Advanced Design of Packing and Cylinders for Hyper-Compressors for LDPE Production

The optimization of packing cup geometry is important for improving the reliability of hyper-compressors. The complex arrangement and the transmission of loads through the various components requires the use of FEA to properly determine the stress level. The need to reduce the sensitivity to external factors requires an investigation with more advanced simulations. The entire cylinder and associated components such as head flanges, cylinder chambers and tie rods, were modeled. This provided the characteristics of the interfaces and the boundary conditions necessary to simulate the packing cups. Considering the thickness, ring housing profile, lube-oil holes, mating surfaces, interference-fit and diameter make it possible to obtain the stresses at the most critical points. This new simulation approach shows the effect of the parameters that influence the stress level at critical points, thus optimizing the packing cup profile and its relevant features.

Development of the New Generation Materials for the Soft Pipe Lining Rehabilitation

With increasing global urbanization and industrialization, many more pipelines for gas, potable water, sewer, oil, and power cables have been installed underground, underwater, in buildings and in factories. Maintenance of such pipelines is crucial. However, it is often difficult and has become a growing problem these days. The PALTEM-HL (Trade mark and stands for Pipeline Automatic Lining SysTEM, Hose Lining Method), a pipeline relining system, was developed as an effective and inexpensive solution for this problem. In this project, we try to develop a new resins and the adhesives system to replace the raw materials used in the PALTEM-HL system. Anionic harder combined two different types of epoxy resins were investigated in this study. After curing, the mechanical properties and glass transition temperature of the mixture were examined and the optimum sample preparation prescription was also found. FTIR (Fourier Transform Infrared Spectroscopy) and DSC (Differential Scanning Calorimeter) were employed to monitor the curing process of the mixtures. The mechanical properties of the mixture were also measured by Instron and micro Vickers.

Square Root 3: Background to the New Design Margin for High Pressure Vessels

The ASME Section VIII Division 3 Pressure Vessel Design Code adopted in its 2004 edition a significant change of the design margin against plastic collapse. There are several reasons and justifications for this code change, in particular the comparison with design margins used for high pressure equipment in Europe. Also, the ASME Pressure Vessel Code books themselves are not always consistent with respect to design margin. This paper discusses not only the background material for the code change, but also gives some practical information on when pressure vessels could be designed to a thinner wall.

Creep Effect of Attached Structures on Bolted Flanged Joint Relaxation

The leakage tightness behavior of bolted flange joints is compromised due to high temperature effects and in particular when creep of the materials of the different components of the bolted flanged joint take place. The relaxation of bolted flanged joints is often estimated from the creep of the gasket and the bolts. The creep behavior of the flange ring and the attached structures such as the shell and the hub is often neglected. Apart from an acknowledgement of relaxation due to creep, the designer has no specific tools to accurately assess this effect on the bolt load relaxation. The objective of this paper is to present an analytical approach capable of predicting the bolt load relaxation due to creep of the attached structures. The proposed approach is validated by comparison with 3D FE models of different size flanges. An emphasis will be put towards the importance of including creep of the attached structures in high temperature flange designs.

Dynamics of Submerged Expandable Tubes in Borehole Wells

Solid Expandable Tubular Technology (SETT) is a new development in the petroleum industry. It consists in accomplishing hydraulic expansion of a submerged tube by propelling a mandrel through it using a differential pressure. The progress of the mandrel deforms the tube beyond its elastic limit. Towards the end of the expansion process, the mandrel pops out of the tube resulting in displacement, stress and pressure waves. A mathematical model is developed to describe the dynamics of the tube-fluid system due to the pop-out phenomenon. The model takes into consideration the effects of the coupling between fluids and structure as well as the inherent system damping on the response. Through a specific field case, the model provides an analytical solution describing the wave propagating in the tube-fluid system and identifies the potential failure locations.

ENIQ European Framework on Risk Informed In-Service-Inspection

The European Network for Inspection and Qualification (ENIQ) is a utility driven network working towards a harmonised European approach on reliable and effective in-service inspection (ISI). Its Steering Committee (SC) has one voting member for each EU member country with nuclear plants and for Switzerland. More specifically ENIQ works on qualification of ISI systems an on risk-informed in-service inspection (RI-ISI) within a European context. To reflect the latter, the SC set up a specific Task Group on Risk (TGR). The primary task for TGR was to produce a European framework document on RI-ISI, following the format of the well-established ENIQ document for qualification of NDT systems “European Methodology for Qualification, EUR 17299 EN”. The framework document for RI-ISI is a high-level document aimed at supporting utilities to implement RI-ISI and to interface with the nuclear regulators. Aim of this paper is to present the work of TGR so far and in particular the contents of the European framework document on RI-ISI, which has been recently approved for publication by ENIQ SC. It gives an overview of the philosophy behind a risk informed approach towards in service inspection and the principles of a risk informed in service inspection. It also defines how roles, responsibilities and interfaces between the different parties involved in a RI-ISI programme should be organised.

The Stress Analysis for the Trenchless Pipeline Rehabilitation

Most of the pipelines will get aging year after year and then they will need to be rehabilitated. Because of the heavy traffic on the ground or the congested pipelines under the ground, the replacement of old pipes will be very difficult in the cities. The dig-free (trenchless) method is a revolutionary pipelining method which uses air pressure, hydraulic pressure or mechanical drag force to pull the flexible piping plastic sheet into the old pipe. This research proposes a stress analysis for trenchless pipeline method by the finite element model with CATIA. The material of piping sheet is combined of two different types of epoxy with the anionic harder. We do the stress analysis of the trenchless rehabilitated pipelines to decide the optimal thickness of flexible piping plastic sheet and whether the material is available or not by finite element method.

Evaluation of Loads on a Hypercompressor Plunger in Service Conditions

The plunger is a very critical component for the operation of hyper-compressors. To achieve long packing ring life it is necessary to select very hard materials for the plunger. As a consequence of the special materials used, the plunger is very brittle. To guarantee safe operation it is necessary to have perfect alignment to avoid bending stress that could cause plunger failure. The effects of the whole system, including packing rings and supporting crossheads were analyzed using a multi-body dynamic simulation to determine the maximum loads acting on the plunger. This analysis verified the viability of this critical component during abnormal machine operating conditions.

Probabilistic Fracture Mechanics Assessment of Wall-Thinned Nuclear Piping System

The integrity of nuclear piping systems must be maintained during operation. In order to maintain the integrity, reliable assessment procedures including fracture mechanics analysis, etc, are required. Up to now, the integrity assessment has been performed using conventional deterministic approaches even though there are many uncertainties to hinder a rational evaluation. In this respect, probabilistic approach is considered as an appropriate method for piping system evaluation. The objectives of this paper are to develop a probabilistic assessment program using reliability index and simulation technique and to estimate the failure probability of wall-thinned pipes in secondary systems. The probabilistic assessment program consists of three evaluation modules that are: first order reliability method, second order reliability method and crude Monte Carlo simulation method. The developed program has been applied to evaluate failure probabilities of wall-thinned piping system subjected to internal pressure, global bending moment and combined loading. The evaluation results showed a promising applicability of the probabilistic integrity assessment program.

Digital Radiography of General Purpose Fissile Packages

Digital radiography provides an effective means of non-destructively examining the effects of physical tests on the interior structure of a Radioactive Materials Packaging. As such it enables evaluation of the effects of the Hypothetical Accident Conditions Sequential Test on a package, following each step in the test sequence. An introduction to digital radiography is given and application of CCD-based, lens-coupled, large area-detector, digital radiography in the HAC testing of the prototype General Purpose Fissile Packaging is described. The radiographs enable correlation of damage with particular steps in the test sequence.