Pipeline Bundles Research Articles

Standalone EST microsatellite mining and analysis tool (SEMAT): for automated EST-SSR analysis in plants

Public databases contain large datasets of plant expressed sequence tags (ESTs) that can be used for mining microsatellite/simple sequence repeat markers. The identification and annotation of these markers take considerable time. Here, we describe an efficient, high-throughput microsatellite mining, and analysis pipeline, standalone EST microsatellite mining and analysis tool (SEMAT). The pipeline bundles sequence trimming, assembly, microsatellite identification, primer selection, and blast annotation, for which it consecutively uses SeqClean, CAP3, MISA, Primer3, and Blast. SEMAT is written using Perl scripts, and it runs under Ubuntu and Fedora Linux. SEMAT is an efficient and time-saving bioinformatics tool to accomplish the high throughput EST-SSR analysis. It is freely available from http://semat.cpcribioinformatics.in/.

Numerical study of scour around a pipeline bundle

A well-established two-dimensional numerical model was employed to study the scour-hole development around a pipeline bundle, which was composed of a main pipeline and a piggyback pipeline. Both the current and wave flow situations were simulated with parameters chosen to represent prototype pipeline scour in adverse weather conditions. Under the same hydraulic and soil conditions, the scour around the main pipeline alone and around an equivalent pipeline was also simulated, and these served as reference cases for studying the scour around pipeline bundles. The focus of this paper is the equilibrium scour depth and the development rate. It was found that the pipeline bundle produced a deeper scour depth with a larger time-scale in comparison with the scour occurring for the single-pipeline case; thus the equivalent-pipeline representation may lead to an unsafe design. The differences between the pipeline bundle and single pipeline scour were larger under the current alone flow condition than those under the wave condition. These differences in the scour development can be explained by examining the flow fields around the pipeline.

Heat Transfer in Offshore Pipeline Bundles

A key design parameter for the operation of subsea pipeline systems is the Overall Heat Transfer Coefficient or "U Value". In some cases for bundles with flow lines insulated in a common sleeve, the steady state flow condition "U Value" is not a characteristic parameter since it varies depending on the individual flowline temperatures and corresponding heat fluxes along the length. It is therefore difficult to specify an overall "U Value" coefficient either for the bundle or for each flowline in the bundle. It is, however, possible to use computational fluid dynamics models to evaluate these heat fluxes and effective "U Values" for each pipeline over a short bundle segment given specified flowline temperatures. Prediction of the flowline temperatures is difficult particularly in cases when fluids are flowing in the opposite directions i.e. production lines and gas injection line, but by using a simplified Rockwater in-house thermal analysis model, the temperature inputs to the CFD model of the bundle section can be estimated. FIDAP, a general purpose CFD code based on the finite element method has been used in the present studies. FIDAP works with the 2-D bundle model to predict heat flux under steady state conditions thus verifying the Rockwater mathematical model by calculating convection velocity and temperature contours.

Hydrodynamic interactions between two vertical circular cylinders in linear oscillatory flow

Linear potential theory is used to investigate the hydrodynamic interactions between two vertical cylinders in harmonic flow. The behaviour of the added mass and damping is studied for various cylinder diameters, lengths of immersion and spacing between the cylinders. In practice, the results have relevance to the fluid loading on offshore structural members, such as risers and platform legs, and pipeline bundles. On a more theoretical level, comparisons are possible between the results of a three-dimensional diffraction program and various asymptotic expressions to establish the range of validity of the latter and the need, where appropriate, of the former.