Fitness-for-service (FFS) assessment is usually used to evaluate the residual strength or residual life of in-service pressure vessels with defects; for ultra-high pressure vessels, due to the high stress level in the shell and the relatively poor plasticity reservation of the material, any small defects or artificial damages on the inner wall are hidden dangers for fatigue failure. Hence fatigue failure is one of the failure modes that must be taken into consideration in the design of ultrahigh pressure vessels. If the ultra-high pressure vessels cannot fail in the mode of leakage before burst, the number of design cycles should be calculated according to the method of fracture mechanics. Therefore, the FFS assessment method should be introduced in the design stage to determine the allowable final crack depth. The FFS assessment method of API 579 has become one of the most widely used methods in the evaluation of pressure vessels with crack-like flaws. The crack-like flaws of ultra-high pressure vessels can be evaluated with level 2, including 12 steps. Finally, based on the failure assessment diagram (FAD), it can be determined whether or not a given crack and operating conditions are acceptable.

Boiling heat exchangers are widely used in petroleum, chemical and other industrial fields. However, the current assumption of the onset entrainment fraction of annular flow in the model for critical heat flux lacks theoretical basis. Based on the relevant experimental results and theoretical understanding of churn flow, the effects of the onset entrainment fraction on the accuracy of critical thermal load prediction is analyzed systematically. The results indicate that the larger droplet size and larger momentum within the churn flow zone have a greater impact on the downstream annular flow field characteristics, especially when the mass flow rate is higher, the selection of the onset entrainment fraction has a drastic effect on the critical heat load prediction accuracy and outlet dryness. Therefore, this paper proposes the improvement idea of advancing the onset calculation of the critical heat load prediction model from the onset of annular flow to that of the churn flow. The improved liquid film flow model not only provides higher prediction accuracy, but also is more in accord with the actual physical process.

The function of the liquid-vapor separation baffle is to divide the inner space of the container into two parts for holding different media. When only one side of the baffle is filled with materials, the stress and deformation of the baffle are large, and the baffle is easy to be damaged, thus causing safety risks. Based on the comparison of the analytical method for calculating the stress of the liquid-vapor separation baffle of the horizontal vessel, this paper deeply analyzed the bearing model and failure mode of the baffle, and investigated the stress and deformation laws of the liquid-vapor separation baffle of the large diameter horizontal vessel and the baffle with reinforced ribs with the help of the finite element analysis software. Meanwhile, the paper also investigated the influences of the thickness of the baffle, the size, position, number and the arrangement of the reinforced ribs on the maximum stress and deflection of the baffle. The following conclusions were obtained: increasing the thickness of the baffle to some extent can obviously improve the stress of the baffle, but when the thickness of the baffle reaches a certain value, increasing the thickness of the baffle cannot obviously improve the stress of the baffle; when arranging the reinforced ribs of the baffle, the area of the partitioned interval by the reinforced ribs should be as close to equal as possible, so that the force of the baffle can reach a better state; the recommended height to thickness ratio of the flat steel is 8~10; setting longitudinal reinforced ribs on the vertical axis of the baffle can improve the force of the baffle obviously; the number of reinforced ribs should be set reasonably and too many reinforced ribs will increase the welding workload and influence its economy.

Aiming at several typical combinations of tube plate and heat exchanger tube materials, ANSYS simulation stress analysis and tube expansion process test are adopted to determine the tube expansion pressure of the tube plate and expansion structure of heat exchanger tube in the shell and tube heat exchanger and to analyze and compare the tube expansion effects. This paper verifies the commonly used expansion pressure calculation methods and the reasonableness of setting pressure. It also analyzes the case of non-compliance with the expansion principles and the expansion effects of pipe holes that are out-of-tolerance slightly.

As a method to evaluate the capacity of flange connection system under external load, equivalent pressure method has the advantages of simple calculation and fast evaluation. It is widely used in petrochemical industry. However, the assessment of flange loadbearing capacity by this method cannot be quantified. Engineers can only compare the equivalent design pressure with the maximum allowable working pressure, resulting in conservative assessment results. This paper focuses on the study of the equivalent pressure method and discusses its conservatism combining with an engineering design case. It also introduces the external load correction coefficient to make it more reasonable to evaluate the reliability of flanges when adopting equivalent pressure method.

The oil-gas-water three-phase separator is an important production equipment for the treatment of high water-content crude oil in oilfield. FLUENT software was used to simulate the separation effect of the separators with different weir plate heights of 3.50 m, 3.30 m, 3.25 m, 3.15 m and 3.00 m respectively at a central platform in Chengdao Oilfield. The velocity fields of oil-gas-water phases and the concentration distribution chart of three phases inside the separators were obtained, and the separation effect at different oil weir plate heights was analyzed. According to the concentration distribution of gas, oil and water at the gas, oil and water outlets, the preferred oil weir plate height to meet the production index requirements for oil, gas and water separation was determined to be 3.30 m. The research shows that the oil weir plate height of separators affects the separation effect of the separators. Adjusting the height of the oil weir plate can solve the problem of high water alarm triggering in the separators and ensure the separation effects as well.

The vibration signals of the air valve of the reciprocating compressor is interfered by strong gas fluctuations. Aiming at such characteristics, this paper proposes a fault diagnosis method based on improved maximum correlation kurtosis deconvolution (MCKD) and refined composite multi-scale fuzzy entropy (RCMFE). Deconvolution of vibration signals of reciprocating compressor air valve using improved maximum correlation kurtosis deconvolution can extract the shock components of the signals effectively; after the deconvolution, the signals are analyzed by adopting the refined composite multiscale fuzzy entropy quantization to obtain the feature vectors of the fault diagnosis of reciprocating compressor air valve and the feature vectors are input in the support vector machine for fault feature identification. The analysis of experimental data of reciprocating compressor air valve faults shows that this method can extract the fault information of reciprocating compressor air valve effectively and realize the accurate diagnosis of air valve faults of reciprocating compressor.

This paper introduced the situation of stabilization tower reboiler furnace of a refinery company and the furnace baking process. It studied the traditional method for steam passing through the furnace tube. It was found that after adopting this method, the furnace outlet temperature was too high or the furnace temperature was too low, which affected the furnace baking effects. Previous furnace baking practice also confirmed the above problems. To solve these problems, a new baking method for furnace was studied. That is, using deoxygenation water vaporization as furnace tube protection medium for furnace baking. Through theoretical research, this method was completely feasible. After practical test, it fully met the requirements of baking furnace curve and good baking furnace effect was achieved. Steam consumption during furnace baking was reduced. This has achieved good effect of energy saving and consumption reduction. The new method for furnace baking can be widely used in reboiler furnace.

For gas cylinders and other typical special equipment, the quality and safety traceability involves many links; the collection workload of traceability information is heavy; dynamic changes occur in the process with the use of special equipment. Aiming at such problems and based on the analysis of gas cylinder quality and safety traceability system architecture and traceability business process, this paper studied and established the Petri net model for quality safety traceability of gas cylinder and other special equipment. Meanwhile, the Petri net simulation tool PIPE is used to simulate and verify the model performances such as the boundedness, safety, accessibility and activity and so forth. The results proved the reliability, reasonability and robustness of the model system. This can provide an effective way to build and optimize the quality traceability system of special equipment.

In recent years, the number of failures such as sudden rise of bearing temperature and jamming of slide valve occurred during the operation of the equipment has been increasing. However, during the disassembly and inspection process, no major equipment problems were found and only some coking materials and carbon laydown were found. After simple cleaning and putting into operation for some time, the same failure would occur again. The problem was studied and the cause of the failure was found to be varnish. This paper expounds the formation principles of varnish, the hazards of varnish, and lubricating oil detection. It introduces several commonly used equipment for varnish removal. At the same time, it compares and analyzes the data before and after the practical application of two varnish removal equipment. The results show that the application of varnish removal equipment reduces the MPC. In addition, conventional lubricating oil detection cannot meet current production requirements, and targeted detection programs need to be developed based on actual lubricating oil application scenarios.

Aiming at the failure case of stress corrosion cracking of steel No. 20 welded with over-matching J507 electrode under wet H₂S condition in petrochemical plant, this paper carried out the sensitivity test of the cracking of steel No. 20 welded with different matching electrodes in hydrogen sulfide corrosion medium. And it studied and analyzed the cracking causes from such aspects as the chemical composition of weld material, the strength, hardness and microstructure and so forth. The paper identified the reasons why the joints welded with over-matching J507 welding electrode for steel No. 20 are more prone to SSCC than those welded with equal matching J427 (or J422) welding electrode. In order to avoid the above problems, the paper puts forward relevant suggestions on equal matching base metal and welding material.

The three-stage cyclone separators of flue gas in catalytic unit is important static equipment in the unit. Among them, the vertical three-stage cyclone separator is the most widely used. Its efficient operation is the guarantee of the long-period efficient operation of the equipment such as flue gas turbine and boiler. Efficiency and reliability of the three-stage cyclone separators are the concern of the industry. Research shows that singletube blowdown cone structure has higher efficiency, but engineering practices prove that its drift diameter should match the dust load, otherwise catalyst dust scale may appear easily, resulting in failure of the single tube. The use of a larger diameter blowdown cone can maintain the flexibility of single tube operation and improve its reliability, which is the key to prevent fouling and maintain the long-cycle operation of the flue gas turbine.

Polyolefin plant is the main unit of benefit output in certain petrochemical company. The operation state of circulating gas compressor determines the stability rate of the plant, which directly affects the completion of annual benefit index of the petrochemical company. The vibration of the bearing bush on the motor coupling side of the Japanese Kobe DH9M circulating gas compressor was always on the high side after the device was shut down for maintenance. During this period, it was treated for many times in the window period, but the effect was not obvious. During one year's operation, the vibration fluctuation frequency and amplitude increased and reached the alarm value for many times. The SG8000 online monitoring system is used to analyze and diagnose the fault causes. The causes of the fault was analyzed and diagnosed through the SG8000 online monitoring system. And the results showed that it was caused by the soft rubbing at the motor drive end. This diagnosis was verified during the overhaul. After shutdown for implementation of treatment measures, the unit ran smoothly and the vibration fault was fundamentally solved.