Non-Linear Numerical Analysis of Large-Sized Double-Cone Sealing Process

2009 ◽  
Author(s):  
Shui-ping Sheng ◽  
Shu-xin Han ◽  
Jin-yang Zheng ◽  
Yong-jian Gao ◽  
Ning Zhou
Keyword(s):  
Internal Pressure ◽  
Working Conditions ◽  
Double Cone ◽  
Radial Clearance ◽  
Ring Strain ◽  
Tightening Force ◽  
Contact Algorithm ◽  
Fea Model ◽  
Sealing Performance ◽  
Nonlinear Contact

An integral FEA model and a nonlinear contact algorithm were emplyed for the double-cone seal structure, which were applied on the large-sized double-cone seal structure under internal pressure. The stress distribution of double-cone ring and gasket under pre-tightening and working conditions, as well as the influence of pre-tightening force and internal pressure on the gasket stress, double-cone ring strain and radial clearance, were obtained. If the radial clearance was designed according to g⩾0.1% D1, the material of double-cone ring would yield globally. Meanwhile, If the radial clearance was designed according to g⩽0.05%D1, the sealing performance in the pressurizing process would not be ensured. A radial clearance g=(0.075%∼0.1%)D1 is recommended.

Leak Behavior and Prediction of Metal Ring Joint Gaskets in Simplified Leak Test With Grooved Platen

2019 ◽  
Author(s):  
Yuya Omiya ◽  
Masahiro Fujii
Keyword(s):  
Internal Pressure ◽  
Evaluation Method ◽  
Compressive Force ◽  
Metal Ring ◽  
Leak Test ◽  
Tightening Force ◽  
Flange Connection ◽  
Sealing Performance ◽  
Sealing Mechanism ◽  
Very High

Abstract Pipe flange connection with metal gasket is used under high temperature and pressure in place required high sealing performance. It has been known that gasket compressive force, which is closely related the leakage decreases by internal pressure action. Since the pressure is very high in metal gaskets, the sealing performance evaluation in internal pressure action is important. However, there is little research that evaluates a little leakage, metal gasket is empirically used up to the present time. Therefore, evaluated sealing performance of metal gasket, it is necessary to clarify the sealing mechanism. In this study, evaluated effect that decreasing of gasket compressive force affects leakage in both octagonal type and oval type in ring joint gasket by simplified leak test using grooved platen and finite element method stress analysis, evaluation method of leakage in metal gasket is proposed. Based on this evaluation method, decision method of initial tightening force that guaranteed one amount of leakage to design internal pressure is shown in pipe flange connection with metal gasket.

Application of Plastic Region Bolt Tightening to Flange Joint Assembly: Behavior of Large Diameter Flange

2009 ◽  
Author(s):  
Shinobu Kaneda ◽  
Hirokazu Tsuji
Keyword(s):  
Internal Pressure ◽  
Large Diameter ◽  
Plastic Region ◽  
Load Factor ◽  
Past Study ◽  
Flange Joint ◽  
The Past ◽  
Sealing Performance ◽  
Assembly Behavior ◽  
Bolted Flange

In the past study the plastic region tightening has been applied to the bolted flange joint with smaller nominal diameter and its advantages have been demonstrated, however, behavior of the bolted flange joint with larger diameter is not investigated. Flange rotation of the bolted flange joint with large diameter increases when the internal pressure is applied. Gasket stress is not uniform and it may cause leak accident. So, it is necessary to investigate the behavior of the larger diameter flange. The present paper describes the behavior of bolted flange joint with large diameter under plastic region tightening. Firstly, API 20-inch flange joint tightened to the plastic region by bolt with a smaller diameter and superiority in the uniformity of the axial bolt force is demonstrated. And then the internal pressure is applied to the bolted flange joint and the behavior of the additional axial bolt force is demonstrated. The axial bolt force decreases with increasing the internal pressure, and the load factor is negative due to increasing of the flange rotation. However, the load factor of the bolted flange joint tightened to the plastic region by using the bolt with the smaller diameter approached zero. Using the bolts with smaller diameter is advantageous to the flange joint with the larger diamter, whose load factor is negative, to prevent the leakage. Additionally, the leak rate from the bolted flange joint is measured and the sufficient sealing performance is obtained.

An Analysis of Pipe Flange Connections Using Epoxy Adhesives/Anaerobic Sealant Instead of Gaskets

1995 ◽  
Vol 117 (4) ◽  
pp. 298-304 ◽  
Author(s):  
T. Sawa ◽  
R. Sasaki ◽  
M. Yoneno
Keyword(s):  
Stress Distribution ◽  
Internal Pressure ◽  
Theory Of Elasticity ◽  
Experimental Results ◽  
Clamping Force ◽  
Bonding Force ◽  
Epoxy Adhesives ◽  
Analytical Results ◽  
Sealing Performance ◽  
Circle Diameter

This paper deals with the strength and the sealing performance of pipe flange connections combining the bonding force of adhesives with the clamping force of bolts. The epoxy adhesives or anaerobic sealants are bonded at the interface partially instead of gaskets in pipe flange connections. The stress distribution in the epoxy adhesives (anaerobic sealant), which governs the sealing performance, and the variations in axial bolt force are analyzed, using an axisymmetrical theory of elasticity, when an internal pressure is applied to a connection in which two pipe flanges are clamped together by bolts and nuts with an initial clamping force after being joined by epoxy adhesives or anaerobic sealant. In addition, a method for estimating the strength of the combination connection is demonstrated. Experiments are performed and the analytical results are consistent with the experimental results concerning the variation in axial bolt force and the strength of combination connections. It can be seen that the strength of connections increases with a decrease in the bolt pitch circle diameter. Furthermore, it is seen that the sealing performance of such combination connections in which the interface is bonded partially is improved over that of pipe flange connections with metallic gaskets.

Effects of Scatter in Bolt Preload of Pipe Flange Connections With Gaskets on Sealing Performance

2003 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Mitsuhiro Matsumoto ◽  
Satoshi Nagata
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Internal Pressure ◽  
Control Method ◽  
Torque Control ◽  
Stress Distributions ◽  
Flange Connection ◽  
Gas Leakage ◽  
Bolt Preload ◽  
Sealing Performance

It has been well known that a scatter in axial bolt forces of pipe flange connections tightened by the torque control method is substantial. It is necessary for evaluating the sealing performance of the pipe flange connections with the gaskets subjected to intemal pressure to know the contact gasket stress distributions due to the scatter of the axial bolt forces in the connections tightened by the torque control method. This paper deals with the leakage of the pipe flange connections with a spiral wound gasket and that with a compressed sheet gasket tightened by the torque control method. The scatter in the axial bolt forces was measured in the experiments. The contact gasket stress distributions at the interfaces of the pipe flange connections with the gaskets were calculated under the measured axial bolt forces by using elasto-plastic finite element method (FEM) taking into account hysteresis and non-linearity in the stress-strain curves of the gaskets. The effects of the scatter in the axial bolt forces tightened by the torque control method on the gas leakage were also examined by using the actual pipe flange connections. As the result, a difference in an amount of gas leakage measured was found to be substantial between our study and PVRC procedure. By using the calculated contact gasket stress distributions under the internal pressure and the results of the leakage tests, the sealing performance was evaluated. It is found that the sealing performance is worse in the actual pipe flange connection than that evaluated by PVRC procedure.

FEM Stress Analysis and the Sealing Performance Evaluation in Stainless Steel Elbow and Tee Fittings Under Internal Pressure: Case Where Internal Fluid is Liquid

2004 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Hideaki Shimazu
Keyword(s):  
Stainless Steel ◽  
Internal Pressure ◽  
Stress Analysis ◽  
Chemical Plants ◽  
Three Dimension ◽  
Sealing Performance ◽  
Internal Fluid ◽  
Calculated Stress ◽  
Stress States ◽  
Screw Threads

Stainless steel fittings such as elbows, tees, nipples and so on have been widely used in mechanical structures and chemical plants, it is well known that the leakage in the fittings used sealing tapes is less than that without the sealing tapes. In a practical design, it is necessary to examine the stress states and the leakage in the fittings under internal pressure and external loads such as tensile loads, bending moments and so on. This paper deals with the FEM stress analysis of the fittings subjected to internal pressure. In the FEM calculations, the engaged screw threads are taken into consideration as helical threads in the three-dimension. The leakage tests for the fittings under internal pressure were also conducted by using liquid (oil). Using the results of the leakage tests and the calculated stress states in the fittings, the sealing performance of the fittings under internal pressure was evaluated and the effect of the tightening torque was clarified on the sealing performance. In addition, the numerical results were compared with the experimental results. As the result, the effects of the sealing tapes on the contact stress distributions were also clarified.

Winding-Autofrettage Study on Reinforced Thermoplastics Vessel Based on ANSYS ACP

2018 ◽  
Author(s):  
Jinhao Huang ◽  
Chenghong Duan ◽  
Liang Wu ◽  
Xiangpeng Luo
Keyword(s):  
Stress Distribution ◽  
Internal Pressure ◽  
Working Conditions ◽  
High Density Polyethylene ◽  
Working Condition ◽  
Filament Winding ◽  
Working Pressure ◽  
Cooling Method ◽  
Plastic Stage ◽  
Reinforced Thermoplastics

The process, by applying an internal pressure higher than the working pressure in advance after completion of the winding to cause the liner entering the plastic stage and producing the corresponding permanent plastic deformation for the purpose of improving the carrying capacity of the vessel, is called internal pressure autofrettage. In this paper, for the high-density polyethylene liner filament winding vessels which are winded by the equivalent cooling method, the ANSYS ACP module is used to analyze the stress distribution under autofrettage condition and working condition. The influence of autofrettage pressure and cooling temperature on the stress distribution under the working conditions of the vessel is addressed. This study could provide a reference for the optimization of winding process.

Experimental and Analytical Leak Characterization for Axial Through-Wall Cracks in a Liquids Pipeline

2014 ◽  
Author(s):  
Mohamed R. Chebaro ◽  
Nader Yoosef-Ghodsi ◽  
David M. Norfleet ◽  
Jason H. Bergman ◽  
Aaron C. Sutton
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Internal Pressure ◽  
Crack Opening ◽  
Full Scale ◽  
Leak Rate ◽  
Propagation Mechanism ◽  
Element Analysis ◽  
Fea Model ◽  
Experimental Findings

Three pipeline sections containing defects of interest were non-destructively tested in the field, cut out and shipped to a structural laboratory to undergo full-scale testing. The common objectives of the experiments were to determine (1) the leak initiation pressure and (2) the leak rate at various specified internal pressures. While two spools (Specimens A and B) contained through-wall cracks, the third (Specimen C) had a partial through-wall crack with similar characteristics. The capacity of through-wall defects to withstand a level of internal pressure without leaking is due to the resultant local, compressive hoop residual stresses. Specimen C underwent full-scale pressure cycling to further comprehend the crack propagation mechanism in order to correlate it to field operation and analytical fatigue life predictions. To enhance the understanding of the physical crack behaviour as a function of internal pressure, a comprehensive finite element analysis (FEA) model was built using SIMULIA’s Abaqus software. The model inputs incorporated results from the above-mentioned laboratory tests, in addition to extensive radial, circumferential and axial residual stress measurements using the X-ray diffraction (XRD) technique, obtained on three pipe spools cut out from the same line. The resulting crack opening parameters from FEA were input into a closed-form fluid mechanics (FM) model, which was calibrated against a computational fluid dynamics (CFD) model, to determine the corresponding leak initiation pressures and leak rates. These outcomes were then compared to experimental findings. The FEA and FM models were subsequently employed to carry out a parametric study for plausible combinations of feature geometries, material properties, operational pressures and residual stresses to replicate field conditions. The key outcome from this study is the experimental and analytical demonstration that, for given fluid properties and pressures, the leak threshold and leak rate for through-wall cracks are primarily dependent upon the crack geometry and local residual stress distributions.

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