Experimental Study on Chloride Stress Corrosion Cracking Sensitivity of 316L Stainless Steel

The slow–strain-rate tensile test was used to study the chloride stress corrosion cracking (SSC) behavior of 316L stainless steel under the simulated condition of a CO2 gas field in the Tarim Basin, and the effects of CO2, Cl− concentration, and temperature on the sensitivity of SCC were discussed. The results show that the increase of CO2 content has no apparent influence on the chloride SCC sensitivity of 316L stainless steel. With the rise in temperature, chloride SCC’s sensitivity increases, and the change in the SCC sensitivity index Iscc is noticeable. When the concentration of Cl− increases, the sensitivity of chloride SCC also increases. The degree of influence of the three factors on the experimental results can be ranked as follows: temperature>Cl− > CO2. In this experiment, when the partial pressure of CO2 is 0.1 MPa, the temperature is 65°C, the concentration of Cl− is 1,20,000 mg/L, and Iscc of 316L tensile samples has a maximum of 26.8%.

Use of Stainless Steel Tubing in Boiling Applications for Shell and Tube Heat Exchangers

The use of stainless steel (SS) tubes in boiling applications must consider the potential risk of chloride stress corrosion cracking (SCC). Most steam generating tube bundles are carbon steel or low alloy steels, but occasionally, higher alloys are needed for the process side corrosion resistance. The use of SS tubes for these cases has had both successes and failures. SS has performed very well in other water and steam services, such as condensing, steam superheating, and boiler feed water (BFW) preheating applications, but for steam generating (i.e. boiling services) the experience has been mixed. Similar failures have also occurred in various process services which are being heated and contain water. The boiling of the water can lead to SCC. Some of the variables that can affect the risk of SCC for SS tube bundles in boiling services include: chloride concentration, tube wall temperature, exchanger design (i.e. kettle, thermosiphons, etc.), vertical vs. horizontal tubes, full vaporization vs. partial vaporization, recirculation rate, and BFW blow down rate. If SS materials are being considered, the risk of SCC can be determined by analyzing these variables as described in this paper. Where the risk of SCC cannot be avoided, an alternate, resistant tube material should be selected. The material options for various services are presented herein.