BS 5150 Gate Valves: Resilient Seat & Non-Rising Stem

Design Characteristics & Advantages

Shijizhuang Metalsin supplies cast iron non-rising stem gate valves with resilient seats manufactured in accordance with BS 5150. Both the body and bonnet, as well as the gate, shall be made of either flake graphite cast iron (grey cast iron) or spheroidal graphite cast iron (ductile iron). The non-rising stem (NRS) design features a stem that remains stationary while the gate moves vertically to open or close the valve. This design is compact and suitable for applications where vertical space is limited. It typically requires less maintenance and is ideal for underground installations. The resilient seat design refers to that the cast iron gate is completely encapsulated/ coated by a thick layer of rubber compound, which is elastomeric or resilient. This rubber seat layer shall be bonded or mechanically attached to the gate. Using high-quality rubber such as EPDM, NBR or fluoroelastomer, the gate is fully encapsulated inside and outside, then placed into the furnace for vulcanization. This process ensures precise geometric dimensions of the gate, and the rubber adheres firmly to the ductile iron, preventing detachment and providing excellent elasticity memory.

When the valve is opened, the elastomer coated gate moves upwards along the stem while the stem remain stationary. In the fully open position, the gate is completely retracted into the cavity formed between the bonnet and the upper body. Compared to the metal-seated cast iron gate valves, the resilient seat design adopts a full-port straight through design, with no grooves at the bottom of the valve body cavity, minimizing debris accumulation and ensuring consistent sealing performance. It also reduces flow resistance and head loss. The entire sealing performance relies primarily on the contact between the rubber-coated gate and the metal surface at the bottom of the valve body. The slight elastic deformation of the rubber under force ensures a reliable seal, achieving zero leakage. With a low friction coefficient and minimal wear, the valve operates with low torque during opening and closing, offering easy operation, long lifespan, and resistance to pollution and corrosion, along with an attractive appearance.

Material Selection & Dimensions

Part No.	Material
1	BS 2789 ASTM A395 ASTM A536
2	EPDM, NBR
3	SS 420
4	BS 2789 ASTM A395 ASTM A536
5	Brass Bronze
6	BS 2789 ASTM A395 ASTM A536
7	EPDM
8	Brass
9	EPDM
10	Carbon Steel
11	EPDM
12	Ductile Iron
13	Brass

*As illustrated in the drawing, the main parts of a BS 5150 non-rising resilient seat gate valve include: (1) body; (2) seat; (3) stem; (4) gate; (5) wedge nut; (6) bonnet; (7) O-ring; (8) thrust washer; (9) back seat ring; (10) socket head screw; (11) O-ring; (12) handwheel; (13) stem nut.

Size DN	L mm	H mm
40	165	285
50	178	300
65	190	345
80	203	390
100	229	430
125	254	510
150	267	565
200	292	680
250	330	820
300	356	930
350	381	1020
400	406	1100
500	457	1250

*The main structural dimensions of BS 5150 NRS resilient seated gate valves, conforming to basic series 3 of BS 2080, applicable to PN10 & PN16. The body flange drilling dimensions shall be furnished in accordance with BS 4504 3.2.