ER Corrosion Probe

Description

The resistance probe method (ER) is a detection method based on the measurement of metal loss. It determines the amount of metal loss through the continuous change of the probe resistance value. In this way, it can get its corrosion rate. This method can be used in almost all environments, regardless of the nature of the process. The sensitive element forms of ER resistance corrosion probes include such as loop type, tube type, ring tube type, flat head type, and strip type. etc. The main material is 316 stainless steel. The material of the sensitive element also can be customized and selected to adapt to different monitoring environments.

• Metal Material: 316、L DUPLEX SS
• Sealing Material: Teflon/ Fluororubber
• Working Temperature: -20~200℃
• Working Pressure: 0~26MPa
• Access Fitting Body and Protective Cover :
• Size of Flange : ANSI 2″ RF (or RJ)
• Material : CS 、316L、 DUPLEX SS
• Working Pressure: 0~26MPa
• Working Temperature: -20~200℃

Product background:

Various pipes widely work in petroleum, chemical, power, food and other industries. Corrosive liquids or gases often attack them. In addition to causing direct economic losses, corrosion is another serious problem that will inevitably lead to the depletion and depletion of natural resources. There are many kinds of protective measures against the principles that cause metal corrosion. But in addition to the anti-corrosion measures we have taken in advance, when the pipe body is corroded, its wall thickness is reduced to a certain extent. So it will leak or break, causing great harm and loss.

Pipeline Corrosion

Therefore, it is very necessary to monitor their corrosion. Through corrosion monitoring, correlative information between corrosion process and operating parameters can be obtained in order to judge the problem. This improves corrosion control, resulting in improved productivity. This technology also prolongs equipment life and reduces capital and operating costs. The biggest advantage of online corrosion monitoring technology is “online”. That is to grasp the real-time corrosion rate and track the corrosion rate at a specific position of the equipment or the change of a certain characteristic variable (value, content, etc.) throughout the process. In this way, it can grasp the corrosion status of materials and equipment at any time. So it can prevent and control the occurrence and development of corrosion. At the same time, it keeps the equipment in a good and controllable operating state.

Among them, the hanging chip method and the resistance probe method are two methods that are widely used. The former is simple and convenient to operate, reliable in data, and people can use in any media environment. Its use is not technically demanding and is moderately expensive. The latter is simple and quick to measure, the signal feedback is fast and it is not affected by corrosive media. In addition, the resistance probe can timely reflect the corrosion change trend during the operation of the equipment.

1. Classification and selection of corrosion probes

Several common corrosion probes Electrochemical probes, resistance probes, and inductance probes are currently the most widely used types in online corrosion monitoring:

Firstly, the electrochemical probe regards corrosion as a battery effect, and the corrosion rate is proportional to the corrosion current. We can calculate the corrosion rate according to the corrosion current.

Secondly, measuring principle of resistance probe: In corrosive medium, the metal wire as the measuring element is corroded. The length of the wire remains the same, the diameter decreases, and the resistance increases. The corrosion thinning of the metal wire is converted by testing the change of resistance. This in turn represents the amount of corrosion in the wall thickness.

At last, the principle of the inductance probe: corrosion changes the probe, directly affects the inductance strength, and then converts the corrosion reduction. They are suitable for different temperature, pressure and environment in application. Several probes also have disadvantages to varying degrees. Users must use it reasonably in the process of use in order to achieve accurate and timely results.

ER Corrosion Probe

The choice of probe form depends on the medium composition of the pipeline. This is determined by the predicted corrosion rate of the pipeline and the sensitivity required. If it is all water, it is better to use a linearly polarized probe. And if there is oil, it is better to use a resistance probe. Then if the flow rate changes or there are solid particles, a flow rate protection cover should be added to the sensitive element, and a resistance probe can be used. For long-term monitoring, selecting a thicker probe element. There are also various types of online corrosion monitoring technologies for equipment and materials. Each monitoring technology has its specific application field and application effect.

At present, there is no monitoring technology that can comprehensively and accurately reflect the entire corrosion pattern of equipment and pipelines in the production process. Therefore, for specific equipment, media combination conditions and specific locations. So it should take various factors into consideration. It is best for the operator to adopt one or two effective online corrosion monitoring techniques

2. Principle of resistance corrosion probe

The resistance probe monitoring method is an online continuous monitoring device. Because it continuously detects the corrosion rate inside the pipe as the fluid changes. So most offshore oil and gas fields have installed resistance probe online corrosion monitoring devices.

Because this causes a corresponding increase in resistance. The increase in resistance is directly related to metal loss. Therefore, through a certain formula, we can convert the corrosion rate of the metal. This technology began in the fifties. It can work in various media. The monitoring period is usually several days. The resistance probe is simple and quick to measure, the signal feedback is fast and the corrosive medium does not affect it. In addition, the resistance probe can timely reflect the corrosion change trend during the operation of the equipment

Resistance probe

Resistance probe corrosion on-line monitoring system is currently the most widely in online monitoring technology. It installs multiple probes at different locations. And then the monitoring instrument can display the change of the speed of the rotten candle. In addition, the probe measuring element can use different materials according to the needs of the site. Another advantage of resistive probes is their wide range of applications. It can work in almost all media environments. Including gas phase, liquid phase, solid phase and flowing particles.
Disadvantages: The signal feedback time of the resistance probe is short and the measurement is rapid. It can reflect the corrosion of equipment pipelines in time, so that the corrosion of equipment pipelines is always under monitoring. However, due to the limitation of instrument measurement sensitivity. The change of the corrosion rate of the process medium also greatly affects the measured data.

3. Structure of resistance corrosion probe

Generally speaking, an online corrosion monitoring system mainly includes probes, corrosion data acquisition and transmission system sensors, data recorders, portable or data continuous download corrosion monitors and data processing systems. Probes at different monitoring points. It is connected with the data acquisition and transmission system installed on site. The data acquisition and transmission system collects the original analog signal related to the candle decay rate, and converts it into a digital signal after being amplified. Then sending the signal to a data processing system such as a monitoring room computer. After the data arrives at the computer, it is processed, displayed, and a database is established. Portable corrosion measuring instruments can also work for monitoring points far away from the data processing system. It stores the data measured by each probe continuously and downloads them to the computer for analysis and storage.

4. Corrosion monitoring points

Due to economic considerations, it is impossible to conduct online corrosion monitoring on every part of the entire platform. Therefore, the correct selection of corrosion monitoring parts directly determines the quality of corrosion monitoring. Under the condition of not affecting the normal production of the station, in order to enable the installed corrosion monitoring equipment to better monitor the corrosion rate of the pipeline, it is advisable to install the probe on:

(1) Pipe sections with high hydrogen sulfide and carbon dioxide content in oil and gas pipelines.
(2) Pipe sections with free water and condensed water.
(3) The more important pipe sections in daily management.
(4) Pipelines considered to be seriously corroded in daily management.
(5) Downstream pipe sections with specific anti-corrosion measures. Such as corrosion inhibitor filling station, etc.

5. Distortion of ER Corrosion Probe

When the corrosion probe loses about half of its initial thickness, the effect of localized corrosion can greatly disturb the accuracy of the measurement data.

And then the reason for this is as follows: In the effective operation of the probe, a layer of coating will be formed on the surface. Under the erosion of potential difference and corrosive media (chloride ions and sulfur elements), it destroys the covering and exposes the iron matrix. Subsequently, there are three steps: the formation of corrosion nuclei, the growth of corrosion pits, and the development of corrosion pits.

The inhomogeneity and non-denseness of the covering are the cause of induced electrochemical localized corrosion. How to correctly judge the data distortion and correctly interpret the data is related to the wider application of inductance probes in refineries and other fields. This requires technicians not only to be able to scientifically manage the probes.