Mechanical Integrity Modeling of Forge Welded Pipes for Offshore Applications

2012 ◽  
Author(s):  
Ganesan S. Marimuthu ◽  
Per Thomas Moe ◽  
Junyan Liu ◽  
Bjarne Salberg
Keyword(s):  
Weld Line ◽  
Base Material ◽  
Full Scale ◽  
Small Scale ◽  
Type Model ◽  
Model Parameters ◽  
Weld Quality ◽  
Line Pipe ◽  
Gurson Model ◽  
Mechanical Integrity

In this paper, we discuss how through-process multi-scale models can be designed and combined with properly constructed experiments in order to assess the mechanical integrity of forge welded connectors. Shielded Active Gas Forge Welding (SAG-FW) is a fully automatic solid state method for joining steel pipes and other metallic articles. After heating, welding occurs almost instantaneously when the mating surfaces of the metallic parts are brought into intimate contact at high temperature and co-deformed. The result is a metallic bond with properties similar to those of the base material. If mating surfaces have been properly prepared and are essentially free from oxides the forge weld line is completely indistinguishable even when studied under a microscope. However, improper surface finish, oxides and contaminants may contribute to reducing weld quality. The paper consists of analytical and experimental parts. First, approaches for modeling forge welding and weld integrity are assessed. Second, a Gurson-type model is studied in great detail as it appears to be the simplest and most promising concept in relation to quantitative modeling and testing of mechanical integrity of forge welds. Third, miniature notched specimens for determining parameters of a modified Gurson-model are proposed and evaluated in relation to small scale forge welding. The small scale forge welding method has been established in order to simulate full scale welding of for example line pipe and casing, but mechanical testing of small samples constitute a significant challenge. Fourth, a set of experiments is performed to further assess the concept, to the extent possible determine material parameters of the Gurson-model and to evaluate the effect of process parameter settings on the weld quality. Results from tests of welds with and without oxides are subsequently compared with results from tests of base material specimens. All tests have been performed for an API 5L X65 alloy. The results demonstrate that both capacity and ductility of the forge welds are similar to those of base material. Finally, Gurson-model parameters are assessed, and a comparison with physical observations is made. Further development of the small scale tests is needed. More extensive test programs should be performed and a comparison with full scale welding should be carried out. However, the experiments demonstrated that the proposed notched specimen designs complements conventional fracture mechanical tests (CT, SENT, SENB) or field tests proposed by various standards (Charpy, Izod, bend tests).

Coupled Thermo-Hydro-Geochemical Models of Engineered Barrier Systems: The Febex Project

2000 ◽  
Vol 663 ◽  
Author(s):  
J. Samper ◽  
R. Juncosa ◽  
V. Navarro ◽  
J. Delgado ◽  
L. Montenegro ◽  
...  
Keyword(s):  
Large Scale ◽  
Reference Model ◽  
Numerical Models ◽  
Full Scale ◽  
Small Scale ◽  
Model Parameters ◽  
In Situ Test ◽  
Wide Range ◽  
Engineered Barrier

ABSTRACTFEBEX (Full-scale Engineered Barrier EXperiment) is a demonstration and research project dealing with the bentonite engineered barrier designed for sealing and containment of waste in a high level radioactive waste repository (HLWR). It includes two main experiments: an situ full-scale test performed at Grimsel (GTS) and a mock-up test operating since February 1997 at CIEMAT facilities in Madrid (Spain) [1,2,3]. One of the objectives of FEBEX is the development and testing of conceptual and numerical models for the thermal, hydrodynamic, and geochemical (THG) processes expected to take place in engineered clay barriers. A significant improvement in coupled THG modeling of the clay barrier has been achieved both in terms of a better understanding of THG processes and more sophisticated THG computer codes. The ability of these models to reproduce the observed THG patterns in a wide range of THG conditions enhances the confidence in their prediction capabilities. Numerical THG models of heating and hydration experiments performed on small-scale lab cells provide excellent results for temperatures, water inflow and final water content in the cells [3]. Calculated concentrations at the end of the experiments reproduce most of the patterns of measured data. In general, the fit of concentrations of dissolved species is better than that of exchanged cations. These models were later used to simulate the evolution of the large-scale experiments (in situ and mock-up). Some thermo-hydrodynamic hypotheses and bentonite parameters were slightly revised during TH calibration of the mock-up test. The results of the reference model reproduce simultaneously the observed water inflows and bentonite temperatures and relative humidities. Although the model is highly sensitive to one-at-a-time variations in model parameters, the possibility of parameter combinations leading to similar fits cannot be precluded. The TH model of the “in situ” test is based on the same bentonite TH parameters and assumptions as for the “mock-up” test. Granite parameters were slightly modified during the calibration process in order to reproduce the observed thermal and hydrodynamic evolution. The reference model captures properly relative humidities and temperatures in the bentonite [3]. It also reproduces the observed spatial distribution of water pressures and temperatures in the granite. Once calibrated the TH aspects of the model, predictions of the THG evolution of both tests were performed. Data from the dismantling of the in situ test, which is planned for the summer of 2001, will provide a unique opportunity to test and validate current THG models of the EBS.

TurkStream Collapse Test Program

2018 ◽  
Author(s):  
Chris Timms ◽  
Doug Swanek ◽  
Duane DeGeer ◽  
Arjen Meijer ◽  
Ping Liu ◽  
...  
Keyword(s):  
Thermal Ageing ◽  
Full Scale ◽  
The Black Sea ◽  
Small Scale ◽  
Test Program ◽  
Line Pipe ◽  
Medium Scale ◽  
Collapse Resistance ◽  
Full Scale Tests ◽  
The Impact

The TurkStream pipeline project is designed to transport approximately 32 billion cubic meters of natural gas annually from Russia to Turkey under the Black Sea, with more than 85% of the deep-water route being deeper than 2000 m. The offshore section is intended to consist of two parallel lines, each approximately 900 km long. The preliminary stages of the front end engineering design (pre-FEED) phase was managed by INTECSEA. To support the analyses and design of the deepest portions, a full scale collapse test program was performed by C-FER Technologies (C-FER). This collapse test program, which included 62 full-scale collapse and pressure+bend tests, 54 medium-scale ring collapse tests, and hundreds of small-scale tests, was primarily aimed at measuring, quantifying and documenting the increase in pipe strength and collapse resistance resulting from the thermal induction heat treatment effect (thermal ageing) that arises during the pipe coating process. Two grades of 32-inch (813 mm) outside diameter (OD) line-pipe, SAWL450 and SAWL485 with wall thicknesses of 39.0 mm or 37.4 mm, respectively, were supplied from various mills for testing. The collapse test program objectives were as follows: • Determine the collapse resistance of line pipes originating from various pipe mills; • Determine the pressure+bend performance of line pipes originating from various pipe mills; • Measure the effect of thermal ageing on material and collapse testing results, including the impact of multiple thermal cycles; and • Evaluate the results of medium-scale ring collapse tests as compared to full-scale tests. This paper presents selected results of this work, along with some comparisons to predictive equations.

Effects of Aging on the Mechanical Properties of Pipeline Steels

2008 ◽  
Author(s):  
Martin Hukle ◽  
Brian Newbury ◽  
Dan Lillig ◽  
Jonathan Regina ◽  
Agnes Marie Horn
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Uniform Elongation ◽  
Weld Line ◽  
Base Material ◽  
Pipeline System ◽  
Line Pipe ◽  
Pipeline Steels ◽  
Reduction Of Area ◽  
Effects Of Aging

The intelligent design of a given pipeline system intended for operation beyond the elastic limit should incorporate specific features into both the base material (line pipe) and girth weld that enable the affected system to deform safely into the plastic regime within the intended strain demand limits. The current paper focuses on the mechanical properties known to influence the strain capacity of the base material (i.e., line pipe steel independent of the girth weld). Line pipe mechanical properties of interest include: longitudinal yield strength, tensile strength, yield to tensile strength ratio, reduction of area, elongation and uniform elongation. Of particular interest (in consideration of the conventional thermally applied corrosion protection coating systems to be employed), are the longitudinal mechanical properties in the “aged” condition. The present study investigates six (6) different pipeline steels encompassing grades X60 (415 MPa) to X100 (690 MPa), and includes both UOE Submerged Arc Welded - Longitudinal (SAW-L) and seamless (SMLS) forming methods.

Full-Scale Reeling Tests of HFI Welded Line Pipe for Offshore Reel-Laying Installation

2014 ◽  
Author(s):  
Karl Christoph Meiwes ◽  
Susanne Höhler ◽  
Marion Erdelen-Peppler ◽  
Holger Brauer
Keyword(s):  
Mechanical Testing ◽  
Mechanical Test ◽  
Strength Properties ◽  
Full Scale ◽  
Bending Test ◽  
Small Scale ◽  
Pipe Material ◽  
Deformation Capacity ◽  
Line Pipe ◽  
Tension And Compression

During reel-laying repeated plastic strains are introduced into a pipeline which may affect strength properties and deformation capacity of the line pipe material. Conventionally the effect on the material is simulated by small-scale reeling simulation tests. For these, coupons are extracted from pipes that are loaded in tension and compression and thermally aged, if required. Afterwards, specimens for mechanical testing are machined from these coupons and tested according to the corresponding standards. Today customers often demand additional full-scale reeling simulation tests to assure that the structural pipe behavior meets the strain demands as well. Realistic deformations have to be introduced into a full-size pipe, followed by aging, sampling and mechanical testing comparable to small-scale reeling. In this report the fitness for use of a four-point-bending test rig for full-scale reeling simulation tests is demonstrated. Two high-frequency-induction (HFI) welded pipes of grade X65M (OD = 323.9 mm, WT = 15.9 mm) from Salzgitter Mannesmann Line Pipe GmbH (MLP) are bent with alternate loading. To investigate the influences of thermal aging from polymer-coating process one test pipe had been heat treated beforehand, in the same manner as if being PE-coated. After the tests mechanical test samples were machined out of the plastically strained pipes. A comparison of results from mechanical testing of material exposed to small- and full-scale reeling simulation is given. The results allow an evaluation of the pipe behavior as regards reeling ability and plastic deformation capacity.

Seamless Linepipe Response Under Small and Full Scale Reeling Simulation

2016 ◽  
Author(s):  
Israel Marines-Garcia ◽  
Jorge A. Aldana-Díaz ◽  
Philippe P. Darcis ◽  
Hector M. Quintanilla
Keyword(s):  
Lead Time ◽  
Cyclic Strain ◽  
Extensive Study ◽  
Full Scale ◽  
Small Scale ◽  
Pipe Material ◽  
Line Pipe ◽  
Offshore Pipelines ◽  
Ageing Condition ◽  
Pipe Materials

Offshore pipelines projects, installed by reel-laying operations, are gaining momentum due to the increasing worldwide capacity of Reel Lay Vessels. It is well known that reel-laying installation causes repeated plastic straining (cyclic deformation) and, as a consequence, cyclic strain and ageing test is usually required for qualifying line pipe materials for such installation method. This qualification is typically named reeling simulation. Reeling simulations can be made via full or small scale. In practice, full scale qualification lead time and full scale reeling simulation machines availability could be a constraint, thus, small scale reeling simulation is usually the best alternative. However, the similitude of small scale versus full scale simulations could be questioned. On this basis, an extensive study was carried-out considering tensile, toughness and sour testing, in order to evaluate the material response after reeling simulation, in order to clarify if the line pipe material will behave similarly regardless the straining method (small scale or full scale). Different small scale samples configuration for straining were tested, depending on the posterior mechanical or sour test, and two different full scale reeling simulation machines were used for plain pipes straining. Five seamless plain pipes, X65 line pipe were used for this study, with 3 (three) different outer diameters of 10.75″, 11.67″ & 16″ (273 mm, 296 mm & 406 mm). The current paper will present the main mechanical results of these materials after strain and ageing condition, comparing full and small scale straining methods.

Anisotropic HFI Welded Steel Pipes for Strain Based Design

2016 ◽  
Author(s):  
Oliver Hilgert ◽  
Susanne Höhler ◽  
Holger Brauer
Keyword(s):  
Full Scale ◽  
Small Scale ◽  
Steel Tubes ◽  
Line Pipe ◽  
Welded Steel ◽  
Bending Tests ◽  
Strain Capacity ◽  
Steel Pipes ◽  
Weld Material ◽  
Anisotropy Parameters

Generally isotropic behavior is assumed and demanded in line pipe specifications. Especially in strain based design, compressive and tensile strain capacity models rely on iso-tropic assumptions. On the other hand every pipe has got an anisotropic material characteristic which effects the performance in strain based design. In this contribution HFI-welded steel tubes are investigated due to their underlying material anisotropy. Depending on their basic strip weld material and production process the anisotropy differs from UOE or spiral welded pipes. Especially, in radial direction of steel pipe mechanical properties are challenging to gain. Thus two methods are suggested to characterize the anisotropic parameters in all three pipe directions. A small scale approach evaluating Lankford values and a full scale method evaluating Hill factors are applied. While Lankford method relies on strains, Hills method relies on stresses. Both methods are explained and validated by internal pressure and full scale bending tests. Using the anisotropy parameters, their effect on strain based design is analyzed — both experimentally and numerically. In the end it is shown that distinct anisotropies can provide a benefit for HFI-welded steel tubes concerning strain capacity in strain based design applications.

Full Scale Application of Thermal Ageing in Line Pipe Material Selection for Deepwater Pipelines

2014 ◽  
Author(s):  
Niels Kerstens ◽  
Ping Liu ◽  
Duane DeGeer
Keyword(s):  
Wall Thickness ◽  
Development Program ◽  
Thermal Ageing ◽  
Full Scale ◽  
Small Scale ◽  
Pipe Material ◽  
The South ◽  
Line Pipe ◽  
Material Development ◽  
South Stream

Comprising 4 pipelines over 900 km in length, with 32-in diameter and traversing water depths over 2200 m, the South Stream project requires a step-out in technology application. Following several years of preparation, the project is now approaching its implementation. In order to document the reliability of the collapse resistance for South Stream, an extensive material development program was initiated and executed, including small scale, medium scale, and full scale testing on over one hundred purposely manufactured pipe joints by world’s 5 leading mills. Testing performed included plate tests, full scale collapse tests on various combinations of plate sources, steel grades, and thermal ageing condition, pressure-bend tests, and reverse bending tests. A large number of medium and small scale tests were performed to allow the development of a suitably reliable statistical database for the probabilistic wall thickness design. In addition, programs were developed and executed for weldability tests, performing over one hundred trial welds, and for H2S resistance tests. This material development program was built on INTECSEA’s extensive experience with deep water large diameter pipelines (i.e. Oman-India, Blue Stream, Medgaz, Mardi Gras, IGI, etc.). Due to its extent and rigorous approach the South Stream material development program was able to conclusively prove the feasibility of the selected technological approach at an industrial scale. This paper provides an overview of the key design issues that were successfully addressed and the major technological advances that have been implemented as part of the linepipe material development process for deepwater pipelines in an H2S containing environment. The practical significance of this program is to optimize the wall thickness to a level that is manufacturable by the industry and hence enables the South Stream Project to proceed with its unprecedented depth and diameter combination.

The Misconception of Employing CVN Toughness as Key-Measure in Ductile Crack Arrest Prediction for Modern Line-Pipe Steels

2014 ◽  
Author(s):  
Alexander Völling ◽  
Christoph Kalwa ◽  
Marion Erdelen-Peppler
Keyword(s):  
Ductile Fracture ◽  
Data Base ◽  
Model Calibration ◽  
Crack Arrest ◽  
Full Scale ◽  
Small Scale ◽  
Material Strength ◽  
Original Material ◽  
Pipe Steels ◽  
Line Pipe

Since the late 1960s’ the Battelle Two-curve (BTC) model is the standard method applied in setting up design requirements with regard to the prevention of long-running ductile fracture in pipelines. It is a straightforward tool employing Charpy-V notch (CVN) toughness as key-measure for material resistance against crack propagation. On basis of pipe dimensions, material strength, and under consideration of decompression behavior of the transferred media, it enables to set up requirements for a minimum CVN toughness level to achieve crack arrest. Overall applicability of the BTC model is based on calibration of the underlying equations to a sound data-base, including both full-scale burst test results and small-scale laboratory testing data involving typical line-pipe grades at that period, i.e. up to grade X70 steels with below 100 J upper-shelf CVN toughness. Now over the last decades, mechanical behavior of line-pipe steels was improved significantly. Responding to market demands, higher grades were designed and also toughness levels were raised as outcome of R&D efforts within the steel industry. Unfortunately, stepping outside the original material data-base from BTC model calibration, this method did forfeit its reliability. At the beginning, mispredictions were mainly related to higher grade steels and elevated operating pressures. But more recent full-scale tests did reveal discrepancies in application of the BTC model also for so-called new vintage steels, i.e. grades actually being inside the original data base for model calibration but from current production routes. With regard to applicability/reliability of BTC model based predictions for crack arrest, the origin of uncertainty has particularly been traced back to the involved material toughness measure. Nowadays, it is common sense that the CVN upper-shelf toughness value inadequately describes the resistance against running ductile fracture. More recent thoughts coherently argue towards closer involving stress-strain response and plastic deformation capacities of the material. On basis of results for grades X65, X80 and X100, the general relation between ductility and toughness is discussed. Finally, an elastic-plastic fracture mechanics related analytical approach is introduced which enables to quantify the resistance against ductile fracture propagation. The objective is to provide a reliable procedure for crack arrest prediction in line-pipe steels.

Full-Scale Step-Load-Hold Tests on X65 and X70 Line Pipe Steels

2020 ◽  
Author(s):  
Andrew Cosham ◽  
Brian N. Leis ◽  
Mures Zarèa ◽  
Fabian Orth ◽  
Valerie Linton
Keyword(s):  
Impact Energy ◽  
Full Scale ◽  
Small Scale ◽  
Battelle Memorial Institute ◽  
Pipe Steels ◽  
Line Pipe ◽  
Delayed Failure ◽  
Hold Period ◽  
Full Scale Tests ◽  
Scale Step

Abstract A time-delayed failure due to stress-activated creep (cold-creep) will occur if the applied load is held constant at a level above the threshold. The results of small and full-scale tests on line pipe steels conducted by the Battelle Memorial Institute and the British Gas Corporation in the 1960s and 70s indicated that the (empirical) threshold for a time-delayed failure was approximately 85–95% SAPF (straight-away-pressure-to-failure). The line pipe steels were Grades X52 or X60, and the full-size equivalent Charpy V-notch impact energy (where reported) did not exceed 35 J. The strength and toughness of line pipe steels has significantly increased over the decades due to developments in steel-making and processing. The question then is whether an empirical threshold based on tests on lower strength and lower toughness steels is applicable to higher strength and higher toughness steels. A Tripartite Project was established to answer this question. The Australian Pipelines and Gas Association (APGA), the European Pipeline Research Group (EPRG) and the Pipeline Research Council International (PRCI) collaborated in conducting six full-scale step-load-hold tests on higher strength and higher toughness steels. Companion papers present the other aspects of this multi-year project. The line pipe supplied for testing is summarised below. • Identifier — Dimensions and Grade — f.s.e. Charpy V-notch impact energy at 0 C • APGA [A] — 457.0 × 9.1 mm, Grade X70M, ERW — 263 J • EPRG [E] — 1016.0 × 13.6 mm, Grade X70M, SAWL — 165 J • PRCI [P] — 609.6 × 6.4 mm, Grade X65, SAWL — 160 J Six step-load-hold tests, each with four part-through-wall defects, were conducted. Test Nos. APGA 1 and 2, and Nos. EPRG 1 and 2 were conducted at Engie, France. Test Nos. PRCI 1 and 2 were conducted at EWI, USA. The full-scale tests, and associated small-scale testing, are described and discussed. A time-delayed failure due to stress-activated creep occurred in each of the step-load-hold tests. The failures occurred during a hold-period at 93.7–104.4% SAPF, after a hold of approximately 1.0–13.9 hours. The results of the six step-load-hold tests are consistent with a threshold for a time-delayed failure of approximately 90% SAPF.

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