Selection of inhibited preservative materials for corrosion protection of gage parts (level transmitter torque tubes in primary and secondary oil processing units) and experience in application of such materials

Int. J. Corros. Scale Inhib., 2013, 2, no. 3, 231–244
Selection of inhibited preservative materials for corrosion protection of gage parts (level transmitter torque tubes in primary and secondary oil processing units) and experience in application of such materials
V. V. Burlov, T. P. Parputs and E. A. Tronova
t.parputs@yandex.ru
OOO NPO NEPhTEKhIM, ul. Pulkovskaya 10, St. Petersburg, 196158 Russian Federation.
Abstract
The reasons of initiation and development of local corrosion attack which is the most hazardous form of destruction of thin-walled tubes in level transmitters at oil processing units are examined. The protective effect of oil-based preservation materials with respect to nickel and copper-nickel alloys in hydrocarbon media containing chlorides and sulfur compounds has been studied. Laboratory studies and industrial tests have shown that the highest protective effect is provided by M-1 inhibitor at 5 mass% concentration in PES-5 silicone oil. The formulation is successfully used for the protection of torque tubes in liquid level transmitters at primary and secondary oil processing units.
When choosing a structural material to provide the guaranteed operation of petrochemical plants for a long inter-repair period, main attention must be given to the character of the corrosive environment, process conditions, and equipment design. In many cases, inaccurate material selection and poor design can decrease the inter-repair period, increase equipment downtime, or even result in a failure.
In recent years, the use of nickel alloys in oil processing and oil chemistry processes started, though they are expensive. This is caused by the high corrosion resistance of such materials, both under atmospheric conditions and at high temperatures, in many corrosive media, especially in acidic ones. The corrosion properties of nickel and its alloys are largely due to their relatively high thermodynamic stability in oxidizing media. Of various nickel-based alloys, it is alloys doped with copper, chromium, molybdenum, and silicon that are most interesting from the practical point of view.
However, data are available that nickel alloys (e.g., Monel) have insufficient corrosion resistance and even tend to undergo intergranular corrosion and pitting in hydrocarbon media containing sulfur compounds. In view of this, the use of nickel alloys in refinery equipment requires a thorough consideration of all factors that affect the corrosion resistance of structural materials and process instrumentation.
Free Full Text Source: http://ijcsi.pro/files/2013/Issue_3/ijcsi-2013-v2-n3-p6-pp231-244.pdf