Fatigue performance monitoring of full-scale PPC beams by using the FBG sensors

2014 ◽  
Vol 13 (6) ◽  
pp. 943-957 ◽  
Author(s):  
Licheng Wang ◽  
Jigang Han ◽  
Yupu Song
Keyword(s):  
Performance Monitoring ◽  
Full Scale ◽  
Fatigue Performance ◽  
Fbg Sensors

The Qualification and Continued Evolution of Reeled Steel Catenary Risers

2009 ◽  
Author(s):  
Fin Gray ◽  
Brett Howard ◽  
Alexandra Pieton ◽  
Ramon Gallart
Keyword(s):  
Full Scale ◽  
Fatigue Performance ◽  
Track Record ◽  
Mechanized Welding ◽  
Steel Catenary Risers ◽  
Weld Fatigue ◽  
Fit For Purpose ◽  
Girth Welds ◽  
The Impact ◽  
Welding Processes

Technip began qualification of reeled Steel Catenary Risers (SCR) back in 1997. Industry had raised concerns at that time over the plastic straining cycles that are intrinsic to the reel lay method and the impact these could have upon the service fatigue life of the girth welds. The qualification programme, therefore, included comparison of reeled welds against virgin welds for a suite of fatigue and mechanical testing including full scale fatigue and fatigue crack growth tests. Reeling was shown to have no discernable impact for the fatigue performance level sought when a controlled SCR fabrication process was adhered to. This provided sufficient confidence that the technology was fit for purpose and led to successful fabrication and installation of the first reeled SCR in 2001. Since then more than 25 have been installed in the Gulf of Mexico, with most projects including full scale weld fatigue test qualification following reeling simulations. This paper includes the following: (a) a summary of the philosophy adopted for qualification, fabrication and installation of a reeled SCR, (b) presentation of the reeled SCR track record and evolution of the technology to include mechanized welding processes (c) a look at ongoing developments targeting even higher fatigue performance, and (d) discussion on the development of fracture mechanics techniques that provide further confidence in the concept and can be used to derive appropriate weld acceptance criteria.

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.

Fatigue Testing of Out-of-Plane Bending Mechanism of Chain Links

2006 ◽  
Author(s):  
Lucile Rampi ◽  
Pedro Vargas
Keyword(s):  
Fatigue Testing ◽  
Empirical Relationship ◽  
Fatigue Tests ◽  
Full Scale ◽  
Fatigue Performance ◽  
Special Focus ◽  
Out Of Plane ◽  
Plane Bending ◽  
Chain Links ◽  
Mooring Chain

Three years ago, several mooring chains of an off-loading buoy failed after only 8 months of service. These chains were designed according to conventional fatigue assessment using API RP 2SK T-N curves to a fatigue life or 20 years with a factor of safety equal to 3 on life. Of particular interest is that the mooring chain failure underwent significant mooring chain motions that caused interlink rotations. Although traditionally neglected, these interlink rotations, when combined with significant chain tensions can cause bending stresses in the chain links (See Figure 1). This recently identified phenomena, Out-of-Plane Bending (OPB), explains the extensive fatigue damage causing the mooring chains of the off-loading buoy to fail [3][4][5]. References [3] and [4] document full scale tests of the OPB mechanism using a full scale test frame with the ability of applying inter-link rotation to a pre-tensioned chain. This testing confirmed that interlink rotations with a constant tension load can result in significantly high stresses. OPB stresses were measured on four different chain sizes of various grades: 1) 81 mm Studded Grade R3S, 2) 107 mm Stud-less Grade RQ3, 3) 124 mm Stud-less Grade R4, and 4) 146 mm Stud-less Grade RQ4, Grade R3 in [3] and [4], but no actual fatigue tests were performed. References [3] and [5] document analytical and computational efforts to explain and quantify the OPB stresses. In this paper, special focus is placed on obtaining actual fatigue failures of chains from OPB loading. Smaller chain sizes (40 mm) are used to accommodate the load limits of the testing frame. To mimic the actual loading as close as possible, sub size models of actual chainhawses were used in the testing. Two chainhawses were used: 1) the chainhawse has internal curvature where a link rests on the intrados, similar to offloading buoy that failed in eight months, and 2) a straight chainhase, a design that is in use today with demonstrated improved fatigue performance over the curved chainhawse. OPB stresses are measured and reported. Fatigue loading in the OPB mode was applied for several configurations. The two chainhawse exhibit very different stress levels and fatigue performance. An empirical relationship previously reported in [3][4][5] is compared to the measured OPB stresses with mixed results. Although limited in number, the fatigue tests indicate that overall the chain fatigue performance is at or above the B1 DnV curve. The BS B1 curve is also compared.

Full Scale Sour Fatigue Testing With Dense Phase Gases

2012 ◽  
Author(s):  
Pedro M. Vargas ◽  
Ben Crowder ◽  
Weiwei Yu ◽  
Sam Mishael ◽  
Keith Armstrong
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Research Work ◽  
Full Scale ◽  
Acceleration Factor ◽  
Fatigue Performance ◽  
Small Scale ◽  
Dense Phase ◽  
Sour Service

The petrochemical industry is very interested in the sour service fatigue performance of girth welded steel pipes. As a result several papers are published every year addressing this issue, and several Joint Industry Projects (JIP) are currently underway addressing different aspects of sour service performance of steel pipelines. To date research work has focused on quantifying the fatigue performance via small scale specimens due to the difficult and danger in dealing with H2S. Currently a JIP is underway that promises to provide full scale fatigue performance of pipeline welds under sour service. This paper documents the knockdown-factor-on-life (KD) determination for full scale sour service testing. In an industry first, a very difficult full scale sour service test was performed: 1) High Pressure, 2) High content of H2S, 3) Dense phase gases with ultra low water content (less than 400 ppm), and 4) Loading rate of 0.01 Hz. The loading was applied in full longitudinal tension. The full scale sour tests are compared with full scale in-air tests to obtain the knockdown factor. Resource constraint limited the number of full scale tests to 3. The main objective of the tests for the practical application was to ensure that the usage of crack growth based knock-down factors, i.e. the use of Fatigue-Crack-Growth-Acceleration-Factor (FCGAR) from small scale fracture mechanics specimens, was reasonable and conservative. Some additional comparisons are done with crack-growth based knockdown factors that may help explain the effect of the ultra-low water concentration. Knockdown factors from small scale crack growth specimens, Fatigue-Crack-Growth-Acceleration-Factor = 60 (FCGAR), are significantly higher than the full scale results, KD = 7. The ultra-low-water dense phase gases do not pit the surface, thus leaving the initiation life relatively intact. The knockdown factor for the full scale test is then mostly the result of the accelerated crack growth that occurs once a macro-crack nucleates.

AMOS DP Research Cruise 2016: Academic Full-Scale Testing of Experimental Dynamic Positioning Control Algorithms Onboard R/V Gunnerus

2017 ◽  
Author(s):  
Roger Skjetne ◽  
Mikkel E. N. Sørensen ◽  
Morten Breivik ◽  
Svenn A. T. Værnø ◽  
Astrid H. Brodtkorb ◽  
...  
Keyword(s):  
Feedback Control ◽  
Performance Monitoring ◽  
Academic Research ◽  
Output Feedback Control ◽  
Time Instant ◽  
Feedback Mechanism ◽  
Full Scale ◽  
Control Algorithms ◽  
Control Law ◽  
Dynamic Positioning

In order to validate relevant dynamic positioning (DP) control algorithms in a realistic environment, a full-scale DP test campaign, the AMOS DP Research Cruise 2016 (ADPRC’16), was organized in a collaboration between the NTNU Centre for Autonomous Marine Operations and Systems (NTNU AMOS) and the company Kongsberg Maritime onboard the research vessel (R/V) Gunnerus. To the authors’ best knowledge, closed-loop DP feedback control algorithms have never been tested full-scale on a ship in an academic research experiment before. However, we have now achieved this by coding our algorithms into a test-module of the DP system, as prepared by Kongsberg Maritime. Among the tested algorithms is an output feedback control law with both good transient and steady-state performance. In another experiment, different adaptive backstepping control laws for DP were tested to compare and contrast their performance and properties. A hybrid state observer with a performance monitoring function proposed to switch between two observers, choosing the best one at any time instant, was also part of the test scope. For this, necessary measurements (including acceleration measurements) were logged to be able to rerun and validate the observer algorithms in post-processing. Finally, several experiments were done to test a pseudo-derivative feedback control law for DP. The feedback mechanism was tested with and without a feedforward disturbance rejection term, called acceleration feedforward. This paper reports the experimental setup, test program, and an overview of results from the ADPRC’16 campaign.

The Rationale for Update of S-N Curves for Single Sided Girth Welds for Risers and Pipelines in DNV GL RP C-203 Based on Fatigue Performance of More Than 1700 Full Scale Fatigue Test Results

2018 ◽  
Author(s):  
Agnes Marie Horn ◽  
Inge Lotsberg ◽  
Oddvin Orjaseater
Keyword(s):  
Deep Water ◽  
Fatigue Testing ◽  
Fatigue Loading ◽  
Full Scale ◽  
Fatigue Performance ◽  
Test Results ◽  
Severe Fatigue ◽  
Adequate Quality ◽  
Two Phases ◽  
Girth Welds

Deep-water tendon and riser systems are often subjected to severe fatigue loading from waves, currents and vessel movements. The girth welds between successive lengths of pipe or at pipe terminations represent fatigue-critical features where failure would be catastrophic. Hence, validation fatigue testing by full scale pipes of the most critical welds are often performed to ensure adequate quality and/or to document a better S-N curves than those available in standards today like DNVGL-RP-C203 [1] and BS7608 [2]. To better understand the fatigue performance with respect to identify trends, dependencies and critical features that influence the fatigue performance, a JIP on Fatigue of Girth Welds were initiated in 2011. Two phases have been conducted and a total of 1700 full scale one sided girth welds, mostly run by Stress Engineering, have been statistically analyzed. The test data has been interrogated to investigate the effect of as-welded condition, OD ground, OD/ID ground, un-reeled pipe, reeled pipe, thickness and effect of misalignment. Based on these analyses, new S-N curves for risers and pipelines have been included in DNVGL-RP-C203 for non-reeled girth welds. This paper presents the findings and trends from the JIP work which has been the rationale for the updates of girth welds in section 2.10 in DNVGL-RP-C203 2016 edition.

Fatigue Qualification of Heavy Wall Line Pipe and Girth Weld for High Pressure Applications

2013 ◽  
Author(s):  
Philippe P. Darcis ◽  
Noe Mota ◽  
Enrique Garcia ◽  
Israel Marines-Garcia ◽  
Hector M. Quintanilla ◽  
...  
Keyword(s):  
High Pressures ◽  
Fatigue Loading ◽  
Fatigue Tests ◽  
Performance Comparison ◽  
Full Scale ◽  
Fatigue Performance ◽  
Thick Wall ◽  
Test Machine ◽  
Line Pipe ◽  
Pipe Materials

As the offshore oil & gas industry moves into deeper waters, more and more offshore projects, specifically the subsea, riser and flowline designs, rely on heavy wall line pipe materials. These pipe materials must be capable of operating in stringent working conditions such as high pressures, high temperatures, large deformations, fatigue loading, sour environments, etc. Within this context, ExxonMobil Development Company and Tenaris have jointly conducted a detailed technical assessment of the mechanical and fatigue performance of the newly developed heavy wall X65 line pipe (LP) developed by Tenaris. The main goal of such project is to evaluate and demonstrate via full-scale testing the fatigue performance of this new generation of heavy wall line pipe materials and the associated girth weld also recently developed by Tenaris. Although conclusive fatigue performance results at ID are not included in the present paper, the comprehensive test/qualification plan also includes a fatigue performance comparison at ID and OD. The present work clearly demonstrates weldability of this Heavy Wall X65 (273 mm OD × 46 mm WT) line pipe. A narrow-groove bevel welding procedure utilizing the STT® process for the root pass and single torch GMAW process for hot-pass, fill, and cap has been successfully developed. Four full scale fatigue tests were also successfully conducted using a resonant fatigue test machine. The presented fatigue results help demonstrate a realistic level of fatigue performance achievable with this thick wall LP/girth weld technology which will help facilitate assessment of riser/flowline design feasibility in ultra-deep water applications and/or high pressures fields.

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