Specific technical measures for SSCC prevention

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Combined with the background of previous LPG storage tank SSCC cases, the following are specific technical measures that can be implemented directly.: 1. Materials and welding control Strictly control the steel hardness ≤HRC22, select low-sulfur, low-phosphorus anti-SSCC special steel, add chromium, titanium and other alloying elements to improve cracking resistance. The preheating temperature before welding is controlled at 150~250℃, and post-heating hydrogen elimination treatment at 250~350℃ is performed after welding. Finally, the residual stress of the weld is eliminated through overall heat treatment to avoid stress concentration. 2. Medium environment control: Deep desulfurization controls the H₂S partial pressure below 0.0003MPa. The medium pH value is stably maintained at 9~11 by adding corrosion inhibitors, which greatly reduces corrosion sensitivity. Equipped with a water removal process to completely eliminate the water environment generated by wet hydrogen sulfide and cut off the conditions for the occurrence of SSCC from the root. 3. Protection and Monitoring Technology The inner wall of the storage tank is coated with a dense inorganic anti-corrosion coating such as ZS-711, coupled with a cathodic protection system to completely isolate the contact between hydrogen sulfide and the steel matrix. Magnetic particle and ultrasonic non-destructive testing of welds are carried out regularly, and online hydrogen probes are used to monitor the hydrogen penetration rate in real time to catch early hidden dangers of SSCC in advance. 4. Operation and maintenance compliance management and control Strictly follow the NACE TM0177 standard to conduct anti-SSCC performance evaluation, and complete comprehensive tank inspections every 3 to 6 years in accordance with GB/T 18442 specifications to ensure full-cycle operation safety.