The safety valve is the last barrier to ensure the safety of petrochemical equipment. The more accurate the prediction of the risk of safety valve failure, the more conducive it is to the safe long-term operation of petrochemical equipment and the reasonable arrangement of safety valve maintenance plans. To efficiently and accurately predict the failure risk of safety valves, a risk assessment method based on XGBoost algorithm for safety valve failure is proposed. The method is a data-driven prediction method based on the XGBoost algorithm modelling, and the key feature parameters affecting the failure risk of safety valves are preferred to predict safety valve failure risk. The experimental data indicate that this method has good performance in predicting safety valve failure risk with an accuracy of 94.0% on the safety valve test set, which is better than the accuracy of traditional machine learning methods. In addition, this method can also provide reference basis for the determination of test and calibration cycle of safety valves.

In the petrochemical sector, it is often considered that the internal floating roof tanks can reduce the incidence of fire in such tanks by reducing the volatilization of oil and gas because of the internal floating roof core component. However, there are still reports of fire accidents in practical applications. This paper analyzes the types, application characteristics and disadvantages and shortcomings of commonly used internal floating deck products in China, and provides an overview of common fire safety issues based on the installation, use and maintenance of internal floating decks. Based on this, it analyzes the main design ideas of various new internal floating deck products developed through structural design and optimization at the present stage. Meanwhile, it compares and summarizes the fire protection requirements and the current status of fire resistance testing standards for internal floating decks covered in domestic and international standards and specifications. Finally, the paper discusses the defects of the internal floating roof tanks used in the domestic petrochemical storage and transport sector at this stage, the differences in fire safety research on internal floating dicks at home and abroad, and the future development focus of this component product.

In recent years, frequent cracking has occurred in the water walls of DG-2070/17.5-II4 type boilers during operation in a thermal power plant. This study focuses on the typical tube burst positions at the junction between the boiler water wall and the enclosure wall superheater under deep peak shaving. The finite element analysis models are established to evaluate the effects of different heating rates and the final temperature inside the boiler on the thermal stress and deformation at these typical tube burst positions. The results indicate that obvious thermal transition zones and stress concentration points are the primary causes of tube damage. The higher final temperature inside the boiler is the main factor leading to damage at the T-junction, while the influence of the heating rate on structural damage is relatively limited. Based on the results of the above study, it is recommended that the discontinuities at the T-junction should be reduced and the connection method of fins and tubes should be optimized, thereby mitigating the impact of flow-induced vibration and preventing tube burst.

Plastic collapse failure is one of the key failure modes for pressure vessels under the condition that load is applied once. A dual evaluation criterion for plastic collapse is introduced in this paper. The criterion integrates the design concept of strength criteria based on ASME code and deformation criteria based on EN standard, and also borrowing the ideas of determining allowable stress. It can prevent both plastic collapse and excessive plastic deformation. The evaluation of the criterion can be carried out by the load-resistance coefficient method based on elastic-plastic analysis. Elastic-plastic analysis shall use the real stress-strain curve of the material and consider the geometric nonlinear effects. Taking the large opening nozzle on cylindrical shell as example, this paper introduces the realization method of this criterion in finite element software and evaluation steps in detail. Compared with the result of stress classification, it is found that the evaluation criteria by stress classification method for plastic collapse failure may be too conservative for some structures. The dual criterion is more advanced and accurate, and can provide a more reasonable solution.

Aiming at the tilting-pad bearing of the introduced compressor, the influence rules of rotating speed, tile clearance, oil inlet pressure and oil inlet temperature on the dynamic and static characteristics of tilting-pad bearings were calculated and analyzed by using sliding bearing performance database technology. The results show that with the increase of the tile clearance, the oil film force, friction power consumption and tile temperature decrease, while the oil film thickness, oil intake and oil discharge of tile increase; with the increase of the oil inlet temperature, the oil film force, the friction power consumption and the minimum oil film thickness decrease, and the watt temperature increases accordingly; within the range of 0.10 to 0.20 MPa of the inlet pressure, the oil inlet, oil drain and friction power consumption increase slightly with the increase of the oil inlet pressure, while the eccentricity, oil film force, watt temperature and the minimum film thickness are basically unchanged with the increase of the oil inlet pressure. The research results are of certain guiding significance for the design and maintenance of the unit bearing. Based on the above research results and domestic technologies, the substitution of an imported compressor bearing has been achieved.

Sedimentation centrifuge is widely used in the field of solid-liquid separation. Centrifuge separation performance is an important performance index of equipment. This paper introduces the design principles and structure of HDPE horizontal sedimentation centrifuge. It analyzes the factors affecting the centrifuge separation performance from such aspects as the centrifuge rotary drum diameter, length-diameter ratio of rotary drum, half-cone angle of rotary drum, particle size and material viscosity and so forth in the hope of providing guidance for production and operation and providing reference for the operation of related equipment of similar devices.

Welding of heat exchange tube to tubesheet joint is a key process in the fabricating process of heat exchanger. The quality of strength welding joint should ensure both the pulling-out force and tightness of the joints. The connection quality impacts on the safety and stability operation of the heat exchanger directly. This paper analyzes and compares the requirements of relevant domestic and foreign standards for strength weld seam size. According to the results of the comparative study, it is recommended that the GB/T 151 standard should be unified with the foreign codes and standards when it is revised; the minimum leak path dimension a₀ should be adopted and the criteria for this weld seam size is suggested.

This paper introduced the short service life and frequent replacement of mechanical seals of the decompression tower bottom pump of an atmospheric and vacuum distillation unit, as well as the obvious axial displacement detected during startup and shut-down by on-line monitoring. Based on the comprehensive analysis on the running condition of the pump, the paper proposed a specific scheme to improve the pump head structure and sealing type of the pump. This has solved the problem of axial displacement of the pump and frequent seal failures, prolonged the operating cycle of the pump and eliminated the potential safety hazards of high-temperature oil pump during operation.

The reliability of the steam inlet regulating valve determines whether the steam turbine can operate for a long period of time or not, which in turn affects the output and the overall benefits of the company. This paper introduces the structural characteristics and fault causes of the control valve of the steam turbine driven by cracking gas compressor unit in certain chemical enterprise. It focuses on analyzing the adjustment methods and technical points of the inlet control valve. The results show that the use of this adjustment method can not only reduce the maintenance time, but also ensure the maintenance quality, which saves the cost for the device maintenance and provides strong guarantee for the stable operation of the device as well. This method is an innovation of the previous overhaul methods based on the familiarity with the working principles of machinery and instrument control. It can provide feasible implementation plan for the same industry in regulating gas valve overhaul, and provide reference for the improvement of the reliability of the valve beam in practical use.

Carrying out compliance checking of old equipment design documents is conducive to accurately controlling the risks accumulated in the development process of the refining and chemical industry. It is an inevitable requirement for overall development and safety. In this paper, the text data in the static equipment design documents of the old device is studied by machine learning algorithm, and the data analysis model is constructed, aiming to obtain and analyze the key information of the old device that does not meet the compliance of the design documents. The research mainly consists of three aspects: the first is to use data preprocessing method for data cleaning; the second is to use TextRank algorithm to achieve automatic acquisition of the keywords and key phrases in a large number of texts; the third is to use LDA algorithm to train the topic model to automatically generate the key topics in the text. The results obtained from this method can assist experts in rapid and accurate investigation and assessment of safety risk information of old equipment.

When it is necessary to perform post-weld stress relief heat treatment for the on-site assembly and welding of supersized towers, the overall heat treatment method with better effect is recommended preferentially in the codes and standards. The on-site vertical overall heat treatment method was adopted to release post-weld stress for the 76.5-meter-high propylene tower described in this paper. However, the structural strength of the tower decreases with high temperature, which poses risks of failure. A 78-meter-high scaffold was erected on site for the vertical assembly welding and heat treatment of the tower. The thermal expansion of the tower during heat treatment which may result in an increase in height and diameter should be taken into consideration for the scaffold. Therefore, the scaffold could not be held against the tower wall and it needed to maintain a certain distance from the tower wall. How to set up this kind of standalone scaffold to ensure safety? The use of internal combustion method for overall heat treatment is economical, practical and efficient., but how to set up the burner to prevent the tower internals from being burned and deformed? This series of problems were the difficulties in implementing this scheme. In this paper, finite element analysis software ANSYS was used to analyze the structural stress during the overall heat treatment process of the propylene tower. The results showed that the strength, rigidity and stability of the tower during the heat treatment process could meet the requirements. Aiming at the above series of difficulties, corresponding countermeasures have been taken to ensure the safe and smooth completion of the overall heat treatment of the tower. The treatment method in the paper can provide reference for the construction of vertical overall heat treatment of large towers.

Dissimilar steel is used to weld the connection between the preheating pipe segment of cracking raw materials and the preheating coil. In the production process, corrosion leakage occurs successively in the cracking furnace for light hydrocarbon medium. In order to find out the causes of pipeline corrosion failure and leakage and to solve the problem completely, the failure analysis of the pipeline section where leakage occurs is carried out through macroscopic inspection, chemical composition analysis, hardness test and microscopic electron microscope scanning combining with the composition of corrosion products. According to the analysis, the galvanic corrosion of dissimilar steel formed in this pipe section due to changes in working conditions during the production process was the root cause of the corrosion leakage. Aiming at the above causes, corresponding solutions were proposed and these methods were adopted to improve three of the cracking furnaces. At present, the three cracking furnaces are operating well and no further corrosion leakage have been detected.