Analysis of 3D Planar Laminations in a Welded Section of API 5L X52 Applying the Finite Element Method

Abstract

Abstract:The mechanical behavior of API 5L X52 steel with planar type laminations was studied in the present work. Planar laminations were proposed in the base metal (BM), heat affected zone (HAZ) and welding bead (WB). Three-dimensional finite element (FE) models, kinematic hardening and mechanical properties for BM, HAZ, and WB were activated in the finite element program. The results showed that crack propagation corresponds to the direction of the main stress. For a crack length (2a) of 10.01 mm, crack propagation may occur at the right crack tip towards the outer wall of the BM. For 2a of 15.12 mm, crack propagation was located on the right crack tip and propagates to the inner wall. For 2a of 17.12 mm, crack propagation was observed at the left crack tip and propagates to the outer wall in the BM. The results achieved by FEM agree when compared with real laminations in API 5L pipelines.

Mechanical resistance of stepped lamination defects in a welded section of oil and gas pipeline: a finite element analysis

“…The above situation agrees with the fracture mechanics postulate because the direction of cracking corresponds to the direction of the main stresses. For pipeline internal pressure values, the mode of the main stress at the crack tips corresponds with the field stress of the plastic zone for mode I 4 [34], which agrees with the model proposed by Ikeda [10].…”

Determination of the Actual Stress–Strain Diagram for Undermatching Welded Joint Using DIC and FEM

“…In the further analysis, numerical verification of coefficients for specimens C1-1 and P1-1 is shown for strains immediately before the fracture: The values obtained in ABAQUS for the quarter of the specimen C1-1 and P1-1 at the characteristic points (1 and 2) are shown in Figure 9. Stress for specimen C1-1, the maximum equivalent stresses (von Misses) are: The equivalent stress values, obtained by ABAQUS and the stresses calculated by the formulas (10)(11)(12)(13)(14)(15), are given in Table 5. One should notice difference between stress values in points 1 and 2 for specimen C1-1 and almost the same stress values in these two points for specimen P1-1.…”

“…The true stress–strain curve was developed by using the modified version of the weighted average method. Yet another overmatched welded joint was considered in [ 12 ], where mechanical behavior with planar type laminations in the base metal (BM), heat-affected zone (HAZ), and welding bead (WB) was studied. By using HV data, an equivalent true stress–strain curve in the HAZ was estimated, based on corresponding hardness value obtained from the BM and WB.…”

On the assessment of non-metallic inclusions by part 13 of API 579 -1/ASME FFS-1 2016

“…In the Level 2 assessment, lamination zones are considered as local thinner areas or a crack-like flaw and evaluated by criteria such as remaining strength factor (RSF) and failure assessment diagram (FAD) [19]. The Level 3 assessment also is done using the Finite Element Method (FEM) for explicit modeling and the most accurate stress analysis of lamination zones, considering defects geometry and loading conditions [17,20]. The equipment's Owners/Users often question the assessment criteria of API 579 and request FFS engineers to provide technical advice for modifying the system due to the high financial cost.…”