Influence of Internal Pressure on the Impact Behavior of Steel Pipelines

1996 ◽  
Vol 118 (4) ◽  
pp. 464-471 ◽  
Author(s):  
N. Jones ◽  
R. S. Birch
Keyword(s):  
Experimental Data ◽  
Mild Steel ◽  
Internal Pressure ◽  
Wall Thickness ◽  
Critical Values ◽  
Impact Behavior ◽  
Steel Pipes ◽  
Impact Tests ◽  
The Impact ◽  
Gas Pressures

This article presents some experimental data recorded from 54 impact tests on pressurized mild steel pipes. The pipes were fully clamped across a span which was ten times the outside pipe diameter of 60 mm. The pipes had a wall thickness of 1.70 mm and were impacted laterally by a rigid wedge indenter at the mid-span and one-quarter-span positions. The impact velocities ranged up to 13.6 m/s and caused large inelastic indentations for the lower values and at higher values a loss of integrity which could occur underneath the indenter and/or at an end support. The critical values for the two failure energies were obtained for a range of internal gas pressures.

Response of Mild Steel Pipes Under High Mass Low Velocity Impacts

2014 ◽  
Author(s):  
Shamsoon Fareed ◽  
Ian May
Keyword(s):  
Finite Element ◽  
Mild Steel ◽  
Impact Energy ◽  
High Mass ◽  
Low Velocity ◽  
Element Analysis ◽  
Steel Pipes ◽  
Impact Tests ◽  
The Finite Element Analysis ◽  
The Impact

Accidental loads, for example, due to heavy dropped objects, impact from the trawl gear and anchors of fishing vessels can cause damage to pipelines on the sea bed. The amount of damage will depend on the impact energy. The indentation will be localized at the contact area of the pipe and the impacting object, however, an understanding of the extent of the damage due to an impact is required so that if one should occur in practice an assessment can be made to determine if remedial action needs to be taken to ensure that the pipeline is still serviceable. There are a number of parameters, including the pipe cross section and impact energy, which influence the impact behaviour of a pipe. This paper describes the response, and assesses the damage, of mild steel pipes under high mass low velocity impacts. For this purpose full scale impacts tests were carried out on mild steel pipe having diameter of 457 mm, thickness of 25.4 mm and length of 2000 mm. The pipe was restrained along the base and a 2 tonnes mass with sharp impactor having a vertical downward velocity of 3870 mm/sec was used to impact the pipe transversely with an impact energy of 16 kJ. It was found from the impact tests that a smooth indentation was produced in the pipe. The impact tests were then used for validation of the non-linear dynamic implicit analyses using the finite element analysis software ABAQUS. Deformations at the impact zone, the rebound velocity, etc, recorded in the tests and the results of the finite element analysis were found to be in good agreement. The impact tests and finite element analyses described in this paper will help to improve the understanding of the response of steel pipes under impact loading and can be used as a benchmark for further finite element modelling of impacts on pipes.

An Experimental Study on the Lateral Impact of Fully Clamped Mild Steel Pipes

1992 ◽  
Vol 206 (2) ◽  
pp. 111-127 ◽  
Author(s):  
N Jones ◽  
S E Birch ◽  
R S Birch ◽  
L Zhu ◽  
M Brown
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Mild Steel ◽  
Failure Modes ◽  
Experimental Results ◽  
Lateral Impact ◽  
Drop Hammer ◽  
Steel Pipes ◽  
Scale Range ◽  
The Impact

This report presents some experimental data that were recorded from 130 impact tests on mild steel pipes in two drop hammer rigs. The pipes were fully clamped across a span which was ten times the corresponding outside pipe diameters which lie between 22 and 324 mm. All of the pipes except five had wall thicknesses of 2 mm approximately and were impacted laterally by a rigid wedge indenter at the mid span, one-quarter span or near to a support. The impact velocities ranged up to 14 m/s and caused various failure modes. Some comparisons between two sets of experimental results indicate that the laws of geometrically similar scaling are almost satisfied over a scale range of approximately five.

scholarly journals Effect of In-Situ Synthesized Boride Phases on the Impact Behavior of Iron-Based Composites Reinforced by B4C Particles

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 554
Author(s):  
Fehmi Nair ◽  
Mustafa Hamamcı
Keyword(s):  
Contact Forces ◽  
Impact Behavior ◽  
Iron Matrix ◽  
Impact Tests ◽  
B4c Particles ◽  
Iron Based ◽  
In Situ Reactions ◽  
Boride Phases ◽  
The Impact

The objective of this study is to investigate the impact behavior of iron-based composites reinforced with boron carbide (B4C) particles and in-situ synthesized iron borides (Fe2B/FeB). The composite specimens (Fe/B4C) were fabricated by hot-pressing under a pressure of 250 MPa at 500 °C, and sintered at a temperature of 1000 °C. The effects of the reinforcement ratio on the formation of in-situ borides and impact behavior were investigated by means of different volume fractions of B4C inside the iron matrix: 0% (un-reinforced), 5%, 10%, 20%, and 30%. Drop-weight impact tests were performed by an instrumented Charpy impactor on reinforced and un-reinforced test specimens. The results of the impact tests were supported with microstructural and fractographical analysis. As a result of in-situ reactions between the Fe matrix and B4C particles, Fe2B phases were formed in the iron matrix. The iron borides, formed in the iron matrix during sintering, heavily affected the hardness and the morphology of the fractured surface. Due to the high amount of B4C (over 10%), porosity played a major role in decreasing the contact forces and fracture energy. The results showed that the in-situ synthesized iron boride phases affect the impact properties of the Fe/B4C composites.

Impact Strength of High Density Solid-State Microcellular Polycarbonate Foams

2000 ◽  
Vol 123 (2) ◽  
pp. 229-233 ◽  
Author(s):  
Chris Barlow ◽  
Vipin Kumar ◽  
Brian Flinn ◽  
Rajendra K. Bordia ◽  
John Weller
Keyword(s):  
Solid State ◽  
Impact Strength ◽  
Cell Size ◽  
High Density ◽  
Gas Content ◽  
Impact Behavior ◽  
Strong Function ◽  
Impact Tests ◽  
Izod Impact ◽  
The Impact

The effect of density (relative densities 0.33 to 0.90) on the impact behavior of microcellular polycarbonate (PC) was investigated. Cell size and foaming gas content were also considered. Flexed-beam Izod impact tests were conducted and the impact strength of these foams appears to be a strong function of both density and cell size. The impact strength was observed to improve over the unprocessed polycarbonate’s impact strength for foams with relative densities of 60 percent and above. In terms of cell size, the impact strength increased with increasing cell size at a given density.

A Study on the Large Ductile Deformations and Perforation of Mild Steel Plates Struck by a Mass—Part II: Discussion

1997 ◽  
Vol 119 (2) ◽  
pp. 185-191 ◽  
Author(s):  
N. Jones ◽  
S.-B. Kim
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Mild Steel ◽  
Steel Plates ◽  
Empirical Formulas ◽  
Mass Part ◽  
The Impact

An experimental study into the ductile deformations and static and impact perforation of mild steel plates is reported in Part I. These results are discussed in this article and compared with other experimental data reported in the literature. The accuracy of various empirical formulas for the impact perforation of plates is also examined.

Influence of Girth Weld Flaw and Pipe Parameters on the Critical Longitudinal Strain of Steel Pipes

2012 ◽  
Author(s):  
Celal Cakiroglu ◽  
Kajsa Duke ◽  
Marwan El-Rich ◽  
Samer Adeeb ◽  
J. J. Roger Cheng ◽  
...  
Keyword(s):  
Internal Pressure ◽  
Wall Thickness ◽  
Tensile Strain ◽  
Critical Strain ◽  
Pipe Wall ◽  
Pipe Wall Thickness ◽  
Strain Capacity ◽  
Steel Pipes ◽  
Tensile Strain Capacity ◽  
Maximum Minimum

The design of steel pipelines against longitudinal loading induced by soil movement and temperature requires an understanding of the strain demand induced by the environment in comparison with the strain resistance of the pipes. Girth weld flaws have been identified as the potential location of failure under longitudinal tensile strains due to being the least ductile. Strain based design for the prediction of the longitudinal tensile strain capacity of steel pipes have been extensively studied by Wang, et al and included in the Canadian standards association code of practice CSA Z662.11 [1]. The extensive track record of tests have culminated into two sets of equations for the critical strain in girth welded pipes with surface breaking and buried defects as functions of the different pipe and flaw parameters. The CSA Z662.11 strain capacity equations were developed using wide plate tests with the obvious limitation of the inability to consider the effect of the internal pressure of the pipe. However, recent studies by Wang et al led to the development of a new set of equations that predict the tensile strain capacity for pipes with an internal pressure factor of 0.72. This paper analyses the two critical strain equations in CSA Z662-11 to understand the effect of different girth weld flaw and pipe parameters on the expected behavior of pipes. Also the critical strain equations developed in [2]have been analysed and compared to the equations in CSA Z662-11. Using the equations in CSA Z662-11, a 34 and 36 full factorial experimental design was conducted for the planar surface-breaking defect and the planar buried defect respectively. For the case of surface breaking defects the dependence of the tensile strain capacity (εtcrit) on apparent CTOD toughness (δ), ratio of defect height to pipe wall thickness (η), ratio of yield strength to tensile strength (λ) and the ratio of defect length to pipe wall thickness (ξ) has been studied. εtcrit has been evaluated at the maximum, minimum and intermediate values of each parameter according to the allowable ranges given in the code which resulted in the evaluation of εtcrit for 81 different combinations of the parameters. The average value of εtcrit at the maximum, minimum and middle value of each parameter has been calculated. The visualization of the results showed that η, δ and ξ have the most significant effect on εtcrit among the four parameters for the case of surface breaking defect. Similarly for buried defects the dependence of εtcrit on δ, η, λ, ξ, and the pipe wall thickness (t) has been studied. The evaluation of εtcrit for all possible combinations of the maximum, intermediate and minimum values of the 6 parameters resulted in εtcrit values for 729 different combinations. The variation of the average εtcrit over the maximum, intermediate and minimum values of the parameters showed that δ, ψ, ξ and η are the parameters having the greatest effect on εtcrit for the case of a buried defect. Further investigations could be carried out to determine suitable upper and lower bounds for the parameters for which no bounded range is defined in the CSA Z662-11 code.

Analytical Investigation and Parametric Study of Lateral Impact Behavior of Pressurized Pipelines and Influence of Internal Pressure

2014 ◽  
Author(s):  
Yangqing Dou ◽  
Yucheng Liu
Keyword(s):  
Internal Pressure ◽  
Analytical Investigation ◽  
Response Surfaces ◽  
Impact Behavior ◽  
Polynomial Functions ◽  
Lateral Impact ◽  
Permanent Displacement ◽  
Quartic Polynomial ◽  
Pressurized Pipelines ◽  
The Impact

This paper provides a combined computational and analytical study to investigate the lateral impact behavior of pressurized pipelines and inspect all the parameters such as the outside diameter and internal pressure affects such behavior. In this study, quartic polynomial functions are applied to formulate the maximum crushing force (F), maximum permanent displacement (W), and absorbed energy (E) of the pressurized pipelines during the impact problem. The effects of the diameter and pressure on F, W, and E are therefore illustrated through analyzing those functions. Response surfaces are also plotted based on the generated quartic polynomial functions and the quality (accuracy) of those functions are verified through several techniques.

The Stresses in Thick-Walled Cylinders of Mild Steel Overstrained by Internal Pressure

1934 ◽  
Vol 126 (1) ◽  
pp. 407-455 ◽  
Author(s):  
Gilbert Cook
Keyword(s):  
Shear Stress ◽  
Mild Steel ◽  
Internal Pressure ◽  
Wall Thickness ◽  
Maximum Shear Stress ◽  
Internal Surface ◽  
Principal Stresses ◽  
Constant Shear Stress ◽  
Axial Compressive Stress ◽  
Set Up

The paper describes a theoretical and experimental investigation of the stress distribution across the walls of thick cylinders of mild steel when the internal pressure is such that the elastic limit of the material is exceeded and a certain amount of overstrain occurs. The main conclusions are:— (1) That in the cylinders in which it was possible to produce overstrain over the whole wall thickness the observed pressure is in close agreement with that calculated on the assumption of constant shear stress equal to the shear stress observed during plastic yield in tension. (2) That in partially overstrained cylinders the maximum shear stress in the elastic region varies as overstrain proceeds. (3) That at the internal surface the effect of overstrain is to reduce the circumferential tensile stress, and to set up an axial compressive stress. With sufficient wall thickness all three principal stresses at the internal surface become compressive for pressures which still permit of the external portions remaining elastic.

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