Specifications
| Parameter | Specification |
|---|---|
| Material | ASTM A216 WCB/WCC; ASTM A351 CF8M/CF8; ASTM A995 4A on request; ASTM A494 and Monel on request |
| Process | Silica sol lost wax investment casting, CNC milling, boring and drilling |
| Tolerance | ISO 8062 CT5-CT7 as cast, ISO 2768-m machined, stem bore to bonnet face perpendicularity to drawing |
| Surface finish | As-cast Ra 6.3 um, machined mounting faces Ra 1.6-3.2 um, painted or powder coated finish optional |
| Weight range | 2.2 kg – 38 kg per yoke |
| Heat treatment | Stress relieving for carbon steel, solution anneal for stainless, normalize and temper where specified |
| Inspection | CMM dimensional report, EN 10204 3.1, MPI and dye penetrant per ASTM E709/E165, PMI on alloy grades |
Key features
- Moreover, Stem bore and bonnet mounting face machined in a single clamping, guaranteeing actuator-to-valve stem alignment.
- Integral cast ribs and gussets deliver high stiffness under diaphragm thrust load with minimal weight.
- Open window geometry cast in, giving clear access to the stem coupling, travel indicator and positioner linkage.
- Machined diaphragm case flange with bolt pattern and gasket surface produced to the actuator manufacturer’s drawing.
- Corrosion resistant stainless and duplex options for offshore and chemical plant atmospheres.
- Mounting pads for positioner, limit switches and handwheel machined in the same setup as the main bores.
- Stable, repeatable geometry across batches, supporting interchangeability on the customer’s assembly line.
Applications
- Pneumatic diaphragm actuators on globe control valves in chemical and petrochemical plants.
- Generally, Control valve retrofit and replacement programs where dimensional interchangeability is essential.
- Water treatment and district energy plants using spring and diaphragm actuators.
- Pulp and paper, food and beverage process skids requiring stainless or coated yokes.
- Offshore and marine installations, in CF8M or duplex with marine grade coating.
- Power station feedwater, condensate and attemperator control valve assemblies.
Quality & compliance
Ningbo Ruican manufactures actuator yokes under an IATF 16949 certified system using documented control plans, first article inspection and ongoing dimensional capability studies on the stem bore, mounting face and bolt circle. Material certification to EN 10204 3.1 accompanies every shipment, and 3.2 third party witnessed certification can be supplied when the project requires it. Where the yoke forms part of the pressure retaining load path, section thickness and design margins follow the customer’s ASME B16.34 design basis, and hydrostatic, seat leakage or load verification testing is performed to the customer’s or a third party’s written procedure with signed reports.
Non-destructive testing options cover radiographic examination of critical rib intersections, ultrasonic survey, magnetic particle inspection per ASTM E709 and dye penetrant inspection per ASTM E165. Positive material identification by handheld XRF is applied to all alloy and stainless parts, and full heat lot traceability ties each yoke to its melt, heat treatment record and inspection data. We supply strictly to the customer’s specification with documented evidence and make no claim to API, CE or PED company certification.
FAQ
Q1. Can you match an existing actuator yoke for a retrofit project?
Yes. Send a sample or a 3D scan and we will reverse engineer the geometry, produce tooling, and machine the mounting bolt pattern and stem bore to the original interface dimensions so the yoke drops into the existing assembly.
Q2. Which material is best for an offshore installation?
CF8M is the standard choice for chloride environments, and ASTM A995 4A duplex is offered where higher strength and pitting resistance are needed. Moreover, we can add an offshore coating system to your specified specification.
Q3. How do you hold alignment between the stem bore and mounting face?
Both features are machined in one clamping on a 4-axis machine, with the datums taken from the cast reference pads we design into the tooling. Generally, perpendicularity and positional results are recorded on the CMM report for each batch.
Q4. Do you provide load or pressure testing of the yoke?
Load verification, hydrostatic shell testing or seat leakage testing can be carried out to your written procedure or to a third party’s procedure, with certified reports. We can also supply calculated section thickness data from the casting simulation.
Q5. Can you supply mounting hardware and fasteners?
We focus on the cast and machined yoke. Studs, nuts, travel indicators and handwheels can be sourced or recommended through our partner network, and we will machine the interface features to suit.
Q6. What is the tooling and sampling process?
After drawing approval we build the wax die in roughly four to five weeks, sample parts follow in about three weeks, and you receive a full first article inspection report with the samples before production release.
