Application Research on Low-Temperature Ethylene Spherical Tank Fabricated With 07MnNiCrMoVDR

摘要

07MnNiCrMoVDR steel plate and tis corollary forgings and welding rods are selected to fabricate 1000m~3 low-temeprature ethylene spherical tank of high requirements. By reducing P and S contents in the steel, the actual quality level of 07MnNiCrMoVDR steel for-40degC application has reached the level of the steel for -45degC application. For low-temperature spherical tank, low-temperature impact toughness is an improtant paraemters for guaranteeing long-term safe operation o spherical tank. In order ot supply high-caliber spherical tank, the actuallevels of all the paltes for building spherical tank reach the average value of impact energy is greater than 80J(individual value is greater than 56J). Using the smelting prodess of electroslag remelting, the actual level of the corollary forgings of 08MnNiCrMoVD reaches that of forgings for-45degC application. In the process of spherical tank fabrication and site installation, the curvature, geometric dimensions and assembling dimensions of spherical petals are strictly controlled so that the notch gap, unfitness of butt joint and angular deforamtion etc. of the assembled spherical tank are far lower than the required limits by the national standards. The welding process parameters such as welding preheating temperature, interpass temperature, welding current, welding voltage, welding speped, welding heat input, postheat temperature and time are controlled so that hte percentage of one-pass for th welding of the four spherical tanks exceed 98