According to the analysis, the source of thermal shock is found as follows: the original hydrophobic system is superheated steam, and the economizer and the reheating system are connected to the same parent tube for hydrophobicity, which is easy to cause high pressure and low temperature hydrophobicity. The hydrophobic pipe is poured into a reheater collecting header of a low pressure and high temperature to cause thermal fatigue, thereby causing thermal fatigue cracking. The trap of the reheater header is far away from the header, and water is easily accumulated in the drain. When the boiler is started, it is easy to generate thermal shock to the header, which causes thermal fatigue cracks. The determination of the crack treatment scheme, the method of removing the crack by using the hole, the method needs to check the diameter of the opening of the header. Determining the calculated pressure for the reheat steam line, the calculated pressure is taken to be 1.15 times the maximum rated working pressure of the boiler. Therefore, if the control box is used for the removal of the control hole, if the maximum allowable opening diameter is 135 mm without considering the reinforcement, the length of the crack according to the coloring inspection is larger than the allowable opening diameter, and the method cannot meet the requirements of the site. Due to the location of the junction box at the site, the construction is more difficult. There is a 159 mm steam communication pipe at the upper part of the header. The crack treatment is at the middle sill. The front and rear construction space is narrow (only one person stands), and the bottom of the header is only 30 cm from the boiler platform. These are for the processing header. Cracks bring a certain degree of difficulty. The treatment of on-site cracks often causes certain difficulties in crack treatment due to the limitation of construction conditions, so that cracks cannot be eliminated or new cracks can be brought about. Therefore, it is necessary to overcome the construction difficulties on site, and strictly comply with the requirements of the specification is a difficult point to completely eliminate cracks. Mechanical removal of pipe sections According to the Welding Code, alloy steel materials should be mechanically machined. Especially for headers with temperatures up to 540 °C, mechanical processing should be used. Ordinary mechanical tools are limited by field conditions, and it is not possible to process the headers up to 426 mm in diameter. The sections are often cut by electric welding or gouging. These methods have more or less influence on the material of the header, leaving The safety hazard, after the new defects are exposed, has to be solved by the entire header replacement. (Finish)

Oil And Air Separator Paper

Oil And Air Separator Paper