CN2389427Y - Buried metal cathode protection permanent reference electrode - Google Patents
Buried metal cathode protection permanent reference electrode Download PDFInfo
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- CN2389427Y CN2389427Y CN 99234809 CN99234809U CN2389427Y CN 2389427 Y CN2389427 Y CN 2389427Y CN 99234809 CN99234809 CN 99234809 CN 99234809 U CN99234809 U CN 99234809U CN 2389427 Y CN2389427 Y CN 2389427Y
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- electrode
- graphite
- graphite electrode
- reference electrode
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Abstract
The utility model relates to a buried metal cathode protection permanent reference electrode, which belongs to the technical field of anti-corrosion of metal. The utility model is composed of a graphite electrode, bag-filling material and an outer sleeve; the bag-filling material is arranged in the outer sleeve; the bag-filling material is provided with the graphite electrode. The non-polar performance of the graphite electrode is better than the copper sulfate electrode; the electric potential of the reference electrode is stable without dispersion. The graphite is the corrosion-resistant material; for the service life of the electrode in the earth, the graphite is considered to be the ideal material of the permanent reference electrode. The surface of the graphite electrode is coated with the bag-filling material of definite components, and is then buried in the earth; therefore, the electric potential of the electrode becomes relatively stable and approaching.
Description
The utility model belongs to the anticorrosive metal technical field, particularly the permanent reference electrode of buried metal cathodic protection.
Sacrificial protection is widely used on the antiseptic project of buried metal structures; received the excellent protection effect; really; this anti-corrosion method is also being updated and is being innovated; except developing efficient cheap new anode material, seeking long-acting (forever) reference electrode and using on the engineering.Generally all adopt saturated copper-copper sulphate (Cu-CuSO on the underground antiseptic project
4) electrode (calling copper sulfate electrode in the following text), as measuring the reference electrode that protection potential is used, it has stable electrode potential and non-polarized preferably performance, can satisfy the general needs on the engineering.But, any copper sulfate electrode, no matter osmosis type, or long-acting type, inner Cu
2+And SO
4 2-Ion is outside seepage or be diffused in the soil all, increases soil corrosivity, the copper sulphate (CuSO in the electrode cavity
4) can lose gradually, electrode can lose function and must change, even long-acting copper sulfate electrode, also have only 2～3 years useful life at the most.Therefore, though copper sulfate electrode is the standard reference electrode of using always, can not make the long permanent reference electrode that buries soil because of electrode life is short.
The purpose of this utility model provides the permanent reference electrode of a kind of buried metal cathodic protection, and length is buried in the soil corrosion-resistant, and current potential is stable.
Technical solution of the present utility model is: the permanent reference electrode of a kind of buried metal cathodic protection; by graphite, fill out construction materials contract, overcoat is formed, overcoat for the punching plastic tube, be provided with in the overcoat and fill out construction materials contract; fill out and be provided with graphite electrode in the construction materials contract, be provided with brass screws and two sheath lead-in wire in the graphite electrode.
The naked area of graphite electrode is accomplished 100cm
2More than be easy to, and copper sulfate electrode is just quite difficult, so the non-polarized property of graphite electrode just is better than copper sulfate electrode.Graphite electrode is insoluble object, and is corrosion-resistant, and current potential is stable.Graphite is corrosion-resistant conductor, can corrosion and damage in soil, certain mechanical strength is arranged again, and it is embedding to be suitable for machinery.The contacted medium character of the current potential of graphite electrode and electrode surface and different is uncertain.But this defective has way to remedy, and is coated with filling out behind the construction materials contract in the embedding again soil of bag definite composition on the graphite electrode surface, can make electrode potential more stable and approaching.Can in time be proofreaied and correct by the survey of regular school at the long current potential drift that buries in the process, this accomplishes on measuring technique easily.The advantage of above-mentioned graphite electrode is that existing reference electrode is unexistent, and graphite electrode is exclusively used in the long permanent reference electrode that buries soil in the cathodic protection system, is that existing reference electrode institute is irreplaceable.The reference electrode of supporting big jar of end commutativity magnesium ribbon anode cathodic protection of the utility model uses, and design service life 30 years is used in North China Oilfield, and measurement effect is fine.
Describe embodiment of the present utility model in detail below in conjunction with accompanying drawing.
Fig. 1 is the utility model structural representation.
Fig. 2 is the variation of graphite electrode current potential in the different medium.
Fig. 3 is the steady-state polarization (medium temperature 25～26 ℃) of graphite electrode in three kinds of media.
The permanent reference electrode of a kind of buried metal cathodic protection; by graphite electrode (1), fill out construction materials contract (2), overcoat (3) is formed; overcoat (3) is punching (4) plastic tube; plastic tube external application cotton (7) parcel; be provided with in the overcoat (3) and fill out construction materials contract (2); fill out consisting of of construction materials contract: bentonite 50%, land plaster 43%, sodium sulphate (NaSO
4) 7%, to fill out and be provided with graphite electrode (1) in the construction materials contract (2), graphite electrode (1) is φ 30 * 110mm, is provided with brass screws (5) and two sheath lead-in wires (6) in the graphite electrode (1), silk mouth and junction, line hole epoxy sealing (8) in the graphite electrode.As everybody knows, the reference electrode that is used to measure cathodic protection potential must possess two conditions: the one, and stable electrode potential; The 2nd, certain non-polarized performance.Below by potential stability and the polarization characteristic experiment of graphite electrode in some medium, inquire into the feasibility of graphite electrode as the permanent reference electrode in the cathodic protection system.Graphite electrode is processed by graphite rod (Nantong Carbon Factory production).Fill out construction materials contract, ooze (East Sea), solonchak (Yancheng, Jiangsu) and red soil (Jiangxi Yingtan) for the examination medium.Table 1 is listed some character of these media.
Table 1 is for some character of examination medium
Medium temperature: 25 ± 0.5 ℃
| Medium | Water content (%) | Conductivity (ms/cm) | PH |
| Fill out construction materials contract | 87.1 | 2.24 | 8.23 |
| Ooze | 37.1 | 7.86 | 7.61 |
| Solonchak | 45.3 | 0.968 | 7.14 |
| Red soil | 57.0 | 0.289 | 5.06 |
Adopt the equilibrium potential of high input impedance millivoltmeter periodic measurement graphite electrode in different medium.Adopt constant potential step method to measure the steady-state polarization of graphite electrode in different medium.The result is as follows:
The equilibrium potential of 1 graphite electrode in different medium.
Red soil, solonchak and two parts are filled out construction materials contract be sub-packed in four plastic cups (750ml), it be (to insert dark 5cm) in the water saturated medium that the graphite electrode of carefully polishing is inserted, and in every cup slotting 2, adds a cover and leaves standstill balance.Potential difference with high input impedance millivoltmeter periodic measurement graphite electrode relative saturation Ag-AgCl electrode.Be 27 days measuring period, and medium temperature is 25～31 ℃ around here.The current potential of 2 graphite electrodes in same plastic cup is close and identical variation tendency arranged.Now select one and illustrate Fig. 2.Clearly visible, for filling out construction materials contract, in 5 days, the current potential of 2 graphite electrodes is very approaching and all have and gradually fall trend, and from the 5th day, the current potential of filling out in one of construction materials contract was constantly risen progressively, rise to 250mv by 150mv in 5 days, and fill out construction materials contract two in current potential only increase about 15mv; Behind two weeks, graphite electrode fill out one of construction materials contract, fill out construction materials contract two in current potential tend towards stability, fluctuate up and down at 290mv and 150mv respectively.The above results proves that fully the phase boundary potential that graphite electrode is presented is different in different medium.Because this current potential depends on the electrochemical properties at interface between graphite surface and the medium fully, it had both comprised the surface characteristic of graphite itself, also comprised the general physicochemical characteristics with the contacted medium of graphite surface.Graphite surface not only has covalently bound oxygen atom, dissociable in addition-COOH and-OH, the variation of medium Eh and pH can cause the chemical reaction of graphite surface group, thereby causes the variation of phase boundary potential.Because graphite surface produces the variation that absorption-desorption also can cause phase boundary potential to some component in the medium, the therefore available construction materials contract of filling out obtains stable and graphite current potential unanimity.As can be seen from Figure 2, graphite electrode changes with equilibration time at two glasss of current potentials of filling out in the construction materials contract, although in 15 days afterpotential values of tending towards stability of balance, stationary value is different, and high person is about 290mv, about the low person 150mv.This may be owing to the redox situation difference of filling out construction materials contract in 2 cups and fill out due to the construction materials contract incomplete mixing.This shows that the available construction materials contract of filling out is isolated graphite electrode and formed graphite-fill out the construction materials contract boundary layer with direct contact of soil, phase boundary potential is identical to be difficult to really but will make.This is to be difficult to control because influence the principal element-redox situation of phase boundary potential.
The polarization characteristic of 2 graphite electrodes in some medium
Adopt constant potential step method, polarization potential Δ E=500mv (250mv～-250mv) in the scope, measured same graphite electrode (naked area 119cm
2) fill out steady-state polarization (Fig. 3) in construction materials contract and the solonchak in ooze, water saturation.Can check in the current density value (table 2) that flows to graphite electrode under the different cathodic polarization potential by cathodic polarization curve.
The Cathodic Polarization Characteristics of graphite electrode in table 2 different medium
| ΔE，mv | -5 | -10 | -20 | -30 | -50 |
| i，μA/cm 2 | |||||
| Solonchak | 0.19 | 0.35 | 0.58 | 0.77 | 1.17 |
| Fill out construction materials contract | 0.23 | 0.51 | 0.89 | 1.28 | 2.13 |
| Ooze | 0.37 | 0.73 | 1.37 | 2.02 | 3.42 |
This shows that the order in three kinds of media of the non-polarized performance of graphite electrode is ooze＞fill out construction materials contract＞solonchak.Just fill out construction materials contract, when the graphite electrode current potential is negative when moving 5mv, polarized current density is 0.23 μ A/cm
2Therefore, when requiring the graphite electrode potential drifting to be no more than 10mv, the electric current that then flows through graphite electrode is 61 μ A.As seen, (as cylindrical shape L10 * φ 3.5cm, surface area can be at 100cm because the surface of graphite electrode can make very greatly
2More than), the non-polarized performance of graphite electrode is splendid.After filling construction materials contract outside the graphite electrode with this configuration in the embedding soil, in order to detect by anode loss protection bury the protection potential of ground structures the time, use input impedance just enough as the millivoltmeter of 50K Ω.
According to above-mentioned analysis and discussion, can be summarized as follows the feasibility of graphite electrode as the permanent reference electrode of cathodic protection system to experimental result:
(1) current potential of graphite electrode in certain medium becomes with equilibration time, and be obvious in a two weeks inner potential fluctuation, then the value of tending towards stability; Stable potential is different in different medium, fills out construction materials contract 150-290mv.Owing to there are differences on graphite electrode surface proterties and the graphite body porousness, fill out the especially difference of Eh of construction materials contract physicochemical character, all can cause the different of graphite electrode current potential; Be not difficult to imagine, in the long-term embedded process of production scene, variation that the graphite electrode current potential is either large or small and fluctuation are inevitable.Therefore, bury the protection potential of ground structures in order to survey standard, the potential value that each embedding graphite electrode relative standard reference electrode is surveyed in regular school on antiseptic project is necessary fully.
(2) the suitable electrode configuration of design as cylindrical, can make contact resistance＜0.5 Ω that connects between lead and graphite body, electrode surface area＞100cm
2, can improve the non-polarized performance of electrode so greatly.When measure with general millivoltmeter relative graphite electrode bury the protection potential of ground structures the time, when flowing through graphite electrode, the reference electrode current potential is stable not to drift about if any little electric current (number μ A), this is that other reference electrode is difficult to reach.
(3) graphite is resistant material, and with regard to the useful life of electrode in soil, graphite is determined the ideal material of permanent reference electrode.
Claims (1)
1, the permanent reference electrode of a kind of buried metal cathodic protection; it is characterized in that: by graphite electrode (1), fill out construction materials contract (2), overcoat (3) is formed; overcoat (3) is punching (4) plastic tube; be provided with in the overcoat (3) and fill out construction materials contract (2); fill out and be provided with graphite electrode (1) in the construction materials contract (2), be provided with brass screws (5) and two sheath lead-in wires (6) in the graphite electrode (1).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 99234809 CN2389427Y (en) | 1999-07-23 | 1999-07-23 | Buried metal cathode protection permanent reference electrode |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 99234809 CN2389427Y (en) | 1999-07-23 | 1999-07-23 | Buried metal cathode protection permanent reference electrode |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN2389427Y true CN2389427Y (en) | 2000-07-26 |
Family
ID=34022894
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 99234809 Expired - Fee Related CN2389427Y (en) | 1999-07-23 | 1999-07-23 | Buried metal cathode protection permanent reference electrode |
Country Status (1)
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|---|---|
| CN (1) | CN2389427Y (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100348970C (en) * | 2004-06-23 | 2007-11-14 | 中国石油天然气股份有限公司 | Reference electrode under cathode protection |
| CN102817037A (en) * | 2011-06-10 | 2012-12-12 | 中国石油天然气股份有限公司 | Oil gas pipeline potential measurement permanent reference electrode |
| CN114002287A (en) * | 2021-09-29 | 2022-02-01 | 天津哈德韦尔自控技术有限公司 | Long-acting reference electrode |
-
1999
- 1999-07-23 CN CN 99234809 patent/CN2389427Y/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100348970C (en) * | 2004-06-23 | 2007-11-14 | 中国石油天然气股份有限公司 | Reference electrode under cathode protection |
| CN102817037A (en) * | 2011-06-10 | 2012-12-12 | 中国石油天然气股份有限公司 | Oil gas pipeline potential measurement permanent reference electrode |
| CN102817037B (en) * | 2011-06-10 | 2014-11-26 | 中国石油天然气股份有限公司 | Oil gas pipeline potential measurement permanent reference electrode |
| CN114002287A (en) * | 2021-09-29 | 2022-02-01 | 天津哈德韦尔自控技术有限公司 | Long-acting reference electrode |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C19 | Lapse of patent right due to non-payment of the annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |