ASME B16.47:2017 pdf free download – Large Diameter Steel Flanges
2.1 General
Pressure–temperature ratings are maximum allowable working gage pressures, in bar units, at the temperatures in degrees Celsius shown in Tables 3 through 28 for the applicable material and class designation. Tables I-1 through I-26 of Mandatory Appendix I lists pressure– temperature ratings using pounds per square inch (psi) units for pressure at the temperature in degrees Fahrenheit. For intermediate temperatures, linear inter- polation is permitted. Interpolation between class desig- nations is not permitted.
2.2 Flanged Joints
A flanged joint is composed of separate and indepen- dent, although interrelated, components: the flanges, the gasket, and the bolting, which are assembled by another influence, the assembler. Proper controls must be exer- cised in the selection and application for all of these elements to attain a joint that has acceptable leak tight- ness. Assembly and tightening techniques, such as controlled bolt tightening, are described in ASME PCC-1.
2.3 Ratings of Flanged Joints
2.3.1 Basis. Pressure–temperature ratings apply to flanged joints that conform to the limitations on bolting in para. 5.3 and on gaskets in para. 5.4, and that are made up in accordance with good practice for alignment and assembly (see para. 2.2). Use of these ratings for flanged joints not conforming to these limita- tions is the responsibility of the user.
2.4 Rating Temperature
The temperature shown for a corresponding pressure rating is the temperature ofthe pressure containing shell ofthe component. In general, this temperature is the same as that of the contained fluid. Use of a pressure rating corresponding to a temperature other than that of the contained fluid is the responsibility of the user, subject to the requirements of applicable codes and regulations. Foranytemperature below−29°C (−20°F) the ratingshall beno greaterthanthe ratingshownfor−29°C (−20°F). See also para. 2.5.3.
2.5 Temperature Considerations
2.5.1 General. Use of flanges at either high or low temperatures shall take into consideration the risk of joint leakage due to forces and moments developed in the connected piping or equipment. Provisions in paras. 2.5.2 and 2.5.3 are included as advisory with the aim of lessening these risks.
2.5.2 High Temperature. Application at temperatures in the creep range will result in decreasing bolt loads as relaxation of flanges, bolts, and gaskets takes place. Flanged joints subjected to thermal gradients may like- wise be subject to decreasing bolt loads. Decreased bolt loads diminish the capacity of the flanged joint to sustain loads effectivelywithoutleakage. Attemperatures above 200°C (400°F) for Classes 75 and 150, and above 400°C (750°F) for other class designations, flanged joints may develop leakage problems unless care is taken to avoid imposing severe external loads and/or severe thermal gradients.
2.5.3 LowTemperature. Some ofthe materials listedin Tables 1 and2, notablysomecarbonsteels, mayundergo a decrease in ductility when used at low temperatures to such an extent as to be unable to safely resist shock loading, sudden changes of stress, or high stress concen- tration. Some codes or regulations may require impact testing for applications even where temperatures are higher than −29°C (−20°F). When such requirements apply, it is the responsibility of the user to ensure these requirements are communicated to the manufac- turer prior to the time of purchase.