All issues
Volume 45 (2007)
- Issue 6 Pages 336-
- Issue 5 Pages 264-
- Issue 4 Pages 180-
- Issue 3 Pages 118-
- Issue 2 Pages 60-
- Issue 1 Pages 4-
Predecessor
Volume 45, Issue 4
Displaying 1-6 of 6 articles from this issue
- |<
- <
- 1
- >
- >|
Original Paper
-
Ken-ichi KOBAYASHI, Kensuke TODA, Gavin C. STRATFORD, Brian WILSHIRE2007 Volume 45 Issue 4 Pages 180-186
Published: 2007
Released on J-STAGE: August 30, 2007
JOURNAL FREE ACCESSA new testing apparatus where constant load is directly applied to a very small disc-type specimen is developed to evaluate creep lives of components at elevated temperatures: Small Punch Creep (SPC) Testing Apparatus. Since failure of structural components mainly breaks out around maximum damaged portion, and heavily damaged components dominate the residual life of structural systems, a methodology to assess the local damage and residual life in components under creep temperatures have been required. However, conventional uni-axial creep specimens need a certain amount of volume, and this often causes a difficulty to repair specific devices after sampling uni-axial creep specimens. Dimensions of the disc-type specimen here employed are very small: 10mm in diameter and 0. 5mm in thickness. After designing and installing the new SPC testing apparatus, a series of SPC tests were conducted using super duralumin. It is clarified that the primary and the secondary creep regimes occupy most of the creep deformation, and that the tertiary creep appears just before fracute. Furthermore it is shown that creep rupture lives obtained in the SPC test have a good correlation with those from uni-axial creep tests.View full abstractDownload PDF (509K) -
Tetsuo TERAMAE, Yoshiaki NAKAZAWA2007 Volume 45 Issue 4 Pages 187-194
Published: 2007
Released on J-STAGE: August 30, 2007
JOURNAL FREE ACCESSA study had been conducted to establish the precise method estimating the creep rupture life of welded steam pipe joints. Firstly, basic creep data of 2. 25Cr1Mo low alloy steel, such as rupture time, minimum creep strain rate, and creep crack growth rate, had been obtained on mother material, fine-grained heat affected zone (HAZ) , coarse-grained HAZ, and weld metal. Secondly, creep rupture tests had been conducted on the internally pressurized pipe specimens of mother material, seam welded joint and girth welded joint. Whereas girth welded pipe joints showed longer lives than those of mother material pipes, seam welded pipe joints showed shorter rupture lives. To clarify the effect of fine-grained HAZ on the rupture life of the seam welded pipe joint, an analytical study had been performed taking the difference of creep deformation between fine-grained HAZ and mother material into account. The analytical creep rupture lives agreed quite well with the experimental results. Finally, creep rupture test had been conducted on the specimens of the internally pressurized seam welded pipe joints with a half elliptic notch introduced along the outer HAZ of weld line. Creep rupture life of these specimens was calculated as the sum of crack incubation time and crack growth time. It was shown that the calculated creep rupture life agreed quite well with the experimental results.View full abstractDownload PDF (385K) -
Norihiro NAGO, Tomohiro TAKAKI, Kouji SATOU2007 Volume 45 Issue 4 Pages 195-204
Published: 2007
Released on J-STAGE: August 30, 2007
JOURNAL FREE ACCESSTo establish a lifetime prediction method of gasket, it is essential to grasp its visco-elastic-plastic properties and to construct a model which can predict a bolt load time variation for bolted gasketed joints due to creep and stress relaxation of gasket. In this paper, first, a strain-time equation of gasket under arbitrary multi-step unloading is established by conducting the compression and creep tests. The tests are performed for two types joint sheet gaskets, or non-asbestos and asbestos gasket. Next, the bolt load relaxations in a simple bolted joint are calculated by utilizing the established strain-time equation, and it is confirmed that the calculated results agree well with the experimental ones performed under some gasket contact stresses. In addition, the bolt load variations with time for a pipe flange connection are simulated by finite element method. As a result, it is concluded that a good agreements between numerical and experimental results are obtained by using the strain-time equation without delayed elasticity strain which occurs in a moment. Furthermore, a method which predicts a long time viscous property of gasket from short time creep test is investigated.View full abstractDownload PDF (473K) -
Report 3 Effect of repair welding thermal cycle near the overlay⁄base metal interface on weld cracking susceptibility of degraded steel.Rinzo KAYANO, Hiroaki MORI, Kazutoshi NISHIMOTO2007 Volume 45 Issue 4 Pages 205-213
Published: 2007
Released on J-STAGE: August 30, 2007
JOURNAL FREE ACCESSCold cracking sometimes occurred in long-term operated petroleum pressure vessels due to hydrogen embrittlement by thermal stress and diffusible hydrogen after repair welding. The cracking was caused by the hydrogen concentration at the base metal of 2. 25Cr-1Mo steel⁄overlaying metal of austenitic stainless steels during the service with high temperature and hydrogen partial pressure. Such tendency was accelerated by carbides precipitation at the interface due to the post weld heat treatment and the operation with high temperature. That is, the crack susceptibility at the interface became markedly higher owing to the hydrogen embrittlement with metallurgical degradation by thermal embrittlement. In this study, the crack susceptibility was evaluated by y-groove weld cracking test varying residual overlay thickness and hydrogen exposure conditions. On the other hand, hydrogen content at the interface was calculated by the theoretical analysis using the diffusion equation based on activity. The cracking test reveals that the crack susceptibility was raised with increase in hydrogen content at the interface. In addition, the theoretical analysis results indicate that the cracking could be prevented by reduction of hydrogen content at the interface to control the repair welding thermal cycles.View full abstractDownload PDF (792K) -
Masami OSHIMA, Takashi KASE, Ken-ichi FUJITA, Kazuyoshi SEKINE2007 Volume 45 Issue 4 Pages 214-219
Published: 2007
Released on J-STAGE: August 30, 2007
JOURNAL FREE ACCESSThe tank fires of Tokachioki earthquake in 2003 made the people attending aware of seismic performance of tanks. And it reminded people that tanks have possibilities to make catastrophic disaster against environment because of their large volume, once their contents are leaked out. So development of procedure for seismic risk management of tanks is required. Authors have already pointed out the fact that the responses of tanks at seismic events are affected by their volume of contents. This study is positioned as fundamental study of the seismic risk control by adjusting liquid height. Damage modes of the cylindrical storage tanks with floating roofs are extracted. The effect of occurrence of the damage modes of tanks by variation of liquid height are discussed.View full abstractDownload PDF (204K)
Lecture
-
Hiroaki MASATOMO2007 Volume 45 Issue 4 Pages 220-227
Published: 2007
Released on J-STAGE: August 30, 2007
JOURNAL FREE ACCESSRecently, Risk Base Maintenance (RBM) or Risk Base Inspection (RBI) becomes popular and already applied to power industries and petrochemical industries in USA and Europe, and also in Japan. But they are not applied to chemical plant so much because chemical plant is relatively complex, generally, and handles various kinds of materials. Therefore, database of the failure of construction materials and properties of fluid are not enough for application of RBI to chemical plant. In this paper, the procedure to apply RBI to chemical plant is explained based on Semi-quantitative evaluation of API Publication 581. Especially, there is often the case that construction materials of equipments and fluid are not included in the database of RBI. Useful advice and idea is also provided.View full abstractDownload PDF (172K)
- |<
- <
- 1
- >
- >|