广东珠海金湾液化天然气一期16万立方米储罐海水试压期间阴极保护最终方案(中英文)2013-02-15

1、GUANGDONG ZHUHAI LNG PROJECT- PHASE 1Project:8521Code: ZHLNG-7A-TK-FCC-MS-0028Rev:BSheet PAGE 113 of NUMPAGES 113储罐海水试压阶段阴极保护工程设计方案Cathodic Protection of LNG Storage Tanks at Seawater Hydrotest StageMethod Statement第 PAGE 113 页 共 NUMPAGES 113 页GUANGDONG ZHUHAI LNG PROJECT- PHASE 1Project:8521Code: Z

2、HLNG-7A-TK-FCC-MS-0027Rev:ASheet PAGE 1 of NUMPAGES 119储罐海水试压阶段阴极保护工程设计方案Cathodic Protection of LNG Storage Tanks at Seawater Hydrotest StageMethod Statement广东珠海金湾液化天然气一期工程 液化天然气储罐海水试压阶段阴极保护工程设计方案Guangdong Zhuhai Golden Bay LNG Project Phase ICathodic Protection of LNG Storage Tanks at Seawater Hydr

3、otest StageMethod StatementA2013/01/26Issue for revision郭明旭陈仁兴费良REV.版本.DATE日期PURPOSE OF THE EDITION发文目的PREPARED BY编制REVIEWED BY审核APPROVRD BY批准目录 Contents TOC o 2-3 h z u t 标题 1,1 HYPERLINK l _Toc345488558 一、临时阴极保护工程概况Project Basic Data for Cathodic Protection PAGEREF _Toc345488558 h 3 HYPERLINK l _T

4、oc345488559 二、临时阴极保护工程实施前的测试与实验 Tests prior to Cathodic Protestion PAGEREF _Toc345488559 h 3 HYPERLINK l _Toc345488560 二、设计依据 Design Reference PAGEREF _Toc345488560 h 3 HYPERLINK l _Toc345488561 三、采用标准 Applicable Standards PAGEREF _Toc345488561 h 3 HYPERLINK l _Toc345488562 四、技术指标 Technical Paramete

5、rs PAGEREF _Toc345488562 h 3 HYPERLINK l _Toc345488563 五、被保护体参数 Data of the Protected Structures PAGEREF _Toc345488563 h 3 HYPERLINK l _Toc345488564 六、阴极保护设计 Cathodic Protection Design PAGEREF _Toc345488564 h 3 HYPERLINK l _Toc345488565 6.1设计应考虑的实际因素Actual Factors to be Considered in the Design PAGE

6、REF _Toc345488565 h 3 HYPERLINK l _Toc345488566 6.2阴极保护设计方案的选用 Design of Cathodic Protection Methods PAGEREF _Toc345488566 h 3 HYPERLINK l _Toc345488567 6.3罐底板及1.5米高罐壁牺牲阳极阴极保护设计 Design of Galvanic Anode Cathodic Protection for Inner Tank Bottom and Shell Paltes up to 1.5m Elevation PAGEREF _Toc34548

7、8567 h 3 HYPERLINK l _Toc345488568 6.3.1保护电流密度的选取 Selection of Protection Current Density PAGEREF _Toc345488568 h 3 HYPERLINK l _Toc345488569 6.3.2保护电流计算 Calculation of Protection Current PAGEREF _Toc345488569 h 3 HYPERLINK l _Toc345488570 6.3.3牺牲阳极材料的选取 Selection of Sacrificial Anode Material PAGER

8、EF _Toc345488570 h 3 HYPERLINK l _Toc345488571 6.3.4牺牲阳极发生电流量的计算 Calculation of Sacrificial Anode Generated Current Volume PAGEREF _Toc345488571 h 3 HYPERLINK l _Toc345488572 6.3.5牺牲阳极的寿命核算 Calculation of the Service Life of Sacrifical Anodes PAGEREF _Toc345488572 h 3 HYPERLINK l _Toc345488573 6.3.6

9、阳极量计算 Calculation of Required Quantity of Anodes PAGEREF _Toc345488573 h 3 HYPERLINK l _Toc345488574 6.3.7阳极安装图 Anodes Installation Plan PAGEREF _Toc345488574 h 3 HYPERLINK l _Toc345488575 6.4罐壁及不锈钢管道等结构物的外加电流阴极保护设计 Design of Impressed Current Cathodic Protection (ICCP) of Inner Tank Tank Shell, Sta

10、inless Steel Piping and other Structure PAGEREF _Toc345488575 h 3 HYPERLINK l _Toc345488576 6.4.1外加电流阴极保护辅助阳极的选用 Selection of AuxiliaryAnodes for Impressed Current Cathodic Protection (ICCP) PAGEREF _Toc345488576 h 3 HYPERLINK l _Toc345488577 6.4.2MMO阳极的发生电流量计算 Calculation of MMO Anode Generated Cur

11、rent Volume PAGEREF _Toc345488577 h 3 HYPERLINK l _Toc345488578 6.4.3罐壁和管道外壁阴极保护电流量计算 Calculation of Cathodic Protection Current Volume on Inner Shell and Piping External Surface PAGEREF _Toc345488578 h 3 HYPERLINK l _Toc345488579 6.4.4阳极数量的计算 Calculation of Required Quantity of Anodes PAGEREF _Toc3

12、45488579 h 3 HYPERLINK l _Toc345488580 6.4.5恒电位仪的选取 Selection of Constant-Potential Potentiometer PAGEREF _Toc345488580 h 3 HYPERLINK l _Toc345488581 6.4.6参比电极 Reference Electrode PAGEREF _Toc345488581 h 3 HYPERLINK l _Toc345488582 6.4.7罐内测试片 Testing Slips inside the Tank PAGEREF _Toc345488582 h 3 H

13、YPERLINK l _Toc345488583 七、临时阴极保护材料清单 Temporary Cathodic Protection Materials List PAGEREF _Toc345488583 h 3 HYPERLINK l _Toc345488584 八、临时阴极保护主材数据单 Datasheets of Main Materials/Equipments for Temporary Cathodic Protection PAGEREF _Toc345488584 h 3 HYPERLINK l _Toc345488585 8.1恒电位仪 Constant-Potentia

14、l Potentiometer PAGEREF _Toc345488585 h 3 HYPERLINK l _Toc345488586 8.2MMO管装阳极数据单 Datasheet of MMO Tubular Anodes PAGEREF _Toc345488586 h 3 HYPERLINK l _Toc345488587 8.3参比电极数据单 Datasheet of ReferenceElectrode PAGEREF _Toc345488587 h 3 HYPERLINK l _Toc345488588 8.4牺牲阳极带数据单 Datasheet of Ribbon Sacrifi

15、cial Anode PAGEREF _Toc345488588 h 3 HYPERLINK l _Toc345488589 8.5阴极保护电缆数据单 Datasheet of Cathodic Protection Cable PAGEREF _Toc345488589 h 3 HYPERLINK l _Toc345488590 九、施工图纸 Construction Drawings PAGEREF _Toc345488590 h 3 HYPERLINK l _Toc345488591 十、外加电流阴极保护系统的调试 Commissioning of ICCP System PAGEREF

16、 _Toc345488591 h 3 HYPERLINK l _Toc345488592 十一、保护期内的管理与服务 Management and Services during the Protection Period PAGEREF _Toc345488592 h 3 HYPERLINK l _Toc345488593 十一、施工组设计 Constution Planning PAGEREF _Toc345488593 h 3一、临时阴极保护工程概况 Project Basic Data for Cathodic Protection广东珠海金湾液化天气一期一程3台储罐位广东省珠海市金湾

17、区高栏港库区，储罐自身有如下特点：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:罐内结构复杂；2）罐内结构物材质差异很大，罐壁及罐底材料为X7Ni9钢、罐内管道为304L不锈钢、管道支架为A240钢、罐内梯子为304L钢；3）罐内焊缝材质也不同于X7Ni9钢；4）经试片海水试验，各材质的电位相差较大；5

18、）经试片试验、不同材质的钢板电性连接时，高电位材质在海水中的腐蚀速度较快，5天的时间，X7Ni9钢表面出现了明显的点蚀现象；6）钢质储罐充海水时的临时阴极保护的设计计算方法与土壤介质中的腐蚀防护的设计计算差别较大；7）保护难度大，要求储罐内海水上升到哪里，就应保护到被海浸没的所有钢结构。1). The tank has complicated internal structures; 2). The materials of internal structures are different, inner shell and bottom plates are X7Ni9 steel, int

19、ernal 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 varies greatly; 5). Metal specimen tests show when electrical conti

20、nuity 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 cathodic protection of steel tanks in seawater is different from

21、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、临时阴极保护工程实施前的测试与实验 Tests prior to Cathodic Protection2.1高栏港海水导电率的测试Test of Gaolan Port seawater resi

22、stivity样品：珠海高栏港天然海水Sample: natural seawater taken at Gaolan Port样品数量：2瓶Sample amount: two bottles取样地点：离本工程所在地的最近海域Sampling point: sea closet to the project location送样单位：青岛成发和创工业技术有限公司Sample sent by: Qingdao Chengfa Hechuang Industrial Technologies, Co., LTD测量单位：中国科学院海洋研究所Analysis done by: Ocean Rese

23、arch Institute of the Academy of Sciences of China测试结果：33.Test result: 33.2.2被保护体试片在海水中的自然电位测试Test of natural potential of the testing slip of the protected structure in seawater 样品来源：中国天辰工程有限公司Sample provided from: China Tianchen Engineering Co., LTD样品数量：Ni9钢2块、304L钢2块Sample quantity: two pieces of

24、 Ni9 Steel, two pieces of 304L steel送样单位：青岛成发和创工业技术有限公司Sample sent by: Qingdao Chengfa Hechuang Industrial Technologies, Co., LTD测量单位：中国科学院海洋研究所Analysis done by: Ocean Research Institute of the Academy of Sciences of China测试结果：Test results:Ni9钢：-480 mV（相对饱和甘汞电极）Ni9 steel: -480 mV (VS SCE)2) 304L钢：-2

25、40 mV（相对饱和甘汞电极） 304L steel: -240 mV (VS SCE)2.3被保护体试片的对比实验Comparative test of the protected structure testing slips样品：2块2/3Ni9钢和1/3304L钢焊接试片，其中1试片加装了牺牲阳极带；Samples: 2 welded testing slips of 2/3Ni9 steel and 1/3304L,test slip 1# is installed with sacrificial anode ribbon;实验环境：20室内，同一容器的天然海水中；Test env

26、ironment: indoors 20, in natural seawater of the same container实验时间：20天；Test period: 20 days实验结果：见最终报告。Test results: see final test report.二、设计依据海水水压试验程序 Sea water hydrotest general proceoure。LNG储罐水压试验期间的阴极保护原理Cathodic protection philosophy for LNG tankas doring hydrotesting。储罐TK-T-0201A、TK-T-0201B、

27、TK-T-0201C水压试验程序 INNER TANKHYDROSTATIC TEST PROCEDDURE FOR TK-T-0201A、TK-T-0201B、TK-T-0201C。广东珠海金湾液化天然气一期一程液化天然气储罐海水试压阶段阴极保护工程招标文件。Bidding Documents of Cathodic Protection of LNG Storage Tank during Seawater Hydrotest in ZHLNG Project Phase I广东珠海金湾液化天然气一期一程液化天然气储罐海水试压阶段阴极保护工程答疑文件。Clarification Docum

28、ents of Cathodic Protection of LNG Storage Tank during Seawater Hydrotest in ZHLNG Project Phase I三、采用标准 Applicable Standards NACE RP0169 埋地或水下金属管道系统的外腐蚀控制Control of External Corrosion of Underground or Submerged Metallic Piping SystemBS7361-1991 阴极保护应用原则和特殊考虑Principles and Special Considerations of

29、 Cathodic Protection ApplicationsDIN30676-1985 外表面阴极保护的设计和应用Design and Application of Cathodic Protection for External SurfacesGB50393-2008 钢质石油储罐防腐工程技术规范Technical Specification for Anticorrosive Engineering of Steel Petroleum TanksGB/T 21448-2008 埋地钢质管道阴极保护技术规范Technical Specification for Cathodic P

30、rotection of Buried Steel PipelineGJB156-2002 港工设施牺牲阳极阴极保护设计和安装；Design and Installation of Galvanic Anode Cathodic Protection for Port Facilities四、技术指标 Technical Parameters罐内阴极保护电位为-0.80-0.90V（相对于Ag/AgCl参比电极，下同），罐内各点电位均匀；Inner tank cathodic protection current potential ranges -0.80-0.90V (VS Ag/AgCl

31、 reference electrodes, below the same), the potentials at different points are uniform;罐内各部件在海水试压期内无锈蚀，排水后在空气中会正常产生浮锈；Tank internal components will not corrode during seawater hydrotest, after drainage of test water rust will appear naturally on the surfaces exposed in the air;保护时间为30天。Protection du

32、ration will be 30 days.五、被保护体参数 Data of the protected structures1、储罐内罐直径为80000Inner tank diameter: 800002、试验注水水位为18460Hydrotest water level: 184603、罐内管道直径 Tank internal pipe diameters名称 SNN1BN2AN2BN2CN2DFK3K4K5K6K7外径（in）9524242424626101010外径（）2413609.6609.6609.6609.6152.450.8152.4254254254 罐内被保护体浸海水

33、面积 单位：m24、罐内被保护体浸海水面积计算:项目罐内管道外表面积罐内管道支架表面积材质图纸内罐底板Inner tank bottom5026.4X7Ni9ZHLNG-5A-TK-DWG-TKI-0216内罐壁板Inner tank shell4639.3672X7Ni9ZHLNG-5A-TK-DWG-TKI-0213内部梯子Internal ladders73.11304LZHLNG-5A-TK-DWG-TKI-0222N1B139.1145611.9A240 TP304ZHLNG-5A-TK-DWG-TKI-0230N2A、B、C、D282.86627212A358 Gr304/304L

34、 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-DWG-TKI-0250K33.495253320A312 TP304/304LZHLNG-5A-TK-DWG-TKI-0252

35、合计 Total10272.5569847.087210319.64418注：计算时，被保护体浸海水面积取小数点后一位：（1）内罐底板面积S1=5026.4 m2Inner tank bottom S1=5026.4 m2（2）内罐壁板面积S2=4639.4 m2Inner shell S2=4639.4 m2（3）罐内管道外表面积S3=533.7 mExternal surface of internal piping S3=533.7 m2（4）罐内支架表面积S4=47.1 m2Surface area of internal supports S4=47.1 m2（5）罐内梯子表面积S5

36、=73.1 m2Internal ladder S5=73.1 m2六、阴极保护设计Cathodic Protection Design6.1设计应考虑的实际因素 Actual factors to be considered in the Design我公司技术人员经过两次勘踏现场，同时对罐体材料试片进行了电化学试验，我们认为本阴极保护设计应考虑如下因素：Our technicians have made two site visits to investigate the actual site conditions and carry out the electromechanical

37、tests of the specimens taken from the tank components. We believe the following factors shall be considered in the design of cathodic protection:X7Ni9钢是低温条件下使用的优质钢，其屈服强度为585MPa的高强钢，所以应严格控制其保护电位在-0.80-0.90V，其保护电位不应过负；X7Ni9 steel is a kind of cryogenic service quality steels, and a type of high streng

38、th 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钢表面涂层很薄，经我们现场仔细观察，罐体内表面及现场堆放的钢板上没有锈蚀，特别是经过近30天的连续雨天，也无浮锈产生，说明其表面涂层有一定的保护作用，因此在储罐在注、排海水过程中不需要过大的保护电流；The stripe coating of X

39、7Ni9 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 continuous storage in exposure to rains, which indicates the surface co

40、ating has played the protective role. Therefore high protection current is not necessary during the seawater filling stage通过试片在海水中的试验，X7Ni9钢与304L不锈钢的电极电位相差很大，两者偶合时，X7Ni9钢腐蚀严重；Through testing of metal specimens in seawater, it is found the electrode potential of X7Ni9 is greatly different from that o

41、f 304L. When the two are coupled, X7Ni9 will experience serious corrosion.焊缝与基材的电位差也很大，也会引起严重的电偶腐蚀；The great difference between the potential of welded seams and that of the base material will also lead to serious galvanic corrosion.从向罐内注海水开始，罐内构件从一接触海水就应得到及时保护。From the start of seawater filling, th

42、e tank internal components shall be protected in a timely manner once they come into contact with the seawater.6.2阴极保护设计方案的选用 Design of Cathodic Protection Methods为了使罐内所有浸海水面积得到及时保护，本设计采用牺牲阳极阴极保护与外加电流阴极保护相结合的方案。虽然此方案相对外加电流方案要复杂，但效果更好、更安全。理由如下：In order to ensure efficient protection of tank component

43、s 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 and safer. The reasons are as follows:罐底板阴极保护：采用牺牲阳极阴极保护。大量的钢质储罐海

44、水试压工程表明，海水水位上升到1.5米时的正常时间需要810小时，如果出现不可预见的因素，可能需要几天时间；同时，根据我公司在高栏港的经验，此海域的海水中泥沙含量较高，清罐也需要几天时间，甚至出现过10多天才完成清罐的情况。如果采用外加电流阴极保护的方法，其辅助阳极外挂在1.5米的高度，罐底板在上水过程中会得不到及时的保护，甚至很长时间得不到保护，罐底板就会被子腐蚀，这样，整个临时阴极保护将是不完整的。因此，我公司设法改善了保护方案，需要说明的是，这一设计是一个成熟的设计、是被大量成功案例所证明的而完全有效的方案；但是，这一设计不是推迟上水速度及清罐速度的理由，因为阳极的寿命为35天，阳极用尽

45、后，腐蚀依旧会发生。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 and this period may extend to a few days in case of unpredicted o

46、ccurrences. 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 hung at a 1.5m elevation, the inner tank bottom would not get prote

47、cted 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. Therefore, we have managed to improve the method design and what s

48、hould 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, as the service life the anodes is 35 days after which corrosion w

49、ill still occur.304L钢在海水中的主要腐蚀控制形态是缝隙腐蚀，主要在焊缝、铆接点、紧固件附近有缝隙腐蚀出现，阴极保护可以防止缝隙腐蚀，点蚀在充气海水环境中很少出现。阴极保护对这种腐蚀的有效性还受到质疑，所以管内阴极保护的意义不大，相反，由于不锈钢过保护析氢，反而会产生有害作用，因此，我公司主张管内牺牲阳极阴极保护取消，或者每根管道内单独进行阴极保护设计，使管内电位控制在-0.6-0.8V之间。The main corrosion geometry of 304L steel in seawater is crevice corrosion which typically ap

50、pears 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 protection against pitting corrosion is still under doubts, so the cath

51、odic 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 protection of pipe inner walls, or design the cathodic protection metho

52、d for each single pipeline and keep the protection potential inside the pipe within the range of -0.6-0.8V.304L钢的阴极保护电流密度与X7Ni9钢是不同的，这些数据在船舶设计中都有明确规定。The cathodic protection current density of 304L steel is different from that of X7Ni9 steel. The data are expressly specified in related ship design c

53、odes/standard.6.3罐底板及1.5米高罐壁牺牲阳极阴极保护设计 Design of Galvanic Anode Cathodic Protection of Inner Tank Bottom and Shell up to 1.5m Elevation6.3.1保护电流密度的选取 Selection of Protection Current Density1）X7Ni9钢的保护电流密度：i1=50mA/m2Protection current density for X7Ni9 steel：i1=50mA/m22）304L钢的保护电流密度：i2=150mA/m2Protec

54、tion current density for 304L steel：i2=50mA/m26.3.2保护电流计算 Calculation of Protection Current式中：IP1罐底、1.5米高罐壁及罐内结构物的保护电流通，AWhere IP1 is the Protection current for inner tank bottom, shell paltes up to 1.5m elevation and internal structures，A i1X7Ni9钢的保护电流密度，mA/m2i1protection current density for X7Ni9

55、steel，mA/m2 i2304L钢的保护电流密度，mA/m2i2protection current density for 304L steel，mA/m2S11罐底、1.5米高罐壁及支架的面积，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积S21Area of external surface of piping under 1.5m water level and ladder6.3.3牺牲阳极材料的选取 Selection of Sacr

56、ificial Anode Material1）牺牲阳极的化学成份 Chemical compositions of sacrificial anodes牺牲阳极的化学成份 Chemical Composition of Sacrificial Anodes化学成份 CompositionZnInSiFeCuAl含量% Percentage2.5-4.50.018-0.0500.100.100.010余量 Margin2）牺牲阳极的规格 Specifications of sacrificial anodes19.09.5300006.3.4牺牲阳极发生电流量的计算 Calculation o

57、f Sacrificial Anode Generated Current Volume式中Where ：阳极的驱动电位，0.35V；Drive potential of anodes，0.35VR阳极的接电阻， QUOTE anode connection resistance， QUOTE 式中 Where： L阳极的长度 length of anode，； 海水电阻率 Seawater resistivity，33.；r阳极截面当量半径 Equivalent radius of anode section；6.3.5牺牲阳极的寿命核算 Calculation of the Service

58、 Life of Sacrificial Anodes式中 Where：T阳极使用寿命Anodes service life，天 day 阳极平均发生电流系数 Coefficient of anodes average generated current 阳极发生电流 Anode generating current，A W阳极的重量 Weight of anode， 24平均每天小时数 average number of hours per day；0.85阳极使用系数Anode utilization factor。6.3.6阳极量计算 Calculation of Required Qu

59、antity of Anodes根实取12根。12 anodes will be used.6.3.7阳极安装图 Anodes Installation Plan为了确保罐底板自注海水开始就能及时得到保护，阳极预制成波浪形状，罐底板牺牲阳极安装详施工图。In order to make sure the tank bottom can be protected in a timely manner from the very start of seawater filling, the anodes will be prefabricated into a wavy shape. For de

60、tails of installation of sacrificial anodes on the bottom, refer to the construction drawings.6.4 2.4米罐内下料管牺牲阳极阴极保护6.4.1 保护面积计算 管道内径：D=2400 浸水高度：L=18890 保护面积：6.4.2 保护电流计算6.4.3 阳极量计算1）牺牲阳极的化学成份牺牲阳极的化学成份化学成份ZnInSiFeCuAl含量%2.5-4.50.018-0.0500.100.100.010余量2）牺牲阳极的规格19.09.5300006.4.4牺牲阳极发生电流量的计算式中：阳极的驱动电