Qualification of Polymer Materials for Dynamic Riser Service

2021 ◽  
Author(s):  
Craig McCord ◽  
Colin Jones
Keyword(s):  
Boundary Conditions ◽  
Failure Modes ◽  
Fatigue Testing ◽  
Interaction Force ◽  
Full Scale ◽  
Steel Pipe ◽  
Vertical Orientation ◽  
Liner System ◽  
Potential Failure ◽  
Polymer Liner

Abstract Polymer liners have been used extensively in water injection flowlines for several years, however, have only recently gained traction as a corrosion protection solution for Steel Catenary Risers and other similar rigid pipe risers as the industry moves to more novel systems. In order to qualify a system for a dynamic service environment such as a riser, it is important to understand the system's fatigue response and characteristics to ensure that all potential failure modes are addressed. This is typically accomplished for rigid pipes via full scale resonance fatigue testing whereby a test specimen is subjected to a representative fatigue environment and point of failure determined. Rigid pipe specimens with polymer liner installed have been trialed and reported previously. In this programme, the full-scale test strings demonstrated that all the lined system components can withstand the standard fatigue performance test curves. However, it did not confirm the boundary conditions for failure of the polymer liner, as failure of the metallic host pipe always occurred first. A similar method can be used to test the polymer material in isolation, however given the strain levels involved and the material's inherent fatigue resistance, it was expected that the duration of testing would be impractical. It was therefore necessary to implement a test method that allowed for identification of the polymer boundary conditions within a reasonable time frame, whilst also allowing for comparison with existing fatigue testing. In order to achieve this, a small-scale fatigue testing programme was setup in line with ISO 18489, whereby pre-notched dumbbell samples would be prepared and tested, firstly at 23°C but also at 0°C and 60°C to not only allow comparison with existing full-scale data, but also allow determination of suitability across the full temperature range expected in service. Testing results have demonstrated that the polymer's fatigue resistance far exceeds that of the steel pipe, even with the inclusion of pre-initiated cracking in the samples. The testing was able to provide key data on parameters and their influence on the material's fatigue life such as temperature, stress and strain. Further to this, an additional test programme was setup to evaluate the influence that the vertical orientation of the riser has on the polymer liner system. In this test programme, the interaction force between the steel pipe and polymer liner was assessed to establish the necessary design criteria to ensure that the interaction force always exceeds the vertical self-weight of the liner. Testing results demonstrated that the steel pipe/liner interaction force exceeded the equivalent self-weight of the liner eliminating potential failure modes associated with creep. As a result, the vertical orientation of the riser does not present a risk to the integrity of the liner system.

Results From Fatigue Testing of Subsea Wellhead Connector Segments

2021 ◽  
Author(s):  
Agnes Marie Horn ◽  
Pedro Barros ◽  
Anders Wormsen ◽  
Per Osen ◽  
Kenneth A. Macdonald
Keyword(s):  
Finite Element ◽  
Failure Modes ◽  
Fatigue Testing ◽  
Fatigue Analysis ◽  
Full Scale ◽  
Test Method ◽  
Stress Fields ◽  
Test Results ◽  
Initiation Point ◽  
Drilling Rig

Abstract For subsea well drilling, the drilling rig is connected to the subsea well by a marine riser and subsea BOP equipped with a remotely controlled wellhead connector latched onto the subsea wellhead profile. The level of cyclic loading on subsea wellheads is steadily increasing due to use of increasingly larger drilling rigs with larger BOPs, the drilling of wells in harsher environments characterized by high waves. The remotely controlled wellhead connector forces a series of locking dogs into an externally machined profile on the wellhead. This external profile is generally referred to as a wellhead profile. The fatigue resistance of this safety-critical connector is typically estimated by finite element analyses (FEA). Due to the large size of the equipment, and high cost of testing, very limited fatigue testing, if any, has been carried out. A test method has therefore been developed, where a special test fixture is used to apply realistic boundary conditions and variable tensile loads to a small sector or segment of the wellhead connector. A primary objective is to generate fatigue-critical stress fields in the segments under tensile test load that closely replicates the stress fields in the full-scale wellhead connector. A secondary objective is to evaluate the possibility of using segment testing to determine the fatigue capacity of the full-scale connector. The testing of narrow sector segments allows the use of readily available test apparatus. It is thereby envisaged that the total cost of testing (specimens and test laboratory costs) can be substantially reduced in comparison with full-scale connector fatigue testing. This paper describes the fatigue testing of wellhead connector segments, and the test results in terms of cycles to failure and the failure modes, i.e. crack initiation point, and final crack geometry. The test scope consists of nine segments tested in-air at ambient temperature (nominal 20 °C), at a frequency of approximately 2 Hz under axial load of R = 0.1. At the time of writing this paper, six out of these nine tests have been performed. These six fatigue tests are presented in this paper. The test results are compared with estimates achieved by FEA of the test assembly and relevant S-N curves for the materials. It will be determined if the test results can be accurately predicted by the fatigue analysis methodology in Section 5.4 of DNVGL-RP-C203 (C203), including use of the new series of S-N curves for high strength materials in Appendix D.2 of C203. This design approach assumes that other failure modes (e.g. fretting or other local effects in the interface between components) do not govern the fatigue life, as this cannot be predicted by the fatigue analysis method applied here. The fatigue test set-up and the finite element analysis of the segment test is presented in the OMAE2020-18652 paper.

scholarly journals Surface Contamination by Antineoplastics in Hospitals: An Observational Study for Mapping of Potential Contamination Associated with Handling Excreta of Babies through Diaper Management

2020 ◽  
Vol 4 (3-4) ◽  
pp. 119-125
Author(s):  
Marie Palamini ◽  
Geneviève Mercier ◽  
Jean-François Bussières
Keyword(s):  
Bone Marrow ◽  
Exploratory Study ◽  
Research Team ◽  
Failure Modes ◽  
Hospital Setting ◽  
Marrow Transplant ◽  
Mother And Child ◽  
Potential Failure ◽  
Key Steps ◽  
Hazardous Drugs

AbstractBackgroundIn the hospital setting, trace contamination with hazardous medications comes primarily from the manipulation of containers used in preparing and administering drugs. However, some traces of medications also come from the excreta of patients.MethodsThis descriptive exploratory study involved direct observation and discussion. The aim was to map potential contamination associated with handling babies’ excreta through diaper management. The study was conducted at CHU Sainte Justine (Montréal, Québec, Canada), a 500-bed mother and child facility with 38 beds for hematology-oncology and bone marrow transplant. A list of key steps related to the management of diapers by a parent or caregiver on a pediatric unit was established by the investigators. A data collection grid was then developed and reviewed by a member of the research team.ResultsA total of six diaper changes, by six distinct individuals, were observed in August and September 2019. Transport of a soiled diaper for weighing outside the baby’s room by an additional caregiver was also observed and recorded. In total, 25 individual steps in diaper management and 28 potential failure modes were identified through mapping.ConclusionsChanging a baby’s diaper involves many individual steps, which are subject to numerous failure modes that can contribute to contamination with traces of hazardous drugs. A good understanding of these process steps and failure modes is desirable to better train caregivers and parents to reduce trace contamination with hazardous drugs.

scholarly journals Rolling Wear of Silicon Nitride Bearing Materials

1990 ◽  
Author(s):  
John W. Lucek
Keyword(s):  
Fatigue Life ◽  
Silicon Nitride ◽  
Failure Modes ◽  
Fatigue Testing ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Wear Performance ◽  
Wear Rates ◽  
Bearing Materials

Rolling-contact fatigue test methods were used to measure the wear performance of several silicon nitride materials. Sintered, hot pressed and hot isostatically pressed materials exhibited wear rates ranging over three orders of magnitude. Hot isostatically pressed materials had the lowest wear rates. Despite the disparity in wear performance, all materials tested had useful rolling-contact fatigue lives compared to steel. Fatigue life estimates, failure modes, and rolling wear performance for theses ceramics are compared to M-50 steel. This work highlights the rapid contact stress reductions that occur due to conformal wear in rolling-contact fatigue testing. Candidate bearing materials with unacceptably high wear rates may exhibit useful fatigue lives. Rolling contact bearing materials must possess useful wear and fatigue resistance. Proper performance screening of candidate bearing materials must describe the failure mode, wear rate, and the fatigue life. Guidelines for fatigue testing methods are proposed.

A Systematized FMEA Practice for Magnet Relays

2010 ◽  
Vol 146-147 ◽  
pp. 757-769
Author(s):  
Ching Ming Cheng ◽  
Wen Fang Wu ◽  
Yao Hsu
Keyword(s):  
New Product Development ◽  
Failure Modes ◽  
New Product ◽  
Risk Priority Number ◽  
Detection Model ◽  
Regulation Function ◽  
Potential Failure ◽  
Weighting Rule ◽  
Rating Criterion

The Design Failure Modes and Effects Analysis (DFMEA) are generally applied to risk management of New Product Development (NPD) through standardization of potential failure modes and effect-ranking of rating criterion with failure modes. Typical 1 to 10 of effect-ranking are widely weighed the priority of classification, that framing effects and status quo senses might cause decision trap happening thus. The FMEA follows considerable indexes which are including Severity, Occurrence and Detection, and need be associated with difference between every two failures individually. However, we suspect that a more systematic construction of the analysis by which failure modes belong is necessary in order to make intellectual progress in this area. Two ways of such differentiation and construction are improvable effect-ranking and systematized indexes; here we resolve for attributes of failures with classification, maturity and experiance of indexes according to an existing rule. In Severity model, the larger differentiation is achieved by separating indexes to the classification of the Law & Regulation, Function and Cosmetic. Occurrence model has its characteristic a reliable ranking indexwhich assists decisionmakers to manage their venture. This is the model most closely associate with product maturity by grouping indexes to the new, extend and series product. Detection model offers a special perspective on cost; here the connections concerned with phase occasion of the review, verification and validation. Such differentiations will be proposed and mapped with the Life Cycle Profile (LCP) to systematize FMEA. Meanwhile, a more reasonable Risk Priority Number (RPN) with the new weighting rule will be worked out for effect-ranking and management system will be integrated systematiclly

Use of DNVGL-RP-C203 for Determining the Fatigue Capacity of Connectors

2021 ◽  
Author(s):  
Anthony Muff ◽  
Anders Wormsen ◽  
Torfinn Hørte ◽  
Arne Fjeldstad ◽  
Per Osen ◽  
...  
Keyword(s):  
Finite Element ◽  
Fatigue Testing ◽  
Experimental Testing ◽  
High Strength ◽  
Element Model ◽  
Fatigue Analysis ◽  
Full Scale ◽  
The Finite Element Model

Abstract Guidance for determining a S-N based fatigue capacity (safe life design) for preloaded connectors is included in Section 5.4 of the 2019 edition of DNVGL-RP-C203 (C203-2019). This section includes guidance on the finite element model representation, finite element based fatigue analysis and determination of the connector design fatigue capacity by use of one of the following methods: Method 1 by FEA based fatigue analysis, Method 2 by FEA based fatigue analysis and experimental testing and Method 3 by full-scale connector fatigue testing. The FEA based fatigue analysis makes use of Appendix D.2 in C203-2019 (“S-N curves for high strength steel applications for subsea”). Practical use of Section 5.4 is illustrated with a case study of a fatigue tested wellhead profile connector segment test. Further developments of Section 5.4 of C203-2019 are proposed. This included acceptance criteria for use of a segment test to validate the FEA based fatigue analysis of a full-scale preloaded connector.

scholarly journals Benefits of sub-component over full-scale blade testing elaborated on a trailing edge bond line design validation

2017 ◽  
Author(s):  
Malo Rosemeier ◽  
Gregor Basters ◽  
Alexandros Antoniou
Keyword(s):  
Structural Reliability ◽  
Fatigue Testing ◽  
Bond Line ◽  
Full Scale ◽  
Testing Time ◽  
Trailing Edge ◽  
Pure Lead ◽  
Component Testing ◽  
Line Design ◽  
Full Scale Testing

Abstract. Wind turbine rotor blades are designed and certified according to the current IEC (2012) and DNV GL AS (2015) standards, which include the final full-scale experiment. The experiment is used to validate the assumptions made in the design models. In this work the drawbacks of traditional static and fatigue full-scale testing are elaborated, i. e. the replication of realistic loading and structural response. Sub-component testing is proposed as a potential method to mitigate some of the drawbacks. Compared to the actual loading that a rotor blade is subjected to under field conditions, the full-scale test loading is subjected to the following simplifications and constraints: First, the full-scale fatigue test is conducted as a cyclic test, where the load time series obtained from aero-servo-elastic simulations are simplified to a damage equivalent load range. Second, the load directions are typically applied solely in two directions, often pure lead-lag and flap-wise directions which are not necessarily the most critical load directions for a particular blade segment. Third, parts of the blade are overloaded by up to 20 % to achieve the target load along the whole span. Fourth, parts of the blade are not tested due to load introduction via load frames. Finally, another downside of a state-of-the-art, uni-axial, resonant, full-scale testing method is that dynamic testing at the eigenfrequencies of today's blades in respect of the first flap-wise mode between 0.4 Hz and 1.0 Hz results in long test times. Testing usually takes several months. In contrast, the sub-component fatigue testing time can be substantially faster than the full-scale blade test since (a) the load can be introduced with higher frequencies which are not constrained by the blade's eigenfrequency, and (b) the stress ratio between the minimum and the maximum stress exposure to which the structure is subjected can be increased to higher, more realistic values. Furthermore, sub-component testing could increase the structural reliability by focusing on the critical areas and replicating the design loads more accurately in the most critical directions. In this work, the comparison of the two testing methods is elaborated by way of example on a trailing edge bond line design.

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