Moreover, the pilot housing body is the control head of a pressure reducing valve. It carries the sensing port. It also carries the pilot seat. It also carries the diaphragm clamp flange and the adjustment spring cavity, and it translates downstream pressure into the throttling motion that holds set pressure on the main valve. Machined-from-solid housings are slow and expensive at the internal port junction, and fab-welded versions distort at the diaphragm flange so the diaphragm pinches and the set point drifts. Ningbo Ruican casts the housing with the sensing passage cored, machines the pilot seat and diaphragm flange concentric in one setup, and holds the port geometry that governs regulation stability.
Specifications
| Parameter | Specification |
|---|---|
| Casting process | Silica sol lost wax investment casting with ceramic core for the internal sensing passage |
| Material options | AISI 316 / CF8M, tin bronze C83600 and C84400, leaded tin bronze on request |
| Dimensional tolerance (ISO 8062-3 CT grade) | CT6 as cast; CT5 machined on pilot seat, sensing port and diaphragm flange |
| Machining | CNC turning of the seat and spring cavity, 4-axis milling of the diaphragm flange, drilling and reaming of the sensing port |
| Surface finish (Ra) | Ra 3.2 um as cast; Ra 1.6 um machined on seat, port bore and diaphragm sealing face |
| Pressure class or size range | DN15 to DN100 (1/2 in to 4 in) pilot bodies; main valve sizes DN50 to DN300 |
| Typical lead time | Tooling 5-6 weeks; first article 3-4 weeks after tooling; production 6-8 weeks |
Key features
- Cored internal sensing passage removes a deep cross-drilling operation and the burr at the port intersection that disturbs flow at the sensing point.
- Pilot seat and sensing port machined concentric within 0.05 mm, holding the seating geometry that prevents the set point drift seen on welded housings.
- Diaphragm clamp flange held flat within 0.05 mm across the sealing land, stopping the pinch leak that follows flange distortion after welding.
- Wall thickness uniformity of +/-0.4 mm through the spring cavity and port boss, avoiding the thin sections that sand-cast pilot bodies show after cleaning.
- AISI 316 gives a PREN of roughly 24 for potable water, seawater-side and mildly chemical duty; bronze C83600 is offered for dezincification-resistant freshwater and marine service.
- One-piece body removes the port boss weld and the two flange attachment welds, taking four operations off the housing routecard.
- Spring cavity and diaphragm flange cast net shape, cutting material removal by roughly 55 percent against the same housing machined from solid bar.
Applications
Overall, typical applications include municipal water distribution pressure reducing and pressure sustaining stations. It also includes building services and high-rise domestic water pressure reducing assemblies. It also includes irrigation district pressure regulation and flow control manifolds. It also includes fire protection system pressure reducing valves on wet and combined risers. It also includes steam and condensate pressure reducing stations with bronze trim. It also includes marine and offshore seawater cooling pressure control skids.
Quality & compliance
We produce pilot housings under IATF 16949 and ISO 9001 process control, with material supplied and inspected to the buyer’s specified material standard and shipped with EN 10204 3.1 certification covering chemistry, mechanical properties and heat identity. Generally, bronze and stainless heats are segregated and traceable from melt through machining to packing. In general, PPAP and FAIR packages are available. Seat leakage and hydrostatic testing follow the pressure, medium and acceptance criteria on your drawing, and dye penetrant or radiographic examination is supplied to your specified acceptance level and reference radiograph plate. Generally, dimensional reports with CMM data on the seat, port and diaphragm flange are issued with the first article.
FAQ
Can you produce the housing from a sample if we have no drawing?
Yes. We scan the sample, build a 3D model and issue a drawing for your approval before cutting tooling. Seat angle, port diameter and diaphragm flange dimensions are confirmed with you because they govern regulation behaviour. Once approved, the model becomes the inspection baseline and the sample is retained as the reference part for the life of the program.
What NDT do you supply on pilot housings?
We supply dye penetrant inspection on machined surfaces and radiography of the port boss and seat junction, both to the acceptance level and reference radiograph plates you specify. If your specification calls for a particular inspection extent, we follow it exactly and report the results with the lot rather than substituting an internal standard.
What is the minimum order quantity?
Moreover, we can produce pilot quantities from 50 pieces from a single tooling set. In general, we support prototype runs below that on a quoted basis. As volume grows we move to multi-cavity tooling to reduce piece cost, and tooling is maintained and stored free of charge between releases so repeat and service orders stay available.
Do you machine and pressure test in-house?
Machining, port reaming, seat finishing and diaphragm flange facing are all performed in-house on CNC turning and 4-axis machining centres. Hydrostatic and seat leakage testing is also carried out in-house to your specified pressure, duration and allowable leakage, with results reported per lot so your incoming inspection has data rather than a visual check.
Which material should we choose, 316 or bronze?
AISI 316 suits potable water, mildly corrosive chemical and seawater-side duty where higher strength at the diaphragm flange matters. We prefer tin bronze C83600 for freshwater, irrigation and marine service where dezincification resistance and machinability are priorities, and it seats well against soft-faced pilot plugs. We review pressure, temperature and medium with you before recommending.
CTA
Send your pressure reducing valve pilot housing drawing or sample for a DFM review, port tolerance study and production quotation. Contact Wendy She – sales@cnsandcasting.com – WhatsApp +86-13777124360, or visit https://cnsandcasting.com to start your control valve program with Ningbo Ruican.
