Leak Testing of a Raised Face Weld Neck Flange by G. Bibel, D. Weinberger, C. Syverson, S. Dockter - January 2002. Library of Congress Card Catalog: 85-647116 (23 pages) more detail...
External Bending Moments on Bolted Gasketed Joints by Yves Birembaut, Hakim Bouzid, Michel Derenne, Thierry Ledauphin, Luc Marchand, Pascal Martelli-Garon, Vincent Masi -- July 2002 (56 pp) more detail...
Test Protocol for Gasket Materials by Jerry Waterland ISSN: 0043-2326 ISBN: 1-58145-502-X Library of Congress Catalog Card Number: 85-647116 Number of Pages: 54 more detail...
Effect of Flange Rotation and Gasket Width on Leakage Behavior of Bolted Flanged Joints Part 1: Effect of Flange Rotation on Leakage Behavior of Bolted Flanged Joints A. Bouzid, M. Derenne, M. El-Rich Part 2: Effect of Gasket Width and Gasket Diameter on Tightness Performance, Gasket Constants and Emissions--An Exploratory Experimental Evaluation A. Bouzid, M. Derenne Part 3: Effect of Gasket Width on Tightness Performance Gasket Constants and Emissions A. Bouzid, M. Derenne, Y. Birembaut more detail...
Long Term Pressurized Graphite Gasketed Joint Tests Report 1: Long Term Pressurized Graphite Gasketed Joint Tests Luc Marchand, Michel Derenne, Olivier Sakr, Hakim A. Bouzid Report 2: Long Term Performance Of Flexible Graphite Based Gaskets Under Nitrogen Exposure; Luc Marchand, Michel Derenne Report 3: Additional Long Term Pressurized Joint Tests On Corrugated Flexible Graphite Gaskets; Luc Marchand, Michel Derenne Number of Pages: 72 The long term performance and elevated temperature capabilities of flexible graphite based gaskets have been the focus of several PVRC research projects. This WRC Bulletin combines a series of recent, inter-related research projects which have been commissioned to further quantify the long term performance of flexible graphite gaskets in different atmospheres, and to validate earlier service life and performance predictions which are based on shorter duration exposure. Initiated in 1996, PVRC project 96-09G was the first of a series of pressurized media tests launched to investigate the effect of long term pressurized hot air exposure on the performance of two different types of reinforced flexible graphite based gaskets that are commonly used in industry today. One a foil reinforced sheet type flexible graphite gasket material and the second a corrugated insert flexible graphite gasket. The project was designed to supplement and confirm the long term graphite gasket life predictions that are based upon the results of previous PVRC projects 91-8, 93-3 and 94-25. While the long duration stress relaxation and leak rate results correlated well with the quantification methods identified in the earlier research for the reinforced sheet type material, the resultant performance of the corrugated insert type gasket was not as expected and, at the time, could not be explained. PVRC project 00-BFC-12G was commissioned to investigate the possible causes for the fast rate of degradation that occurred with the corrugated insert flexible graphite gaskets in the earlier PVRC 96-09G investigation. This experimental work studied the effect of long term pressurized hot air exposure on the performance of two different brands of corrugated insert flexible graphite gaskets, and in particular identified the effect of three important parameters on the degradation rate of these gaskets. All previous performance qualifications and the resultant service life prediction tools were performed under hot air exposure. In an effort to qualify the accuracy of the qualification and service life prediction tools in non-oxidizing atmospheres, PVRC project 99-04G was commissioned. This project investigates the effect of long term pressurized hot nitrogen exposure on the performance of foil reinforced flexible graphite type gaskets and corrugated insert flexible graphite gaskets. Comparisons were made with the long term pressurized hot air test results of earlier PVRC projects and a method was established that can adjust the PVRC qualification tools for the calculation of long term gasket temperature and service life for these materials when employed in non-oxidizing environments. The method is based on the establishment of a recommended Ag (Equivalent Aging Parameter for Flexible Graphite) value that is specific for an internal fluid exposure condition. more detail...
This bulletin reports a common core room temperature leakage test procedure for generation of design data for both the draft ASME Non-mandatory Appendix BFJ and CEN EN 1591-1. The work has been prepared from the results of over 400 ROTT tests performed since 1994 according to the proposed ASTM ROTT Draft 9 [7] or Draft 10 [3] methods. There was no CEN prEN13555 test data available to perform an analysis of the method, as was done for the ASTM ROTT Draft methods in this report. The differences between the draft ASTM and CEN prEN-13555 methods (points of harmonization) are outlined following. There are, in reality, only three differences between the requirements placed on the ROTT gasket test procedure by the draft ASTM and CEN prEN-13555 methods. These differences listed below are: 1) fluid pressure level, 2) gasket stress levels and test sequence, 3) gasket size. For each difference, a conclusion from this report regarding the proposed method of harmonization is included. In addition, a measure of the level of variation or error associated with the proposed harmonization change is also listed. The level of variation associated with that aspect of harmonization should be compared with overall levels found in the ASTM ROTT / ASME-BFJ more detail...
Thermal events and transient thermal effects are known to play a major role in pressurized flanged joint leakage. When a leak occurs the engineering challenge is to understand and properly diagnose the role temperature and thermal transients in that failure and thereby specify measures necessary avoid future leaks. Also, since most pressure vessel codes require the consideration of thermal effects without providing the methodology, perhaps the greater engineering challenge is to the flanged joint designer. This is not only to determine temperature effects on flanged joint designs to comply with code requirements but also an evaluation of the design to assure leak free operation considering anticipated thermal events. This Bulletin provides a set of analytical tools and guidelines for addressing these challenges. The purpose of PVRC Project 01-BFC-05 was to summarize the findings of the Author?s doctoral project on the effects of temperature loads on bolted flange joints and publish a summary document providing design guidelines to deal with temperature effects and the relative magnitude of these effects. Reporting on this work, the Bulletin provides users with simplified thermal calculation methods that enable the flanged joint designer or field troubleshooter to determine the effect of steady state or transient temperatures on flanged joints, including an evaluation of leakage possibilities. This is accomplished by the author in a readable step by step process that provides the tools to answer along the way questions such as: What increase in assembly bolt load would be sufficient to overcome anticipated thermal events? Is flange deflection caused by joint component thermal interaction sufficient to cause a leak from loss of gasket load? Could radial shearing of the gasket from differential radial expansion of the flanges or tube-sheet caused either by differences in mating flange temperatures or material properties result in failure? Is gasket crushing a possibility due to increased load caused by joint component thermal interaction? How much bolt and gasket load could be lost because of a process thermal transient, or a sudden cool-down, without failure? If insulation is applied to an operating un-insulated flanged joint, how much hotter than the flange ring might the bolts be? Is this transient sufficient cause a leak? Following an overview of bolted flanged joint response to thermal loads, causes of failure and a background description of mechanical and thermal analysis, a detailed calculation procedure is presented. For simplicity axisymmetric and generally identical mating flanges are assumed by the calculation method. Detailed guidance is then provided on extending this approach to non-identical flange pairs, joints with a tube-sheet (Heat exchanger girth joints) and coverplates. The method first provides steady state thermal and deformation results followed by means to calculate the steady state bolt load using component compliance. An evaluation of transient effects by extension of these findings and the use of a series of graphs providing the time to reach 95% and 5% the steady state temperature for each component completes the process. Appendices A through D provide additional information on the details of the calculation methodology. Appendices E and F illustrate the calculation method via an available Excel spreadsheet. more detail...
This Bulletin documents a European experimental study conducted on behalf of the ?pressure vessel equipment ? industrial piping commission of CETIM?. This experimental work was conducted, funded and published in French by CETIM. The work was inspired by PVRC BFC Project 97-04 ?Effect of Bending Moments on the Tightness of Bolted Flange Gaskets?, now published within WRC Bulletin 473. It demonstrated that external moments applied to a joint have little effect on the tightness of a properly tightened joint, raising the question: to what degree would flange misalignment affect the tightness of the same joint and assembly bolt loads? n this study, the tightness of a CEN joint with fiber reinforced and expanded graphite gasket sheets and graphite filled spiral wound gaskets was measured for various types and degrees of flange facing misalignment. These misalignment ?defects? were axial (10mm), radial (10mm) and angular (1.5 o, 2.5o). Upon the application of ?proper? bolt loads, leak tightness was directly measured for each defect case over a range of internal pressures up to 4 Mpa (580 psi). The CEN study joint is similar to an ASME B16.5 NPS 8 Cl 300 pipe joint. The spiral wound gasket was the most alignment sensitive, and angular (non-parallel facing) misalignment defects had the most influence on assembled joint tightness. The 2.5o defect could not be sealed for the spiral wound gasket! Although this finding is for a specific test system or ?piping system stiffness?, and a less stiff system may have sealed adequately, it is nevertheless useful to have a direct experimental conformation of specific angular misalignment effects. A similar study for an ASME B16.5 NPS 8 Cl 300 joint has been proposed but remains un-funded. The reader of this Bulletin may find sufficient information to formulate a rule for the allowable amount of misalignment in piping system joints with known stiffness and gaskets. It could be argued that angular flange misalignment sufficient to be excessive for a critical pump nozzle flange might also be excessive for flanged joints in general. Therefore the alignment rule for critical pump nozzle flanges suggested by Appendix 1 of WRC Bulletin 449 might also be considered useful for application to piping system joints in general given the findings of this Bulletin. more detail...
3D Modeling of Bolted Flanged Joints and Development of a Transducer for Measuring Gasket Contact Stress Olivier Sakr, Hakim A. Bouzid, Michel Derenne This bulletin reports on development of a three dimensional finite element model (3D FEM) to evaluate the effect of bending loads on the mechanical and tightness integrity of bolted flanged connections, and to compare the numerical results obtained with the 3D FEM to existing experimental data. Bolted flanged joints can be subjected to external loads from many different sources including thermal expansion of piping and piping components, misalignments of pipe supports, and non-symmetrical thermal expansion of the joint components. In most of theses cases bending moments are induced in the pipes and are transmitted to the flanges. For the design of bolted flanged joints, the effect of these moments must be accounted for as it can affect their mechanical and tightness behaviors. The use of the finite element technique for the analysis of bolted flanges subjected to non-symmetrical loadings is powerful and economical. This is particularly true for large dimension flanges for which experimental testing is very expensive and difficult to achieve. For non-symmetrical loading, the use of a three dimensional modeling of the joint components is appropriate to study the effect of external bending moments. A three dimensional model allows realistic behavior of the structure when compared to two dimensional model, particularly if the flange holes and the bolts need to be modeled. A three dimensional approach is essential to obtain a realistic circumferential and radial distribution of the gasket contact stress which is the key parameter that controls leakage. The gasket stress distribution generated by flange rotation has a major impact on the leakage behavior of a bolted flanged joint. A special transducer, located in the flange beneath the gasket, to measure the radial variation of the contact stress developed in a bolted flanged connection has been developed and evaluated. The experimental results obtained with this transducer will be compared to the available numerical contact stress distributions obtained with a 3D-finite element model. more detail...
