MSS SP 70 | ASTM A126 Gr.B | Gray Iron Gate Valves

Technical Drawings, Design Characteristics & Materials

Cast iron gate valves designed in accordance with MSS SP 70 shall be furnished with ASTM A126 Grade B gray iron bodies and bonnets. Two classes are available: Class 125 and Class 250. We supply Class 125 in both rising stem and non-rising stem styles; Class 250 is only available in rising-stem style. Although MSS SP 70 permits the resilient seating design, generally the valve will be provide with metal-to-metal seating with one-piece solid wedge. The purpose of the wedge is to introduce a high supplementary seating load that enables metal-seated wedge gate valves to seal not only against high, but also low, fluid pressures. The wedge seating surfaces are separate brass or bronze rings securely fastened to the disc (wedge). The body seats shall be separate brass or bronze rings bottom seated/ mounted on the valve body. The end connection shall be either flanged or threaded, according to ASME B16.1 or ASME B1.20.1, respectively. Valves bodies and bonnets shall meet the minimum wall thickness requirements specified in ASME B16.1 for the same NPS and Class gray iron fitting. Face-to-face dimensions of flanged end valves shall be in accordance with ASME B16.10.

Valve Part	Material
Body	ASTM A216 Gr.B
Bonnet	ASTM A216 Gr.B
Wedge	ASTM A216 Gr.B
Seat Ring on Wedge	ASTM B62 C83600
Seat Ring on Body	ASTM B62 C83600
Stem	ASTM B16 C36000 AISI 420
Packing	Graphite
Handwheel	ASTM A126 Gr.B

*MSS SP 70 gray cast iron gate valves, metal seated, Class 125 & 250, are available in sizes 2″ through 24″. Dimensions are provided on the basis of handwheel operation. Valves may also be operated by gear boxes, or actuators (pneumatic, hydraulic, electrical).

Dimensions

NPS	L mm	H mm	D mm
2"	178	375	178
2-1/2"	190	422	178
3"	203	475	200
4"	229	606	254
5"	254	683	300
6"	267	828	300
8"	292	1003	348
10"	330	1211	400
12"	356	1421	457
14"	381	1641	560
16"	406	1828	560
18"	432	2047	610
20"	457	2246	610
24"	508	2632	765

*For Class 125, metal seated, OS&Y rising stem gray iron gate valves, 2″~24″.

NPS	L mm	H mm	D mm
2"	216	384	175
2-1/2"	241	436	200
3"	283	492	254
4"	305	610	300
5"	381	715	300
6"	403	812	348
8"	419	1024	400
10"	457	1211	457
12"	502	1386	457

*For Class 250, metal seated, OS&Y rising stem gray iron gate valves, 2″~12″.

NPS	L mm	H mm	D mm
2"	178	302	178
2-1/2"	190	332	178
3"	203	335	200
4"	229	423	254
5"	254	485	300
6"	267	545	300
8"	292	644	348
10"	330	769	400
12"	356	860	457
14"	381	987	560
16"	406	1044	560
18"	432	1148	610
20"	457	1257	610
24"	508	1418	765

*For Class 125, metal seated, non-rising stem (NRS) gray iron gate valves, 2″~24″.

Tests

A shell test and a hydraulic seat test shall be made on all completed valves prior to shipment. A gas seat test may be done upon buyer’s request.

In the shell test, the gray iron gate valve in partially open position with both ends sealed shall be subjected to hydrostatic or gas test pressure specified in Table A. No visible leakage is permitted through the pressure boundary walls or body-bonnet joint. The test pressure shall be held for the duration specified in Table B.

Max. Service Rating @150°F		Test Pressure Minimum
psi	bar	psi	bar
150	10.3	265	18.3
200	13.8	350	24.1
300	20.7	525	36.2
500	34.5	875	60.3

*Table A: the minimum shell test is related to the maximum service rating at 150°F.

NPS	Shell Test Duration (seconds)	Seat Test Duration (seconds)
2"~8"	30	30
10"~18"	60	60
20"~24"	180	120

*Table B: test duration, minimum.

Valves shall be subjected to a hydraulic seat test at not less than the maximum service pressure for which the valve is rated. Test pressure shall be applied successively on each side of the closed gate, and the opposite side checked for leakage. The maximum permissible leakage rate on each seat shall be 10 ml/hr/NPS. Test pressures shall be held for periods specified in Table B. When a gas seat test is performed, the test pressure shall be not less than 80 psi [5.5 bar] in lieu of hydraulic seat test. The maximum permissible leakage rate for each gate seat shall be 0.1 scf/hr/NPS (2.8cc/hr/NPS). Test pressures shall be held for periods specified in Table B.