Pipe Joint Management for Risers and Pipelines

2021 ◽  
Author(s):  
Ghiath (Guy) Mansour
Keyword(s):  
Fatigue Strength ◽  
Stress Concentration ◽  
Software Development ◽  
Wall Thickness ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Joint Management ◽  
Pipe Joints ◽  
Best Fit ◽  
Pipe Joint

Abstract Minimizing the stress concentration factor (SCF) in pipe joint welding subjected to fatigue is a major concern. Machining the joint ends is one way to achieve this. However, this adds cost, time, risk of potential crack starters, and loss of wall thickness which is detrimental for fatigue, strength, and engineering criticality assessment (ECA) in particular. Pipe joint sorting (certain joints in sequence) and end matching (rotating the pipe joints for best fit) are other ways. However, this adds time, costly logistics, risk of errors, and does not guarantee the minimum possible SCF is achieved. In a typical project, more pipe joints are procured than required in order to mitigate contingencies. For pipelines, this overage is typically a percentage of the required number of joints or pipeline length. For risers, typically double the required number of joints is procured where half of the joints is sent offshore for installation and the remaining half is kept onshore for a spare riser. Then, it becomes very important to send for installation the best pipe joints that produce the best (lowest) SCFs out of the entire batch of pipe joints. This requires calculating the SCF for every potential match of any random joints to be welded together, and then choosing the best joints. Performing such calculations by spreadsheet is not feasible considering the tremendous number of required iterations and calculations. A pipe joint management software development is presented herein which accomplishes this task and examples provided to illustrate the benefits. Note: Selecting pipe joints with the best end measurements, whether ID, OD, OOR, or thickness does not guarantee that the minimum possible SCFs will be achieved since the SCF is a function of all those measurements.

Fatigue Behavior of the Low-Strength Steel Welded Joints Treated by TIG Dressing and Ultrasonic Peening Combined Method

2011 ◽  
Vol 295-297 ◽  
pp. 1885-1889
Author(s):  
Sen Li ◽  
Dong Po Wang ◽  
Hai Zhang ◽  
Bo Tan
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Stress Concentration ◽  
Compressive Stress ◽  
Stress Level ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Combined Method ◽  
Ultrasonic Peening ◽  
Weld Toe

Butt-joint specimens of Q235B low-strength steel were treated by TIG dressing and ultrasonic peening combined method. The paper presents comparative fatigue test for welded specimens in the as-welded condition and specimens treated by TIG dressing, ultrasonic peening treatment (UPT) and the combined method. When the ratio of stress R=0.1, contrasted with the specimens in as welded condition, the fatigue strength of the specimens treated by TIG dressing is increased by 36%. The fatigue strength of the specimens treated by the combined method and UPT are almost the same, which are increased by 57% and 56% respectively. In the high stress level, weld toe treated by the combined method has smaller stress concentration factor than that of UPT, resulting in less release of residual compressive stress. So it's more effective to improve the fatigue life by the combined method. While in the low stress level, the residual compressive stress of weld toe treated by the combined method and UPT are nearly the same. Besides, the effect of stress concentration factor is smaller, thus the fatigue life of the two methods have little difference.

Mechanical Properties on the Welded Connection of Pipe and Hollow Spheres Joints

2011 ◽  
Vol 189-193 ◽  
pp. 3452-3457
Author(s):  
Ya Jie Yan ◽  
Hong Gang Lei ◽  
Xue Yang
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Stress Distribution ◽  
Wall Thickness ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Hollow Spheres ◽  
Steel Structures ◽  
Element Analysis ◽  
Static Tests

Taking pipe - hollow spherical node as the object, and using ANSYS finite element analysis software, established five kinds of finite element model to analyze the stress concentration at the weld connection of the different connections of steel structures - hollow ball under the uniaxial tension. Obtained this node’s stress concentration factor, stress distribution, by changing the hollow spherical diameter and wall thickness, pipe’s diameter and wall thickness, obtained the trend of the stress concentration factor under different control ball matches. Take static tests on typical structures of two specifications 6 hollow sphere nodes, get the measured stress concentration factor, and stress distribution of this node. Through comparative analysis of theoretical analysis and experimental results, show that the two rules are consistent. The research results can provide basis for improving the pipe - hollow spherical joints connecting structural.

Use of Tubular Joint Stress Concentration Factor Parametric Formulae in the Analysis of Large Diameter Pipework Connections

2000 ◽  
Author(s):  
R. M. Andrews ◽  
S. Wheat ◽  
M. Brown ◽  
C. Fowler
Keyword(s):  
Stress Concentration ◽  
Stress Analysis ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Large Diameter ◽  
Joint Stress ◽  
Tubular Joints ◽  
Tubular Joint ◽  
Potential Use ◽  
Pipe Joint

Parametric formulae derived for offshore structural tubular joints have been assessed for potential use for estimating stress intensification factors for pipe stress analysis. The background to these equations is given and comparisons made for a range of typical geometries. Despite the absence of a “plug” of material in a pipe joint, the tubular joint equations appear suitable for the estimation of stress intensification factors for fabricated tees subjected to moment loading of the branch. It is considered that this approach should be investigated further by code developers.

Two- and Three-Dimensional Cases of Stress Concentration, and Comparison With Fatigue Tests

1936 ◽  
Vol 3 (1) ◽  
pp. A15-A22 ◽  
Author(s):  
R. E. Peterson ◽  
A. M. Wahl
Keyword(s):  
Fatigue Strength ◽  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Practical Importance ◽  
Three Dimensional ◽  
Fatigue Tests ◽  
Carbon Steels ◽  
Dimensional Case ◽  
Strain Measurements

Abstract This paper reports the results of a study of some two- and three-dimensional cases of stress distribution with particular reference to shafts having fillets or transverse holes, these being of considerable practical importance. To determine the stress-concentration factor kt in such cases, strain measurements were made, using a specially developed extensometer with a gage length of 0.1 in. The results of these strain measurements indicate that for shaft fillets in bending (three-dimensional case) the stress-concentration factor kt is little different from the values obtained photoelastically on flat specimens having the same r/d ratio (a two-dimensional case). A comparison of these values of kt (both for shafts with fillets and with transverse holes), with data from fatigue tests, leads to the following observations: (1) In some cases fatigue results are quite close to theoretical stress-concentration values. (2) Fatigue results for alloy steels and quenched carbon steels are usually closer to theoretical values than are the corresponding fatigue results for carbon steels not quenched. (3) With decrease in size of specimen, the reduction in fatigue strength due to a fillet or hole becomes somewhat less; and for very small fillets or holes the reduction in fatigue strength is comparatively small. (4) Sensitivity factors determined for small specimens should not be applied to the design of machine parts regardless of size.

Practical Criterion for Estimation of Notch Fatigue Strength: Fatigue Diagrams and Material-Dependency of Notch Effects

2005 ◽  
Author(s):  
Hiroshi Matsuno ◽  
Yoshihiko Mukai
Keyword(s):  
Fatigue Strength ◽  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Stress Ratio ◽  
Notch Root ◽  
Equivalent Stress ◽  
Reduction Factor ◽  
Strength Reduction Factor ◽  
Fatigue Criterion

In the previous paper, authors considered a notch fatigue criterion on the basis of an equivalent stress ratio which was newly proposed as the parameter for the correspondence between cyclic stress conditions of a notched and unnotched specimen. The equivalent stress ratio is represented as a function of a nominal stress ratio and a theoretical stress concentration factor of a notched specimen. It could be derived without difficulty from a hypothesis of plastic adaptation which was newly proposed by the authors and the mechanical models which reflected the hypothesis. In the present paper, in order to confirm the applicability of the equivalent stress ratio, a wide range of published fatigue test data is rearranged on the diagram where the abscissa represents the equivalent stress ratio and the ordinate does the notch-root-concentrated stress range. As a result, the consistent relation proper to material is obtained in spite of the difference of a notch stress concentration factor, a specimen type (a plate or a round-bar) and a loading type (axial, bending, torsional or their combined loading). The relation is formulated in a simple form as an empirical equation. Such a result leads to a notch fatigue criterion that the notch-root-concentrated stress range at the fatigue strength of the notched specimen for any nominal stress ratio is identical with the fatigue strength of the unnotched specimen for the equivalent stress ratio. Moreover, the equation for estimation of a fatigue strength reduction factor can be derived by relating its definition with the notch fatigue criterion. As a result, it is shown that a usually defined fatigue strength reduction factor is represented by multiplying the theoretical stress concentration factor by the unnotched specimen’s fatigue strength ratio which is dependent upon the mean stress. Accordingly, it is clear that the material-dependency of notch effects can be characterized by the steepness of slope of the unnotched specimen’s fatigue strength diagram.

Evaluation of Back-Beveled and Counterbore-Tapered Joints in Energy Pipelines

2016 ◽  
Author(s):  
Xiaotong Huo ◽  
Shawn Kenny ◽  
Amgad Hussein ◽  
Michael Martens
Keyword(s):  
Stress Concentration ◽  
Wall Thickness ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Mechanical Performance ◽  
Pipe Diameter ◽  
Burst Pressure ◽  
Parameter Study ◽  
Stress Concentrations ◽  
Axial Forces

Wall thickness transition joints are used to connect energy pipeline segments; such as straight pipe to fittings with different wall thicknesses. The transition joint may be subject to axial forces and bending moments that may result in a stress concentration across the transition weld and may exceed stress based design criteria. Current engineering practices, such as CSA Z662, ASME B31.4, and ASME B31.8, recommend the use of back-bevel transition welded connections. An alternative transition weld configuration is the counterbore-taper design that is intended to reduce the stress concentration across the transition. In this study, the relative mechanical performance of these two transition design options (i.e., back-bevel and counterbore-taper) is examined with respect to the limiting burst pressure and effect of stress concentrations due to applied loads. The assessment is conducted through numerical parameter study using 3D continuum finite element methods. The numerical modelling procedures are developed using Abaqus/Standard. The performance of continuum brick elements (C3D8I, C3D8RH, C3D20R) and shell element (S4R) are evaluated. The continuum brick element (C3D8RI) was the most effective in terms of computational requirements and predictive qualities. The burst pressure limits of the transition weld designs were evaluated through a parameter study examining the significance of pipe diameter to wall thickness ratio (D/t), wall thickness mismatch ratio (t2/t1), material Grade 415 and Grade 483 and end-cap boundary condition effects. The limit load analysis indicated the burst pressure was effectively the same for both transition weld designs. The effect of pipe diameter, D/t, t2/t1, and counterbore length on the stress concentration factor, for each transition weld design, was also assessed. The results demonstrate the improved performance of the counterbore-taper weld transition; relative to the back-bevel design as recommended by current practice, through the relative decrease in the stress concentration factor. The minimum counterbore length was found to be consistent with company recommended practices and related to the pipe diameter and wall thickness mismatch.

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