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Volume 31 (1993)
- Issue 6 Pages 324-
- Issue 5 Pages 264-
- Issue 4 Pages 192-
- Issue 3 Pages 114-
- Issue 2 Pages 58-
- Issue 1 Pages 3-
Predecessor
Volume 31, Issue 5
Displaying 1-6 of 6 articles from this issue
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Effect of Clad Metal on Buckling Strength of Clad Pipe in BendingJoe KONDO, Moriyasu NAGAE, Masao TSUJI, Fumiyoshi MINAMI, Masao TOYODA1993 Volume 31 Issue 5 Pages 264-269
Published: September 25, 1993
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSThe new design concept which treated clad metal as the equivalent base metal thickness of bi⋅(σTC/σTB) was proposed in the first paper. This paper describes applicability of the new design concept from the view point of bending properties. As the results of 4-point bending test of large-diameter clad pipe, the critical buckling strain of the clad pipe was smaller than that of a carbon steel “solid” pipe with the same mechanical properties and pipe dimensions as the clad pipe.
The reason could be thought to be due to an additional bending moment caused by inhomogeneous strength between clad metal and base metal. However, disbonding did not occur at the interface of buckled portion and there was no significant difference in shear strength obtained by shear test between before and after buckling. Furthermore, the local buckling did not affect the overall deformation behavior of the clad pipe.
As a clad pipe designed by the new concept is thinner than those by the conventional ones when strength of the clad thickness is higher than that of base metal, the critical buckling strain of clad pipe designed by the new concept is smaller than the conventional ones. However, applied stress is practically restrained to 72% of specified minimum yield strength or lower during laying of clad pipe. It was confirmed that the clad pipe designed by the new concept had sufficient safety factor for the practical level. Therefore, it was concluded that plastic buckling did not become a negative factor for practical level when the new design concept was applied.View full abstractDownload PDF (1920K) -
Naoki KOMIYA, Isao OHKAWA1993 Volume 31 Issue 5 Pages 270-279
Published: September 25, 1993
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSFatigue tests on a Cu safety rupture disc were carried out under constant and two-step variable pressure amplitudes. Fatigue strength and change of burst pressure caused by repeated pressure were studied. In addition, deformation behaviour, tensile properties and crack growth in fatigue process were observed.
Under the application of constant pressure amplitude PC, burst pressure PCS decreased with increasing cycle ratio R. Variation of PCS is expressed by a following empirical equation
(PCS-PC)/(PS-PC)=(1-R)m
where PS is rated burst pressure and m is a material constant which is dependent on PC. The decrease of PCS could be attributed to reduction of tensile strength and growth of fatigue cracks. Allowable number of cycles NL (critical number of cycles in which PCS falls below 95% of the rated burst pressure PS) may be estimated by use of above equation.
Experimental cycle ratio sums with respect to NL as well as fatigue life Nf were greater than unity for variable amplitude tests in which the lower cyclic pressure was followed by higher pressure. These values tend to become larger with increasing the difference between primary and secondary pressure level. Estimation of Nf and NL based on above equation results in conservative prediction.View full abstractDownload PDF (4492K) -
Yuzuru SAKAI, Hideo NOBUTIKA1993 Volume 31 Issue 5 Pages 280-287
Published: September 25, 1993
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSAn experimental investigation of Charpy impact energy was conducted utilizing hand-lay-up made GFRP materials which were fabricated using three types of glass fiber sheets. Then, Weibull distribution analyses were applied to clarify the effects of types and volume ratio of glass fibers, crack orientations on impact energy of GFRP materials. It was shown that within volume ratio below 20%, data scatter was relatively small and 2 parameters Weibull distribution was applicable, however, volume ratio above 30%, data scatter became large and 3 parameters Weibull distribution was useful to get best fitted curves of Charpy impact data. Fracture appearences were also observed to recognize the fracture process of each type of GFRP specimens. It was noted that using woven roving sheets, damaged zones grew relatively large, which caused the high values of impact energy. While using chopped strandmats, a damaged zone was limited near a crack surface and impact energy decreased to about a half of woven roving made GFRP specimens.View full abstractDownload PDF (2273K) -
Michio INAGAKI, Takayasu TAHARA1993 Volume 31 Issue 5 Pages 289-297
Published: September 25, 1993
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSUpgrading of heavy crude oil and coal liquifaction requires large size pressure vessels for higher pressure and temperature operation in hydrogen service than conventional hydrotreating process. In order to meet such industrial needs, study on advanced Cr-Mo steel which has higher design stress, excellent resistance to hot hydrogen damages has been studied in recent 10 years in worldwide development programs such as API/ MPC in USA, NEDO in Japan. ASTM/ASME, JIS and Europian standard materials are available in many kinds of advanced Cr-Mo steel such as Enh. 21/4 Cr-1Mo, Mod. 3cr-1Mo. Mod. 21/4Cr-IMo, Manufacturing of large size pressure vessel weighs over 1, 000m-tons using new grade steel have been commenced and application of new grade steel in large size pressure vessel increases in recent years.
The ECM committee in Iron and Steel Division in the Japan Welding Engineering Society established the enginering guide line of Advanced Cr-Mo Steels in 1992 after two years extensive study which includes proposed material standards, data base of mechanical properties, design stress values, phisical properties, recommendable welding practice and data of enviromental properties. This report interprets the engineering guide line and recent trend in application of advanced Cr-Mo steel in pressure vessel industries.View full abstractDownload PDF (2596K) -
Shoichi YOSHIDA1993 Volume 31 Issue 5 Pages 298-305
Published: September 25, 1993
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSAn explosion can be produced when ignition of hydrocarbon gas is caused in an oil storage tank. Such accidents happen with higher probability than other types of accidents in oil storage tanks. In relation to the explosion, the top end closure of the tank is designed to be frangible while maintaining the vaportight requirement of the welded steel structure, and is expected to fail before failure occurs in the sidewall-to-bottom joint in order to release the pressure upward and to minimize the damage. This paper presents the current design procedure according to API Standard 650 for the frangible joint, and describes the static and dynamic bifurcation buckling of the top end closure under internal pressure by using the finite element method.View full abstractDownload PDF (799K) -
Kazutoshi SUDA, Yoshio KANBE1993 Volume 31 Issue 5 Pages 306-312
Published: September 25, 1993
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSThe paper describes on a new development of a high current density welding process “Hi-WELD” for high deposition rate welding by CO2 gas shielding. The process provides high-quality, high-efficient welding at lower cost by using both CO2 shielding gas and a seamless copper plated flux cored electrode wire of 1.2mm in diameter, in combination with a 600A inverter controlled power supply with a high speed wire feeder unit having 40m/min maximum feeding speed. In the paper, investigation for fundamental characteristics of the process, such as metal transfer phenomena, effect on penetration shape and mechanical properties and so on, was done for successful application to welding of steel frames and heavy constructions.View full abstractDownload PDF (5876K)
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