5/31/12AdvancePipeliner MAIN MENU Home Archives Resources Downloads Job Search Engine AdvancePipeliner Global Buckling and Walking in Subsea Pipelines: Consequences and Mitigation Measures User Rating: Poor /1 Best RA TE SEARCH Pipeline ADVERTISEMENT CALCULATORS Gas Pipeline Flow Capacity Gas Pipeline Wall Thickness (ASME B31.8, Java) Gas Pipeline Wall Thickness (ASME B31.8, PHP) Beam Deflection Calculator Pipeline Global Buckling Pipelines like other slender strcutures with compressive forces, can buckle globally if the axial compresssion goes beyond a certain level. Buried pipeline normally tend to buckle in upheaval direction (upheaval buckling) and exposed pipelines normally tend to buckle laterally (lateral buckling). In most cases, evaluations relevant to the global buckling threat will already start taking place in e.g. feasibility studies carried out during the concept phase. With regard to global buckling, the system risk review and strategy development activity should be initiated by participating in such early studies [1]. FRIENDS Pipeng The most relevant failure modes of global buckling are as follows [1]: Local buckling, which is normally the governing failure mode resulting from excessive utilization. Local buckling appears as wrinkling or as a local buckle on the compressive side of the cross section. Local buckling can lead to excessive ovalisation and reduced cross-section area. This means reduced production, or even full production stop if e.g. a pig should get stuck. A locally buckled pipeline cannot stand an increased bending moment in the pipeline. This could lead to pipeline collapse and full production stop. Loss of containment, as a result of: Fracture, is failure on the tensile side of the cross section also resulting from excessive utilization. Fracture leads to leakage or full bore rupture, meaning reduced production, or even full production stop. Low cycle fatigue, which can occur for limited load cycles in case each cycle gives strains in the plastic region; i.e. the utilization is excessive in periods. Low cycle fatigue may lead to leakage or rupture, meaning reduced production, or full production stop. Hydrogen induces stress cracking (HISC), can occur in martensitic steels ("13%Cr) and ferritic-austenitic steels (duplex and super-duplex). Blisters of free hydrogen can create cracks in steel or weld at a CP/anode location when the steel is exposed to seawater and stresses from the buckle. The pipeline utilization does not have to necessarily be excessive. HISC leads to leakage or full bore rupture, meaning reduced production, or full production stop. True Stories In January 2000, a 17km 16-Inch pipeline in Guanabara Bay, Brazil, suddenly buckled 4m laterally and ruptured, leading to a damaging release of about 10,000 barrels of oil, and to great embarrassment to the operator. Field observation showed that as a result of temperature increase, the pipeline displaced laterally, when failure took place. Operating pressure and temperature of the pipeline were 400bar and 95°C, respectively. The soil beneath the pipeline was very soft clay with about 2kPa undrained shear strength at seabed [2]. In December 2003, side-scan sonar survey of a 10km pipeline transported wet gas in South East Asia, identified six lateral buckles along the pipeline length. The original pipeline design did not consider lateral buckling as a design issue; consequently, the effect of lateral buckling on the pipeline integrity was not clear. Results of a detailed lateral buckling study showed that the pipeline should be replaced within few years. Design Methodologies Pipeline design against lateral buckling involves three main Levels: LEVEL 1: SCREENING In this level, an analytical approach (e.g. Hobbs [4]) will be used to check if the pipeline is susceptible to lateral buckling. The results of this level answer to the following questions: Is pipeline susceptible to lateral buckling? Which areas of the pipeline are susceptible to lateral buckling? Can we avoid lateral buckling by changing the concrete coating thickness of the pipeline? LEVEL 2: LATERAL BUCKLING ANALYSIS OF THE PIPELINE In this level, a detailed finite element analysis will be performed on the areas of the pipeline, which found to be susceptible to lateral buckling in Level 1 analysis. The results of this level answer to a main question: are limit state conditions www.advancepipeliner.com/site/ 1/4 Journal of Transportation Engineering. and Baobab field. M. “ In-Service Buckling of Heated Pipelines”. a detailed finite element analysis will be performed to evaluate maximum pipeline movement after each start-up and shut-down transient. Lee. S.advancepipeliner. 32-Inch inline spool for a 16-Inch gas line Combination of abovementioned approaches References 1.com/site/ Corrosion Rates 2/4 .. which may cause expansion spool or riser failure. Corrosion Determination The principal method of sweet corrosion assessment in the pipelines is as follows [1]: www. et. These purposes generally include one or more of the following: Diagnosis of corrosion problems. 30 May 2012 00:30 Corrosion Monitoring and Systems Sweet Corrosion Rate in Oil and Gas Pipelines There are many purposes to the application of corrosion monitoring in pipeline systems. Penguins flow line in North Sea Laying of the pipeline on pre-installed sleepers (vertical upset method). DNV-RP-F116. At least one loss of containment failure due to pipeline walking has been recorded in North Sea. expansion of one end of the pipeline would be more than the expected value calculated during the design stage. Monitoring of corrosion control methods (e. Following mitigation measures normally are used for pipeline walking: Anchoring the pipeline (50 to 350 tonnes). This method has been implemented successfully in BP Azeri field development. The effects of the selected mitigation measure will also be included into the finite element model. Add new comment Last Updated on Wednesday. Soft Soil Engineering.. a mitigation measure will be selected based on project and client requirements. Laying of the pipeline in zig-zag shape (snake lay).. al. inhibition. 2010 2. Suction pile anchor Increase of pipeline submerged weight Changing pipeline operational conditions (transient condition) Changing size of the expansion spool. Caspian sea. This method was successfully utilized in South Pars Phase 6 and 7. Design Methodologies LEVEL 1: SIMPLIFIED ANALYTICAL METHOD In this level. Other less popular methods such as adding either expansion spool or buoyancy modules at selected intervals. King flow line in gulf of Mexico. 2. By end of 2000.g. (eds). No. “Integrity Management of Submarine Pipeline Systems”. E. the concrete weight coating thickness of the first 5km of the pipeline was increased from 45mm to 65mm. The results of this level answer to a main question: are limit state conditions acceptable in areas of the pipeline with unplanned buckle? LEVEL 3: MITIGATION If the answer to Level 2 question is no. al.5/31/12 AdvancePipeliner to lateral buckling in Level 1 analysis. et. Jade pipeline in North Sea. S. this level will be commenced. Almeida. pp 175-189. 3. This method was successfully utilized in PC4B11 pipeline in Malaysia. Swets & Zeitlinger. Pipeline Walking (Creep) Pipeline walking occurs during pipeline startup and shut down mainly when the pipeline just has one anchor point at the middle (basically this is not correct for XHP/HT Pipelines) under the following conditions: Tension at one end of the pipeline exerted by a steel catenary riser Seabed slop Thermal transient along the pipeline As a result of pipeline walking. offshore Cote d’Ivoire. and rock dumping also may be used. offshore Angola. One example of this approach is Reshadat 16-Inch oil pipeline in Persian Gulf. 2001. This method has been implemented successfully in BP greater Plutonio. “Pipeline Failure on Very Soft Clay”. there were six incident reported in North Sea. LEVEL 2: FINITE ELEMENT ANALYSIS OF THE PIPELINE In this level. 110. a simplified analytical method will be used to estimate maximum pipeline movement after each start-up and shut-down transient. which caused by excessive expansion of the pipeline. R. The most well known mitigation methods are as follows: Increasing the concrete coating thickness in selected regions of the pipeline.. Hobbs. In this level. March/April 1984. Vol. Ultrasonic Intelligent Spools The extent and type of corrosion monitoring should be established during front end engineering design of pipelie. etc. Chemical analysis. 03 June 2010 01:02 Corrosion Rates The not corrected corrosion rate in pipelines containing sweet hydrocarbon can be calculated using the following equation: ? t = corrosion rate (mm/yr) = temperature in ºC. The rate of corrosion dictates how long components can be usefully and safely operated. Advanced warning of system upsets leading to corrosion damage. Where. = partial pressure of CO2 (in bar) x fugacity coefficient fugacity coefficient 273) x total pressure) = 10 (0. FCO2 = fugacity of CO2 in bar. flow rate. Monitoring Types The main techniques. Read more. etc.0031 ... The application of corrosion monitoring techniques can be very important when the consequences of internal corrosion are considered.). loss of production and hence loss of revenue. Linear Polarisation Resistance (LPR) probes Hydrogen probes. By diagnosing a particular corrosion problem. are as follows: Weight loss coupons. such as pressure. for example. Invoke process controls.5/31/12 AdvancePipeliner pH control. By providing management the information necessary to relate maintenance requirements to ongoing conditions of operation. which are available for corrosion monitoring. and pollution of the environment may be occured in pipeline systems without adequate corrosin monitoring systems. loss of capital equipment. Estimation of used and remaining service lifes. with a signal response taking place www. by de Waard & Smith [2].4 / (t + The following factors have been derived to adjust the corrosion rates determined from above equation. hazard to personnel. Electrical resistance (ER) probs. Add new comment Last Updated on Thursday. Corrosion monitoring techniques can help in several ways: By providing an early warning that damaging process conditions are developing. By revealing the correlation between changes in process parameters and their effect on system corrosivity. dependent upon the process stream constituents.com/site/ 3/4 . Determination of inspection and/or maintenance schedules.1.. unscheduled shutdowns. Bacteria probs. identifying its cause and the rate controlling parameters. temperature. Data Integration Real-time corrosion measurements refer to highly sensitive measurements.advancepipeliner. By evaluating the effectiveness of a corrosion control/prevention program. pH. The measurement of corrosion and the action to remedy high corrosion rates permits the most cost effective plant operation to be achieved while reducing the life-cycle costs associated with the operation. . 10 October 2010 14:41 More Articles.advancepipeliner..com/site/ 4/4 . for use as input to the management information system. Complementary data from other relevant sources such as process parameter logging and inspection reports can be acquired together with the data from corrosion sensors.5/31/12 AdvancePipeliner essentially instantaneously as the corrosion rate changes. Numerous real-time corrosion monitoring programs in diverse branches of industry have revealed that the severity of corrosion damage is rarely uniform with time. Add new comment Last Updated on Sunday. Sandy Soil Axial Resistance On Buried Section of a Pipeline In-Service Buckling of Heated Pipelines Avoiding Vortex Induced Vibration (Strakes) World Database on Protected Areas « Start Prev 1 2 3 4 5 6 7 8 9 10 Next End » Page 1 of 12 www.