Experimental Verification of Fracture Toughness Requirement for Leak-Before-Break Performance for 155–175 ksi Strength Level Gas Cylinders

1987 ◽  
Vol 109 (4) ◽  
pp. 435-439 ◽  
Author(s):  
M. D. Rana
Keyword(s):  
Fracture Toughness ◽  
High Pressure ◽  
Plane Stress ◽  
Experimental Work ◽  
Strength Level ◽  
State Problem ◽  
Gas Cylinder ◽  
Gas Cylinders ◽  
Leak Before Break

This paper deals with a determination of the fracture toughness requirement to obtain leak-before-break performance for a 155–175 ksi strength level high-pressure gas cylinder. Analytical LEFM methods along with Irwin’s KIc-Kc equation related by the parameter βIc were used to predict the fracture toughness requirement for the plane-stress fracture state problem. Experimental work was conducted on flawed cylinders to quantify the fracture toughness requirement for leak-before-break performance. The results indicated that the analytically predicted toughness requirement is 4 to 25 percent higher than that established experimentally. The results also indicated that the minimum specified KIc(J) value of 85 ksi in. (93.5 MPam) for the gas cylinder is sufficiently higher than the analytically and experimentally established toughness values to provide the desired leak-before-break performance.

Determination of Fracture Toughness and K-R Curve for 2524-T3 Aluminum Alloy

2011 ◽  
Vol 291-294 ◽  
pp. 1039-1042
Author(s):  
Wei Xie ◽  
Shao Wei Tu ◽  
Qi Qing Huang ◽  
Ya Zhi Li
Keyword(s):  
Fracture Toughness ◽  
Aluminum Alloy ◽  
Stress Fracture ◽  
Test Data ◽  
Plane Stress ◽  
Crack Extension ◽  
Room Temperature ◽  
Mode I ◽  
Average Value

In the present work, the resistance to crack extension of 2524-T3 aluminum alloy under Mode I loading was studied by using the middle-cracked tension M (T) specimens. The curve, plane-stress fracture toughness and apparent plane-stress fracture toughness were calculated by test data. The average value of measured fracture toughness at room temperature was 161 MPam1/2. The results and conclusions can be referred in airplane skin design.

The Use of “Fitness for Service” Assessment Procedures to Establish Critical Flaw Sizes in High-Pressure Gas Cylinders

2003 ◽  
Vol 125 (2) ◽  
pp. 177-181 ◽  
Author(s):  
John H. Smith ◽  
Mahendra D. Rana ◽  
Clark Hall
Keyword(s):  
High Pressure ◽  
Experimental Work ◽  
Burst Pressure ◽  
Periodic Inspection ◽  
Critical Flaw ◽  
Analytical Procedures ◽  
Corrosion Pits ◽  
Assessment Procedures ◽  
Gas Cylinders

Typical flaws that can occur in high-pressure seamless gas cylinders during service are: corrosion pits, line corrosion, gouges, local thin areas of corrosion, and cracks. The required periodic inspection of seamless cylinders requires that “critical flaw sizes” be established. To establish “critical flaw sizes” an assessment of typical flaws that occur in seamless cylinders was carried out using the analytical procedures described in the API Recommended Practice 579 “Fitness-for-Service.” To verify the API 579 analysis procedures, a number of hydrostatic tests were conducted on selected cylinders with various sizes of flaws to determine the burst pressure of cylinder containing flaws. These results showed that the analysis conducted according to API 579 reliably estimated the actual measured burst pressure of the cylinders for all flaw sizes and types. After the API 579 analysis procedures were verified by these experiments to reliably estimate the burst pressure of cylinders with various types of flaws, the “critical flaw sizes” to cause failure of the cylinders at selected pressures were determined by analysis. This paper presents the results of the analytical and experimental work that was performed on the assessment procedures to establish the “critical flaw sizes” in high-pressure gas cylinders.

Analysis of High Pressure Gas Cylinder Preload of Screw Connection

2015 ◽  
Vol 757 ◽  
pp. 33-37
Author(s):  
Hai Xia Du ◽  
Ying Juan Yue ◽  
Fang Xie ◽  
Fei Chen
Keyword(s):  
High Pressure ◽  
3D Model ◽  
Weak Link ◽  
Screw Thread ◽  
Finite Element Software ◽  
Threaded Connection ◽  
Gas Cylinder ◽  
Operating Process ◽  
3D Solid ◽  
Gas Cylinders

High pressure gas cylinder thread joint is the weak link in high pressure gas cylinders, The cylinders in use and the operating process, the main causes of cylinder screw thread failure is the improper preload. In this paper, cylindrical high-pressure cylinders threaded,connection for example,according to the bottleneck and the bottlevalve for high pressure gas cylinder structure, material and mechanical characteristics, establishing 3D solid model of the high-pressure cylinders connected by using the finite element software ANSYS, 3D model is applied to high pressure cylinders, thread connection analysis.

Single Crystal Growth of High-Pressure Phases of Ice and Salt Hydrate Far Below the Original Melting Point by Mixing Alcohol: Crystal Structure Determination of Magnesium Chloride Heptahydrate

2020 ◽  
Author(s):  
Keishiro Yamashita ◽  
Kazuki Komatsu ◽  
Hiroyuki Kagi
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Crystal Growth ◽  
Single Crystal ◽  
Room Temperature ◽  
Growth Technique ◽  
Salt Hydrate ◽  
X Ray

An crystal-growth technique for single crystal x-ray structure analysis of high-pressure forms of hydrogen-bonded crystals is proposed. We used alcohol mixture (methanol: ethanol = 4:1 in volumetric ratio), which is a widely used pressure transmitting medium, inhibiting the nucleation and growth of unwanted crystals. In this paper, two kinds of single crystals which have not been obtained using a conventional experimental technique were obtained using this technique: ice VI at 1.99 GPa and MgCl<sub>2</sub>·7H<sub>2</sub>O at 2.50 GPa at room temperature. Here we first report the crystal structure of MgCl2·7H2O. This technique simultaneously meets the requirement of hydrostaticity for high-pressure experiments and has feasibility for further in-situ measurements.

RMI 6Al-ELI

Alloy Digest ◽  
1988 ◽  
Vol 37 (12) ◽  
Keyword(s):  
Fracture Toughness ◽  
High Pressure ◽  
Room Temperature ◽  
Base Alloy ◽  
Heat Treating ◽  
Age Hardening ◽  
Bend Strength ◽  
Annealed Condition ◽  
Room Temperature Yield Strength ◽  
Alpha Beta

Abstract RMI 6A1-4V ELI is an alpha-beta type of titanium-base alloy that can be strengthened by age hardening. In the mill-annealed condition it has a guaranteed minimum room-temperature yield strength of 120,000 psi and can be increased to as much as 160,000 psi by solution treating and aging. This alloy may be used for high-pressure cryogenic vessels down to 320 F. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and bend strength as well as fracture toughness. It also includes information on corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ti-89. Producer or source: RMI Company.

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