Development of Materials, Design, Calculation and Testing of High Pressure Equipment, Especially for Low Density Polyethylene Plants

2002 ◽  
Author(s):  
Johannes Schedelmaier ◽  
Manfred Po¨lzl
Keyword(s):  
High Pressure ◽  
Fatigue Strength ◽  
Fatigue Testing ◽  
Basic Knowledge ◽  
Surface Finishing ◽  
Cold Forming ◽  
Safety Requirements ◽  
Material Characteristics ◽  
High Pressure Equipment ◽  
Load Conditions

The trend of new projects for polyethylene plants indicates a significant increase of production capacity per year. There is a continuous enlargement of pressurised cross sections in the product line of heat exchanger, reactor and remote controlled valves. Consequently an essentially higher load has to be considered on the installed high pressure equipment. Basic knowledge about process and load conditions including pressure pulsation are the fundamental information provided by the process licensor for product optimisation. The level and amplitude of pulsation have a very significant impact on lifetime of the equipment. Cyclic load conditions and measures for improvement of fatigue strength are indicated on diagrams and described. In order to follow the process licensor and safety requirements detailed investigations on proper material selection and improvement of mechanical properties have been performed. Fatigue analysis and fatigue testing are included in the material evaluation. Modern steel technology like vacuum technology, electroslag remelting, heat treatment of special steels, several further hot and cold forming processes and autofrettage are mandatory to achieve an optimised product with satisfactory lifetime, which also fulfils the safety requirements. References to material characteristics including fatigue testing are available from literature, Universities, research laboratories and manufacturers. Parameters like geometry, surface finishing and autofrettage have also an essential impact on fatigue strength. Further activities including fatigue testing with different parameters and load conditions are needed in the future in order to extend the available information about material characteristics and design criteria for high pressure applications.

OVAKO 803 J/EN 100CR6

Alloy Digest ◽  
2008 ◽  
Vol 57 (7) ◽  
Keyword(s):  
Fatigue Strength ◽  
North America ◽  
Physical Properties ◽  
Tensile Properties ◽  
Heat Treating ◽  
Cold Forming ◽  
Bearing Steels

Abstract Ovako 100Cr6 comprises a group of through-hardening bearing steels with modification to improve machining, cold forming, and cleanliness for better fatigue strength. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on casting, forming, and heat treating. Filing Code: SA-582. Producer or source: Ovako North America Inc.

Fatigue Life Improvement of Welded Elements and Structures by Ultrasonic Impact Treatment

2011 ◽  
Author(s):  
Yuriy Kudryavtsev ◽  
Jacob Kleiman
Keyword(s):  
Mechanical Properties ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Residual Stresses ◽  
Fatigue Testing ◽  
Highway Bridges ◽  
Surface Layers ◽  
Ultrasonic Impact Treatment ◽  
Stress Relieving ◽  
Life Improvement

The ultrasonic impact treatment (UIT) is relatively new and promising process for fatigue life improvement of welded elements and structures. In most industrial applications this process is known as ultrasonic peening (UP). The beneficial effect of UIT/UP is achieved mainly by relieving of harmful tensile residual stresses and introducing of compressive residual stresses into surface layers of a material, decreasing of stress concentration in weld toe zones and enhancement of mechanical properties of the surface layers of the material. The UP technique is based on the combined effect of high frequency impacts of special strikers and ultrasonic oscillations in treated material. Fatigue testing of welded specimens showed that UP is the most efficient improvement treatment as compared with traditional techniques such as grinding, TIG-dressing, heat treatment, hammer peening and application of LTT electrodes. The developed computerized complex for UP was successfully applied for increasing the fatigue life and corrosion resistance of welded elements, elimination of distortions caused by welding and other technological processes, residual stress relieving, increasing of the hardness of the surface of materials. The UP could be effectively applied for fatigue life improvement during manufacturing, rehabilitation and repair of welded elements and structures. The areas/industries where the UP process was applied successfully include: Shipbuilding, Railway and Highway Bridges, Construction Equipment, Mining, Automotive, Aerospace. The results of fatigue testing of welded elements in as-welded condition and after application of UP are considered in this paper. It is shown that UP is the most effective and economic technique for increasing of fatigue strength of welded elements in materials of different strength. These results also show a strong tendency of increasing of fatigue strength of welded elements after application of UP with the increase in mechanical properties of the material used.

Investigating Fatigue Strength of Vacuum Carburized 17CrNi6-6 Steel Using a Resonance High Frequency Method

2014 ◽  
Vol 225 ◽  
pp. 45-52 ◽  
Author(s):  
Piotr Kula ◽  
Konrad Dybowski ◽  
Sebastian Lipa ◽  
Robert Pietrasik ◽  
Radomir Atraszkiewicz ◽  
...  
Keyword(s):  
High Pressure ◽  
Fatigue Strength ◽  
High Frequency ◽  
Vacuum Carburizing ◽  
Frequency Method ◽  
Single Degree Of Freedom ◽  
Bending Fatigue ◽  
Single Degree ◽  
Bending Fatigue Strength ◽  
Frequency Changes

The bending fatigue strength of 17CrNi6-6 steel subjected to vacuum carburizing with high pressure gas hardening has been measured using a novel high-frequency technique. The test records the changes in resonance and consists of observing resonance frequency changes in a vibrating system with a single degree of freedom as a result of the forming of a fatigue crack. Moreover, a mechanism of fatigue nucleation and propagation in steel hardened by vacuum carburizing is presented.

scholarly journals Fatigue Strength Analysis of S34MnV Steel by Accelerated Staircase Test

2020 ◽  
Vol 10 (1) ◽  
pp. 394-400 ◽  
Author(s):  
I. M. W. Ekaputra ◽  
Rando Tungga Dewa ◽  
Gunawan Dwi Haryadi ◽  
Seon Jin Kim
Keyword(s):  
Standard Deviation ◽  
Fatigue Strength ◽  
Fatigue Limit ◽  
Fatigue Testing ◽  
Reliability Estimation ◽  
Test Method ◽  
Strength Analysis ◽  
Staircase Method ◽  
Staircase Test ◽  
Number Of Cycles

AbstractThis paper presents the reliability estimation of fatigue strength of the material used for crank throw components. The material used for crank throw components is forged S34MnV steel and subsequently heat-treated by normalising and tempering. High cycle fatigue testing under fully reversed cycling (R = −1) was performed to determine the fatigue limit of the material. The staircase test method is used to obtain accurate values of the mean fatigue limit stress until a number of cycles up to 1E7 cycles. Subsequently, the fatigue test results depend strongly on the stress step and are evaluated by the Dixon-Mood formula. The values of mean fatigue strength and standard deviation predicted by the staircase method are 282 MPa and 10.6MPa, respectively. Finally, the reliability of the design fatigue strength in some selected probability of failure is calculated. Results indicate that the fatigue strength determined from accelerated staircase test is consistent with conventional fatigue testing. Furthermore, the proposed method can be applied for the determination of fatigue strength and standard deviation for design optimisation of S34MnV steel.

Fatigue Assessment of Welded Joints Taking Into Account Effects of Residual Stress

2010 ◽  
Author(s):  
Nur Syahroni ◽  
Stig Berge
Keyword(s):  
Residual Stress ◽  
Fatigue Strength ◽  
Welded Joints ◽  
Fatigue Testing ◽  
International Association ◽  
Hot Spot ◽  
Mean Stress ◽  
Element Analysis ◽  
Structural Rules ◽  
Fatigue Design

Residual stress may have a significant effect on the fatigue strength of welded joints. As a non-fluctuating stress, it has an effect similar to that of the mean stress. Recently the International Association of Ship Classification Societies (IACS) has issued Common Structural Rules (CSR) for respectively tankers (IACS 2006a) and bulk carriers (IACS 2006b). The effect of mean stress in fatigue design is taken into account in both sets of rules. However, the treatment is quite different, in particular with regard to residual stress and shakedown effects. In the present paper a comparative study of fatigue design procedures of the IACS rules is reported, with emphasis on residual stress effects. Testing was carried out with longitudinal attachment welds in the as-welded condition. The initial residual stress was measured by a sectioning method using strain gages. Hot spot stress was determined experimentally by strain gauges and numerically by finite element analysis using different types of elements. Fatigue testing was carried out and SN-curves were plotted according to the relevant stress as specified by the rules. In order to investigate the shake-down effect of residual stress, testing was performed for several pre-load conditions which could be taken to represent maximum load levels in a load history. The aim of the study is to contribute towards better understanding of the effect of residual stress and shakedown on fatigue strength of welded joints.

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