Overall, this section covers knife gate valve yoke head casting. It also covers investment cast valve yoke WCB CF8M. It also covers knife gate valve actuator mounting head.
Specifications
| Parameter | Detail |
|---|---|
| Material | The range covers ASTM A216 WCB carbon steel, ASTM A351 CF8M and CF8 stainless steel, and ASTM A995 4A or 2205 duplex. AISI 420 or 17-4PH covers stem and wear parts. |
| Process | Water glass lost wax for larger yoke heads and heavy sections, silica sol lost wax where tighter tolerance and finer finish are required |
| Dimensional tolerance | ISO 8062 CT4 to CT6 on silica sol parts, CT6 to CT7 on water glass parts; stem bore, gate slot and mounting pad machined to drawing |
| Surface finish | As-cast Ra 3.2 to 6.3 micrometres (silica sol) or Ra 6.3 to 12.5 micrometres (water glass); machined pad and bore Ra 1.6 to 3.2 micrometres |
| Machining | Machining covers CNC work on the stem nut pocket, stem bore, gate guide slot and body mounting faces. It also machines the ISO 5211 actuator mounting pad with drilled and tapped holes. |
| Pressure class | Yoke heads for ASME class 150 knife gate valves, with higher class designs up to class 300 for slurry and process duty |
| Inspection & certificates | Documentation covers the EN 10204 3.1 material certificate (type 3.2 on request) and heat-lot traceability. It also covers MT or PT on load-bearing sections and UT or RT where specified. Dimensional FAIR, plus hydrostatic and seat testing of the assembled valve to API 598 or ISO 5208, come on request. |
Key features
- One-piece cast yoke head carries the full stem thrust, so there are no welds in the load path between the gate, stem and actuator.
- We size cast legs and ribs with the stem thrust and actuator torque from your calculation. We verify the section by 3D modelling before tooling is cut.
- Moreover, Stem bore, gate guide slot and stem nut pocket are machined in-house, keeping the stem axis parallel with the gate travel to avoid side loading.
- ISO 5211 mounting pad is machined and drilled to your actuator pattern, so pneumatic, electric or hydraulic actuators bolt on without an adapter.
- WCB gives a low-cost, high-stiffness head for water and slurry; CF8M and 2205 duplex are used for corrosive and chloride-bearing media.
- Wear strips, guide shoes and stems can be supplied in AISI 420 or 17-4PH for abrasive slurry service.
Applications
- Mining and mineral processing slurry lines, thickener underflow and tailings disposal.
- Pulp and paper stock preparation, white water and black liquor service.
- Wastewater treatment plants, sludge lines and grit handling.
- Generally, Chemical and petrochemical process lines carrying abrasive or solids-laden fluids.
- Bulk solids handling, silo discharge and hopper isolation gates.
- Power plant ash handling and flue gas desulphurisation slurry circuits.
Quality & compliance
Ningbo Ruican works under an IATF 16949 and ISO 9001 certified quality system with full heat-lot traceability from
raw material to finished yoke head. Additionally, we supply castings to ASTM A216 WCB, ASTM A351 CF8M or ASTM A995 4A. Carbon steel gets normalising, while stainless and duplex grades get solution annealing. In general, test coupons from the same heat verify the mechanical properties. We offer magnetic particle and liquid penetrant examination of load-bearing sections, plus ultrasonic or radiographic examination where the drawing calls for it. Assembled valves can then be hydrostatically and seat tested to API 598 or ISO 5208 with recorded results.
Additionally, Ningbo Ruican does not hold PED or API monogram certification in its own name. We can still provide testing and documentation to those standards per project, and we can arrange third-party witness inspection. EN 10204 3.1 certificates are standard,
EN 10204 3.2 is available on request, and PPAP or FAIR packages can be issued for repeat production.
FAQs
Is the yoke head a pressure boundary part?
On most knife gate valve designs the yoke head is a load-bearing structural part rather than a pressure-retaining
part, so the pressure class applies to the body. We still supply it with full material certification and NDT, and
we test the assembled valve to API 598 or ISO 5208 when the order includes assembly.
Can you machine the actuator mounting pad to our standard?
Yes. In general, we machine the ISO 5211 pad flange, bolt circle and pilot diameter to your drawing. Also, that covers F05 through F14 patterns and custom drilling for hydraulic cylinders or bevel gear operators.
Which material should I choose for abrasive slurry?
WCB is normally the best value for abrasive slurry where corrosion is not severe, because the head can be made
stiff and thick at low cost. If the slurry is also corrosive or high in chlorides, CF8M or 2205 duplex is the better choice. We then add AISI 420 or 17-4PH guide wear parts.
How do you make sure the stem lines up with the gate?
The stem bore, the stem nut pocket and the body mounting faces are machined in one fixtured setup using datums
agreed at the tooling stage. First-article inspection checks bore-to-face squareness and slot alignment, and the
same datums are used for the production sampling plan.
Do you supply the yoke head as a kit with other parts?
Yes. We regularly supply yoke heads together with bodies, gates, stems, glands and stem nuts so the whole valve
assembly arrives matched and machined to one datum scheme.
What documentation comes with the shipment?
Each shipment includes the EN 10204 3.1 material certificate, heat treatment record, dimensional inspection report
and NDT reports where specified. Type 3.2 certification, third-party witness reports and PPAP or FAIR packages can
be added on request.
