scholarly journals INFLUENCE OF EDGE DISTANCE ON SPLITTING STRENGTH OF STEEL-TIMBER CONNECTIONS USING HIGH-STRENGTH BOLTS AND STEEL PIPES

2016 ◽  
Vol 22 (51) ◽  
pp. 501-504
Author(s):  
Mai MATSUOKA ◽  
Jiro TAKAGI ◽  
Toshiki ENDO
1983 ◽  
Vol 105 (1) ◽  
pp. 97-102 ◽  
Author(s):  
A. Royer ◽  
B. Dumas ◽  
M. Gantois

Many parts either for sea-line pipes as “buckle” or “crack arrestor,” or for structures may require the use of wall tubular products with high mechanical properties. Such heavy-wall pipes may be produced by centrifugal casting. Two Mn-Mo steels have been developed for medium-wall pipes (e≤35 mm) to be used under very severe climatic conditions: an acicular ferritic steel, a pearlite reduced steel produced by controlled rolling techniques [1, 2, 3]. More alloyed chemical composition and heat-treatments are needed to produce heavy-wall pipes. Then, production of such pipes is more difficult and sometimes impossible. Observations made on controlled-rolled Mn-Mo steel led to a better understanding of the influence of metallurgical structures and chemical composition on steel characteristics. Similar metallurgical structures can only be reached via other routes, for example centrifugal-casting of steel associated with heat-treatment, lead to the production of heavy-wall pipes with high strength and suitable transition temperature. After a brief description of the centrifugal casting technique, we introduce the grades developed for heavy-wall pipes with yield strength up to 100,000 psi. The mechanical properties, Battelle, fatigue, static bending, C.O.D., weldability, etc., of Centrishore II are given and compared to other materials. Possible offshore applications and other potential applications of parts produced by centrifugal casting are described.


Author(s):  
Matteo Ortolani ◽  
Ettore Anelli ◽  
Paolo Novelli ◽  
Emanuele Paravicini Bagliani

In case of a Weld On Connector’s riser using ASTM A182 F22 forged joints, high strength (SMYS of 80 ksi) steel pipes for sour service (hardness below or equal to 250 HV10) suitable for welding to the connectors are required. Welding is challenging because of the Post Weld Heat Treatment (PWHT) needed to reduce the hardness in the F22 HAZ while maintaining the required strength in the pipe. Theoretical evaluations were performed by means of metallurgical models and a potential solution was identified in grade P22-like steel (2¼ Cr - 1 Mo), with minor modifications with respect to the standard ASTM A335 and supplied in Q&T condition. A trial heat was cast and hot-rolled into pipes. After water quenching, the response to tempering was assessed by means of laboratory heat treatments and subsequent mechanical testing, together with metallurgical examination. Simulated PWHTs were also performed on Q&T material. 80 ksi grade P22 seamless pipes were finally produced and qualification involved mechanical testing before and after simulated PWHT: SMYS of 80 ksi and HV10 ≤ 250 requirements were met. The material also exhibited excellent toughness and resistance to HIC and SSC cracking.


Author(s):  
Yan-Bo Wang ◽  
Yi-Fan Lyu ◽  
Guo-Qiang Li

This paper presents an experimental research on bearing-type bolted connections consisting of two bolts positioned perpendicular to the loading direction. A total of 24 connections in double shear fabricated from high strength steels with yield stresses of 677MPa and 825MPa are tested. Two failure modes as tearout failure and splitting failure are observed in experiments. The effect of end distance, edge distance, bolt spacing and steel grade on the failure mode and bearing behavior are discussed. For connection design with bolts positioned perpendicular to loading direction, it is further found that combination of edge distance and bolt spacing effectively determines the failure mode and ultimate load. The test results are compared with Eurocode3. An optimal combination of edge distance and bolt spacing as well as related design suggestion is thus recommended. 


Author(s):  
Lixin Xu ◽  
Paul Stanton

Dry-tree solutions with top-tensioned risers (TTRs) have been successfully used with floating production systems (FPS), such as Spars and TLPs, in a wide range of deepwater applications. Both single-casing and dual-casing top-tensioned risers are field-proven in existing field developments. The top-tensioned risers bring technical advantages and operational cost benefits. However, recent oil and gas developments that have high pressure and high temperature (HPHT) in combination with severe environmental loads push the design limits of conventional steel pipes in deepwater risers. High-strength steel pipes are therefore considered for risers for both technical and economic reasons. This paper discusses the impact of the above requirements on design of top-tensioned risers, and proposes feasible design concepts for top tensioned risers with extremely high pressure requirements. Part I of the topic here addresses strategies of top-tensioned riser sizing and weight management, and design considerations for TTR specialty joints. Part II of this topic will follow for top-tensioned riser tensioning system configuration and tension performance optimization, as well as coupled motion compensation on the host platform. The objective of the study that forms the basis for this paper is to provide top-tensioned riser system configurations that meet the challenges of the extremely high operational pressure and environmental loads in deep and ultra-deep waters.


Author(s):  
Markus R. Dann ◽  
Marc A. Maes ◽  
Mamdouh M. Salama

Dry fiber augmented steel technology pipelines (FAST-Pipe™) have recently been the object of considerable attention due to both cost and availability advantages (as opposed to high strength steels) and due to their promising use in future Arctic pipeline solutions. The present paper focuses on the development and the use of a burst limit state for such fiber wrapped pipes. It describes in detail a probabilistic mechanical burst limit state model for FAST. The model is based on a large strain Cauchy stress formulation using Stewart’s isotropic strain hardening for steel pipe which is hoop-constrained by elastic fiber wrapping. The limit state model is used for a reliability comparison between FAST-Pipes and traditional pure steel pipes as well as for a risk-based equivalence between different design solutions.


2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Muntaseer Kainat ◽  
J. J. Roger Cheng ◽  
Michael Martens ◽  
Samer Adeeb

The geometric imperfections in high strength U-ing, O-ing and expanding (UOE) manufactured pipes are investigated in this paper using a high-resolution 3D surface scanner, and a reverse engineering and inspection software. The geometric analyses show that the initial imperfection patterns in the UOE manufactured pipes are not at all random, although the magnitudes of imperfections may vary across specimens. These patterns of outside radii and pipe wall thickness imperfections consistently appear along the length of the specimens regardless of their D/t ratios and manufacturer. The sources of these imperfections can potentially be traced back to the UOE manufacturing process.


2017 ◽  
Vol 896 ◽  
pp. 202-208
Author(s):  
Qing Chao Tian ◽  
Xian Ping Dong ◽  
Hai Chao Cui ◽  
Ke Xu

The welded joint of a S890QL grade steel pipes containing 1.2% Ni have been prepared to characterize the use performance under high cycle fatigue test. It has been found that the fatigue strength of the welded joint is 290MPa with a fatigue life of more than 10 million cycles, and the obtained Basquin equation is σa=488*(2N)-0.02758 . It is found that the steel exhibits the whole bainite microstructure when the cooling rate is less than 1°C/s. The welded joint is divided into the weld zone, the coarse grain zone, the fine grain zone, the softening zone and the matrix. The fine grain characteristic in the welded area determines the good anti fatigue performance of the investigated steel.


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