Data And Test Analysis Of Lost Efficacy On The Welding Welding Connection In The Coke Tower Between Chack Tower Between Tower Body And Its Skirt

Coke towers in a rei?inery have two major characteristics: ﹐f large volume ; (2) periodic operation in an alternative circular between high and low temperature .Both domestic and foreign experiences show that during the long term operation, lots of encircle cracks occur in the welding which connect the tower body and the skirt, which to the serious extent even caused the whole tower body split away from the skirt. But in the past, some refineries lacked deep understanding of mechanics for such damage and incorrectly thought the body should be reinforced. So they usually referred to the traditional way and conducted patch welding to strengthen the support ing bumps.But later they found cracks appeared very soon after the patch welding. The more patch welding, the more new cracks. Some refineries have no way but demolish the whole tower, thus caused great loss. The author of this thesis checked such damage in the Maoming Refinery, analyzed spot measuring data, developed computerized .emulation research and conducted stability analysis on the connecting weld area. He concludes that under the distortion and thermal load effect, which are caused by periodic change of operation load ( operation temperature, pressure, weight, etc.), the welding area stands an alternatively changing effect featuring high press, big deforming and edge effecting. Besides material mechanic performance will fall down under high temperature and material has its own micro defects. All these cause the fatigue of metals and flaws occur. The author also put forward his solution which is on the contrary to the traditional one, i.e. cut slot on the skirt to decrease its rigid restraint and partially transfer such restraint to the bottom part of the skirt. In this way the deforming ability of the connecting weld area isincreased while the thermal load decreased, thus realize the purpose of preventing dehisconce of welding . Maoming adopted such solution and after several operation, got satisfactory effect.Because the type and operation conditions of coke towers in domestic refineries are similar, this research finding is worth to be recommended nation widely.