Regarding to construction conditions and taking site installation of reaction subsider and regenerator of 800, 000 t/a heavy oil catalysis unit as example, this paper introduces site assembly technology, assembly, welding model and auto - submerged are technology for large pressure vessel.

Heat treatment of large pressure vessel on spot is complicated construction technology. The requirement includes exact and reasonable thermal process calculation, economical and applicable technology design and meeting the needs of the project.

Regarding to construction conditions and taking site installation of reaction subsider and regenerator of 800, 000 t/a heavy oil catalysis unit as example, this paper introduces site assembly technology, assembly, welding model and auto - submerged are technology for large pressure vessel.

Heat treatment of large pressure vessel on spot is complicated construction technology. The requirement includes exact and reasonable thermal process calculation, economical and applicable technology design and meeting the needs of the project.

During one of the fabrication trials of a large pressure vessel made of 18 Ni 1800 MPa maraging steel plates, 7.8 mm thick, defects were observed in the welds which were to be repaired.

A large pressure vessel was used, which holds rock samples approx.

Part of it is a large pressure vessel containing the SF6 insulating gas at a pressure of 8 bar.

During one of the fabrication trials of a large pressure vessel made of 18 Ni 1800 MPa maraging steel plates, 7.8 mm thick, defects were observed in the welds which were to be repaired.

A large pressure vessel was used, which holds rock samples approx.

Part of it is a large pressure vessel containing the SF6 insulating gas at a pressure of 8 bar.

A large-scale pressure vessel, especially a spherical tank, is apt to have some defects of tsagger toes or angular distortion while it is welded assembly Such defects are even unavoidable-Some additional stresses will be raised by the effect of the hastening circle due to the internal pressure. If the additional stresses are excessive, they will become one of the important causes of a disaster. Therefore, it is badly needed to deal properly with the quantitative relation between the stagger toes, the angular...

A large-scale pressure vessel, especially a spherical tank, is apt to have some defects of tsagger toes or angular distortion while it is welded assembly Such defects are even unavoidable-Some additional stresses will be raised by the effect of the hastening circle due to the internal pressure. If the additional stresses are excessive, they will become one of the important causes of a disaster. Therefore, it is badly needed to deal properly with the quantitative relation between the stagger toes, the angular distortion and the additional stresses in order to well solve the problems of checking, repairing and using the pressure vessel safely.In this paper, the results of the determination of the additional stresses due to the stagger toes the angular distortion are described. The mechanical model for deriving the calculating formula is presented. The calculating formula of the additional stresses is derived. The structure of the formula is simple, the calculation is easy, and the calculating result is accurate. Besides, a measurement of the suitable angular distortion far the formula and the exchange relation between the numerical values determined respectively with this measurement and with the measurement set by the ministerial standard are presented.Finally, an analysis of the theory and the errors of the additional stresses is made

More a thousand large scale pressure vessel, spherical tank, are operating in our country. Some of them have been detected.Results detected confirm that the better part of these presure vessels contain various cracks and the other welding defects. Therefore thire operation has to be arrested and they have to be repaired in some degree. It is well known that the residtal stress is produced after welding. Effect of them on performance of the vessel is very bad.Understanding residual stress peak and distribution...

More a thousand large scale pressure vessel, spherical tank, are operating in our country. Some of them have been detected.Results detected confirm that the better part of these presure vessels contain various cracks and the other welding defects. Therefore thire operation has to be arrested and they have to be repaired in some degree. It is well known that the residtal stress is produced after welding. Effect of them on performance of the vessel is very bad.Understanding residual stress peak and distribution is of great realistic significance for the safe service of the pressure vessel. In this paper, the equipment and procedure of measuring residual stress on spherical tank by means of the small hole relaxation method with was investigated greatly at last few years was introduced. Quantity and distribution of residual stress in the regions measured was given out.

The engineering technicians decide construction plan for the techniqne design of heat treatment of large pressure vessel ofter welding in-situ mostly based on their experiences、 utilizing the Principle of heat conduction,the author calcnlated the measured data of 10 exsarnples of local heat treatments and set up a calcniating model and relative coeffi- cient that suites for engineering design.Such data and coefficients have been applied to the heat treatment after welding for large tower introduced from Japan....

The engineering technicians decide construction plan for the techniqne design of heat treatment of large pressure vessel ofter welding in-situ mostly based on their experiences、 utilizing the Principle of heat conduction,the author calcnlated the measured data of 10 exsarnples of local heat treatments and set up a calcniating model and relative coeffi- cient that suites for engineering design.Such data and coefficients have been applied to the heat treatment after welding for large tower introduced from Japan. In the light of analysis to the cylindrical structure the author considers;the axil heat conduction of cylindes and radial heat conduction of insulating glass wood belong to plate heat conduction.So it can be used for calcnlating with the formular of plate heat con- dution.According to the rate of temperature decrease specified in specification, the thermal insulation materials can be choosen and the thickness.covering area can be calculated and decided.The required quantity of heat during increasing temperature and maintaining constant temperature are calculated according to the conditions of thermal insulation.So the suitable heater can be choosen correcfly.