A valve body is the pressure-containing heart of any flow system. It holds the seat, guides the closure member, and keeps fluid exactly where it belongs—often at hundreds of bar and temperatures that would cook lesser metals. When the envelope is tight and the spec is unforgiving, machined custom metal valve bodies beat castings on leak tightness, traceability, and dimensional control. Here is how we turn your drawing into a sealed, inspection-ready body, from material choice through final seat verification.
What a Valve Body Must Do
Beyond containing pressure, a body must locate the seat and stem precisely, survive repeated cycling, and resist the fluid itself. Any shift in bore concentricity or seat flatness shows up as leakage or premature wear. That is why we treat a valve body as a precision assembly carved from one solid block rather than a porous casting. Many of the same disciplines apply to hydraulic component manufacturing, where internal passages and seat faces decide whether a system holds pressure or weeps at the flange.
Materials: 304, 316, and Duplex
Stainless 304 covers general service; 316 adds molybdenum for chloride resistance in marine and food lines; duplex grades (2205, 2507) roughly double the yield strength for compact, high-pressure designs. We source certified bar and plate, and our stainless steel machining cells are set up to control heat and work-hardening on austenitic stock. For sour-service and upstream hardware, we also run oil and gas machined parts programs with full material traceability, positive material identification, and documented heat numbers on every lot that leaves the shop.
CNC and 5-Axis Machining
Valve bodies are rarely simple prisms. Ports, bonnet faces, and internal galleries come from CNC milling, while the bore and stem thread are turned on CNC turning. Complex multi-port bodies are best done on 5-axis CNC machining, which reaches compound angles in one setup and protects concentricity between the bore and the flange. Fewer setups means fewer stacks of tolerance and a body that seats correctly the first time instead of after a frustrating round of rework and chased dimensions.
Tolerances and Sealing Surfaces
Seat and bonnet faces usually run ±0.01–0.02 mm with flatness under 0.01 mm; bores hold IT7–IT8. We verify with CMM and, where needed, blue-check the seat so you can see the contact pattern before the valve is built. After roughing we apply heat treatment to relieve stress so the body does not move between machining and service, then finish-critical faces on surface grinding for the flatness sealing actually demands in the field.
Plating and Corrosion Protection
For chemical and offshore duty we add nickel plating or electroless nickel to harden and shield the surface. Hard chrome is an option on stems and trim. Every coating is specified against the fluid and the pressure class so the body still seals after years in service rather than after months, and we mask threads and seats so the coating never interferes with assembly or leakage paths.
How to Prepare a Quote-Ready Drawing
Send the 3D model plus a drawing that calls out the seat flatness, bore tolerance, and pressure class. Tell us the fluid, temperature, and cycle count, because those decide material and finish. If you have a preferred standard—ASME B16.34, API 6D, or your own—name it at quote time so we scope inspection and paperwork correctly from the start rather than discovering it late.
Lead Times and What to Expect
A prototype body typically turns around in one to two weeks once the blank is on hand; volume runs follow on the same fixturing so the seat geometry you validated stays put. We quote a firm lead time with the price, flag any long-lead material up front, and keep you posted if a proof test moves the date. If your program is gated on a sample, ask for a first-article body before we commit the full lot—it is the cheapest insurance against a dimension you cannot see on a drawing. Throughout the run we hold the same setups and the same inspection plan so the thousandth body matches the first.
Common Failure Modes
Most valve-body problems trace to three causes. First, seat leakage from a flatness or finish miss—fixed by grinding the face and blue-checking the contact. Second, bore bell-mouthing from a worn or deflected tool, which we catch on the CMM and correct with a stiffer holder. Third, corrosion at a weld or uncoated pocket, avoided by specifying the right grade and finish up front. A body that fails in the field is almost always a body where one of those three was left to chance. We treat the seat, the bore, and the coating as the three things that decide the part’s life, and we verify all three before the body ships rather than hoping the test catches it later.
Frequently Asked Questions
Machined or cast valve body—which should I choose?
Machined bodies win on leak tightness, dimensional control, and low volume. Castings win on cost for very large runs. If your volumes are under a few thousand and the spec is tight, machine it.
Can you hold API or ASME dimensions?
Yes. We machine to ASME B16.34 flange and face dimensions and can work to API 6D or your customer standard, with inspection reports on request.
What is the smallest batch you will run?
From a single prototype through production. We regularly bridge prototype to volume on the same fixturing to protect repeatability and seat geometry.
Do you hydrostatic-test the body?
We can proof or hydrostatic-test to your pressure class and supply the test record with the lot when the program calls for it.
Ready to Start Your Project?
Get a build-ready quote on your custom metal parts within 24 hours. Share your drawing and our engineers will respond with process, lead time, and pricing.
