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