JP3177049B2 - Corrosion protection potential estimation method - Google Patents
Corrosion protection potential estimation methodInfo
- Publication number
- JP3177049B2 JP3177049B2 JP03761193A JP3761193A JP3177049B2 JP 3177049 B2 JP3177049 B2 JP 3177049B2 JP 03761193 A JP03761193 A JP 03761193A JP 3761193 A JP3761193 A JP 3761193A JP 3177049 B2 JP3177049 B2 JP 3177049B2
- Authority
- JP
- Japan
- Prior art keywords
- potential
- anticorrosion
- current
- corrosion
- soil
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Landscapes
- Testing Resistance To Weather, Investigating Materials By Mechanical Methods (AREA)
- Prevention Of Electric Corrosion (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、電気防食を施された埋
設管等の防食電位の推定方法に関し、さらに詳細には、
負極側が土壌内に埋設された防食対象物に接続されると
ともに、正極側が土壌内に備えられる対極に接続される
外部電源を設け、土壌側より防食対象物側へ防食電流を
供給して電気防食される防食対象物の防食電位推定方法
に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for estimating an anti-corrosion potential of a buried pipe or the like which has been subjected to cathodic protection.
The negative electrode side is connected to the anticorrosion object buried in the soil, and the positive electrode side is provided with an external power supply connected to the counter electrode provided in the soil. The present invention relates to a method for estimating the anticorrosion potential of an anticorrosion target to be performed.
【０００２】[0002]
【従来の技術】現在、埋設管の防食対策としては、塗覆
装の形成と共に電気防食が施されており導管の保全に大
きな威力を発揮している。電気防食においては、防食効
果を判断する重要な指標として、埋設管周部の土壌と埋
設管との間の電位である防食電位が所定の値（Ｅ≦−８
５０ｍＶvs.Ｃｕ／ＣｕＳＯ4）の範囲内にあるかどうか
が判断基準とされる。このような防食電位を測定あるい
は推定するにあたっては、土壌表面５０に照合電極６を
設けるとともに、前記埋設管１に他端を接続されたケー
ブルを設けて、両者間の直流電位差（みかけの防食電
位）を測定することにより、測定値を上記の値と比較し
てその判定をおこなっている。このような方法をとる場
合は、このみかけの防食電位の測定にあたって、土壌抵
抗と防食電流とによるＩＲ損が存在することとなる。従
って、みかけの防食電位（測定される電位）は真の防食
電位（埋設管近傍の土壌と埋設管との間の電位）より低
く計測され、あたかも十分な防食効果があるかのような
不安全サイドの評価をすることが起こる。そこで、この
防食電流成分を除去する目的で、直流電源である外部電
源を一時的にＯＦＦ（防食電流をゼロ、即ちＩＲ損をゼ
ロ）にして、グラフ上に電位変化を取りＯＦＦ操作直後
の瞬時に示す電位により真の防食電位を推定することが
行われている。2. Description of the Related Art At present, as a countermeasure against corrosion of a buried pipe, an electrolytic protection is provided together with the formation of a coating, which is very effective in preserving a pipe. In the cathodic protection, as an important index for judging the anticorrosion effect, the anticorrosion potential, which is the potential between the soil around the buried pipe and the buried pipe, has a predetermined value (E ≦ −8).
It is used as a criterion for determining whether the difference is within the range of 50 mV vs. Cu / CuSO 4 ). In measuring or estimating such an anticorrosion potential, a reference electrode 6 is provided on the soil surface 50, and a cable having the other end connected to the buried pipe 1 is provided, and a DC potential difference between the two (apparent anticorrosion potential) is provided. Is determined by comparing the measured value with the above value. When such a method is employed, IR loss due to soil resistance and anticorrosion current is present in measuring the apparent anticorrosion potential. Therefore, the apparent anti-corrosion potential (measured potential) is measured lower than the true anti-corrosion potential (the potential between the soil near the buried pipe and the buried pipe), and unsafe as if there is a sufficient anti-corrosion effect. It happens to have a side rating. Therefore, in order to remove the anti-corrosion current component, the external power supply, which is a DC power supply, is temporarily turned off (the anti-corrosion current is zero, that is, the IR loss is zero), the potential is changed on the graph, and the instantaneous operation immediately after the OFF operation is performed. Estimation of the true anti-corrosion potential has been performed using the potential shown in FIG.
【０００３】[0003]
【発明が解決しようとする課題】しかしながら、この方
法では、外部電源を一時的にＯＦＦする操作あるいは装
置が必要であり、また一つの防食路線に多数の外部電源
が設置されている場合には、全数同時に（ｍｓオーダ
で）ＯＦＦする必要があり、実施する上で困難を伴う。
従って、本発明の目的は、外部電源を稼動状態にさせた
ままでより正確な真の防食電位を測定もしくは推定する
ことが可能な防食電位推定方法を得ることにある。However, this method requires an operation or a device for temporarily turning off the external power supply, and when a large number of external power supplies are installed in one anticorrosion route, All of them need to be turned off at the same time (on the order of ms), which is difficult to implement.
Accordingly, it is an object of the present invention to provide a method for estimating a corrosion protection potential that can measure or estimate a more accurate true corrosion protection potential while an external power supply is kept operating.
【０００４】[0004]
【課題を解決するための手段】この目的を達成するため
の本発明による防食電位推定方法の特徴的な手段は、防
食電流として周期的に０値を採る電流を使用し、防食対
象物と土壌表面間の電位で、防食電流が周期的に０値を
採る瞬間に於ける電位を、防食対象物の防食電位と推定
することにある。その作用・効果は次の通りである。A characteristic means of the method for estimating the anticorrosion potential according to the present invention for achieving this object is to use a current that periodically takes a zero value as the anticorrosion current, and to prevent the object to be anticorrosion The potential at the moment when the anticorrosion current periodically takes a zero value with the potential between the surfaces is to be estimated as the anticorrosion potential of the anticorrosion target. The operation and effect are as follows.
【０００５】[0005]
【作用】つまり、本願の防食構成においては、防食電流
として周期的に０値を採る電流が採用される。そして、
防食電位の測定においては、従来通り地表面と埋設管と
の間の電位で測定される。ただし、その測定時としては
防食電流が０値となる時点でのものが測定される。従っ
て、この時点においては、防食電流自体が無いため、従
来問題となっていた地表面と埋設管近傍部間のＩＲ損が
存在せず、結果、計測される電位が真の防食電位を代表
するものとなっている。In other words, in the anticorrosion structure of the present invention, a current that periodically takes a zero value is adopted as the anticorrosion current. And
In the measurement of the anticorrosion potential, it is conventionally measured at the potential between the ground surface and the buried pipe. However, the measurement is performed at the time when the anticorrosion current becomes zero. Therefore, at this time, since there is no anticorrosion current itself, there is no IR loss between the ground surface and the vicinity of the buried pipe, which has conventionally been a problem, and as a result, the measured potential represents the true anticorrosion potential. It has become something.
【０００６】[0006]
【発明の効果】従って、防食電流供給用の外部電源とし
て各別のものを採用して、本願の方法により防食電位を
測定する場合は、外部電源の電流供給状態を保持したま
まで、任意の地点での”真の電位”を測定することがで
きるようになった。Therefore, when each of the external power supplies for supplying the anticorrosion current is adopted and the anticorrosion potential is measured by the method of the present invention, any external power supply can be used while maintaining the current supply state of the external power supply. It is now possible to measure the "true potential" at a point.
【０００７】さらにここで、防食電流として正弦波交流
を全波整流した電流を使用し、電位の直流成分及び交流
成分を夫々直流電圧計、交流電圧計で検出し、直流成分
と交流成分より、前述の防食電流が０となる時点での防
食電位を求めることとすると、みかけの防食電位計測側
の出力は、図３に示すように直流成分に、防食電流の周
期に見合った交流成分が乗ったものとすることができ、
防食電流が０となる周期と電位が最大値（最貴値）を示
す時期の周期が一致し、直流成分計測値に交流成分計測
値の定数倍（実際の交流電圧振幅巾を交流電圧計の出力
値から換算する換算係数）したものを加えて割り出せ
ば、これが真の防食電位となる。Further, a current obtained by full-wave rectification of a sine wave alternating current is used as the anticorrosion current, and a DC component and an AC component of the potential are detected by a DC voltmeter and an AC voltmeter, respectively. Assuming that the anticorrosion potential at the time when the anticorrosion current becomes 0 is obtained, the output on the apparent anticorrosion potential measurement side has a direct current component and an alternating current component corresponding to the period of the anticorrosion current as shown in FIG. Can be
The period when the anticorrosion current becomes 0 and the period when the potential shows the maximum value (noble value) coincide, and the DC component measurement value is a constant multiple of the AC component measurement value. If a value obtained by adding a value obtained by converting the output value (a conversion coefficient) is obtained, this becomes a true anticorrosion potential.
【０００８】[0008]
【実施例】本願の実施例を図面に基づいて説明する。図
１には本願の方法が適用される防食対象物としての埋設
管１の状況が示されている。An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a state of a buried pipe 1 as an anticorrosion target to which the method of the present invention is applied.
【０００９】先ず電気防食の構成から説明する。防食対
象としての埋設管１に対して、この埋設管１が埋設され
ている土壌５中に対極３が設置されるとともに、埋設管
１、対極３に渡って負極側が埋設管１に接続され、正極
側が対極３に接続される外部電源４が設けられる。外部
電源４から供給される防食電流は、図２に示すように正
弦波交流を全波整流したものとされる。ここで、電源と
しては通常の商用電源が利用されるため、防食電流の周
波数は１２０Ｈｚとなる。防食電流は周期的に０値をと
りながら、対極３から土壌５内の塗覆装欠陥部２を介し
て、埋設管１へ流れることとなる。First, the configuration of the cathodic protection will be described. A counter electrode 3 is installed in the soil 5 in which the buried pipe 1 is buried, and a negative electrode side is connected to the buried pipe 1 across the buried pipe 1 and the counter electrode 3 with respect to the buried pipe 1 as an anticorrosion target. An external power supply 4 whose positive electrode is connected to the counter electrode 3 is provided. The anticorrosion current supplied from the external power supply 4 is obtained by performing full-wave rectification on a sine wave alternating current as shown in FIG. Here, since a normal commercial power supply is used as the power supply, the frequency of the anticorrosion current is 120 Hz. The anticorrosion current flows from the counter electrode 3 to the buried pipe 1 via the coating defect 2 in the soil 5 while periodically taking a zero value.
【００１０】さて、防食電位の測定にあたっては、土壌
表面５０に設けられている照合電極６と埋設管１との間
に、直流及び交流電圧計７が配設されて、この間の電位
差が計測される。さらに、本願の埋設管１の防食電位測
定方法においては、即ちこれらの電圧計７により計測さ
れる計測電位から、直流成分電位ＥDCと交流成分電位Ｅ
ACが測定され、これらの値より以下の式より得られる値
を真の防食電位ＥTと推定する。 ＥT＝ＥDC＋定数×ＥAC ここで、定数は計測される交流の実際の電圧振幅（ＥDC
より上側の振幅）÷交流電圧計の出力値 以下、計測手順を順を追って説明する。外部電源４より
商用電流（正弦波交流６０Ｈｚ）を全波整流したもの
が、防食電流として流される。この防食電流には、その
電流値が瞬間的にゼロになる点がある（１秒間に１２０
回）。従って、埋設管１の電位も１２０Ｈｚで変化する
交流成分を含んでいる（図２，３参照）。この状態で、
埋設管１の”特定点”で電圧計７を用いて電位測定を行
うと、図３に示すような測定結果が得られる。同図にお
いて、直流成分がＥDCで、さらに、交流成分はＥACであ
る。これらの測定値（直流成分ＥDCと交流成分ＥAC）を
用いてＥT（真の電位）が求められ、防食電位が推定さ
れる。In measuring the anticorrosion potential, a DC and AC voltmeter 7 is provided between the reference electrode 6 provided on the soil surface 50 and the buried pipe 1, and the potential difference between them is measured. You. Further, in the method for measuring the anticorrosion potential of the buried pipe 1 of the present application, that is, the DC component potential E DC and the AC component potential E are measured from the potential measured by these voltmeters 7.
AC is measured to estimate the value obtained from the following expression from these values and the true corrosion potential E T. E T = E DC + constant × E AC where the constant is the actual voltage amplitude of the measured alternating current (E DC
(Amplitude above) 出力 Output value of AC voltmeter The measurement procedure will be described below step by step. A commercial current (sine wave AC 60 Hz) obtained by full-wave rectification from the external power supply 4 is supplied as a corrosion protection current. The anticorrosion current has a point where the current value instantaneously becomes zero (120 points per second).
Times). Therefore, the potential of the buried pipe 1 also includes an AC component that changes at 120 Hz (see FIGS. 2 and 3). In this state,
When the potential is measured at the "specific point" of the buried pipe 1 using the voltmeter 7, a measurement result as shown in FIG. 3 is obtained. In the figure, the DC component is E DC , and the AC component is E AC . E T (true potential) is obtained using these measured values (DC component E DC and AC component E AC ), and the anticorrosion potential is estimated.
【００１１】〔別実施例〕上記の実施例においては、全
波整流された電流を使用する防食電流を採用し、この電
流が０値を採る時点における測定防食電位を真の防食電
位として推定したが、これは必ずしも正弦波形のものに
限られるものではない。即ち、防食電流として周期的に
０値を採る電流を使用し（ただし、防食電流は土壌側か
ら埋設管側に流れる必要がある）、埋設管１と土壌表面
５０間の電位で、防食電流が周期的に０値を採る瞬間に
於ける電位を、埋設管１の防食電位と推定すればよい。
従って、波形に任意の設定が可能で、測定時点で急激に
０値となるもの、あるいはその逆に漸近的に０値となる
もの等が採用可能である。さらに、防食対象物として
は、埋設管１の他、地中埋設構造体等、様々なものが考
えられる。さらに、直流電圧計、交流電圧計７を備える
変わりに、図４に示すように埋設管１と照合電極６との
間の電位を出力するトランジェントメモリー装置（７
０）を備えておき、その出力曲線より真の防食電位を求
めるものとしてもよい。さらに、防食電位の検出にあた
って、図５に示すように分離手段としてのＦＲＡ、ＦＦ
Ｔ等の波形解析装置（７ａ）を備え、この装置により防
食電流が０値となる特定瞬間の電位を推定手段（７ｂ）
によって推定してもよい。[Another Embodiment] In the above embodiment, a corrosion protection current using a current subjected to full-wave rectification was employed, and the measured corrosion protection potential at the time when this current took a zero value was estimated as a true corrosion protection potential. However, this is not necessarily limited to a sinusoidal waveform. That is, a current that periodically takes 0 value is used as the anticorrosion current (however, the anticorrosion current needs to flow from the soil side to the buried pipe side), and the anticorrosion current is a potential between the buried pipe 1 and the soil surface 50. The potential at the moment when the zero value is periodically taken may be estimated as the anticorrosion potential of the buried pipe 1.
Therefore, it is possible to arbitrarily set the waveform, and it is possible to employ a waveform that suddenly takes a zero value at the time of measurement or a vehicle that asymptotically takes a zero value at the time of measurement. Further, as the anticorrosion target, various things such as the underground pipe 1 and the underground buried structure can be considered. Further, instead of having a DC voltmeter and an AC voltmeter 7, a transient memory device (7) for outputting a potential between the buried tube 1 and the reference electrode 6 as shown in FIG.
0) may be provided so that the true anti-corrosion potential is obtained from the output curve. Further, in detecting the anticorrosion potential, as shown in FIG.
A waveform analyzing device (7a) for estimating the potential at a specific moment when the anticorrosion current becomes 0 value by this device (7b)
May be estimated.
【００１２】尚、特許請求の範囲の項に図面との対照を
便利にするために符号を記すが、該記入により本発明は
添付図面の構成に限定されるものではない。In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the attached drawings.
【図１】電気防食構成と防食電位の測定状態を示す図FIG. 1 is a diagram showing a configuration of a cathodic protection and a measurement state of a cathodic protection potential.
【図２】防食電流を示す図FIG. 2 is a diagram showing an anticorrosion current;
【図３】検出される防食電位を示す図FIG. 3 is a diagram showing a detected anticorrosion potential.
【図４】トランジェントメモリー装置による測定例を示
す図FIG. 4 is a diagram showing a measurement example using a transient memory device.
【図５】ＦＲＡ、ＦＦＴ等の波形解析装置による測定例
を示す図FIG. 5 is a diagram showing a measurement example by a waveform analyzer such as FRA and FFT.
１ 防食対象物 ３ 対極 ４ 外部電源 ５ 土壌 ５０ 土壌表面 1 Corrosion protection object 3 Counter electrode 4 External power supply 5 Soil 50 Soil surface
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.7，ＤＢ名) G01N 27/26 351 C23F 13/22 G01N 17/02 ＪＩＣＳＴファイル（ＪＯＩＳ)──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. 7 , DB name) G01N 27/26 351 C23F 13/22 G01N 17/02 JICST file (JOIS)
Claims (2)
対象物（１）に接続されるとともに、正極側が前記土壌
（５）内に備えられる対極（３）に接続される外部電源
（４）を設け、前記土壌（５）側より前記防食対象物
（１）側へ防食電流を供給して電気防食される防食対象
物（１）の防食電位推定方法であって、 前記防食電流として周期的に０値を採る電流を使用し、
前記防食対象物（１）と土壌表面（５０）間の電位で、
前記防食電流が周期的に０値を採る瞬間に於ける電位
を、前記防食対象物（１）の防食電位と推定する防食電
位推定方法。1. An external power supply (1) in which a negative electrode side is connected to an anticorrosion object (1) embedded in soil (5) and a positive electrode side is connected to a counter electrode (3) provided in the soil (5). 4), a method for estimating the anti-corrosion potential of the anti-corrosion target (1), which is provided with an anti-corrosion current from the soil (5) side to the anti-corrosion target (1) side, wherein the anti-corrosion current is Use a current that periodically takes 0 value,
The potential between the anticorrosion target (1) and the soil surface (50),
An anticorrosion potential estimation method for estimating a potential at the moment when the anticorrosion current periodically takes a zero value as an anticorrosion potential of the anticorrosion target (1).
流した電流を使用し、前記防食対象物（１）と土壌表面
（５０）間の電位の内、直流成分を直流電圧計で、交流
成分を交流電圧計で検出し、前記直流成分測定値と前記
交流成分測定値より前記防食電流が周期的に０値を採る
瞬間に於ける電位を求める請求項１記載の防食電位推定
方法。2. A current obtained by full-wave rectification of a sine wave alternating current is used as the anticorrosion current, and a direct current component of the electric potential between the anticorrosion target (1) and the soil surface (50) is measured by a direct current voltmeter and an alternating current component is measured. 2. A method for estimating a corrosion prevention potential according to claim 1, wherein the potential is detected at the moment when the anticorrosion current periodically takes a zero value from the DC component measurement value and the AC component measurement value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03761193A JP3177049B2 (en) | 1993-02-26 | 1993-02-26 | Corrosion protection potential estimation method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03761193A JP3177049B2 (en) | 1993-02-26 | 1993-02-26 | Corrosion protection potential estimation method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06249820A JPH06249820A (en) | 1994-09-09 |
| JP3177049B2 true JP3177049B2 (en) | 2001-06-18 |
Family
ID=12502402
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP03761193A Expired - Fee Related JP3177049B2 (en) | 1993-02-26 | 1993-02-26 | Corrosion protection potential estimation method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3177049B2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1082865A (en) * | 1996-07-17 | 1998-03-31 | Osaka Gas Co Ltd | Position searching method for underground buried pipe |
| JP2006257532A (en) * | 2005-03-18 | 2006-09-28 | Nakabohtec Corrosion Protecting Co Ltd | Method for measuring potential of corrosion-prevented body by cathodic protection, device for measuring potential, cathodic protection method and device |
| KR100806961B1 (en) * | 2006-05-23 | 2008-03-06 | 주식회사 예스코 | Integrated measurement device capable of measuring corrosion against protection direct voltage, alternating voltage and ground resistance |
| CN104947118B (en) * | 2015-06-17 | 2017-12-01 | 中国石油天然气股份有限公司 | Flexible anode breakpoint detection method |
-
1993
- 1993-02-26 JP JP03761193A patent/JP3177049B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH06249820A (en) | 1994-09-09 |
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