Pipeline Integrity Design for Differential Settlement in Discontinuous Permafrost Areas

1996 ◽  
Author(s):  
Z. Joe Zhou ◽  
Raymond P. Boivin ◽  
Alan G. Glover ◽  
Phil J. Kormann
Keyword(s):  
Structural Integrity ◽  
Pipe Wall ◽  
Cost Effective ◽  
Differential Settlement ◽  
Pipeline System ◽  
Design Problems ◽  
Pipe Wall Thickness ◽  
Discontinuous Permafrost ◽  
Design Options ◽  
Effective Design

The NOVA Gas Transmission Ltd. (NGTL) gas pipeline system is expanding northwards as the producers search for and find new gas reserves. This growth has taken the system into the discontinuous permafrost zone, and also into new design problems. One such problem is the structural integrity of a pipeline subjected to the settlement differentials that occur between frozen and unfrozen soils. Adequate integrity design for differential settlement is required by design codes, such as CSA Z662, but the procedures and criteria must be established by the pipeline designers. This paper presents the methodology of pipeline integrity design for differential settlements used on a number of pipeline projects in Northwest Alberta. Outlined in the paper are the procedures, rationales and models used to: (a) locate discontinuous permafrost; (b) quantify the potential differential settlement; (c) predict pipeline stresses and strains; (d) establish strain limits; and (e) determine the pipe wall thickness to withstand those potential differential settlements. Several design options are available and are briefly discussed. For the projects mentioned, the heavy wall pipe option was identified as a cost effective design for medium to large differential settlements.

Uncertainty Quantification of Wall Thickness of Onshore Gas Transmission Pipelines

2020 ◽  
Author(s):  
Wenxing W. Zhou ◽  
Ji Bao
Keyword(s):  
Wall Thickness ◽  
Pipe Wall ◽  
Metal Loss ◽  
Pipeline System ◽  
Pipe Wall Thickness ◽  
Reliability Based Design ◽  
Wide Range ◽  
Pipe Joints ◽  
Welded Pipe ◽  
Transmission Pipelines

The present study quantifies probabilistic characteristics of the wall thickness of welded pipe joints in onshore gas transmission pipelines based on about 5900 field-measured wall thicknesses collected from a pipeline system in Canada. The collected data cover a wide range of the pipe nominal wall thickness, from 3.18 to 16.67 mm. By considering the measurement error involved in the collected wall thickness data, statistical analyses indicate that the actual-over-nominal wall thickness ratio (AONR) follows a normal distribution with a mean of 1.01 and a coefficient of variation (COV) ranging from 1.6 to 2.2% depending on the nominal pipe wall thickness. The implications of the developed AONR statistics for the reliability analysis of corroded pipe joints are investigated. This study provides key input to the reliability-based design and assessment of pipelines with respect to various threats such as metal-loss corrosion and stress corrosion cracking.

scholarly journals A Case Study of Pipeline Route Selection and Design Through Discontinuous Permafrost Terrain in Northwestern Alberta

1996 ◽  
Author(s):  
Cory Wiechnik ◽  
Raymond Boivin ◽  
Jim Henderson ◽  
Mark Bowman
Keyword(s):  
Life Cycle Cost ◽  
Field Data ◽  
Differential Settlement ◽  
Frozen Soil ◽  
Geophysical Data ◽  
Design Solution ◽  
Pipeline System ◽  
Permafrost Degradation ◽  
Discontinuous Permafrost ◽  
Pipeline Route

As the natural gas pipeline system in Western Canada expands northward, it traverses the discontinuous permafrost zone. As the ground temperature of the frozen soil in this zone is just below freezing, it can be expected that within the design life of a pipeline the permafrost adjacent to it will melt due to the disturbance of the insulating cover by construction activities. Differential settlement at the thawing frozen/unfrozen soil interfaces gives rise to pipeline strain. Based on the calculated settlement and resulting strain level, a cost effective mechanical or civil design solution can be selected to mitigate the differential settlement problem. Since these design solutions can be costly, it is desirable to combine them with a pipeline route that traverses the least amount of discontinuous permafrost terrain while minimizing the overall length of the pipeline. This paper will detail the framework utilized to select the routing for a package of pipeline projects in northwestern Alberta. The process began with a review of the state of the art in permafrost engineering in order to benefit from past experiences. Airphoto interpretation and terrain mapping were performed for potential pipeline corridors. Preliminary routing options through the corridors were chosen from this mapping information that minimized both pipeline length and amount of permafrost terrain traversed. The next step was to collect field data for each route that would determine the extent and characteristics of the permafrost. Essentially two sets of field data were collected: geophysical mapping of representative sections of each terrain type and physical sampling of the permafrost. Boreholes were located following field interpretation of the geophysical data to ensure they were optimally located to help in calibration of the geophysical data. Permafrost samples were tested in the laboratory for thaw settlement. Anticipated thaw settlements were used to estimate pipe strain levels. This information was then extrapolated for the entire proposed pipeline route and used to finalize both the pipeline route and the differential settlement design options. Monitoring sites will be instrumented to obtain data on the longer term performance of the pipeline, as well as for assessing permafrost degradation effects on the right-of-way such as settlement and impact on drainage patterns. It is believed that the increased front end effort will result in lower operating costs and an overall reduced life-cycle cost. This basic design methodology can be applied to any project that traverses discontinuous permafrost terrain.

scholarly journals The infrastructure cost planning model : an integrated solution to cost effective design

2009 ◽  
Author(s):  
◽  
Shian Hemraj Saroop
Keyword(s):  
Planning Process ◽  
Cost Effective ◽  
Design Stage ◽  
Planning Model ◽  
Infrastructure Projects ◽  
Cost Planning ◽  
Design Options ◽  
The Cost ◽  
Cost Report ◽  
Effective Design

Infrastructure project costs are being scrutinised more closely and with greater skill and accuracy as projects have become larger, more complex and more expensive, and clients have become more exacting in their requirements. These and other factors compel engineers to design with greater care and in more detail. However, public planners spend very little time generating alternative project options, often presenting decision-makers with only a few poorly differentiated alternatives borrowed ad hoc from other projects. Even more disturbing is that they often devote the greatest amount of decision making resources to the development of a single decision rather than a variety of options. A systematic and iterative analysis of the cost consequences of different design solutions is commonly suggested for infrastructure projects, but rarely happens. There is a growing need to integrate design and costs. This study concentrates on the issue of cost optimisation of infrastructure projects (particularly at the design stage of the project) and applies construction economics, cost planning, cost optimisation and value engineering techniques to the design of such projects. The methodology proposed in this study for the optimisation of cost and design planning is the Infrastructure Cost Planning Model. This model divides the planning of a project into four stages and utilises twelve Cost Report Forms across these stages. The Cost Report Forms define in a comprehensive, precise and verifiable manner the essential characteristics of a deliverable component. They are used to measure, quantify, verify and audit the different design options. By means of the Cost Report Forms, the Infrastructure Cost Planning Model enables the client to select a combination of alternatives and evaluate a number of possible design options – with their cost implications – at each stage of the design process. This i promotes transparency and accountability, and enables consultants and clients to have greater control over the planning process and overall costs. Two case studies on infrastructure related projects were conducted and confirm that the Infrastructure Cost Planning Model can reduce costs. This study demonstrates that it is possible to overcome the problem of over expenditure by introducing cost effective design decisions prior to the infrastructure design approval process. The Infrastructure Cost Planning Model can improve infrastructure standards and procure design in a cost effective, equitable, competitive and transparent manner. This study contributes to the underdeveloped area of cost planning and forecasting of infrastructure projects. The findings are relevant to the South African government's infrastructure service delivery programme and the general issue of affordable infrastructure services.

Brazilian Onshore Pipelines Rehabilitation Program

2004 ◽  
Author(s):  
Elinaldo Albuquerque Vasconcelos ◽  
Marcos Jose´ Pessoa de Resende ◽  
Jose´ Lu´cio Silva Ju´nior ◽  
Carlos Alberto Lira Menezes ◽  
Jose´ Edson Ribeiro Santos
Keyword(s):  
Wall Thickness ◽  
Pipe Wall ◽  
Rehabilitation Program ◽  
Northeastern Brazil ◽  
Pipeline System ◽  
Pipe Wall Thickness ◽  
Engineering Construction ◽  
Flow Capacity ◽  
Future Demands

The majority of the pipeline system in Brazil has more than 20 years in operation. The economy and demand for hydrocarbons, including natural gas, is growing in Brazil. Nowadays PETROBRAS-TRANSPETRO, Latin America’s largest carrier, is developing services to upgrade and rehabilitate sections of pipelines to provide compatible operational pressures with the actual and future demands for products. Services include pigging to check the pipe wall thickness, corrosion section replacement, evaluation of the class locations during the operation life of the pipeline, upgrading wall thickness where necessary and installation of new block valves. This is a case study of a 424 km pipeline in northeastern Brazil that crosses 32 municipal districts and supplies 180 direct consumers. The work included 37 replacements and upgrades that were completed in 36 days without affecting consumers. In Brazil, PETROBRAS-TRANSPETRO provides high investments for the rehabilitation of its pipelines, in order to guarantee the integrity and to increase the flow capacity. It is an important market that opens up in Latin America for engineering, construction and specialized inspection services companies.

scholarly journals Case History of Local Wrinkling of a Pipeline

2000 ◽  
Author(s):  
S. A. Wilkie ◽  
R. M. Doblanko ◽  
S. J. Fladager
Keyword(s):  
Structural Design ◽  
Structural Integrity ◽  
Pipe Wall ◽  
Oil Pipeline ◽  
Field Instrumentation ◽  
Discontinuous Permafrost ◽  
Pipe Line ◽  
History Of ◽  
Structural Stresses

Enbridge Pipelines (NW) Inc. (formerly Interprovincial Pipe Line (NW) Ltd.) owns and operates a buried 323mm diameter crude oil pipeline from Norman Wells, NWT to Zama, AB. The pipeline is approximately 869 km in length, with the route following a portion of the Mackenzie River Valley in the Northwest Territories. The pipeline routing is through discontinuous permafrost that has the potential to interact with the pipeline through frost heave, slope movement and thaw settlement that can produce extreme structural stresses in the pipe wall. Given the proper conditions, these stresses may localize and the pipeline will deform plastically, causing pipe wall wrinkling. This paper reviews the general structural design and discusses the inspection and monitoring of the structural integrity of the pipeline, as well as the intervention criteria used to determine when structural mitigation is required. This case study will discuss the discovery of a wrinkle from internal inspection pig data, field dig verification, installation and monitoring of field instrumentation and the pipeline repair technique that was utilized.

Development of a mathematical model of the influence of wall thickness on the strain rate when profiling pipes by drawing

2020 ◽  
pp. 49-52
Author(s):  
R.A. Okulov ◽  
N.V. Semenova
Keyword(s):  
Mathematical Model ◽  
Strain Rate ◽  
Wall Thickness ◽  
Pipe Wall ◽  
Strain Intensity ◽  
Thickness Strain ◽  
Pipe Wall Thickness

The change in the intensity of the deformation of the pipe wall during profiling by drawing was studied. The dependence of the strain intensity on the wall thickness of the workpiece is obtained to predict the processing results in the production of shaped pipes with desired properties. Keywords drawing, profile pipe, wall thickness, strain rate. [email protected]

scholarly journals Bayesian maintenance decision optimisation based on computing the information value from condition inspections

2021 ◽  
pp. 1748006X2097812
Author(s):  
Guang Zou ◽  
Kian Banisoleiman ◽  
Arturo González
Keyword(s):  
Decision Making ◽  
Structural Integrity ◽  
Fatigue Cracking ◽  
Cost Effective ◽  
Offshore Structures ◽  
Information Value ◽  
Bayesian Decision ◽  
Maintenance Strategies ◽  
Optimal Maintenance ◽  
Maintenance Decision

A challenge in marine and offshore engineering is structural integrity management (SIM) of assets such as ships, offshore structures, mooring systems, etc. Due to harsh marine environments, fatigue cracking and corrosion present persistent threats to structural integrity. SIM for such assets is complicated because of a very large number of rewelded plates and joints, for which condition inspections and maintenance are difficult and expensive tasks. Marine SIM needs to take into account uncertainty in material properties, loading characteristics, fatigue models, detection capacities of inspection methods, etc. Optimising inspection and maintenance strategies under uncertainty is therefore vital for effective SIM and cost reductions. This paper proposes a value of information (VoI) computation and Bayesian decision optimisation (BDO) approach to optimal maintenance planning of typical fatigue-prone structural systems under uncertainty. It is shown that the approach can yield optimal maintenance strategies reliably in various maintenance decision making problems or contexts, which are characterized by different cost ratios. It is also shown that there are decision making contexts where inspection information doesn’t add value, and condition based maintenance (CBM) is not cost-effective. The CBM strategy is optimal only in the decision making contexts where VoI > 0. The proposed approach overcomes the limitation of CBM strategy and highlights the importance of VoI computation (to confirm VoI > 0) before adopting inspections and CBM.

Price structures for electricity supply and potential consequences for building services systems

2021 ◽  
pp. 014362442199081
Author(s):  
Roger Hitchin
Keyword(s):  
Cost Effective ◽  
Building Design ◽  
Electricity Supply ◽  
Cooling Systems ◽  
Price Structure ◽  
Heating And Cooling ◽  
Future System ◽  
The Cost ◽  
Supply Systems ◽  
Effective Design

Policies to reduce carbon emissions are leading to substantial changes in the demand for electricity and to the structure of electricity supply systems, which will alter the cost structure of electricity supply. This can be expected to result in corresponding changes to the price structure faced by customers. This note is an initial exploration of how possible new price structures may impact on HVAC system and building design and use. Changes in the price structure of electricity supply (separately from changes in price levels) can significantly affect the cost-effective design and operation of building services systems; especially of heating and cooling systems. The nature and implications of these changes can have important implications for future system design and operation.

Sign in / Sign up

Export Citation Format

Share Document