Integrity Assessment of HP/HT Infield Pipelines: Experiences With a New Methodology Applied in the Norwegian Sea

2008 ◽  
Author(s):  
Birger Etterdal ◽  
Hroar Nes ◽  
Stig Olav Kvarme ◽  
Stian Svardal
Keyword(s):  
Hot Spot ◽  
Operating Conditions ◽  
Pipeline System ◽  
Operating Pressure ◽  
Assessment Methodology ◽  
Long Term Conditions ◽  
Norwegian Sea ◽  
Integrity Assessment ◽  
Analysis Models

The subsea pipeline development for the A˚sgard and Midgard fields in the Norwegian Sea has been challenging due to high operating pressure and temperature (HP/HT pipelines), uneven seabed conditions and the potential for trawl gear interference. A general experience from the first years of operation is that it is not easy to use design information as basis for an integrity assessment of the lines. This is mainly due to the complexity of the global buckling process and the significant load fluctuations applied to the lines. As a consequence of this, analysis models established during design may not represent the actual pipeline behaviour properly, and established design limits do not fit intermediate operational load conditions and configurations observed during surveys. StatoilHydro has developed an integrity assessment methodology where analysis models are calibrated according to the as-surveyed condition, and then exposed to operational cyclic loads in order to predict both intermediate long term conditions and a final design condition. In the assessment of long term fatigue accumulation, process parameters monitored during pipeline operation are used as input. The integrity condition of the HP/HT pipelines is assessed based on a staged approach, depending on the criticality of the considered failure mode. The first level is used for screening and initial ranking. At level two the risk of integrity failure is quantified based on general design criteria, covering relevant operating conditions and the most important input parameters. If the uncertainty related to the assessment of an individual hot-spot location is assumed too high, a detail level three assessment may be specified. The operating condition of the pipeline system is expressed as the risk of failure defined by a limited number of hot-spot locations. The risk matrix concept used for the HP/HT pipelines, provides for a consistent comparison between individual failure modes, between different locations and sections, and between different pipeline systems. StatoilHydro has worked in close cooperation with DNV to develop software tools required to implement this integrity assessment methodology. These tools are now used for integrity assessment and follow-up of all HP/HT pipelines operated by StatoilHydro in the Norwegian Sea. The objective of this paper is to show how the methodology is used in practice, discuss major results and findings, and give general recommendations with respect to operational integrity assessment of HP/HT pipelines.

Pressure Cycling Monitoring Helps Ensure the Integrity of Energy Pipelines

2010 ◽  
Author(s):  
Peter Song ◽  
Doug Lawrence ◽  
Sean Keane ◽  
Scott Ironside ◽  
Aaron Sutton
Keyword(s):  
Fatigue Life ◽  
Pipeline System ◽  
Outer Diameter ◽  
Operating Pressure ◽  
Potential Growth ◽  
Integrity Assessment ◽  
Pressure Cycling ◽  
Pressure Cycle ◽  
Primary Focus ◽  
Pump Stations

Liquids pipelines undergo pressure cycling as part of normal operations. The source of these fluctuations can be complex, but can include line start-stop during normal pipeline operations, batch pigs by-passing pump stations, product injection or delivery, and unexpected line shut-down events. One of the factors that govern potential growth of flaws by pressure cycle induced fatigue is operational pressure cycles. The severity of these pressure cycles can affect both the need and timing for an integrity assessment. A Pressure Cycling Monitoring (PCM) program was initiated at Enbridge Pipelines Inc. (Enbridge) to monitor the Pressure Cycling Severity (PCS) change with time during line operations. The PCM program has many purposes, but primary focus is to ensure the continued validity of the integrity assessment interval and for early identification of notable changes in operations resulting in fatigue damage. In conducting the PCM program, an estimated fatigue life based on one month or one quarter period of operations is plotted on the PCM graph. The estimated fatigue life is obtained by conducting fatigue analysis using Paris Law equation, a flaw with dimensions proportional to the pipe wall thickness and the outer diameter, and the operating pressure data queried from Enbridge SCADA system. This standardized estimated fatigue life calculation is a measure of the PCS. Trends in PCS overtime can potentially indicate the crack threat susceptibility the integrity assessment interval should be updated. Two examples observed on pipeline segments within Enbridge pipeline system are provided that show the PCS change over time. Conclusions are drawn for the PCM program thereafter.

Integrity Assessment of Spherical Pressure Components With Local Corrosion and Hot Spots

2006 ◽  
Author(s):  
Pattaramon Tantichattanont ◽  
Seshu Adluri ◽  
Rangaswamy Seshadri
Keyword(s):  
Lower Bound ◽  
Hot Spots ◽  
Structural Integrity ◽  
Hot Spot ◽  
Corrosion Damage ◽  
Pressure Vessels ◽  
Operating Conditions ◽  
Local Corrosion ◽  
Integrity Assessment ◽  
Spherical Pressure

Corrosion damage and hot spots are typical of damages that can occur in ageing pressure vessels and pipelines used in industrial processes. Internal and external corrosion could be the result of corrosive products stored inside or harsh environmental conditions on the outside. Hot spots are caused by damage due to loss of refractory lining on the inside wall of pressure components or due to maldistribution of flow containing catalyst and reactive fluids. The structural integrity of such ageing components needs to be evaluated periodically to establish the continued suitability of the vessels under operating conditions. The present paper develops a method for Level 2 (as categorized by API 579) structural integrity evaluations of spherical pressure vessels containing local corrosion damage or hot spot. The decay lengths for spherical shells subject to local damages have been studied based on stretching and bending effects using elastic shell theories so as to identify the reference volume participating in plastic action. A limit for “local” corroded spot or hot spot is defined by the size of damage that an onset of pure membrane action occurs inside the damaged area. The size of damage indicating the crossover from dominance of stretching effects on the damage behavior to that of bending effects is also presented. The lower bound recommended “remaining strength factors” for spherical pressure vessels containing corrosion or hot spot are formulated by application of Mura’s integral mean of yield criterion and the improved lower bound mα-multiplier. Three alternative recommendations are proposed. The effectiveness of the proposed methods is evaluated and demonstrated through illustrative examples and comparison with inelastic finite element analyses.

Condition Management of HP/HT Pipelines: A New Approach

2008 ◽  
Author(s):  
Hroar Nes ◽  
Birger Etterdal ◽  
Stian Svardal
Keyword(s):  
Survey Data ◽  
Failure Modes ◽  
Hot Spot ◽  
Operating Conditions ◽  
Maximum Temperature ◽  
Design Criteria ◽  
Integrity Assessment ◽  
Safety Margins ◽  
Wide Range ◽  
Relative Utilization

StatoilHydro operates a large number of High Pressure/High Temperature (HP/HT) pipeline systems in the Norwegian Sea. These lines connect remote subsea templates to floating processing and storage units. Flowlines are designed for a maximum temperature up to 155 °C and a pressure in the range of 390–500 bar. Design pressure for injection lines are in general 500 bar. In addition to high operating loads, the infield lines are exposed to challenging seabed conditions and a potential for interference with on-bottom trawl gear. The objective of this paper is to present the principles and the methodology used for integrity assessment of the HP/HT lines, which provides the basis for specification of optimum maintenance requirements. The risk of integrity failure, associated with any hot-spot location, is consistently estimated based on safety margins predicted for the actual design criterion and as a function of the pre-defined Safety Class. The developed methodology assumes that the pipeline configuration and associated response parameters are accurately determined for relevant operating conditions. This requires finite element models that are calibrated according to survey data and corresponding operating parameters. A cyclic load history is applied to the post-buckled pipeline model in order to simulate actual operating conditions. Design criteria for relevant degradation and failure modes are established for a wide range of operating configurations and conditions. These criteria are used both to identify potential hot-spots and to estimate the relative utilization. The relative utilization may be estimated for an extreme single event, i.e. a design condition, or due to long term degradation. The risk of integrity failure is then determined as a function of the Safety Class and the relative utilisation, expressing the consequences and the probability of failure, respectively. A risk matrix, configured according to design safety principles, determines the risk of integrity failure. A software interface has been developed to compare and to visualize pipeline simulation results, survey data and corresponding design criteria. This information is used for documentation of the pipeline operating condition, and finally, for specification and follow-up of maintenance measures. The new integrity assessment methodology has been implemented as part of the condition management system for more than 30 HP/HT pipelines operated by StatoilHydro.

A Structural Integrity Assessment Methodology for Pressurized Vessels

2005 ◽  
Vol 128 (4) ◽  
pp. 541-546 ◽  
Author(s):  
Raymond K. Yee ◽  
Mike Kapper
Keyword(s):  
Power Plants ◽  
Structural Integrity ◽  
Design Tool ◽  
Remaining Useful Life ◽  
Operating Conditions ◽  
Assessment Methodology ◽  
Nondestructive Examination ◽  
Integrity Assessment ◽  
Useful Life ◽  
Steam Drum

Pressurized vessels such as a steam drum in a typical power plant can often experience in-service cracking. Structural integrity assessment methodology can be a useful tool to determine the suitability of a vessel for service. This methodology may include fitness-for-service and remaining useful life analyses of a vessel based on the nondestructive examination (NDE) results and operating conditions. In this paper, the structural integrity assessment methodology applied to a steam drum case study is described. The analysis procedure, material property determination, stress analysis, limiting flaw size evaluation, and remaining useful life evaluation for the drum are discussed. A thermal shock design tool is briefly introduced. Recommendations for appropriate action are also presented. The assessment methodology employed in this paper can be applied to other similar pressurized vessels and structures in power plants.

Infrared Emission Spectroscopy as a Reliability Tool

1999 ◽  
Author(s):  
Q. Kim ◽  
S. Kayali
Keyword(s):  
Spatial Resolution ◽  
Emission Spectroscopy ◽  
Hot Spot ◽  
Cost Effective ◽  
Infrared Emission ◽  
Test System ◽  
Operating Conditions ◽  
Yield Enhancement ◽  
Infrared Emission Spectroscopy ◽  
Channel Temperature

Abstract In this paper, we report on a non-destructive technique, based on IR emission spectroscopy, for measuring the temperature of a hot spot in the gate channel of a GaAs metal/semiconductor field effect transistor (MESFET). A submicron-size He-Ne laser provides the local excitation of the gate channel and the emitted photons are collected by a spectrophotometer. Given the state of our experimental test system, we estimate a spectral resolution of approximately 0.1 Angstroms and a spatial resolution of approximately 0.9 μm, which is up to 100 times finer spatial resolution than can be obtained using the best available passive IR systems. The temperature resolution (<0.02 K/μm in our case) is dependent upon the spectrometer used and can be further improved. This novel technique can be used to estimate device lifetimes for critical applications and measure the channel temperature of devices under actual operating conditions. Another potential use is cost-effective prescreening for determining the 'hot spot' channel temperature of devices under normal operating conditions, which can further improve device design, yield enhancement, and reliable operation. Results are shown for both a powered and unpowered MESFET, demonstrating the strength of our infrared emission spectroscopy technique as a reliability tool.

Effect of operating conditions on rejection of anionic pollutants in the water environment by nanofiltration especially in very low pressure range

1996 ◽  
Vol 34 (9) ◽  
pp. 149-156 ◽  
Author(s):  
C. Ratanatamskul ◽  
K. Yamamoto ◽  
T. Urase ◽  
S. Ohgaki
Keyword(s):  
Water Environment ◽  
Chloride Ions ◽  
Operating Conditions ◽  
Transmembrane Pressure ◽  
Operating Pressure ◽  
Nanofiltration Membranes ◽  
Single Solution ◽  
Crossflow Velocity ◽  
Membrane Type ◽  
New Generation

The recent development of new generation LPRO or nanofiltration membranes have received attraction for application in the field of wastewater and water treatment through an increasingly stringent regulation for drinking purpose and water reclamation. In this research, the application on treatment of anionic pollutants (nitrate, nitrite, phosphate, sulfate and chloride ions) have been investigated as functions of transmembrane pressure, crossflow velocity and temperature under very much lower pressure operation range (0.49 to 0.03 MPa) than any other previous research used to do. Negative rejection was also observed under very much low range of operating pressure in the case of membrane type NTR-7250. Moreover, the extended Nernst-Planck model was used for analysis of the experimental data of the rejection of nitrate, nitrite and chloride ions in single solution by considering effective charged density of the membranes.

The use of a bespoke website developed for people with dementia and carers: Users’ experiences, perceptions and support needs

Dementia ◽  
2021 ◽  
pp. 147130122110284
Author(s):  
Emma Wolverson ◽  
Caroline White ◽  
Rosie Dunn ◽  
Katie Cunnah ◽  
David Howe ◽  
...  
Keyword(s):  
Personal Information ◽  
Information Source ◽  
Website Design ◽  
Long Term Conditions ◽  
People With Dementia ◽  
Barriers To Use ◽  
Credible Information ◽  
Training And Support ◽  
Design And Methods

Background: Current policy emphasises the role of digital technologies in facilitating the management of long-term conditions. While digital resources have been developed for carers, there has been little attention to their development for people with dementia. The Caregiverspro-MMD website was developed as a joint resource for people with dementia and carers, delivering access to information, informal content, games and peer support. Research Design and Methods: This study explored the experiences of dyads consisting of people with dementia and carers of using the website. Interviews and focus groups were conducted with 43 participants. Findings: Thematic analysis identified 10 subthemes grouped under three superordinate themes which highlight participants’ experiences of and responses to the website functions; important aspects of the website design and delivery; and barriers to use. Discussion: Findings highlight the value of a credible information source which negated the need for arduous online searches, the pleasure associated with playing games and interacting with others online. However, participants were reluctant to share personal information online, preferring to create ‘informal content’ which celebrated everyday life, and were reluctant to ‘friend’ people online who they had not met in person. The importance of training and support to use the website was highlighted. Health problems, lack of interest or difficulties using technology, and time were all identified as barriers to use.

Sign in / Sign up

Export Citation Format

Share Document