Load Carrying Capacity Of Pipes Research Articles

Manufactured sand for the development of reinforced concrete spun pipes

Due to overexploitation of natural resources, the deficiency of river sand as a fine aggregate is a major problem and manufactured sand is replaced as a suitable alternative material. This paper investigates the influence of Manufactured sand as a replacement for fine aggregate material in the manufacture of RCC spun pipes. M35 grade concrete is prepared with cement, coarse aggregate, superplasticizers, and river sand is replaced with 50%,75% and 100 % manufactured sand. Test results shows that the compressive strength of concrete cubes with 50% replacement levels leads to higher compressive strength at early ages, and their reactivity decreases at later age strength. Test conducted on concrete pipes reveals that the load-carrying capacity of pipes with 50% replacement levels increases and delays the crack formation on the surface and postponed the ultimate failure. Similarly, the hydrostatic test also shows positive results with the addition of MSand. The cost of Manufactured sand is lower than the river sand and it is free from impurities such as silt and clayey matters and it gives a possible solution to the shortage of fine aggregate in the production of RCC pipes.

Experimental stand for internal pressure testing of pipes

The experimental programs carried out on the stands for the research of mechanical stress behaviour typically target the following objectives: to determine the behaviour of the pipes at internal pressure and / or other mechanical stresses (which may secondary occur as accidental loads during exploitation), to establish the processes and factors of in-service degradation and to determine the load carrying capacity of pipes and other components of pipelines systems with defects of different types and configurations. For this paper an experimental stand was designed and developed for the purpose of determining the behaviour of the pipes with different types of imperfections / defects. The experimental results were verified and validated using the finite element method.

Fracture studies on carbon steel straight pipes having off-centred circumferential through-wall crack under finite compliance

The level-3 Leak-Before-Break (LBB) assessment of nuclear piping system is based on simplified fracture mechanics calculations. A postulated through-wall circumferential crack is shown to be stable even under extreme loading conditions. An important aspect of this fracture assessment, which is generally not considered, is the reduction in load at the cracked section that occurs due to the local and global compliance of the piping system. In this study, the effect of piping system compliance, crack size and crack location on the load carrying capacity of SA-333 Gr. 6 carbon steel pipes was analysed. Experimental investigations were performed on 8״ NB Schedule 100 pipes (Outer diameter 219 mm and wall thickness of approx. 12.6 mm) under quasi-static four point bending loads. Out of the six fracture tests, one specimen had a through-wall circumferential crack at the centre (along the length of pipe) and the remaining five tests had off-centred cracks. While the initial crack size showed a weak influence on the load carrying capacity of a stiff piping system, the effect of crack location was, however, quite significant. Calculations based on twice-elastic slope (TES) method and limit analysis of uncracked piping system (in some cases) for evaluation of load carrying capacity of pipes under finite compliance may lead to large safety margins.

OS0805 有限要素解析による矩形減肉を有する配管の破裂圧力の推定

Boilers and pressure vessels are heavily used in chemical industrial plant. The equipments are investigated the presence of damages periodically. The most damage types in the equipments are a wall thinning. Any damage must be repaired or replaced as necessary. On the other hand, optimization of the time required in order to replace damaged equipment by evaluating the load carrying capacity of pipes with wall-thinning is expected in chemical industrial field. In the present study, the estimated burst pressure of pipes with rectangular-wall-thinning is calculated by using FEA. And then, the estimated burst pressure is compared with experimentally obtained burst pressures. The estimated burst pressures agree well with the experimental results, because the difference between the estimated burst pressures and the experimental results is within ±10%.

Failure Bending Moment for Pipes With an Arbitrary-Shaped Circumferential Flaw

When a flaw is detected in a stainless steel piping system, an evaluation has to be performed to determine its suitability for continued operation. The failure bending moment of the flawed pipe can be predicted by limit load criterion in accordance with Appendix E-8 in the JSME S NA-1-2008 and/or Appendix C in the ASME Code Section XI. However, in these current codes, the limit load criterion is only calculated for the case of pipes containing a single flaw with constant depth, although the actual flaw depth is variable along the circumferential direction. Particularly, geometrical shapes of stress corrosion cracks are generally complex. The objective of this paper is to propose a method by formula for predicting the load-carrying capacity of pipes containing a circumferential surface flaw with any arbitrary shape. The failure bending moment is obtained by dividing the surface flaw into several subflaw segments. Using this method, good agreement is observed between the numerical solution and the reported experimental results. Several numerical examples are also presented to show the validity of the proposed methodology. Finally, it is demonstrated that three subflaw segments are sufficient to determine the collapse bending moment of a semi-elliptical surface flaw using the proposed methodology.

Experimental investigation of the failure behavior of notched wall-thinned pipes

The present study performed full-scale pipe tests using 100A Schedule 80 pipe specimens with simulated notched and circular wall thinning to investigate the failure behavior of notched wall-thinned pipes. The tests were conducted under both monotonic and cyclic bending moments at a constant internal pressure of 10 MPa at room temperature. The failure pattern, load carrying capacity, deformation ability, and fatigue strength of the notched wall-thinned pipes were evaluated by comparing results to those of circular wall-thinned pipes. The investigation showed that the effect of the type of thinning on the failure behavior was more sensitive under cyclic loading conditions than under monotonic loading conditions. The load carrying capacity of pipes with notched wall thinning was approximately the same or slightly less than that of pipes with circular wall thinning when the thinning area was subjected to tensile stress. However, when the thinning area was subjected to compressive stress, the load carrying capacity of pipes with notched wall thinning was greater than that of pipes containing circular wall thinning. The deformation ability and fatigue strength increased proportionally with the axial length of the thinning defect, and thus these properties were significantly reduced in notched wall-thinned pipes.

Effect of defects on the load carrying capacity of pipes of transmission oil and gas pipelines under biaxial loading

Effect of defects on the load carrying capacity of pipes of transmission oil and gas pipelines under biaxial loading

Diagnosis of the load-carrying capacity of pipes containing a longitudinal crack when loaded by an axial force and internal pressure

A method is developed for evaluating the load-carrying capacity and safe life of pipes with a through longitudinal crack when loaded by an axial force and internal pressure. The method is based on the use of previously developed nomograms of strain and limit load. The first nomogram is calculated on the basis of constitutive relations of the theory of plasticity, while the second is calculated in accordance with a fracture criterion for biaxial loading. The proposed method makes it possible to determine one of three parameters — critical crack length, limiting pressure, or limiting axial load — without preliminary calculations if the other two parameters are already known. As an example, nomograms are presented for a steel 15G2 pipe having a diameter of 1420 mm and wall thickness of 21.5 mm and containing a longitudinal crack.

Analysis of Part-Throughwall Crack in a Pipe Under Combined Tension and Bending

J-resistance curve solution is developed for a circumferential part-throughwall crack in a pipe under combined tension and bending. The J solution can be applied with load-displacement-crack extension data from one pipe test. Material resistance curves are developed for part-throughwall cracks in Type-304 stainless steel base material and SAW weld, and SA333 Gr6 and A106 GrB carbon steel base materials. Posttest tearing instability analyses are performed to predict the load carrying capacity of pipes containing part-throughwall cracks and to assess the accuracy of a Jestimation scheme solution.