罐充海水時的臨時陰極保護(hù)的設(shè)計計算方法與土壤介質(zhì)中的腐蝕防護(hù)的設(shè)計計算差別較大；7）保護(hù)難度大，要求儲罐內(nèi)海水上升到哪里，就應(yīng)保護(hù)到被海浸沒的所有鋼結(jié)構(gòu)。1). The tank has complicated internal structures; 2). The materials of internal structures

18、are different, inner shell and bottom plates are X7Ni9 steel, internal piping 304L SS, pipe supports and ladders A240 steel; 3). Material of the weld of inner tank is also different from X7Ni9; 4). Tests of metal test pieces using seawater have shown the corrosion potential of different materials va

19、ries greatly; 5). Metal specimen tests show when electrical continuity between different materials is established, material with a higher potential has a higher corrosion rate in seawater, after 5 days apparent pitting corrosion occurs on the surface of X7Ni9 steel; 6). The calculation of temporary

20、cathodic protection of steel tanks in seawater is different from the design calculations of corrosion protection of structures in soil; 7). More difficult to protect, all the steel structures immersed in seawater as the test water level rises need to be protected.二、臨時陰極保護(hù)工程實施前的測試與實驗 Tests prior to C

21、athodic Protection2.1高欄港海水導(dǎo)電率的測試Test of Gaolan Port seawater resistivity樣品：珠海高欄港天然海水Sample: natural seawater taken at Gaolan Port樣品數(shù)量：2瓶Sample amount: two bottles取樣地點：離本工程所在地的最近海域Sampling point: sea closet to the project location送樣單位：青島成發(fā)和創(chuàng)工業(yè)技術(shù)有限公司Sample sent by: Qingdao Chengfa Hechuang Industrial

22、Technologies, Co., LTD測量單位：中國科學(xué)院海洋研究所Analysis done by: Ocean Research Institute of the Academy of Sciences of China測試結(jié)果：33.Test result: 33.2.2被保護(hù)體試片在海水中的自然電位測試Test of natural potential of the testing slip of the protected structure in seawater 樣品來源：中國天辰工程有限公司Sample provided from: China Tianchen Engi

23、neering Co., LTD樣品數(shù)量：Ni9鋼2塊、304L鋼2塊Sample quantity: two pieces of Ni9 Steel, two pieces of 304L steel送樣單位：青島成發(fā)和創(chuàng)工業(yè)技術(shù)有限公司Sample sent by: Qingdao Chengfa Hechuang Industrial Technologies, Co., LTD測量單位：中國科學(xué)院海洋研究所Analysis done by: Ocean Research Institute of the Academy of Sciences of China測試結(jié)果：Test res

24、ults:Ni9鋼：-480 mV（相對飽和甘汞電極）Ni9 steel: -480 mV (VS SCE)2) 304L鋼：-240 mV（相對飽和甘汞電極） 304L steel: -240 mV (VS SCE)2.3被保護(hù)體試片的對比實驗Comparative test of the protected structure testing slips樣品：2塊2/3Ni9鋼和1/3304L鋼焊接試片，其中1試片加裝了犧牲陽極帶；Samples: 2 welded testing slips of 2/3Ni9 steel and 1/3304L,test slip 1# is inst

25、alled with sacrificial anode ribbon;實驗環(huán)境：20室內(nèi)，同一容器的天然海水中；Test environment: indoors 20, in natural seawater of the same container實驗時間：20天；Test period: 20 days實驗結(jié)果：見最終報告。Test results: see final test report.二、設(shè)計依據(jù)海水水壓試驗程序 Sea water hydrotest general proceoure。LNG儲罐水壓試驗期間的陰極保護(hù)原理Cathodic protection philo

26、sophy for LNG tankas doring hydrotesting。儲罐TK-T-0201A、TK-T-0201B、TK-T-0201C水壓試驗程序 INNER TANKHYDROSTATIC TEST PROCEDDURE FOR TK-T-0201A、TK-T-0201B、TK-T-0201C。廣東珠海金灣液化天然氣一期一程液化天然氣儲罐海水試壓階段陰極保護(hù)工程招標(biāo)文件。Bidding Documents of Cathodic Protection of LNG Storage Tank during Seawater Hydrotest in ZHLNG Project

27、Phase I廣東珠海金灣液化天然氣一期一程液化天然氣儲罐海水試壓階段陰極保護(hù)工程答疑文件。Clarification Documents of Cathodic Protection of LNG Storage Tank during Seawater Hydrotest in ZHLNG Project Phase I三、采用標(biāo)準(zhǔn) Applicable Standards NACE RP0169 埋地或水下金屬管道系統(tǒng)的外腐蝕控制Control of External Corrosion of Underground or Submerged Metallic Piping System

28、BS7361-1991 陰極保護(hù)應(yīng)用原則和特殊考慮Principles and Special Considerations of Cathodic Protection ApplicationsDIN30676-1985 外表面陰極保護(hù)的設(shè)計和應(yīng)用Design and Application of Cathodic Protection for External SurfacesGB50393-2008 鋼質(zhì)石油儲罐防腐工程技術(shù)規(guī)范Technical Specification for Anticorrosive Engineering of Steel Petroleum TanksGB/

29、T 21448-2008 埋地鋼質(zhì)管道陰極保護(hù)技術(shù)規(guī)范Technical Specification for Cathodic Protection of Buried Steel PipelineGJB156-2002 港工設(shè)施犧牲陽極陰極保護(hù)設(shè)計和安裝；Design and Installation of Galvanic Anode Cathodic Protection for Port Facilities四、技術(shù)指標(biāo) Technical Parameters罐內(nèi)陰極保護(hù)電位為-0.80-0.90V（相對于Ag/AgCl參比電極，下同），罐內(nèi)各點電位均勻；Inner tank cat

30、hodic protection current potential ranges -0.80-0.90V (VS Ag/AgCl reference electrodes, below the same), the potentials at different points are uniform;罐內(nèi)各部件在海水試壓期內(nèi)無銹蝕，排水后在空氣中會正常產(chǎn)生浮銹；Tank internal components will not corrode during seawater hydrotest, after drainage of test water rust will appear na

31、turally on the surfaces exposed in the air;保護(hù)時間為30天。Protection duration will be 30 days.五、被保護(hù)體參數(shù) Data of the protected structures1、儲罐內(nèi)罐直徑為80000Inner tank diameter: 800002、試驗注水水位為18460Hydrotest water level: 184603、罐內(nèi)管道直徑 Tank internal pipe diameters名稱 SNN1BN2AN2BN2CN2DFK3K4K5K6K7外徑（in）952424242462610

32、1010外徑（）2413609.6609.6609.6609.6152.450.8152.4254254254 罐內(nèi)被保護(hù)體浸海水面積 單位：m24、罐內(nèi)被保護(hù)體浸海水面積計算:項目罐內(nèi)管道外表面積罐內(nèi)管道支架表面積材質(zhì)圖紙內(nèi)罐底板Inner tank bottom5026.4X7Ni9ZHLNG-5A-TK-DWG-TKI-0216內(nèi)罐壁板Inner tank shell4639.3672X7Ni9ZHLNG-5A-TK-DWG-TKI-0213內(nèi)部梯子Internal ladders73.11304LZHLNG-5A-TK-DWG-TKI-0222N1B139.1145611.9A240

33、TP304ZHLNG-5A-TK-DWG-TKI-0230N2A、B、C、D282.86627212A358 Gr304/304L CL1ZHLNG-5A-TK-DWG-TKI-0231F50.975444521.1872A312 TP304/304LZHLNG-5A-TK-DWG-TKI-0238K6K731.648562411A312 TP304/304LZHLNG-5A-TK-DWG-TKI-0248K515.82428125.5A312 TP304/304LZHLNG-5A-TK-DWG-TKI-0249K49.755408525.5A312 TP304/304LZHLNG-5A-TK

34、-DWG-TKI-0250K33.495253320A312 TP304/304LZHLNG-5A-TK-DWG-TKI-0252合計 Total10272.5569847.087210319.64418注：計算時，被保護(hù)體浸海水面積取小數(shù)點后一位：（1）內(nèi)罐底板面積S1=5026.4 m2Inner tank bottom S1=5026.4 m2（2）內(nèi)罐壁板面積S2=4639.4 m2Inner shell S2=4639.4 m2（3）罐內(nèi)管道外表面積S3=533.7 mExternal surface of internal piping S3=533.7 m2（4）罐內(nèi)支架表面積S

35、4=47.1 m2Surface area of internal supports S4=47.1 m2（5）罐內(nèi)梯子表面積S5=73.1 m2Internal ladder S5=73.1 m2六、陰極保護(hù)設(shè)計Cathodic Protection Design6.1設(shè)計應(yīng)考慮的實際因素 Actual factors to be considered in the Design我公司技術(shù)人員經(jīng)過兩次勘踏現(xiàn)場，同時對罐體材料試片進(jìn)行了電化學(xué)試驗，我們認(rèn)為本陰極保護(hù)設(shè)計應(yīng)考慮如下因素：Our technicians have made two site visits to investigat

36、e the actual site conditions and carry out the electromechanical tests of the specimens taken from the tank components. We believe the following factors shall be considered in the design of cathodic protection:X7Ni9鋼是低溫條件下使用的優(yōu)質(zhì)鋼，其屈服強度為585MPa的高強鋼，所以應(yīng)嚴(yán)格控制其保護(hù)電位在-0.80-0.90V，其保護(hù)電位不應(yīng)過負(fù)；X7Ni9 steel is a ki

37、nd of cryogenic service quality steels, and a type of high strength steel with a yield strength of 585 Mpa, therefore, its protection potential should be strictly controlled within the range of -0.80-0.90V and shall not be more negative;X7Ni9鋼表面涂層很薄，經(jīng)我們現(xiàn)場仔細(xì)觀察，罐體內(nèi)表面及現(xiàn)場堆放的鋼板上沒有銹蝕，特別是經(jīng)過近30天的連續(xù)雨天，也無浮銹產(chǎn)生

38、，說明其表面涂層有一定的保護(hù)作用，因此在儲罐在注、排海水過程中不需要過大的保護(hù)電流；The stripe coating of X7Ni9 steel is very thin. After careful site observation, we found there was no rust on the surfaces of inner tank and the plates stacked at jobsite. It is especially noticeable that there has been no rust generated after 30 days contin

39、uous storage in exposure to rains, which indicates the surface coating has played the protective role. Therefore high protection current is not necessary during the seawater filling stage通過試片在海水中的試驗，X7Ni9鋼與304L不銹鋼的電極電位相差很大，兩者偶合時，X7Ni9鋼腐蝕嚴(yán)重；Through testing of metal specimens in seawater, it is found

40、the electrode potential of X7Ni9 is greatly different from that of 304L. When the two are coupled, X7Ni9 will experience serious corrosion.焊縫與基材的電位差也很大，也會引起嚴(yán)重的電偶腐蝕；The great difference between the potential of welded seams and that of the base material will also lead to serious galvanic corrosion.從向

41、罐內(nèi)注海水開始，罐內(nèi)構(gòu)件從一接觸海水就應(yīng)得到及時保護(hù)。From the start of seawater filling, the tank internal components shall be protected in a timely manner once they come into contact with the seawater.6.2陰極保護(hù)設(shè)計方案的選用 Design of Cathodic Protection Methods為了使罐內(nèi)所有浸海水面積得到及時保護(hù)，本設(shè)計采用犧牲陽極陰極保護(hù)與外加電流陰極保護(hù)相結(jié)合的方案。雖然此方案相對外加電流方案要復(fù)雜，但效果更好、更

42、安全。理由如下：In order to ensure efficient protection of tank components at the seawater filling state, a combined method of galvanic anode cathodic protection plus ICCP has been designed. Despite that this method design is more complicated than simply applying ICCP, the protection effects will be better

43、and safer. The reasons are as follows:罐底板陰極保護(hù)：采用犧牲陽極陰極保護(hù)。大量的鋼質(zhì)儲罐海水試壓工程表明，海水水位上升到1.5米時的正常時間需要810小時，如果出現(xiàn)不可預(yù)見的因素，可能需要幾天時間；同時，根據(jù)我公司在高欄港的經(jīng)驗，此海域的海水中泥沙含量較高，清罐也需要幾天時間，甚至出現(xiàn)過10多天才完成清罐的情況。如果采用外加電流陰極保護(hù)的方法，其輔助陽極外掛在1.5米的高度，罐底板在上水過程中會得不到及時的保護(hù)，甚至很長時間得不到保護(hù)，罐底板就會被子腐蝕，這樣，整個臨時陰極保護(hù)將是不完整的。因此，我公司設(shè)法改善了保護(hù)方案，需要說明的是，這一設(shè)計是一個成熟

44、的設(shè)計、是被大量成功案例所證明的而完全有效的方案；但是，這一設(shè)計不是推遲上水速度及清罐速度的理由，因為陽極的壽命為35天，陽極用盡后，腐蝕依舊會發(fā)生。Cathodic protection of inner tank bottom: galvanic anode cathodic protection will be used. According to the steel tank seawater hyrdotest experiences, the time required to fill the tank to a 1.5m level is normally 8-10 hours

45、and this period may extend to a few days in case of unpredicted occurrences. In the meanwhile, the seawater around Gaolan port has a higher sand content which will require a few days time for tank cleaning. Sometimes it may take more 10 days. If ICCP method were adopted, with its auxiliary anodes hu

46、ng at a 1.5m elevation, the inner tank bottom would not get protected in a timely fashion or even experience a long time immersion without protection, in which case pitting corrosion will occur on the bottom plates and this means incomplete protection from the temporary cathodic protection system. T

47、herefore, we have managed to improve the method design and what should be noted is that the improved design is a mature one proved to be complete and effective by many successful cases; however, this design shall not be taken as the reason of reducing the water filling rate and tank cleaning speed,

48、as the service life the anodes is 35 days after which corrosion will still occur.304L鋼在海水中的主要腐蝕控制形態(tài)是縫隙腐蝕，主要在焊縫、鉚接點、緊固件附近有縫隙腐蝕出現(xiàn)，陰極保護(hù)可以防止縫隙腐蝕，點蝕在充氣海水環(huán)境中很少出現(xiàn)。陰極保護(hù)對這種腐蝕的有效性還受到質(zhì)疑，所以管內(nèi)陰極保護(hù)的意義不大，相反，由于不銹鋼過保護(hù)析氫，反而會產(chǎn)生有害作用，因此，我公司主張管內(nèi)犧牲陽極陰極保護(hù)取消，或者每根管道內(nèi)單獨進(jìn)行陰極保護(hù)設(shè)計，使管內(nèi)電位控制在-0.6-0.8V之間。The main corrosion geometry

49、of 304L steel in seawater is crevice corrosion which typically appears at the welded joints, fit-up points and locations around the fasters. Cathodic protection may be applied to prevent such crevice corrosion. Pitting corrosion rarely occurs in aerated seawater. The effectiveness of cathodic protec

50、tion against pitting corrosion is still under doubts, so the cathodic protection inside pipes does not have the significance, on the contrary, as SS protection process is accompanied by hydrogen evolution which is detrimental to the material, we recommend to cancel the galvanic anode cathodic protec

51、tion of pipe inner walls, or design the cathodic protection method for each single pipeline and keep the protection potential inside the pipe within the range of -0.6-0.8V.304L鋼的陰極保護(hù)電流密度與X7Ni9鋼是不同的，這些數(shù)據(jù)在船舶設(shè)計中都有明確規(guī)定。The cathodic protection current density of 304L steel is different from that of X7Ni9

52、 steel. The data are expressly specified in related ship design codes/standard.6.3罐底板及1.5米高罐壁犧牲陽極陰極保護(hù)設(shè)計 Design of Galvanic Anode Cathodic Protection of Inner Tank Bottom and Shell up to 1.5m Elevation6.3.1保護(hù)電流密度的選取 Selection of Protection Current Density1）X7Ni9鋼的保護(hù)電流密度：i1=50mA/m2Protection current d

53、ensity for X7Ni9 steel：i1=50mA/m22）304L鋼的保護(hù)電流密度：i2=150mA/m2Protection current density for 304L steel：i2=50mA/m26.3.2保護(hù)電流計算 Calculation of Protection Current式中：IP1罐底、1.5米高罐壁及罐內(nèi)結(jié)構(gòu)物的保護(hù)電流通，AWhere IP1 is the Protection current for inner tank bottom, shell paltes up to 1.5m elevation and internal structur

54、es，A i1X7Ni9鋼的保護(hù)電流密度，mA/m2i1protection current density for X7Ni9 steel，mA/m2 i2304L鋼的保護(hù)電流密度，mA/m2i2protection current density for 304L steel，mA/m2S11罐底、1.5米高罐壁及支架的面積，m2S11Area of inner tank bottom, shell up to 1.5m elevation and supports，m2S211.5米水位以下管道外表面及梯子的面積S21Area of external surface of piping

55、under 1.5m water level and ladder6.3.3犧牲陽極材料的選取 Selection of Sacrificial Anode Material1）犧牲陽極的化學(xué)成份 Chemical compositions of sacrificial anodes犧牲陽極的化學(xué)成份 Chemical Composition of Sacrificial Anodes化學(xué)成份 CompositionZnInSiFeCuAl含量% Percentage2.5-4.50.018-0.0500.100.100.010余量 Margin2）犧牲陽極的規(guī)格 Specifications

56、 of sacrificial anodes19.09.5300006.3.4犧牲陽極發(fā)生電流量的計算 Calculation of Sacrificial Anode Generated Current Volume式中Where ：陽極的驅(qū)動電位，0.35V；Drive potential of anodes，0.35VR陽極的接電阻， QUOTE anode connection resistance， QUOTE 式中 Where： L陽極的長度 length of anode，； 海水電阻率 Seawater resistivity，33.；r陽極截面當(dāng)量半徑 Equivalent

57、radius of anode section；6.3.5犧牲陽極的壽命核算 Calculation of the Service Life of Sacrificial Anodes式中 Where：T陽極使用壽命Anodes service life，天 day 陽極平均發(fā)生電流系數(shù) Coefficient of anodes average generated current 陽極發(fā)生電流 Anode generating current，A W陽極的重量 Weight of anode， 24平均每天小時數(shù) average number of hours per day；0.85陽極使

58、用系數(shù)Anode utilization factor。6.3.6陽極量計算 Calculation of Required Quantity of Anodes根實取12根。12 anodes will be used.6.3.7陽極安裝圖 Anodes Installation Plan為了確保罐底板自注海水開始就能及時得到保護(hù)，陽極預(yù)制成波浪形狀，罐底板犧牲陽極安裝詳施工圖。In order to make sure the tank bottom can be protected in a timely manner from the very start of seawater fi

59、lling, the anodes will be prefabricated into a wavy shape. For details of installation of sacrificial anodes on the bottom, refer to the construction drawings.6.4 2.4米罐內(nèi)下料管犧牲陽極陰極保護(hù)6.4.1 保護(hù)面積計算 管道內(nèi)徑：D=2400 浸水高度：L=18890 保護(hù)面積：6.4.2 保護(hù)電流計算6.4.3 陽極量計算1）犧牲陽極的化學(xué)成份犧牲陽極的化學(xué)成份化學(xué)成份ZnInSiFeCuAl含量%2.5-4.50.018-0.

60、0500.100.100.010余量2）犧牲陽極的規(guī)格19.09.5300006.4.4犧牲陽極發(fā)生電流量的計算式中：陽極的驅(qū)動電位，0.35V；R陽極的接電阻， QUOTE 式中： L陽極的長度，； 海水電阻率，33.；r陽極截面當(dāng)量半徑；6.4.5犧牲陽極的壽命核算式中：T陽極使用壽命，天 陽極平均發(fā)生電流系數(shù) 陽極發(fā)生電流，A W陽極的重量， 24平均每天小時數(shù)；0.85陽極使用系數(shù)。6.4.6陽極量計算根實取1根。6.4.7陽極安裝圖為了保證陽極不被沖擊，陽極在海水水位最大高度時安裝，詳見施工圖。6.5罐壁及不銹鋼管道等結(jié)構(gòu)物的外加電流陰極保護(hù)設(shè)計 Design of Impresse