Flange Sealing Guide; Gasket and Bolted Connections
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FLANGE SEALING GUIDE GASKETS AND BOLTED CONNECTIONS TABLE OF CONTENTS SECTION 1: Nut Factor and Coefficient PIPES AND FLANGES of Friction .............................................................33 Pipes .......................................................................5-7 Relaxation of Material ............................33-34 Materials ............................................................... 6 Elastic Interactions ....................................33-34 Jointing Methods ...........................................6-7 Tolerance, Component Fit, Flanges ................................................................7-13 and Condition ....................................................35 Connecting the Pipe to the Flange ........ 8-9 Thread Engagement ......................................35 Flange Facings .............................................. 9-10 Thermal Expansion and Surface Finish ............................................. 10 -11 Contraction ...................................................36-37 Flange Parallelism ......................................11-12 Other Factors ....................................................37 Flange Rotation ............................................... 12 Hydrostatic End Thrust ................................. 13 SECTION 4: HEAT EXCHANGERS SECTION 2: Overview ........................................................ 39-40 GASKETING Heat Exchanger Types ............................41-43 Gaskets ................................................................... 15 Basic Headers ................................................... 41 Sheet Gaskets ................................................... 15 One Piece Bonnet ...................................... 41 Compressed Fiber Sheets .................... 15-16 Bolted Channel ........................................... 41 Elastomer Binders ..................................... 15-16 Shell and Tube .................................................. 41 Manufacturing Compressed Fixed Tubesheet .............................................. 41 Fiber Sheets ...................................................... 16 U-tube ................................................................. 41 PTFE Sheet Gaskets ........................................ 17 Split Back Floating Head ..............................42 Pull-through Floating Head ........................42 Flexible Graphite Sheet Gaskets .......17-18 Oxidation of Graphite .................................... 18 SECTION 5: Metallic Gaskets .........................................19-21 THE WHOLE JOINT: FLANGE, Spiral Wound Gaskets.................................... 19 GASKET, AND BOLTS Camprofile Gaskets ........................................ 19 Steel Trap™ Gaskets ..................................20-21 Overview ...............................................................45 Gasket Test Standards ............................21-23 ASME Boiler and Pressure Compressibility and Recovery ..............21-22 Vessel Code .........................................................46 Creep Relaxation .............................................22 Installation Procedures .........................46-48 Sealability .....................................................22-23 Disassembly ............................................... 46-47 Alternative Gasket Tests ...............................23 Assembly ......................................................47-48 Selecting the Proper Gasket ...............23-25 Chemical Compatibility ................................23 SECTION 6: Temperature .....................................................23 REFERENCE Pressure ..............................................................24 Appendix A Thickness ......................................................24-25 Glossary of Terms ......................................49-50 Plant Specifications ........................................25 Appendix B Troubleshooting Guide ...........................51-52 SECTION 3: BOLTED FLANGE JOINTS Appendix C Useful Conversions ...................................52-53 Bolts and Threads .....................................27-29 Appendix D Thread Design ............................................27-28 Heat Exchanger Gasket How Bolts Work .........................................28-29 Configuration Drawings .........................54-55 Strength of Materials .....................................29 Appendix E Tightening Methods ................................30-31 Instructions and Example Heat Factors Affecting Bolted Joints .............. 31 Exchanger Data Collection Sheet .......56-57 Friction .............................................................31-32 Endnotes and Bibliography ......................58 Section 1 – Pipes and Flanges Flange Sealing Guide 4 SECTION 1 PIPES AND FLANGES Pipes In industry, the term “pipe” is simply defined as a tube used to transport fluid/medium between two points. TabLE A: Common Standard GroUps “Piping” is the broader term that refers to the pipes and Standards Group Country fittings that make up a system used to transport fluids— a fluid being defined as a gas, liquid, or solid.1 “Tubing” (Abbriviation/Full Name) is another term for pipe, but this is usually used to refer ASTM/American Society for USA to specific components of boilers, heat exchangers, and Testing and Materials other equipment. The US Navy differentiates the two by ANSI/American National USA defining tubing as any tubular product whose specified Standards Institute size is actual measured outside diameter and actual wall thickness; pipe is any tubular product whose size ASME/American Society USA is specified as a nominal size and wall thickness. Piping of Mechanical Engineers systems come in a wide variety of materials and designs API/American Petroleum Institute USA that depend on, among other things, the fluid being DIN/Deutsche Institut für Normung Germany transported, the temperature and pressure of the fluid, safety requirements specific to the system, and cost. ISO/International Standards Worldwide Pipe is manufactured using a number of different Organization methods, each specific to the material and service JIS/Japanese Industrial Standard Japan requirements. In order to maintain consistency and ensure reliability of a piping system, organized standardization BS/British Standard United groups such as those shown in Table A have established Kingdom well defined guidelines for piping systems. Note that the ISO is a worldwide organization that is made up of steam, refrigerant, and seawater are a number of fluids members of many different national standards groups; required for normal operation. To accomodate pressure consolidation of many national standards into a more and temperature factors, the main steam system requires universal collection is intended to create a global high strength, high temperature piping material, and standard rather than many stand-alone national must have valves and fittings designed to handle this standards. The standards established by these groups application. A seawater cooling system doesn’t require cover everything from methods of testing material the high strength, high temperature piping, but must be properties, to specified dimensions for pipes, flanges, resistant to the corrosion often encountered in salt water and fittings of pressure classes, to maximum temperatures applications. The requirements of each system vary and pressure capability of each pipe size, to support widely, as does the equipment designed for each system. methods for piping systems; the list goes on and on. It is Pipes are manufactured in nominal sizes and schedules. important to be aware of these specifications for they The schedule number of a pipe refers to its wall thickness provide a great deal of information useful to engineers (higher schedule number = thicker pipe), and is calculated and maintenance personnel alike. based on the system design pressure (maximum) and the Piping systems can be extremely complicated, and a plant allowable stresses of the pipe material. Typically, wall can have several types of piping systems to handle a thicknesses increase with the maximum internal pressure variety of applications. A classic example is a shipboard the pipe can withstand. It is important to identify a pipe’s engine room. Fuel oil, lube oil, high and low pressure schedule and to use that same exact schedule in any repairs; otherwise, the piping system’s integrity may 5 Section 1 – Pipes and Flanges Flange Sealing Guide be compromised. Tables detailing the dimensions FRP, fiberglass reinforced pipe, is used in chemical services. of various pipe schedules can be found in various This material is a thermoset plastic resin reinforced with machinists, handbooks or in literature supplied by pipe fiberglass filaments, and it can withstand a wide variety manufacturers. Pipe is normally supplied in lengths of chemicals that attack steel pipe. FRP is resistant to between 3,6 and 6+ m (12 and 20+ feet). corrosion internally and externally because the whole pipe is made of FRP, not bonded to another material, as found Materials in lined pipes. One concern with this material is its coefficient of thermal expansion. FRP tends to expand Given the wide variety of applications in any plant, there and contract much more than steel pipe during thermal are dozens of different piping materials used. The choice cycling. This sometimes creates difficulty in maintaining of material is made by the design engineer and depends load on