Research On Corrosion Behavior Of Tungsten-based Alloy Coating Under High H₂S Environment

Autoclave tests and SEM, EDS, XRD, technologies were used to study corrosionbehavior of tungsten-based alloy coating which include analyzing original tungsten-basedcoating and studying corrosion behavior under the environment of high H2S and acidresistance property. When improving the tubing corrosion resistance through the surfaceanti-corrosion technology, the strength and sealing performance of threaded joint arc notaffecetd. So that evaluating the mateiral object of tungsten-based coating is essential and thatinciude shackle test and sealing test.The resultes of autoclave tests of simulating actual working conditions showed that underthe same conditions，the corrosion resistance of tungsten-based coating is higher than P110S.We know that S element content is the highest, followered by iron after analysis of bothsurface passivation membrane, showed that passivation film is mainly composed of FeS andsome surface deposition of salts, And the difference is collected some W element inpassivation film of tungsten-based coating that showed collecting W element played a verypositive role in its corrosion resistance. In addition, the test of HIC and SCC according to thestandard NACE TM0284-2003and NACE TMO177-2005showed that the surface oftungsten-based coating in good condition, no crack, peeling, bubble and so on.The test of acidification demonstrated that both corrosion inhibitors TG201and DJ-04have corrosion inhibition to tungsten-based coating. But more specifically, under the sameconditions, the corrosion inhibition of TG201is superior to DJ-04in the test of simulatingacidification and the residual acid flowback.Three samples with thread jointer do not appear thread gluing atfer three dischaige onfour experiment acorrding to the88.90x6.45mm PI10BGT1recommended best torquevalue, but in the test of gas seal of API RP5C5all they leaked out. Atfer adjust the test plan,the samples do not appear thread gluing, according to the88.90x6.45mm PI10BGT1recommended big torque value. And atfer hydrostatic pressure and gas seal test the samples donot leaked out under the torque value.