Susceptibility of steel to cracking-either by contact with gas in wet H_2S environments or near neutral solutions- is a dominant factor or residual life of gas-line pipes. Three different phenomena are concerned with cracking, namely hydrogen induced cracking (HIC), sulphide stress cracking (SSC) and stress orientated hydrogen induced cracking (SOHIC). Whereas laboratory test methods for HIC are established the situation is different in combination with stress. If the coating is damaged and a near neutral liquid medium is penetrating the pipe surface a strain induced crack might occur. This type of corrosion is named near neutral SSC (NNSCC). A qualified test method with simulated cyclic loading conditions was not available. A test stand including pulsating tension on a high level qualified for high strength steels, wet environments with pH-values between 2.7 (sour gas) and 8,3 (synthetic seawater) and bubbling several gases such as H_2S, CO_2 or N_2 through the best solution with controlled room temperature was developed. The test-method enables to qualify steels and pipes for line pipes in tests of short duration compared to lifecycles of line pipes.
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