TEMA exchangers

Rubin, F. L. "What s the Difference Between TEMA Exchanger Classes," Hydrocarbon Processing, 59, June 1980, p. 92. 

Rubin, E. L., What s the Difference between TEMA Exchanger Classes, Hydrocarbon Processing, V. 59, p. 92, June (1980). 

Standards of Tubular Exchanger Manufacturers Mssociation, TEMA, Inc., New York, 1974. 

The other space-saving approach is to use the Kobe (Kobe Steel) type of channel enclosure, which does not have all the external head bolts of typical TEMA Type B or Type C head enclosures. These exchangers require special tools to remove the tube bundles and trained maintenance personnel to do the work. These exchangers should never be located in stmctures because of the need to be able to access the channel from grade as it is difficult to remove the channel cover plate by using special equipment. 

TEMA-STYLE SHELL-AND-TUBE HEAT EXCHANGERS... 

TEMA-style shell-and-tube-type exchangers constitute the bulk of the unfired heat-transfer equipment in chemical-process plants, although increasing emphasis has been developing in other designs. These exchangers are illustrated in Fig. 11-35, and their features are summarized i n Table 11-11. 

TEMA Numbering and Type Designation Recommended practice for the designation of TEMA-style shell-and-tube heat exchangers by numbers and letters has been established by the Tubular Exchanger Manufacturers Association (TEMA). This information from the sixth edition of the TEMA Standards is reproduced in the following paragraphs. 

TABLE 11-11 Features of TEMA Shell-and-Tube-Type Exchangers... 

FIG. 11-35 TEMA-type designations for shell-and-tube beat exchangers. (Standards of Tubular Exchanger Manufacturers Association, 6tb ed., 1978.)... 

Shell and Tube Heat Exchangers for General Piefineiy Seivices, API Standard 660, 4th ed., 1982, is published by the American Petroleum Institute to supplement both the TEMA Standards and the ASME Code. Many companies in the chemical and petroleum processing fields have their own standards to supplement these various requirements. The Jnterrelation.ships between Codes, Standards, and Customer Specifications for Proce.ss Heat Tran.sfer Equipment is a symposium volume which was edited by F. L. Rubin and pubhshed by ASME in December 1979. (See discussion of pressure-vessel codes in Sec. 6.)... 

Figure 11-36 shows details of the construction of the TEMA types of shell-and-tube heat exchangers. These and other types are discussed in the following paragraphs. 

Tubes Standard heat-exchanger tubing is V4, Yh, V2., Yh, %, 1, IV4, and IV2. in in outside diameter (in X 25.4 = mm). Wall thickness is measured in Birmingham wire gauge (BWG) units. (A comprehensive list of tubing characteristics and sizes is given in section 9, table D-7 of TEMA.) The most commonly used tubes in chemical plants and petroleum refineries are 19- and 25-mm (%- and 1-in) outside diameter. Standard tube lengths are 8, 10, 12, 16, and 20 ft, with 20 ft now the most common (ft x 0.3048 = m). 

FIG. 11-41 Costs of basic exchangers—all steel, TEMA Class R, 150 Ibl/in, 1958. To convert pollnds-force per square inch to Idlopascals, mllltiplyhy 6.895 to convert square feet to square meters, mllltiplyhy 0.0929 to convert inches to millimeters, multiply hy 25.4 and to convert feet to meters, multiply hy 0..3048. 

The hairpin heat exchanger, unhke the removable bundle TEMA styles, is designed for bundle insertion and removal from the return end rather than the tubesheet end. This is accomplished by means of removable spht rings which shde into grooves machined around the outside of each tubesheet and lock the tubesheets to the external closure flanges. This provides a distinct advantage in maintenance since bundle removal... 

Fouhng factors are typically Mo of TEMA values or a percent oversurfacing of 10-20 percent is used. ( Sizing Plate Exchangers Jeff Kernel, Chemical Engineering, November 1993). 

Standards of Tubular Exchanger Manufacturers Association (TEMA), 7th Edition. 

Standards of Tubular Exchanger Manufacturers Association (latest edition) Tubular Exchanger Manufacturers Association, Inc. (TEMA), 707 Westchester Ave., White Plains, New York 10604. 

The assumptions hold so well that the F factor charts are standardized by TEMA for shell and tube heat exchanger design. 

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