The High Pressure and High Temperature (HP–HT) subsea field developments are increasingly using Pipe-In-Pipe (PIP) systems for transportation of production fluids due to superior thermal conductivity performance compared to wet insulated single pipe system. PIP systems can provide the necessary thermal insulation with very low Overall Heat Transfer Coefficient (OHTC) in the order of 0.5 to 1.0 W/m2.K whether installed exposed on the seabed or trenched and buried. An additional inherent feature of PIP systems is that they offer increased protection against third party interaction such as fishing gear and dropped object impact. PIP system will provide a very long "no touch time" before any intervention (e.g. depresurisation) becomes necessary. This aspect can also be improved by using e.g. hot water circulating and electrical heating in order to overcome difficulties which may arise from prolonged shutdown periods. The mechanical design of a HP–HT PIP systems is more complex than conventional single pipe system and involves consideration of additional failure modes. This paper gives an overview of the PIP system design, with particular emphasis on in–service buckling and fatigue design. Design considerations for trawl gear impact on lateral buckling and operational aspects of clad and lined pipes for HP–HT and sour service applications are also discussed.

The pipeline inplace buckling design by residual curvature method for controlled thermal expansion during operation is a novel and cost effective method for initiating multiple expansion loops for a reel-laid pipeline. The controlled thermal expansion will be initiated and managed by planned buckle sites at regular intervals of say, 1km spacing with residual curvature corresponding to 0.20%–0.25% residual strain. The pipelines installed by the reel Lay process are required to be straightened by a reverse curvature process which results in pipeline with nominally zero curvature and axial strain. In order to achieve a residual strain of 0.20%–0.25%, two options are available either to over-straight or under-straight the pipelines. This paper discusses the methodology used laying of pipeline with 0.20%–0.25% residual strain at pre-determined intervals by an under-straightening process with a combination of a central 40m under straight section with a residual strain of 0.2%–0.25% and a 15m transition section on either side of the central section, at 1km intervals. The paper presents the methodology used to determine the settings for the top straightener module of reel lay vessel using finite element analyses, as the equipment settings for under or over straight pipes are not readily available from analytical methods. The optimum settings were obtained after substantial number of FEA simulations allowing for the statistical range in pipe material properties from “strong” to “weak” and these settings are used in reeling trials to make necessary adjustments. The residual strain, out-of-straightness and axial force distributions in pipe sections for straight, under-straight and transition sections are discussed. The paper discusses how these settings were used on-board the vessel and the modifications and adjustments required to select the final settings for the under-straight curvature for the field development of Statoil Skuld project as a case study. This paper briefly discusses the vessel equipment specific features and limitations that may need to be taken into consideration in finite element analyses to optimise the straightener settings for residual strain.

A real time wearable medical device for monitoring of urological parameters like bladder pressure, urine flow rate is measured by using cyst metric test and uroflow metric test. It is a invasive method, Patients needs local anesthesia, and patient may feel discomfort for few days. Such problems will be overcome by using a Near Infrared Spectroscopy Device. Near Infrared Spectroscopy is an optical technique, utilizes light in the NIR Spectrum ranges between 700nm – 1000nm has a high penetration depth in the living tissue. In urology, NIRS has been utilized to screen bladder muscle work and to analyze bladder brokenness. Since, it is a Noninvasive method; it is compatible for patients like Multiple Sclerosis, Stroke, Spinal Card injury, elderly patients with incontinence and neurological disorders. With such a gadget utilized as a sensor with a caution, it is thus achievable to caution the subject when the volume of pee in his/her bladder arrives at a pre-decided edge of bladder limit. This technique would possibly empower patients in danger for urinary maintenance to shield themselves from renal harm.

The residual curvature (RC) method has been implemented by Subsea 7 for lateral buckling mitigation on various projects in recent years. The method involves deploying short sections of under-straight pipe in the catenary from a reel-lay vessel. The objective of this paper is to present RC results on bending moment and curvature and to show how these results can be combined with those from dynamic Orcaflex runs to predict the allowable sea-state for installation. ABAQUS models to simulate the reeling/unreeling/straightening procedure on one of Subsea 7’s reel-lay vessels are presented, together with a description of the settings adjustment to achieve under-straight pipe with a prescribed level of residual plastic strain. These models describe the pipe profile on the reel, free-span, aligner, passage through the straightener and finally within the catenary to the seabed. The model is used to simulate the deployment of an RC section and to quantify its tendency to rotate in the sag-bend. The dynamic loads are captured by running an equivalent RC section model in Orcaflex. Results for installation of a typical 14″ × 18″ pipe-in-pipe (PIP) are presented in 115m water depth (WD). Plots showing the spatial distribution of the bending moment and curvature of the RC section at various time increments within the catenary are provided. Attention is focused on the sag-bend. Stress-strain hysteresis loops are presented showing the multiple bending cycles experienced by the RC section from initial spooling-on until eventual deployment on the seabed. The impact that the RC length, residual plastic strain and ramp angle has on the bending moment/curvature is discussed. Orcaflex results are presented which show dynamic change in curvature at the sag-bend over a typical three-hour interval due to vessel motion. The most characteristic dynamic load (Ref. /15/) on the RC section is calculated to establish the loading envelope seen in the sag-bend region. Checks are also undertaken at other locations to ensure that the dynamic loads are not introducing any additional residual plastic strain in the RC section. The maximum bending moment seen by the RC section in the sagbend has an important bearing on the allowable sea-state for installation. The presented methodology for calculating the allowable sea-state (combining results of static and dynamic simulations) is a novel feature in the present work.

Global buckling is a behavior observed on subsea pipelines operating under high pressure and high temperature conditions which can jeopardize its structural integrity if not properly controlled. The thermo-mechanical design of such pipelines shall be robust in order to manage some uncertainties, such as: out-of-straightness and pipe-soil interaction. Pipeline walking is another phenomenon observed in those pipelines which can lead to accumulated displacement and overstress on jumpers and spools. In addition, global buckling and pipeline walking can have strong interaction along the route of a pipeline on uneven and sloped seabed, increasing the challenges of thermo-mechanical design. The P-55 oil export pipeline has approximately 42km length and was designed to work under severe high pressure and high temperature conditions, on a very uneven seabed, including different soil types and wall thicknesses along the length and a significant number of crossings. Additionally, the pipeline is expected to have a high amount of partial and full shutdowns during operation, resulting in an increase in design complexity. During design, many challenges arose in order to “control” the lateral buckling behavior and excessive walking displacements, and finite element analysis was used to understand and assess the pipeline behavior in detail. This paper aims to provide an overview of the lateral buckling and walking design of the P-55 oil export pipeline and to present the solutions related to technical challenges faced during design due to high number of operational cycles. Long pipelines are usually characterized as having a low tendency to walking; however in this case, due to the seabed slope and the buckle sites interaction, a strong walking tendency has been identified. Thus, the main items of the design are discussed in this paper, as follows: lateral buckling triggering and “control” approach, walking in long pipelines and mitigate anchoring system, span correction and its impact on thermo-mechanical behavior.