A global supplier of specialty rubber seals and shock absorbers.
Strong manufacturing and R&D capabilities.
More than 30 years of R&D and manufacturing experience.
Views: 0 Author: Site Editor Publish Time: 10-17-2025 Origin: Site
Hebei Huami New Material Technology Co., Ltd. — 30 years in rubber and metal sealing components; built-to-drawing / by OE number; TÜV/ISO systems; rapid prototyping & small lots.
Key part definitions
• Gate (Gate/Wedge): obturator of a gate valve (flexible wedge/solid wedge/twin-disc), mates with the seat to shut off.
• Seat / Seat Ring: body seating surface or replaceable seat ring forming the static–dynamic sealing pair.
• Disc / Plug: obturator of globe and check valves; globe uses conical/flat seating; check includes swing/lift/dual-plate.
Soft seat vs metal seat
• Soft-seated: metal substrate with PTFE/EPDM/NBR/FKM etc. Pros: very low leakage and low torque. Cons: limited by temperature/medium; lower abrasion/erosion resistance.
• Metal-seated: metal-to-metal (e.g., Stellite 6 overlay, hardened stainless). Pros: high-temp & wear resistance; suitable for steam/light solids. Cons: stringent machining & lapping; higher torque.
Mapping to valve types
• Gate valve: gate + seat (single/double wedge; soft or metal seat) — on/off isolation.
• Globe valve: disc + seat (conical/flat) — better throttling.
• Check valve: disc + seat (swing/lift/dual-plate) — backflow prevention.
• Butterfly valve: disc + seat liner (mostly soft seat; metal-seat variants exist).
Takeaway: Medium, temperature, pressure, and solids dictate soft vs metal seat; valve type and motion dictate geometry and wear strategy.
Next step: Record valve type/size/service for material matching.
Metallic substrates & hardfacing (typical ranges)
Substrate / Hardface | Typical Hardness | Temp Range (°C) | Medium Compatibility | Typical Use |
WCB (ASTM A216) | 150–180 HB (QT) | −29 ~ 425 | Clean water, oil, steam | Carbon-steel bodies/gate blanks |
CF8 (304 SS) | 150–190 HB | −196 ~ 425 | Water, mild acids/alkalis, low chlorides | Corrosion-service seat rings/discs |
CF8M (316 SS) | 150–200 HB | −196 ~ 540 | Better in chlorides | Seawater/chemical seats & gates |
2205 Duplex SS | 250–290 HB | −46 ~ 315 | Pitting/crevice resistant | Seawater & chloride oil/gas |
Stellite 6 overlay | HRC 38–45 | ≤ 600 | High wear/galling resistance | Metal seats/gate sealing faces |
13Cr (Type 420) hardened | HRC 40–50 | ≤ 450 | Clean water/steam | High-pressure gate seating |
Non-metallic sealing (soft seats)
Material | Typical Hardness | Temp (°C) | Chemical / Medium | Notes |
PTFE | — | −196 ~ 260 | Broad chemical resistance, anti-stick | Cold-flow → needs backup/limiters |
EPDM | 60–80 IRHD | −40 ~ 120/150 | Hot water/condensate/ozone | Not oil-resistant |
NBR | 60–80 IRHD | −20 ~ 100/110 | Oils/fuels/lubricants | Moderate ozone resistance |
FKM (Viton®) | 70–90 IRHD | −20 ~ 200 | Oils/solvents/some acids/alkalis | Preferred for higher temperature soft seats |
Takeaway: CF8M/2205 for seawater/chlorides; Stellite 6 for erosion/high temp; PTFE for broad compatibility; NBR/FKM for oil service.
Next step: Shortlist two material stacks and confirm by standards & testing.
• API 600 — Steel gate valves: design/materials/testing (gate/seat forms, hardface thickness, replaceable seats).
• API 602 — Compact forged steel valves (gate/globe/check).
• ASME B16.34 — Pressure–temperature ratings, material groups, wall thickness, end connections.
• API 598 / ISO 5208 — Pressure & seat tightness testing (shell strength, seat leakage, air/hydro; ISO 5208 leakage rates A–F).
• QA suggestions: PT/MT/UT/PMI on critical seating/welds; include surface roughness & flatness in final inspection.
Takeaway: Design standards + pressure testing enable mutual acceptance; sampling & records ensure traceability.
Next step: Specify standard editions and test levels/media (e.g., ISO 5208 Rate A air tightness) in RFQ.
• Service evaluation: medium, temperature, pressure class, velocity & erosion risk.
• Leakage class: soft seat → zero-leak (ISO 5208 Rate A / API 598); metal seat → allowable leakage per standard.
• Interchangeability: seat OD/thread/press-fit, seating angle (gate wedge commonly 8–10°), contact width; confirm with existing body.
• Tolerances & surface finish: Ra 0.4–0.8 μm after lapping; contact band 1.5–3.0 mm; coaxiality/parallelism typically 0.03–0.05 mm.
Takeaway: Front-load leakage class & interchange sizes to reduce rework.
Next step: Send legacy dimensions and target leakage class for material/angle/band-width advice and a machining route.
• Blanks: castings or forgings for gates/discs; seats typically replaceable rings (threaded/pressed/welded).
• Machining: hold wedge angle/taper/contact-band; machine seat pockets & body guides in one setup when possible.
• Hardfacing: Stellite 6, 13Cr, 316L via GTAW/PTA/SMAW; typical 2–4 mm with controlled interpass temperature & dilution.
• Heat treatment: stress relief / QT for carbon steel; solution treatment for stainless.
• Lapping & match-lapping: full-circumference contact verified by dye.
• Replaceable seat design: external thread + sealing cone; anti-rotation & positive locking (tack weld/set screw).
Takeaway: Hardface quality + thorough lapping drives metal-seat performance.
Next step: Choose hardfacing alloy/thickness and define NDE/dye acceptance criteria.
• Clean & verify: deburr, protect seating; verify PMI/heat-treatment marks.
• Centered assembly: keep gate and seat coaxial; apply anti-seize/sealant to seat threads/press fits as designed.
• Tightening sequence: cross-tighten bonnet/yoke bolts in steps; use torque table.
• Operational check: full open/close without binding; metal seats may show slight contact damping.
• Air/hydro test: API 598 / ISO 5208; air first, then hydro; record leakage and retests.
• Soft-seat notes: PTFE cold flow → metal backups/limiters; avoid mineral oils with EPDM.
Takeaway: Alignment + surface protection + standard testing = right-first-time.
Next step: Use our assembly/test record templates for site documentation.
Symptom | Likely Cause | Remedy |
Won’t shut tight / leakage | Band too narrow; lapping incomplete; soft seat cold flow | Re-lap/increase band; replace soft seat and add limiters |
Galling/binding | Abrasive scratches; stem–guide misalignment | Re-lap; correct guides/replace bush |
Erosion pits | High velocity with sand / cavitation onset | Upgrade to Stellite 6 / hardened 13Cr; optimize velocity |
Seat ring loosening | No locking or overheating | Re-locate and lock (tack weld/set screw); check thermal growth |
Rubber aging/swelling | Material–medium mismatch | Re-check compatibility; switch to NBR/FKM/EPDM |
Takeaway: Most issues stem from material matching & precision; re-lapping + limiters often restore performance quickly.
Next step: Send failure photos & service data for RCA.
• Full material coverage: WCB, CF8/CF8M, 2205, Stellite 6; PTFE/EPDM/NBR/FKM.
• Replaceable seat rings and dedicated lapping fixtures achieving Ra 0.4–0.8 μm.
• Reverse-engineering by drawing/OE with interchange drawings and test records.
• TÜV/ISO quality; NDE/PMI/heat-treat reports traceable.
• Rapid prototypes + small MOQs; expedited engineering support.
Strong CTA: Request Samples | Get a Quote | Custom Review (upload drawing/OE No.)
• SEO Title: Gate/Seat/Disc Materials & Process Selection Guide | WCB/CF8M/2205 | Stellite 6 | PTFE/EPDM/NBR/FKM
• Meta Description: Hebei Huami — 30 years in sealing components. Covers soft vs metal seating, materials & heat treatment, API 600/602/598 and ISO 5208 testing, selection steps, manufacturing & lapping, installation & troubleshooting. Built-to-drawing/OE customization, rapid sampling & small lots.
• URL Slug: /solutions/gate-seat-disc-selection
• Open Graph: og:title/description as above; og:image /images/valve-seat-stellite-overlay-01.jpg; og:type article
Q: Is a metal seat always better than a soft seat?
A: No. Metal seats handle temperature and erosion; soft seats target very low leakage and low torque.
Q: How to choose between Stellite 6 and 13Cr hardfacing?
A: Use Stellite 6 for high-temperature abrasion/galling; 13Cr for cost-effective clean services.
Q: PTFE cold flow—how to mitigate it?
A: Use metallic backup rings/limiters and control compression & temperature.
Q: Why use replaceable seat rings?
A: Faster maintenance; add anti-rotation and positive locking (tack weld or set screw).
Q: Do we need ISO 5208 Rate A?
A: Achievable with soft seats; metal seats often select Rate C/D after duty–cost evaluation.
Q: Materials for seawater?
A: CF8M or 2205 with metal-seat hardfacing; manage crevices and velocity.
Q: Universal gate wedge angle?
A: No. Commonly 8–10°; must match the seat geometry; measure legacy valves before retrofit.
Q: What’s included in Huami’s documentation package?
A: Material certificates, heat-treat/NDE/PMI reports, pressure-test records, roughness & lapping records.
For gates, seats, and discs, material matching + hardfacing & lapping + standardized testing determine life and reliability. By front-loading service → leakage class → interchange dimensions, we can deliver a prototype & lead-time plan within 48 hours. Share your drawings/OE numbers/service sheet with the Huami engineering team to get started.
