Thermal growth

The pump-mounting feet are located close to the centerline. As a result, the pump thermal growth is uniform on both sides of the centerline, leading to minimal distortions. The design is governed by the American Petroleum Institute (API) standard 610, "Centrifugal Pumps for General Refinery Service" (30). 

Expander proeess eonditions induee thermal growth and/or shrinkage in the expander and eompressor housing. Therefore, the expander ease is normally eenterline mounted and the eompressor ease is allowed to move along the eenterline of the maehine. Modern maehines have allowable flange forees and moments that generally exeeed three times NEMA (National Eleetrie Manufaeturers Assoeiation) requirements. 

A simple graphie plotting exereise for the reverse-dial indieator method indieates the basie prineiples involved. A steam turbine eompressor train is shown in Figure 18-17. Assume this train is a new installation and the manufaeturer s estimated thermal growths are as indieated in Figure 18-17. 

Reverse-dial indieator readings are taken to determine the relative shaft positions. Onee readings are taken, the estimated thermal growths are ineorporated by shimming in the hope that a good, hot alignment ean be aehieved. 

The hot alignment eheek is used to determine the aetual thermal growth, and then the final shim ehanges are made if needed. This example addresses only vertical movements. Horizontal movements are obtained in a similar fashion. The graphic plot uses an amplified scale on the vertical Y axis of one inch equals five mils vertical growth, while the X axis has a scale of one inch equals 10 inches (25 cm) of train length. 

Now, using estimated thermal growth of Machines A and B, a cold target B line is drawn. This line is where shaft B should lie so that when hot it will be colinear with shaft A on the hot running line. 

A similar procedure is followed for horizontal movements. If the hot alignment check indicates a significant deviation from expected thermal growths and an unacceptable amount of misalignment, further shim changes can be achieved by similar plotting. 

Another vulnerable area of concern is the result of the design requirement for high temperature service. To accommodate the thermal growth potential, the various sections of the expander are quite compliant. As a result, piping and forces need to be kept to a minimum. 

Computations, adjustments, and plots 54/1004 54.7.1 Adjustments for thermal growth 54/1004... 

Variations in machine-component configuration and thermal growth can cause mounting-feet elevations... 

Note that it is important for final drive-train alignment to compensate for actual operating conditions because machines often move after start up. Such movement is generally the result of wear, thermal growth, dynamic loads, and support or stmctural shifts. These factors must be considered and compensated for during the alignment process. 

Note The thermal growth formula is usually applied only to the vertical components of the machine. While the formula can be applied to horizontal growth, this direction is often ignored. 

The particles can be immobilized from solution in the gap between the Pt electrodes. The electrodes were fabricated by thermal growth on Si and their size could be reduced down to 4 nm. On top of the structoe a 60 nm SiN film was deposited, whereas a lOOnm slit in the SiN film with a local constriction with 20 nm spacing was opened by... 

Note Bushings must be sized to allow for thermal growth of the shaft. The clearances in Table 2-4 are based upon carbon bushings at pumping temperature. Other materials may require other clearances. Axial space limitations may make it impractical to fit floating bushings on dual seals. 

In each case three thermal growth regions were observed. Initially, no deposition is... 

If in Example 1, I/j + L2 is of considerable length, the thermal growth will be large, A 50% cold spring is therefore advisable. The formulae then alter to ... 

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