Corrosion Coupon For Oil&gas Pipeline Testing

Description

The corrosion coupon is hung in the monitoring container. Or on-site monitoring of heat exchangers or test pipes. It is a standard metal test piece for determining corrosion. It is a standard metal test piece for the determination of corrosion.

To monitor or evaluate the corrosion condition of the cooling water system. Generally, the pre-processed and weighed metal test pieces are placed in the test system for a period of time. (e.g. 30-90 days). Then we took it out and observed the corrosion. Finally, clean and weigh the metal to determine the annual corrosion rate. (in mils / year, 1mpy = 0.0254mm/a). There are also types of corrosion and pitting depth. The data of metal hanging pieces are affected by corrosive media. It is also related to the surface treatment, placement position, exposure time, and metallurgical method of the coupon.

Corrosion types :

• Galvanic corrosion;
• Crevice corrosion;
• Pitting;
• Intergranular corrosion;
• Delamination corrosion (selective etching);
• Stress corrosion;

Interference of some special trace elements in the water. If necessary, we should do further research in the laboratory.

Matters needing attention

• Firstly, the operator strictly handled the hanging piece according to the experimental requirements.
• Then, the operator will record the status of each link in detail.
• Precautions for electronic balance: try the electronic balance correctly.
• Hands or other dirt are not allowed to touch the hung test piece
• Place the original packaged test piece in a place free of corrosive gas and store it moisture-proof;
• Finally, for the standard corrosion test pieces (corrosion coupon) that have been unsealed but not used up, they are still placed in the anti-rust paper and placed in the dryer.

CO2 corrosion risk and protection measures in oil and gas pipeline

Overview

CO2 corrosion is one of the most common corrosion forms in oil and gas fields. When CO2 is dissolved in water or crude oil, it is highly corrosive. This will cause serious corrosion to the gathering pipeline and downhole oil casing. Therefore, CO2 corrosion has become an important problem for the corrosion and protection of oil and gas fields.

Hazards of CO2 corrosion

(1) uniform corrosion

When CO2 forms full-scale corrosion, the material is mainly subject to uniform corrosion. First, the temperature is below 60 ℃. There is a small amount of soft and low adhesion FeCO3 corrosion product film on the surface of steel materials. Its metal surface is smooth. So it is mainly uniform corrosion. Then, the CO2 partial pressure is lower than 0.483 × 10-1mpa. It is prone to uniform corrosion.

(2) local corrosion

Local corrosion is relative to uniform corrosion. Local corrosion caused by CO2 has the following forms:

• Pitting: pits appear in the corrosion area and the surrounding is smooth;
• Honeycomb corrosion: there are multiple pitting holes in the corrosion area;
• Platform erosion: a large area of the concave platform will appear. The bottom is flat. Peripheral vertical concave bottom;
• Flow-induced local corrosion: developed from platform erosion. The flow will induce the formation of gullies in the eroded area of the platform. Knife line groove parallel to the logistics direction.

Protective measures

At present, there are mainly four ways to protect against CO2 corrosion:

• Corrosion-resistant materials: select materials with CO2 corrosion resistance. Research shows that chromium (CR) can improve the CO2 corrosion resistance of steel materials. But the cost of the resist material is high;
• Agent injection: form a firm corrosion inhibitor film on the metal surface. This isolates the metal from the corrosive medium. It can achieve the effect of inhibiting corrosion. But its protection effect against local corrosion is not good;
• Coating protection: the anti-corrosion inner coating can effectively isolate the pipe material from the corrosive medium. This can prevent CO2 corrosion of the pipeline. But the process is complicated. It is easy to fall off under scouring and other conditions;
• Process optimization: adjust temperature, pressure and other parameters. This can avoid being in the CO2 corrosion-sensitive zone. Moreover, we carry out active and effective corrosion inspection and monitoring. And feedback adjustment effect.

If you need Corrosion Coupon, please contact our professionals to answer them for you.

Our Service