2000 Hook-up Book

Sizing Superheated Mains

Sizing Superheated Mains When sizing steam mains for superheated service, the follow ing procedure should be used. Divide the required flow rate by the factor in Table 2. This will give an equivalent saturated steam flow. Enter Fig. 1, Steam Velocity Chart on page 4 to select appro priate pipe size. If unable, then use the formula on page 3 to cal culate cross sectional area of the pipe and then Tables 38 and 39, page 81, to select the pipe size which closely matches calculated internal transverse area.

Example: Size a steam main to carry 34,000 lb/h of 300 psig steam at a temperature of 500° F. From Table 2 the correction factor is .96. The equivalent capacity is 34,000 .96 = 35,417 lb/h. Since 300 psig is not found on Fig. 1, the pipe size will have to be calculated. From the formula on page 3: 2.3 x Q x Vs A Solving for area the formula becomes: V =

Select a velocity of 10,000 ft/min. (which is within the process velocity range of 8,000 - 12,000 ft/min.) and determine Vs (specif ic volume) of 1.47 ft 3 /lb (from the Steam Table on page 7). The for mula is now: 10,000 From Tables 38 and 39 (page 81) the pipe closest to this area is 4" schedule 40 or 5" schedule 80. A = 2.4 x 35,417 x 1.47 = 12.5 in 2

SYSTEM DESIGN

2.4 x Q x Vs V

A =

Table 2: Superheated Steam Correction Factor

Gauge Saturated Pressure Temp.

TOTAL STEAM TEMPERATURE IN DEGREES FARENHEIT

PSI ˚F 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 15 250 .99 .99 .98 .98 .97 .96 .95 .94 .93 .92 .91 .90 .89 .88 .87 .86 .86 .85 20 259 .99 .99 .98 .98 .97 .96 .95 .94 .93 .92 .91 .90 .89 .88 .87 .86 .86 .85 40 287 1.00 .99 .99 .98 .97 .96 .95 .94 .93 .92 .91 .90 .89 .88 .87 .86 .86 .85 60 308 1.00 .99 .99 .98 .97 .96 .95 .94 .93 .92 .91 .90 .89 .88 .87 .86 .86 .85 80 324 1.00 1.00 .99 .99 .98 .97 .96 .94 .93 .92 .91 .90 .89 .88 .87 .86 .86 .85 100 338 – 1.00 1.00 .99 .98 .97 .96 .95 .94 .93 .92 .91 .90 .89 .88 .87 .86 .85 120 350 – 1.00 1.00 .99 .98 .97 .96 .95 .94 .93 .92 .91 .90 .89 .88 .87 .86 .85 140 361 – – 1.00 1.00 .99 .97 .96 .95 .94 .93 .92 .91 .90 .89 .88 .87 .86 .85 160 371 – – – 1.00 .99 .98 .97 .96 .95 .94 .93 .92 .91 .90 .89 .88 .87 .86 180 380 – – – 1.00 .99 .98 .97 .96 .95 .94 .93 .92 .91 .90 .89 .88 .87 .86 200 388 – – – 1.00 .99 .99 .97 .96 .95 .94 .93 .92 .91 .90 .89 .88 .87 .86 220 395 – – – 1.00 1.00 .99 .98 .96 .95 .94 .93 .92 .91 .90 .89 .88 .87 .86 240 403 – – – – 1.00 .99 .98 .97 .95 .94 .93 .92 .91 .90 .89 .88 .87 .86 260 409 – – – – 1.00 .99 .98 .97 .96 .94 .93 .92 .91 .90 .89 .88 .87 .86 280 416 – – – – 1.00 1.00 .99 .97 .96 .95 .93 .92 .91 .90 .89 .88 .87 .86 300 422 – – – – – 1.00 .99 .98 .96 .95 .93 .92 .91 .90 .89 .88 .87 .86 350 436 – – – – – 1.00 1.00 .99 .97 .96 .94 .93 .92 .91 .90 .89 .88 .87 400 448 – – – – – – 1.00 .99 .98 .96 .95 .93 .92 .91 .90 .89 .88 .87 450 460 – – – – – – – 1.00 .99 .97 .96 .94 .93 .92 .91 .89 .88 .87 500 470 – – – – – – – 1.00 .99 .98 .96 .94 .93 .92 .91 .90 .89 .88 550 480 – – – – – – – – 1.00 .99 .97 .95 .94 .92 .91 .90 .89 .88 600 489 – – – – – – – – 1.00 .99 .98 .96 .94 .93 .92 .90 .89 .88 650 497 – – – – – – – – – 1.00 .99 .97 .95 .94 .92 .91 .90 .89 700 506 – – – – – – – – – 1.00 .99 .97 .96 .94 .93 .91 .90 .89 750 513 – – – – – – – – – 1.00 1.00 .98 .96 .95 .93 .92 .90 .89 800 520 – – – – – – – – – – 1.00 .99 .97 .95 .94 .92 .91 .90 850 527 – – – – – – – – – – 1.00 .99 .98 .96 .94 .93 .92 .90 900 533 – – – – – – – – – – 1.00 1.00 .99 .97 .95 .93 .92 .90 950 540 – – – – – – – – – – – 1.00 .99 .97 .95 .94 .92 .91 1000 546 – – – – – – – – – – – 1.00 .99 .98 .96 .94 .93 .91

700 720 740 760 .84 .83 .83 .82 .84 .83 .83 .82 .84 .84 .83 .82 .84 .84 .83 .82 .84 .84 .83 .82 .85 .84 .83 .82 .85 .84 .83 .82 .85 .84 .83 .82 .85 .84 .83 .82 .85 .84 .83 .83 .85 .84 .83 .83 .85 .84 .84 .83 .85 .84 .84 .83 .85 .85 .84 .83 .85 .85 .84 .83 .86 .85 .84 .83 .86 .85 .84 .83 .86 .85 .84 .84 .86 .86 .84 .84 .87 .86 .85 .84 .87 .86 .85 .84 .87 .86 .85 .84 .87 .86 .86 .85 .88 .87 .86 .85 .88 .87 .86 .85 .88 .87 .86 .85 .89 .88 .87 .86 .89 .88 .87 .86 .89 .88 .87 .86 .90 .89 .87 .86

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