An Investigation of the Fatigue Performance of Riser Girth Welds

2006 ◽  
Author(s):  
Stephen J. Maddox ◽  
Julian B. Speck ◽  
G. Reza Razmjoo
Keyword(s):  
Oil And Gas ◽  
Welding Process ◽  
Fatigue Loading ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Steel Catenary Riser ◽  
Gas Recovery ◽  
Fatigue Design ◽  
Pipeline Welding ◽  
Girth Welds

Increasing deep-water oil and gas recovery has highlighted the need for high integrity, high fatigue performance girth welds in steel catenary riser systems. Such systems include girth welds made from one side. However, the widely used fatigue design classification, UK Class F2, for such welds is not well founded, but probably over-conservative for pipeline welds. In an attempt to justify upgrading current fatigue design classifications and providing a better basis for design, fatigue tests were performed on a range of girth-welded pipes produced by pipeline welding contractors. This paper presents the results of those tests and their evaluation in terms of the factors that influence the fatigue performance of girth welds, including welding process, welding position, backing system, joint alignment, weld quality, specimen type and fatigue loading conditions. Conclusions are drawn regarding the scope for adopting higher design classifications and the conditions that must be met to justify them.

An Investigation of the Fatigue Performance of Riser Girth Welds

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Stephen J. Maddox ◽  
Julian B. Speck ◽  
G. Reza Razmjoo
Keyword(s):  
Oil And Gas ◽  
Welding Process ◽  
Fatigue Loading ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Steel Catenary Riser ◽  
Gas Recovery ◽  
Fatigue Design ◽  
Pipeline Welding ◽  
Girth Welds

Increasing deep-water oil and gas recovery has highlighted the need for high integrity, high fatigue performance girth welds in steel catenary riser systems. Such systems include girth welds made from one side. However, the widely used fatigue design classification, UK Class F2, for such welds is not well founded, but probably overconservative for pipeline welds. In an attempt to justify upgrading current fatigue design classifications and providing a better basis for design, fatigue tests were performed on a range of girth-welded pipes produced by pipeline welding contractors. This paper presents the results of those tests and their evaluation in terms of the factors that influence the fatigue performance of girth welds, including welding process, welding position, backing system, joint alignment, weld quality, specimen type, and fatigue loading conditions. Conclusions are drawn regarding the scope for adopting higher design classifications and the conditions that must be met to justify them.

Sour Environmentally Assisted Fatigue of Welded SCR Materials: Post-Weld Finishing Treatment Evaluation

2010 ◽  
Author(s):  
Philippe P. Darcis ◽  
Israel Marines-Garcia ◽  
Stephen J. Hudak ◽  
Mariano Armengol ◽  
Hector M. Quintanilla
Keyword(s):  
Oil And Gas ◽  
Fatigue Tests ◽  
Oil And Gas Development ◽  
Intermediate Scale ◽  
Fatigue Design ◽  
X65 Steel ◽  
Girth Welds ◽  
Welded Pipe ◽  
Welding Procedure ◽  
Brine Environment

The current work aims to point out the influence of sour brine environment on the fatigue resistance of welded SMLS (seamless) steel pipe used for design and fabrication of risers for oil and gas development. A C-Mn steel X65 pipe 10.75″ (273.1 mm) outside diameter (OD) and 25.4 mm wall thickness (WT) was chosen for this program. The Welding Procedure designed for girth welds manufacturing involved the use of Lincoln STT-GMAW™ process for the root pass and SAW process with twin wire configuration for the fill and cap passes. This welding procedure presents a special post-weld finishing treatment, which consist in flapping the inner and outer weld overfills to produce a flush profile between weld metal and outer/inner pipe surfaces. The experimental approach focused on quantifying the effect of H2S using a sour brine environment. For this purpose, intermediate-scale fatigue data in the sour brine environment, using full thickness’ strip specimens extracted from the welded SMLS (seamless) pipe, have been generated. Intermediate-scale fatigue tests in air have also been obtained to provide a baseline for comparison with the sour brine data. Those results have been compared with full-scale fatigue tests in air environment. Finally, results were statistically analyzed to determine which standard fatigue design curves best represent the measured S-N fatigue endurance in air and sour brine environments. Results were also compared with available literature and results on other seamless’ welded pipe of the same API 5L, Grade X65 steel in comparable environments.

High-Cycle and Low-Cycle Fatigue Resistance of Girth Welds in Sour Service

2008 ◽  
Author(s):  
Jaime Buitrago ◽  
Stephen Hudak ◽  
David Baxter
Keyword(s):  
Low Cycle Fatigue ◽  
Water Injection ◽  
Fatigue Performance ◽  
Cycle Fatigue ◽  
Production Lines ◽  
Hydrocarbon Production ◽  
Steel Catenary Riser ◽  
Fatigue Design ◽  
Girth Welds ◽  
Constant Slope

The fatigue performance of fracture-critical production lines, such as risers and flowlines, has been shown to significantly degrade in the presence of sour hydrocarbon production caused by water injection of reservoirs. To ensure the reliability of the fatigue design under such conditions, experimental verification of the degradation effect on fatigue life due the presence of H2S is required. To that end and over the past several years, ExxonMobil has developed new testing methodologies to evaluate the riser fatigue performance for both in-air and sour conditions. This paper reviews the general elements of the fatigue qualification process and presents new sour fatigue data aimed at assessing performance at the high-cycle fatigue (HCF) and low-cycle fatigue (LCF) regimes. These new data are relevant to that seen in steel catenary riser (SCR) and flowline thermal responses, respectively. Testing methodologies for each regime are discussed and results presented. The new data are interpreted within the context of previous data in the intermediate-cycle fatigue (ICF) to provide a more robust basis for riser design. The main finding is that the new data support a constant slope S-N curve for the practical domain of fatigue lives to which offshore lines are typically designed under sour conditions.

Guidance for Fatigue Design and Assessment of Pipeline Girth Welds

2003 ◽  
Author(s):  
P. J. Haagensen ◽  
S. J. Maddox ◽  
K. A. Macdonald
Keyword(s):  
Fatigue Loading ◽  
Performance Improvements ◽  
Fatigue Design ◽  
Current Design ◽  
Flow Induced Vibrations ◽  
Pipeline Welding ◽  
Girth Welds ◽  
Design Guidance ◽  
Made In

Risers and sections of pipeline in free-span can be subjected to cyclic loading from flow-induced vibrations and other fluctuating forces leading to fatigue loading of the structure. Single-sided welds are of particular interest, however current design codes take a pessimistic view of their fatigue performance. Improvements in the quality of the finished weld produced by modern pipeline welding technology, and indeed advances made in knowledge about fatigue of such welds, mean that revision of the design guidance is now warranted. This paper reviews the fundamental basis of the existing S-N curves used for North Sea applications and considers their applicability in the light of research on fatigue of girth welds. Based on the review, proposals are made for revised fatigue design rules for girth welds in pipelines.

Effects of Nonlinear Riser-Soil Interaction Model on Fatigue Design of Steel Catenary Riser Under Random Waves

2017 ◽  
Author(s):  
Mehrdad Kimiaei
Keyword(s):  
Oil And Gas ◽  
Structural Response ◽  
Interaction Model ◽  
Nonlinear Behavior ◽  
Random Waves ◽  
Steel Catenary Riser ◽  
Oil And Gas Fields ◽  
Fatigue Design ◽  
Time Histories ◽  
Main Components

Steel Catenary Risers (SCRs) are one of the main components in development of oil and gas fields in deep waters. Fatigue design of SCRs in touch down zone (TDZ) is one of the main engineering challenges in design of riser systems. Nonlinear riser-soil interaction models have recently been introduced and used widely in advanced structural analysis of SCRs. Due to hysteretic nonlinear behavior of the soil, SCR system will show different structural response under different loading time histories. This paper investigates the effects of nonlinear riser-soil interaction in the TDZ on fatigue performance of an example SCR subjected to randomly generated waves. Sensitivity of fatigue life of the system, location of the critical node and the maximum stress range to different wave realizations and different soil types are discussed in detail.

Development of an Effective ASME IX Welding Procedure Qualification Program for Pipeline Facility and Fabrication Welding

2016 ◽  
Author(s):  
Junfang Lu ◽  
Bob Huntley ◽  
Luke Ludwig
Keyword(s):  
Oil And Gas ◽  
Material Selection ◽  
Base Material ◽  
Welding Process ◽  
Notch Toughness ◽  
Essential Variable ◽  
Performance Qualification ◽  
Pipeline Welding ◽  
Welding Consumable ◽  
Welding Procedure

For cross country pipeline welding in Canada, welding procedures shall be qualified in accordance with the requirements of CSA Z662 Oil and Gas Pipeline Systems. For pipeline facility and fabrication welding on systems designed in accordance with CSA Z662 or ASME B31.4, welding procedures qualified in accordance with the requirements of ASME Boiler & Pressure Vessel Code Section IX are permitted and generally preferred. Welding procedures qualified in accordance with ASME IX provide advantages for pipeline facility and fabrication applications as a result of the flexibility achieved through the larger essential variable ranges. The resulting welding procedures have broader coverage on material thickness, diameter, joint configuration and welding positions. Similarly, ASME IX is more flexible on welder performance qualification requirements and accordingly a welder will have wider range of performance qualifications. When applied correctly, the use of ASME IX welding procedures often means significantly fewer welding procedures and welder performance qualifications are required for a given scope of work. Even though ASME IX qualified welding procedures have been widely used in pipeline facility and fabrication welding, it is not well understood on how to qualify the welding procedures in accordance with ASME IX and meet the additional requirements of the governing code or standard such as CSA Z662 in Canada. One significant consideration is that ASME IX refers to the construction code for the applicability of notch toughness requirements for welding procedure qualification, yet CSA Z662 and ASME B31.4 are both silent on notch toughness requirements for welding procedure qualification. This paper explains one preferred method to establish and develop an effective ASME IX welding procedure qualification program for pipeline facility and fabrication welding while ensuring suitability for use and appropriate notch toughness requirements. The paper discusses topics such as base material selection, welding process, welding consumable consideration and weld test acceptance criteria.

Fatigue Performance of High Strength and Large Diameter Mooring Chain in Seawater

2019 ◽  
Author(s):  
Yan-Hui Zhang ◽  
Philip Smedley
Keyword(s):  
Large Diameter ◽  
High Strength ◽  
Crack Size ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Link Failures ◽  
Fatigue Design ◽  
Steel Grades ◽  
Chain Links ◽  
Mooring Chain

Abstract Fatigue design recommendations provided by API RP 2SK, ISO 19901-7 and DNVGL-OS-E301 for studless chain links are based on data of steel grades R3 and R4 and mainly of link diameter of 76mm. Mooring systems utilising larger diameter links and higher strength steels (e.g. grade R5) are now in operation. Consequently, industry expressed a need for fatigue test data in seawater of higher steel grade and larger diameter chain to confirm whether the existing fatigue design guidance is applicable. A joint industry project (JIP) was launched by TWI to investigate fatigue performance of high strength and large diameter mooring chain in free corrosion seawater. A test rig was designed and manufactured which was capable of testing studless mooring chain links up to 127mm link diameter under tension-tension loading. Twenty-three full-scale fatigue tests were conducted on high strength steel grades (R4 and R5) and larger diameter chains (76mm and 127mm) generating 72 link failures. Magnetic particle inspections (MPI) were carried out to characterise the location of cracking, crack size and crack growth rate. This paper describes the results obtained in the JIP.

Fatigue Performance of Grade R4 and R5 Mooring Chains in Seawater

2014 ◽  
Author(s):  
Jonathan Fernández ◽  
Walther Storesund ◽  
Jesús Navas
Keyword(s):  
Fatigue Test ◽  
Fatigue Damage ◽  
Fatigue Tests ◽  
Design Methods ◽  
Full Scale ◽  
Fatigue Performance ◽  
Test Program ◽  
Gas Industry ◽  
Fatigue Design ◽  
Cumulative Fatigue Damage

With more than 50.000 tons in service to date, the Oil&Gas Industry has the need to understand the tension fatigue performance of grade R5 chains in straight tension, and corroborate the validity of the existing design methods. The chain fatigue design curves in API and DNV are based on fatigue tests obtained in the nineties and early two thousands. However the tests were performed on lower grades such as ORQ, R3 and R4, and small chains, 76 mm diameter being the largest studless chain tested. The industry has moved towards the use of large studless chains, especially in permanent units, where chain diameters above 150 mm are not unusual. This paper gathers information from a full scale fatigue test program on grade R4 and R5 studless chains, performed in seawater and with diameters between 70 mm and 171 mm. The chains being tested are actual production chains supplied for different drilling units and large permanently moored production floating units. The paper analyses the data and determines tension-tension fatigue curves based on API and DNV methods for computation of cumulative fatigue damage, regardless of other damaging mechanisms. Improved fatigue capacity is obtained with respect to the above recommended design methods.

Corrosion Fatigue of Welded C-Mn Steel Risers for Deepwater Applications: A State of the Art Review

2005 ◽  
Author(s):  
S. J. Maddox ◽  
R. J. Pargeter ◽  
P. Woollin
Keyword(s):  
Oil And Gas ◽  
Current Knowledge ◽  
Fatigue Loading ◽  
Fatigue Behaviour ◽  
Manganese Steel ◽  
Gas Field ◽  
Internal Surfaces ◽  
Oil And Gas Field ◽  
Offshore Oil And Gas ◽  
Girth Welds

Steel risers for deepwater offshore oil and gas field developments are subject to seawater on the external surfaces, produced fluids on the internal surfaces and to fatigue loading. This paper reviews current knowledge of the fatigue behaviour of welded carbon-manganese steel for risers in relevant environments. A substantial body of data exists relating to the performance of girth welds in seawater with cathodic protection and consequently recent attention has been turned to establishing the fatigue performance in the internal environment, which may contain water, CO2, H2S and chloride and bicarbonate ions.

Fatigue Design and Performance Verification of Deepwater Risers

2003 ◽  
Author(s):  
Jaime Buitrago ◽  
Michael S. Weir ◽  
Wan C. Kan
Keyword(s):  
Fatigue Tests ◽  
Postmortem Examination ◽  
Fatigue Performance ◽  
Fatigue Design ◽  
Industry Practice ◽  
And Performance ◽  
Critical Components ◽  
Deepwater Risers ◽  
Testing Protocols ◽  
Better Than

With the advent of the development of deepwater projects, ExxonMobil developed and successfully implemented a fatigue design and verification protocol for fracture-critical components, such as risers and tendons, to ensure design performance and reliability. This protocol has now become an industry practice. This paper discusses the analytical, fabrication, and testing aspects of the design process. The linkage among actual weld performance, welding procedures and inspection reliability is addressed. From the design implementation standpoint, reliability of the fabrication inspection is the key issue. Practical methodologies were developed to conduct and interpret the fatigue tests. In particular, specimen design, instrumentation, testing protocols, and postmortem examination are discussed. Data generated by testing 56 full-scale risers of various sizes and welded by different procedures are also presented. These data, including tests past 100 million cycles, show that (1) actual riser fatigue performance can be substantially better than that recommended by codes, (2) failures can occur in the long-life regime, and (3) fatigue performance varies with riser size and thickness. However, as a matter of practice, analyses, fabrication and testing are required for particular designs.

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