A universally accepted code for shell and tube exchangers is TEMA (1988), which although designed to supplement ASME VIII, can be used in conjunction with other pressure vessel codes. To give guidance and protection to designers, manufacturers and purchasers, a supplementary code is desirable. Asme Y14.5 Y14.5M Iso Standard Gps Tci Training Dimensioning Ansi.A pressure vessel design code alone cannot be expected to cover all the special features of heat exchangers. The pressurized components of the shell and tube exchanger are designed to be in accordance with a pressure vessel design code such as ASME VIII (1993) or BS5500 (1994).ASME Y14.5 is a standard published by the American Society of Mechanical Engineers (ASME) to establish rules, symbols, definitions, requirements, defaults, and recommended practices for stating and interpreting Geometric Dimensions and Tolerances (GD&T).The following are basic ASME standards: ASME Y14.1- Drawing sheet size and format ASME Y14.1M- Metric sheet size and format ASME Y14.100- Engineering drawing and practices ASME Y14.2- Line conventions and lettering ASME Y14.3- Multi-view and sectional view drawings ASME Y14.4- Pictorial drawings ASME Y14.5- Dimensioning and TolerancingTo meet the relevant regulations (see Pressure Vessels) the pressurized components of alternative types of exchangers must meet at least the principles of a relevant pressure vessel design code.So, the thickness dimension (X) with the tolerance zone of assembly would be: X 72. The shell and tube exchanger basically consists of a number of connected components, some of which are also used in the construction of other types of exchangers. ANSI Y14.5M-1982, Dimensioning and Tolerancing ANSI Y14.5M-1973, Dimensioning and Tolerancing ANSI Y14.5M-1966, Dimensioning and Tolerancing ISO/R1101 (E)-2004, & Associated Documents ANSI B4.2-1978, Preferred Metric Limits and Fits ANSI B5.10-1981, Machine tapers Self Holding and Steep Taper Series ANSI/ASME B46.1-1985, Surface Texture.
![]() Ansi Dimensioning Standards Plus And MinusThe thickness tolerances for minimum wall tubes are minus zero, plus 18% to 22% of the nominal thickness, while those of average wall tubes are plus and minus 8% to 10% of the nominal wall thickness. Tubes may be purchased to minimum or average wall thickness. The usual outside diameter range for petroleum and petrochemical applications is 15 to 32 mm, with 19 and 25 being the most common. The main components of the exchanger shown in Figure 2 feature in most shell and tube exchangers and are given a reference number which relates to the component descriptions below.Tubes. This is shown in Figure 2, and has the TEMA designation AEM. More information on the choice of types, their main features and their design, is given in Saunders (1988).A common type of shell and tube exchanger is the fixed tubesheet type.Ansi Dimensioning Standards Code For ShellFor exchangers with multiple tube passes, the channels are fitted with flat metal plates which divide the head into separate compartments. TEMA specifies minimum tube pitch/ outside diameter ratios and minimum gaps between tubes.Channel partition plates. Removable bundle weights are often limited to 20 tons. The most common tube length range is 3600 to 9000 mm for removable bundles and 3600 to 15000 mm for the fixed tube type. Download recovery for windows 10Split backing ring and pull through floating head exchangers have a special support type baffle adjacent to the floating head to take the weight of the floating head assembly. Segmentally single cut baffles are the most common, however, thermal or pressure drop may dictate baffles of more complicated shape. Shell cross baffles have the dual purpose of supporting the tubes at intervals to prevent sag and vibration, and also of forcing the shell side fluid back and forth across the bundle, from one end of the exchanger to the other. If the tubesheet or cover is not welded to the channel, the tubesheet or cover is grooved and the edge of the partition plate sealed by a gasket embedded in the grooves.Shell baffles. Except for special high pressure heads, the partition plates are always welded to the channel barrel and also to the adjacent tubesheet or cover if either of these components is in turn welded to the channel. Tie rods and spacers are used to hold the tube bundle together and to locate the shell baffles in the correct position. Figure 3 shows a typical flexible strip.Tie rods. When removable bundles are used, this leakage gap is sealed by flexible strips or packing devices. Leakage of the shell side fluid between the shell and the longitudinal baffle edges must be minimized. Two shell pass exchangers (see Figure 2 shell types F, G or H) require a longitudinal baffle, which for F type exchangers is welded to the stationary tubesheet. Basic pneumatics pdfThe shell barrel must be straight and true as a tightly fitting tube bundle must be inserted and particular care has to be taken in fabrication. Most barrels larger than 450 mm internal diameter are fabricated from rolled and welded plate. TEMA specifies minimum barrel thicknesses depending on diameter, material and class. Shell barrel and channel barrel. Their design is carried out in accordance with the relevant pressure vessel code, see Pressure Vessels.5/6. The number of tie rods depends on shell diameter and is specified, by TEMA.The following components perform a function mainly related to pressure and fluid containment. The minimum thickness of dished heads is the same as for adjacent barrels. Small diameter, low pressure dished heads are sometimes cast but most dished heads are fabricated from plate and are of semi-ellipsoidal, torispherical or hemispherical shape. Dished heads and flat heads. ![]() ![]() In explosive expansion a charge is placed inside the tube within the tubesheet thickness. The most common method is roller expansion where the force produced by an expanding tool deforms the tube radially outward to give a mechanical seal. Different methods are available for the attachment of the tube end to the tubesheet. It also specifies tolerances for tube hole diameter, ligament width and for drill drift. TEMA gives design rules to calculate the tubesheet thickness, which give similar but not identical results to the rules in ASME and BS5500. This is discussed in detail in Saunders (1988).12. The success of the tube end joints is highly dependent on the correct choice of type and the experience of the manufacturer. Welded tube joints can be produced at the "outer" face of the tubesheet or downhole at the "inner" face of the tubesheet. They are discussed in more detail in Expansion joints.
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