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Introduction to Gate valves

  • Publish Time: 2019-03-25
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Gate valves

Gate valves are primarily designed to start or stop flow, and when a straight-line flow of fluid and minimum flow restriction are needed. In service, these valves generally are either fully open or fully closed.

The wedge of a Gate valve is completely removed when the valve is fully open; the wedge is fully drawn up into the valve Bonnet. This leaves an opening for flow through the valve at the same inside diameter as the pipe system in which the valve is installed. A Gate valve can be used for a wide range of liquids and provides a tight seal when closed.

Construction of a Gate valve

Gate valves consists of three main parts: body, bonnet, and trim. The body is generally connected to other equipment by means of flanged, screwed or welded connections. The bonnet, which containing the moving parts, is attached to the body, usually with bolts, to permit maintenance. The valve trim consists of the stem, the gate,
the disc or wedge and the seat rings.
Cast steel wedged gate valve for oil and gas industry.

Wedge of a Gate valve

Gate valves are available with different wedges. Ranging of the Gate valves is usually made by the type of wedge used.

The most common were:

· Solid wedge is the most commonly used disk by its simplicity and strength.

A valve with this type of wedge can be installed in each position and it is suitable for almost all liquids. The solid wedge is a single-piece solid construction, and is practically for turbulent flow.

· Flexible wedge is a one-piece disc with a cut around the perimeter to improve the ability to correct mistakes or changes in the angle between the seats.The reduction will vary in size, shape and depth. A shallow, narrow cut gives little flexibility but retains strength.A deeper and wider cut, or cast-in recess, leaves little material in the middle, which allows more flexibility, but compromises strength.

· Split wedge is self-adjusting and self-aligning to both seats sides. This wedge type consists of two-piece construction which seats between the tapered seats in the valve body. This type of wedge is suitable for the treatment of non-condensing gases and liquids at normal temperatures, particularly corrosive liquids.



Stem of a Gate valve

The stem, which connects the hand-wheel and wedge with each other, is responsible for the proper positioning of the wedge. Stems are usually forged, and connected to the disk by threaded or other techniques. To prevent leakage, in the area of the seal, a fine surface finish of the stem is necessary.

Gate valves are classified as either:

· Rising Stem Gate Valve

· Non Rising Stem Gate Valve

For a valve of the Rising Stem type, the stem will rise above the hand-wheel if the valve is opened. This happens, because the stem is threaded and mated with the bushing threads of a Yoke. A Yoke is an integral part from a Rising Stem valve and is mounted to the Bonnet.

For a valve of the non Rising Stem type, there is no upward stem movement if the valve is opened. The stem is threaded into the wedge. As the hand-wheel on the stem is rotated, the disk travels up or down the stem on the threads while the stem remains vertically stationary.


Seats of a Gate valve

Seats for Gate valves are either provided integral with the valve body or in a seat ring type of construction. Seat ring construction provides seats which are either threaded into position or are pressed into position and seal welded to the valve body. The latter form of construction is recommended for higher temperature service.

Integral seats provide a seat of the same material of construction as the valve body while the pressed-in or threaded-in seats permit variation. Rings with hard facings may be supplied for the application where they are required.


Advantages and Disadvantages of Gate valves

ADVANTAGES:

· Good shutoff features

· Gate valves are bidirectional and therefore they can be used in two directions
· Pressure loss through the valve is minimal



DISADVANTAGES:

· They can not be quickly opened or closed

· Gate valves are not suitable for regulate or throttle flow
· They are sensitive to vibration in the open state



DIMENSIONAL DATA

Wedge Gate Valves - API 600


Sizes: 2" - 48"
Class: 150

SIZE IN 2 2.5 3 4 6 8 10 12 14 16 18 20 24 28 30 32 34 36 40 42 48
MM 50 65 80 100 150 200 250 300 350 400 450 500 600 700 750 800 850 900 1000 1050 1200
L - RF IN 7 7.5 8 9 10.5 11.5 13 14 15 16 17 18 20 24 24 26 28 28 30 31 34
MM 178 191 203 229 267 292 330 356 381 406 432 457 508 610 610 660 711 711 762 813 864
L - BW IN 8.5 9.5 11.12 12 15.87 16.5 18 19.8 22.5 24 26 28 32 36 36 38 40 40 42 43 46
MM 216 241 282 305 403 419 457 503 572 610 660 711 813 914 914 965 1016 1016 1067 1092 1168
L - RTJ IN / / / / / / / / / / / / / / / / / / / / /
MM / / / / / / / / / / / / / / / / / / / / /
H1 IN 15.4 16.7 18.1 22.8 30.6 38.4 46.4 54.6 60 68.7 79.1 91.7 109.6 127.4 134.5 143.7 155 161.8 183.9 174.4 217.5
MM 390 425 461 580 776 976 1178 1387 1523 1745 2010 2330 2784 3236 3417 3650 3950 4109 4670 4430 5525
W IN 7.9 7.9 7.9 9.8 11.8 14 17.7 17.7 19.7 22 13.8 17.7 17.7 22 22 22 27.9 27.9 31.5 31.5 35.4
MM 200 200 200 250 300 355 450 450 500 560 350 450 450 560 560 560 710 710 800 800 900
WGT LB 49 55 66 99 187 295.5 445 639 816 1177 1475 1786 3153 4558 4827 5351 5481 7856 10370 10143 15677
(RF) KG 22 25 30 45 85 134 202 290 370 534 669 810 1430 2067 2189 2427 2486 3563 4703 4600 7110
WGT LB 44 46 62 92.6 161 244 399 584 750 1111 1365 1697 3336 4756 4981 5458 5596 8011 10436 10198 15545
(BW) KG 20 21 28 42 73 111 181 265 340 504 619 770 1513 2157 2259 2476 2538 3633 4733 4625 7050


Sizes: 2" - 48"
Class: 300

SIZE IN 2 2.5 3 4 6 8 10 12 14 16 18 20 24 28 30 32 34 36 40 42 48
MM 50 65 80 100 150 200 250 300 350 400 450 500 600 700 750 800 850 900 1000 1050 1200
L IN 8.5 9.5 11.12 12 15.9 16.5 18 19.75 30 33 36 39 45 53 55 / / 68 76 78 87.2
(RF) MM 216 241 282 305 404 419 457 502 762 838 914 991 1143 1346 1397 / / 1727 1930 1981 2215
L1 IN 9.12 10.12 11.75 12.62 16.5 17.12 18.62 20.37 30.62 33.62 36.62 39.75 45.88 54 56 / / 69.12 / / /
(BW) MM 232 257 298 321 419 435 473 518 778 854 930 1010 1165 1372 1422 / / 1756 / / /
L2 IN 8.5 9.5 11.12 12 15.9 16.5 18 19.75 30 33 36 39 45 53 55 / / 68 76 78 87.2
(RTJ) MM 216 241 282 305 404 419 457 502 762 838 914 991 1143 1346 1397 / / 1727 1930 1981 2215
H1 IN 16.2 17.7 19 23.7 32 40.2 48.8 56.8 66.1 78.4 85.9 93.5 112.6 130 148.5 / / 169.8 188.6 198.1 217.4
MM 412 450 483 601 813 1020 1239 1443 1679 1993 2181 2376 2860 3302 3772 / / 4312 4791 5032 5522
W IN 7.9 7.9 S.8 9.8 14 15.7 17.7 19.7 17.7 17.7 22 22 27.9 35.4 35.4 / / 30 30 30 30
MM 200 200 224 250 355 400 450 500 450 450 560 560 710 900 900 / / 760 760 760 760
WGT IB 64 88 106 163 313 485 721 1094 1530 2170 2880 3409 5204 8070 9592 / / 15104 18654 20947 27342
(RF) KG 29 40 48 74 142 220 327 496 694 984 1306 1546 2360 3660 4350 / / 6850 8460 9500 12400
WGT IB 52.9 77 82 141 269 379 512 862 1420 1839 2317 2703 4212 6637 7629 / / 11003 13583 14994 19845
(BW) KG 24 35 37 64 122 172 232 391 644 834 1051 1226 1910 3010 3460 / / 4990 6160 6800 9000


Sizes: 2" - 42"
Class: 600

SIZE IN 2 2.5 3 4 6 8 10 12 14 16 18 20 24 28 30 36 40 42
MM 50 65 80 100 150 200 250 300 350 400 450 500 600 700 750 900 1000 1050
L IN 11.5 13 14 17 22 26 31 33 35 39 43 47 55 61 65 82 94 98
(RF) MM 292 330 356 432 559 660 787 838 889 991 1092 1194 1397 1594 1651 2083 2387 2489
L2 IN 11.62 13.12 14.12 17.12 22.12 26.12 31.12 33.12 35.12 39.12 43.12 47.25 55.38 61.5 65.5 82.62 / /
(BW) MM 295 333 359 435 562 664 791 841 892 994 1095 1200 1406 1562 1664 2098 / /
L2 IN 11.5 13 14 17 22 26 31 33 35 39 43 47 55 61 65 82 94 98
(RTJ) MM 292 330 356 432 559 660 787 838 889 991 1092 1194 1397 1594 1651 2083 2387 2489
H1 IN 18.5 19.5 22.1 26.7 37.2 43.7 52.1 65.9 72.1 82.9 98 104.8 116.9 140.2 152.8 179.5 207.6 240
MM 471 495 561 677 944 1110 1323 1675 1832 2106 2489 2662 2970 3562 3880 4560 5273 6098
W IN 8.8 8.8 9.8 11.8 17.7 19.7 24.8 22 22 27.9 27.9 31.5 35.4 30 30 30 30 30
MM 224 224 250 300 450 500 630 560 560 710 710 800 900 760 760 760 760 760
WGT IB 95 132 154 296 628 988 1499 2355 2836 4059 5700 6853 10337 13340 15313 21476 23262 24144
(RF) KG 43 60 70 134 285 448 680 1068 1286 1841 2585 3108 4688 6050 6945 9740 10550 10950
WGT IB 62 99 132 229 452 690 1180 2145 2571 3332 4741 5640 8595 10980 12590 17948 18830 19337
(BW) KG 28 45 60 104 205 313 535 973 1166 1511 2150 2558 3898 4980 5710 8140 8540 8770


Sizes: 2" - 24"
Class: 900

SIZE IN 2 2.5 3 4 6 8 10 12 14 16 18 20 24
MM 50 65 80 100 150 200 250 300 350 400 450 500 600
L IN 14.5 16.5 15 18 24 29 33 38 40.5 44.5 48 52 61
(RF) MM 368 419 381 457 610 737 838 965 1029 1130 1219 1321 1549
L1 IN 14.62 16.62 15.12 18.12 24.12 29.12 33.12 38.12 40.88 44.88 48.5 52.5 61.75
(BW) MM 371 422 384 460 612 740 841 968 1038 1140 1232 1333 1568
L2 IN 14.5 16.5 15 18 24 29 33 38 40.5 44.5 48 52 61
(RTJ) MM 368 419 381 457 610 737 838 965 1029 1130 1219 1321 1549
H1 IN 21.2 26.4 26.4 30.8 42.4 55.5 67.7 77.4 74.9 80.7 88.8 110.2 124
MM 539 670 672 782 1076 1411 1720 1965 1902 2051 2256 2800 3150
W IN 11.8 11.8 14 15.7 22 17.7 22 22 24 24 30 30 24
MM 300 300 355 400 560 450 560 560 610 610 760 760 610
WGT IB 181 342 364 384 999 1720 2752 3400 4895.1 6615 8533.4 10716.3 16096.5
(RF) KG 82 155 165 174 453 780 1248 1542 2220 3000 3870 4860 7300
WGT IB 130 375 287 295 789 1378 2267 2844 4167.5 5655.8 7276.5 8730.3 13494.6
(BW) KG 59 170 130 134 358 625 1028 1290 1890 2565 3300 4050 6120


Sizes: 2" - 24"
Class: 1500

SIZE IN 2 2.5 3 4 6 8 10 12 14 16 18 20 24
MM 50 65 80 100 150 200 250 300 350 400 450 500 600
L IN 14.5 16.5 18.5 21.5 27.75 32.75 39 44.5 49.5 54.5 60.5 65.5 76.5
(RF) MM 368 419 470 546 706 832 991 1130 1257 1384 1536 1664 1943
L1 IN 14.62 16.62 18.62 21.62 28 33.13 39.38 45.12 50.25 55.38 61.38 66.38 77.62
(BW) MM 371 422 473 549 711 841 1000 1146 1276 1406 1559 1686 1972
L2 IN 14.5 16.5 18.5 21.5 27.75 32.75 39 44.5 49.5 54.5 60.5 65.5 76.5
(RTJ) MM 368 419 470 546 706 832 991 1130 1257 1384 1536 1664 1943
H1 IN 21.2 26.4 29.1 30.8 47.1 60.8 66.5 82.3 85.1 97.9 108.7 122.1 146.5
MM 539 670 738 783 1196 1546 1688 2090 2162 2486 2762 3102 3721
W IN 11.8 11.8 15.7 19.7 13.8 22 27.9 27.9 30 30 30 24 24
MM 300 300 400 500 350 560 710 710 760 760 760 610 610
WGT IB 181 341.8 401 573 1360 3175 4412 8414 9073.6 15324.8 19845 24541.7 35875.4
(RF) KG 82 155 182 260 617 1440 2001 3816 4115 6950 9000 11130 16270
WGT IB 130 286.7 324 353 975 2646 3541 7080 7056 13230 17066.7 21079.8 30362.9
(BW) KG 59 130 147 160 442 1200 1606 3211 3200 6000 7740 9560 13770


Sizes: 2" - 12"
Class: 2500

SIZE IN 2 2.5 3 4 6 8 10 12
MM 50 65 80 100 150 200 250 300
L IN 17.75 20 22.75 26.5 36 40.25 50 56
(RF) MM 451 508 578 673 914 1022 1270 1422
L1 IN 17.87 20.25 23 26.8 36.5 40.87 50.88 56.88
(BW) MM 454 514 584 683 927 1038 1292 1445
L2 IN 17.75 20 22.75 26.5 36 40.25 50 56
(RTJ) MM 451 508 578 673 914 1022 1270 1422
H1 IN 24.4 31.9 31.9 42.2 57.1 63 82.5 90.2
MM 619 809 809 1073 1451 1600 2096 2292
W IN 11.8 17.7 17.7 24.8 24 24 24 30
MM 300 450 450 630 610 610 610 760
WGT IB 205 331 443 1336 3506 5380.2 10085.7 15831.9
(RF) KG 93 150 201 606 1590 2440 4574 7180
WGT IB 128 221 289 1083 2866.5 4410 8379 13230
(BW) KG 58 100 131 491 1300 2000 3800 6000

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