Overview
An actuator mounting yoke brackets the gap between a valve bonnet and a pneumatic, electric or hydraulic actuator. It must carry the actuator weight, react the full output torque without flexing, and locate the drive coupling on the valve stem axis within a few hundredths of a millimetre. Casting is ideal because the load path is three-dimensional: a cast yoke puts material exactly along the rib and flange load paths that a fabricated weldment can only approximate. Ningbo Ruican casts these brackets in CF8M, CF8, CF3M, duplex 2205, WCB, LCB/LCC and ductile iron QT450-10, then CNC machines the mounting faces to the purchaser’s specified ISO 5211 pattern.
Specification
| Parameter | Capability |
|---|---|
| Materials | CF8M / AISI 316, CF8 / 304, CF3M / 316L, duplex 2205, WCB carbon steel, LCB/LCC low-temperature carbon steel, ductile iron QT450-10 |
| Process | Silica-sol or water-glass investment casting; resin sand casting + CNC for large and heavy-section brackets |
| Dimensional tolerance | ISO 8062 CT5–CT7; mounting faces and pilot diameters to CT4–CT5 after machining |
| Size range | ISO 5211 F05 to F25; custom patterns machined to drawing |
| Pressure rating | Non-pressure-retaining part; load rated to the actuator torque specified by the purchaser |
| NDT | MT per ASTM E709 and PT per ASTM E165 on all load-bearing sections; RT per ASTM E446 or UT per ASTM A609 where specified |
| Testing | Dimensional verification of drive axis concentricity and bolt pattern, load or proof test on request, coating thickness check |
| Heat treatment | Solution annealing for stainless and duplex; normalising or quench & temper for WCB and LCB/LCC |
| Surface finish | Shot blast, pickling and passivation; machined Ra 1.6 µm on pilot and coupling faces |
| Documentation | EN 10204 3.1 or 3.2, FAI and PPAP, PMI report, heat-to-part traceability |
Key features
- Cast load-path ribbing delivers higher torsional stiffness at lower mass than a fabricated bracket.
- ISO 5211 mounting flange, pilot diameter and coupling bore machined in one setup to keep the drive axis true.
- Optional integral stem coupling adapter, handwheel boss or limit-switch bracket cast in place.
- Ductile iron QT450-10 available for cost-sensitive general industrial duty; CF8M for corrosive or washdown service.
- Finite element review of the rib layout offered at quotation stage for high-torque actuators.
- Marine and offshore coatings available, including epoxy systems applied to the purchaser’s specification.
Applications
- Pneumatic rack-and-pinion and scotch-yoke actuator mounting on ball and butterfly valves
- Electric motor actuator mounting on gate, globe and control valves
- Hydraulic actuator yokes for subsea and pipeline valves
- Water and wastewater treatment plant actuated valve retrofits
- Chemical and food processing plants requiring washdown-capable stainless brackets
Quality & compliance
Yoke brackets are manufactured under an IATF 16949-certified quality system. Because the bracket carries the actuator load, MT or PT is performed on all load-bearing sections to the purchaser’s specified acceptance level, with RT or UT added where the drawing calls for internal soundness. Material certification to EN 10204 3.1 is standard and EN 10204 3.2 is available with third-party witness. PMI confirms grade on stainless and duplex heats. Dimensional FAI reports cover the ISO 5211 bolt pattern, pilot concentricity and coupling bore, and PPAP Level 3 with capability data supports volume release. Components are supplied to customer specification with full traceability; we do not hold or claim an API monogram licence or a PED notified-body licence.
FAQ
Can you machine to any ISO 5211 flange size?
Yes, F05 through F25 and any non-standard pattern shown on your drawing. The pilot diameter, bolt PCD and coupling bore are machined in one setup, and the FAI reports the actual measured values.
Do you supply the coupling and fasteners?
We supply the cast and machined bracket. Stem couplings, adaptors and fastener kits can be sourced and kitted with the bracket if you prefer a single line item; tell us at quotation stage.
How do you verify the bracket will not flex under actuator torque?
We review the rib layout by finite element analysis at quotation stage and confirm the design against the actuator output torque you specify. Production parts are dimensionally verified and, where required, proof-load tested with the results recorded in the job pack.
Is ductile iron QT450-10 strong enough for actuator mounting?
For general industrial duty in a non-corrosive environment, yes, and it is substantially cheaper than stainless. Where the bracket is exposed to washdown, salt spray or process chemicals, CF8M or duplex 2205 is the safer choice.
Can you add our logo and part number to the casting?
Yes. Raised or recessed branding, part numbers and cast-in foundry marks are produced as part of the tooling. We can also laser mark finished parts for serialised traceability.
What information do you need to quote an actuator yoke?
The valve bonnet interface drawing, the actuator mounting pattern and output torque, the stem diameter and coupling type, the material and coating specification, and the annual volume. A 3D model plus a 2D drawing is ideal.
