A Noncyclic Method for Determination of Accumulated Strain in Stainless Steel 304 Pressure Vessels

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Gongfeng Jiang ◽  
Gang Chen ◽  
Liang Sun ◽  
Yiliang Zhang ◽  
Xiaoliang Jia ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Internal Pressure ◽  
Pressure Vessel ◽  
Peak Stress ◽  
Pressure Vessels ◽  
Experimental Results ◽  
Elastic Domain ◽  
Ratcheting Strain ◽  
Stainless Steel 304 ◽  
Accumulated Strain

Experimental results of uniaxial ratcheting tests for stainless steel 304 (SS304) under stress-controlled condition at room temperature showed that the elastic domain defined in this paper expands with accumulation of plastic strain. Both ratcheting strain and viscoplastic strain rates reduce with the increase of elastic domain, and the total strain will be saturated finally. If the saturated strain and corresponded peak stress of different experimental results under the stress ratio R ≥ 0 are plotted, a curve demonstrating the material shakedown states of SS304 can be constituted. Using this curve, the accumulated strain in a pressure vessel subjected to cyclic internal pressure can be determined by only an elastic-plastic analysis, and without the cycle-by-cycle analysis. Meanwhile, a physical experiment of a thin-walled pressure vessel subjected to cyclic internal pressure has been carried out to verify the feasibility and effectiveness of this noncyclic method. By comparison, the accumulated strains evaluated by the noncyclic method agreed well with those obtained from the experiments. The noncyclic method is simpler and more practical than the cycle-by-cycle method for engineering design.

Very thin torispherical pressure vessel ends under internal pressure: Test procedure and typical results

1981 ◽  
Vol 16 (3) ◽  
pp. 171-186 ◽  
Author(s):  
P Stanley ◽  
T D Campbell
Keyword(s):  
Stainless Steel ◽  
Internal Pressure ◽  
Elastic Stress ◽  
Test Procedure ◽  
Pressure Vessels ◽  
Time Dependent ◽  
Test Installation ◽  
Stress Indices ◽  
Pressure Test ◽  
Strain Data

Very thin cylindrical pressure vessels with torispherical end-closures have been tested under internal pressure until buckles developed in the knuckles of the ends. These were prototype vessels in an austenitic stainless steel. The preparation of the ends and the closed test vessels is outlined, and the instrumentation, test installation, and test procedure are described. Results are given and discussed for three typical ends (diameters 54, 81, and 108in.; thickness to diameter ratios 0.00237, 0.00158, and 0.00119). These include measured thickness and curvature distributions, strain data and the derived elastic stress indices, and pole deflection measurements. Some details of the observed time-dependent plasticity (or ‘cold creep’) are given. Details of two types of buckle that developed eventually in the vessel ends are also reported.

The effect of proof testing on the shakedown behaviour of pressure vessel nozzles

1994 ◽  
Vol 29 (2) ◽  
pp. 81-92 ◽  
Author(s):  
N I Crawley ◽  
D N Moreton ◽  
D G Moffat ◽  
A F Tolley
Keyword(s):  
Stainless Steel ◽  
Internal Pressure ◽  
Pressure Vessel ◽  
Steel Type ◽  
Pressure Cycling ◽  
Proof Testing ◽  
Pressure Tests ◽  
Test Pressure ◽  
Design Pressure

Cyclic internal pressure tests were conducted over several hundreds of cycles at pressures up to and in excess of the calculated proof test pressure on two nominally ‘identical’, stainless steel type 316 flush 90 degrees pressure vessel nozzles, designed and manufactured to BS 5500. Prior to this pressure cycling, one vessel was subjected to the required proof test of 1.25 times the design pressure. Significant incremental straining was recorded in the non-proof tested vessel during cycling at all pressures above the first yeild pressure (0.336 × design pressure). For the proof tested vessel significant incremental straining was not recorded during cycling until 15 percent above the design pressure.

Use of Duplex Stainless Steel in Economic Design of a Pressure Vessel

2006 ◽  
Vol 129 (1) ◽  
pp. 155-161 ◽  
Author(s):  
Milan Veljkovic ◽  
Jonas Gozzi
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Stainless Steels ◽  
Pressure Vessel ◽  
Design Procedure ◽  
High Strength Steels ◽  
High Strength ◽  
Pressure Vessels ◽  
Economic Design ◽  
European Standard

Pressure vessels have been used for a long time in various applications in oil, chemical, nuclear, and power industries. Although high-strength steels have been available in the last three decades, there are still some provisions in design codes that preclude a full exploitation of its properties. This was recognized by the European Equipment Industry and an initiative to improve economy and safe use of high-strength steels in the pressure vessel design was expressed in the evaluation report (Szusdziara, S., and McAllista, S., EPERC Report No. (97)005, Nov. 11, 1997). Duplex stainless steel (DSS) has a mixed structure which consists of ferrite and austenite stainless steels, with austenite between 40% and 60%. The current version of the European standard for unfired pressure vessels EN 13445:2002 contains an innovative design procedure based on Finite Element Analysis (FEA), called Design by Analysis-Direct Route (DBA-DR). According to EN 13445:2002 duplex stainless steels should be designed as a ferritic stainless steels. Such statement seems to penalize the DSS grades for the use in unfired pressure vessels (Bocquet, P., and Hukelmann, F., 2001, EPERC Bulletin, No. 5). The aim of this paper is to present an investigation performed by Luleå University of Technology within the ECOPRESS project (2000-2003) (http://www.ecopress.org), indicating possibilities towards economic design of pressure vessels made of the EN 1.4462, designation according to the European standard EN 10088-1 Stainless steels. The results show that FEA with von Mises yield criterion and isotropic hardening describe the material behaviour with a good agreement compared to tests and that 5% principal strain limit is too low and 12% is more appropriate.

Study on the Stress Concentration at the Round Corners of Flat Heads in Pressure Vessels Subjected to Internal Pressure

1996 ◽  
Vol 118 (4) ◽  
pp. 429-433
Author(s):  
H. Chen ◽  
J. Jin ◽  
J. Yu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Intensity ◽  
Stress Concentration ◽  
Internal Pressure ◽  
Pressure Vessel ◽  
Pressure Vessels ◽  
Stress Index ◽  
Element Analysis ◽  
Approximate Formulas

Results from finite element analysis were used to show that the stress index kσ and the nondimensionalized highly stressed hub length kh of a flat head with a round corner in a pressure vessel subjected to internal pressure are functions of three dimensionless parameters: λ ≡ h/dt, η ≡ t/d, and ρ ≡ r/t. Approximate formulas for estimating kσ and kh from λ, η, and ρ p are given. The formulas can be used for determining a suitable fillet radius for a flat head in order to reduce the fabricating cost and to keep the stress intensity at the fillet under an acceptable limit.

Elastic-Plastic Stress Analysis of Pressure Vessels

2012 ◽  
Author(s):  
Yang-chun Deng ◽  
Gang Chen
Keyword(s):  
Internal Pressure ◽  
Stress Analysis ◽  
Strain Hardening ◽  
Pressure Vessel ◽  
Plastic Instability ◽  
Pressure Vessels ◽  
Structural Deformation ◽  
Elastic Plastic ◽  
Thin Walled ◽  
Plastic Stress

To save material, the safety factor of pressure vessel design standards is gradually decreased from 5.0 to 2.4 in ASME Boiler and Pressure Vessel Codes. So the design methods of pressure vessel should be more rationalized. Considering effects of material strain hardening and non-linear structural deformation, the elastic-plastic stress analysis is the most suitable for pressure vessels design at present. This paper is based on elastic-plastic theory and considers material strain hardening and structural deformation effects. Elastic-plastic stress analyses of pressure vessels are summarized. Firstly, expressions of load and structural deformation relationship were introduced for thin-walled cylindrical and spherical vessels under internal pressure. Secondly, the plastic instability for thin-walled cylindrical and spherical vessels under internal pressure were analysed. Thirdly, to prevent pressure vessels from local failure, the ductile fracture strain of materials was discussed.

Flaw Size Acceptance Limits for a Stainless Steel Pressure Vessel

2013 ◽  
Author(s):  
Consuelo E. Guzman-Leong ◽  
Stephen R. Gosselin ◽  
Frederic A. Simonen
Keyword(s):  
Stainless Steel ◽  
Fracture Mechanics ◽  
Failure Mode ◽  
Pressure Vessel ◽  
Pressure Vessels ◽  
Flaw Size ◽  
Ductile Tearing ◽  
Size Acceptance ◽  
Acceptance Levels ◽  
Size Limits

The ASME Boiler and Pressure Vessel Code Section XI provides flaw size acceptance standards for ferritic steel pressure vessels. Section XI Table IWB-3510-1 presents allowable flaw size limits in terms of flaw depth, length and vessel thickness. These flaw size limits are based on linear elastic fracture mechanics calculations that assume a brittle fracture failure mode. As yet, no allowable flaw size standards are provided in Section XI for stainless steel reactor or non-reactor pressure vessels. This paper presents allowable flaw size limits for a stainless steel pressure vessel. These limits were based on elastic plastic fracture mechanics analyses that considered limit load and ductile tearing failure modes. Although the flaw acceptance levels were developed for a specific stainless steel vessel, insights gained from this work may be useful in a general methodology for ASME Code purposes. Tabulated flaw size acceptance levels, for several aspect ratios and inspection intervals, are presented for the axial shell welds. Results show the axial seam welds were the most flaw sensitive of the various welds analyzed. The acceptable flaw sizes were limited by the ductile tearing failure mode.

Ratcheting Studies on Type 304LN Stainless Steel Elbows subjected to Combined Internal Pressure and In-Plane Bending Moment

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
S. Vishnuvardhan ◽  
G. Raghava ◽  
P. Gandhi ◽  
M. Saravanan ◽  
D. M. Pukazhendhi ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Internal Pressure ◽  
Accumulation Rate ◽  
Bending Moment ◽  
Cyclic Bending ◽  
Ratcheting Strain ◽  
Bending Load ◽  
304Ln Stainless Steel ◽  
Number Of Cycles ◽  
Opening And Closing

“Ratcheting” is a phenomenon which leads to reduction in fatigue life of a structural component by loss of ductility due to cycle by cycle accumulation of plastic strain. Ratcheting occurs in a structure subjected to a combination of steady/sustained and cyclic loads such that the material response is in inelastic region. Ratcheting studies were carried out on Type 304LN stainless steel elbows, subjected to steady internal pressure and cyclic bending. The elbows filled with water were pressurized between 27.6 MPa and 39.2 MPa. Cyclic bending load, under opening and closing moments, was applied on the elbows at ambient temperature. Number of cycles corresponding to occurrence of a through-wall crack was recorded. Crack was observed in the bent portion at one of the crown locations in all the four specimens. Maximum strain was observed at the intrados and crown locations of the elbows. The ratcheting strain increased with number of cycles at crown and intrados locations. However, the strain accumulation rate decreased with number of cycles. Strain was observed to be minimum at the extrados location and the same stabilized toward the end of the tests. The specimens have failed by occurrence of through-wall axial crack accompanied by simultaneous ballooning. The ballooning was found to be varying from 3.8% to 5.8% with respect to the original circumference in the bent portion. The reduction in thickness was found to be around 12%–15%.

Material Test and Analysis for Pressure Vessel Rupture Study Under Fire in Plant

2015 ◽  
Author(s):  
Yoshiyasu Itoh ◽  
Yoshiyuki Waki ◽  
Kazuyuki Kasuya
Keyword(s):  
Internal Pressure ◽  
Pressure Vessel ◽  
Oil And Gas ◽  
Pressure Vessels ◽  
Design Guidelines ◽  
Plant Design ◽  
Design Code ◽  
Safe Level ◽  
Fire Incident ◽  
Vessel Rupture

In case fire incident occurs in Oil and Gas plant, pressure vessels will be exposed to fire. Though entire system will be depressurized when the fire is detected, internal pressure may still remain in the pressure vessels. Therefore, pressure vessels, if leakage of its internal fluids will escalate the incident, shall be confirmed that they will withstand internal pressure without rupture at least until internal pressure is decreased down to safe level. For design for such critical pressure vessel, a pressure vessel rupture study is conducted in addition to design code calculations. As safer plant design is requested in recent projects, demands for the pressure vessel rupture study are also growing. In this research, material data at high temperature range, that are necessary to obtain reliable results by the pressure vessel rupture study, were measured for carbon steel and stainless steel type304 and type304L. In addition, pressure vessel rupture studies were performed for two sample pressure vessels by means of FEM analyses and calculation methods in published design guidelines.

Prestressing a Two-Layer Pressure Vessel by Plastic Deformation

1965 ◽  
Vol 87 (1) ◽  
pp. 97-103
Author(s):  
R. W. Schneider
Keyword(s):  
Plastic Deformation ◽  
Internal Pressure ◽  
Pressure Vessel ◽  
Work Hardening ◽  
Design Method ◽  
Strain Curve ◽  
Pressure Vessels ◽  
Stress Strain Curve ◽  
Initial Clearance ◽  
Actual Stress

A method of prestressing two-layer pressure vessels by controlled yielding of the inner layer by internal pressure is described. The required prestressing pressure depends upon the dimensions of the vessel, the initial clearance between layers, and the properties of the material of construction. The design method takes into account the actual stress-strain curve of the material and satisfies the rules of plastic flow with work-hardening. Two-layer, cylindrical vessels are discussed in detail.

Design of Angle Adjustable Electrochemical Micro-Machining System

2009 ◽  
Vol 407-408 ◽  
pp. 619-623
Author(s):  
Shao Fu Huang ◽  
Di Zhu ◽  
Yong Bin Zeng ◽  
Yong Liu ◽  
Wei Wang
Keyword(s):  
Stainless Steel ◽  
High Speed ◽  
Experimental Results ◽  
Micro Machining ◽  
Reaction Products ◽  
Feed System ◽  
Stainless Steel 304 ◽  
Interelectrode Gap ◽  
Micro Ecm ◽  
Machining System

In order to remove the reaction products generated from the interelectrode gap of the electrochemical micro-machining, an angle adjustable electrochemical micro-machining equipment has been developed, which consists of angle adjustment unit, feed system unit, etc. Small holes have been drilled on thin stainless steel 304 by using our developed equipment. The experimental results show that the adjusted cathode working angle and high speed of cathode rotation improves micro-ECM performance characteristics.

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