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The anti-hydrogen cracking of seamless tube material

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The seamless pipe line is mainly used for pumping high pressure oil and gas near the wellhead. As the corrosion problem of hydrogen sulfide is becoming more and more serious, the development of anti-sulfur seamless pipeline tube is urgent, and the anti-sulfur performance is the key. Discusses the influence of hydrogen induced crack (HIC) resistance of medium and material factors, Cu, Ni join can improve the performance of seamless line pipe material HTC reduce the S content in the steel, by spraying calcium silicon powder also can reduce the sensitivity of hydrogen bubble.

With the development of oil and gas exploration, the problem of hydrogen sulphide corrosion is very acute because of the increasing amount of oil and gas Wells in the complex and sulfur environment. In recent years, there has been an increase in demand for the seamless pipe line. The seamless pipeline pipe is mainly used for pumping high pressure oil and gas near the wellhead, and it is made by seamless tube production. This paper intends to discuss the development of the seamless pipeline tube.

1 test method

In the lab according to the ISO3183 standard, using the method of immersion, smelting furnace 1 t steel ingot, after forging, perforation, pipe jacking and decrease manufacturing into tube, on the steel pipe intercept 20 mm x 100 mm x 5 mm thickness or pipe thick specimen, immerse the stipulated in the standard configuration in the solution, take out after 96 h and vertical mill to take section, using metallographic method to calculate the three parameters (crack length ratio CLR, crack thickness ratio CSR CTR, crack sensitive rate), in order to compare the resistance to hydrogen induced crack (HIC) sensitivity.

Factors affecting the performance of the HIC

2.1 factor

1) pH value. A large number of studies have shown that the sensitivity of the hydrogen bubbles decreases with pH in the range of 1 ~ 6, and when the pH > 6 is not occurring, the hydrogen bubble will not be bubbling [1].

2) H2S concentration. The higher the concentration of hydrogen sulfide, the greater the sensitivity of the hydrogen bubble.

3) chloride ions. In a range of 3.5 to 4.5, the presence of cl-is increasing the rate of corrosion, and the sensitivity of hydrogen bubbles increases.

4) temperature. 25 ℃ when the CLR, the sensitivity of the hydrogen bubble is the largest. Below 25 ℃, the temperature and the corrosion reaction of hydrogen diffusion speed, increased sensitivity to hydrogen bubble. After the above 25 ℃, due to the concentration of H2S, but decreased the sensitivity of the hydrogen bubble.

5) time. Compared with 96 h, the degree of corrosion tends to be severe as the test time increases.

2.2 factor

The effect of the chemical composition of 2.2.1

In the laboratory, a round of steel is designed according to different levels of design, the specific components are shown in table 1, and the HIC immersion test is carried out. From the surface of the specimen, the area of B6, B6 and B7 is significantly more than B9, B10, and the results of crack sensitivity are shown in table 2. As you can see from table 2, the anti-hic performance of B2, B6, and B7 is significantly inferior to B9 and B10. In table 1, B2, B6, B7 steel do not contain Cu, Ni, and B9 and B10 steel are Cu and Ni. Thus, Cu, Ni, make the corrosion products formed on the surface of steel protective film, inhibit the corrosion of the surface reaction, so as to reduce the escape of hydrogen, reduce the hydrogen from the environment into the steel substrate, reduce the sensitivity to hydrogen bubble and increase the performance of resistance to HTC, this has to do with Oriani results [2] is very consistent, and Oriani also points out that only 0.2% of Ni and Cu can produce effect of greater than 0.2%.