Alloy 20 (Carpenter 20) Ball Valves

Exceptional Sulfuric Acid Resistance: Outstanding resistance to sulfuric acid (H₂SO₄) across a wide range of concentrations and temperatures, making Alloy 20 the premier material for sulfuric acid plant ball valves, acid coolers, and heat exchanger isolation.

Excellent Phosphoric and Nitric Acid Resistance: Superior performance in phosphoric acid (H₃PO₄) and nitric acid (HNO₃) service, suitable for fertilizer production, chemical processing, and pickling operations.

Superior Chloride Stress Corrosion Cracking Resistance: High nickel content (32-38%) provides excellent resistance to chloride-induced SCC, significantly outperforming 304L, 316L, and 317L stainless steel ball valves.

Good Pitting and Crevice Corrosion Resistance: Molybdenum (2-3%) and copper (3-4%) additions provide enhanced resistance to pitting and crevice corrosion in chloride-containing environments.

Excellent Weldability – Niobium Stabilized: Niobium stabilization (8×C max) prevents sensitization and intergranular corrosion after welding, eliminating the need for post-weld heat treatment for most applications.

Bidirectional Shut-Off: Full port design provides minimal pressure drop and reliable bubble-tight shut-off in both flow directions.

Low Operating Torque: Precision-machined ball and PTFE seats provide smooth quarter-turn operation with low torque requirements.

Fire-Safe Design: Available with fire-safe certification (API 607/ISO 10497) for critical chemical applications.

Anti-Static Device: Optional anti-static design to prevent static electricity accumulation across the valve.

Blow-Out Proof Stem: Stem design prevents accidental blow-out under pressure, ensuring operator safety.

Multiple End Connections: Flanged (ASME B16.5), threaded (NPT/BSP), socket weld (SW), and butt weld (BW).

Full Range of Types: Floating ball (1/2″–12″), three-piece (1/2″–6″), top entry (2″–8″), and V-port control ball valves.

Pressure Ratings: Available in Class 150, 300, 600, and 900 (PN16 to PN160).

Temperature Range: Suitable for -196°C to 400°C (-321°F to 752°F) depending on seat material.

International Certifications: Ball valves can be certified by ABS, BV, DNV, LR, GL, RINA, CCS, KR, and NK, and comply with API 607, API 6D, ASME B16.34, and NACE MR0175 (limited) standards.

Secondary Metal-to-Metal Seats: After PTFE seat burnout, secondary metal seats provide shut-off.

Graphite Stem Seals: Fire-resistant stem packing for emergency sealing.

Anti-Static Device: Spring-loaded plunger ensures electrical continuity between ball and body.

Blow-Out Proof Stem: Stem design prevents accidental ejection under extreme pressure.

Raw Material Selection: High-quality Alloy 20 (UNS N08020) nickel-iron-chromium billets from certified premium mills (Special Metals, VDM Metals, Carpenter) with certified chemical composition (Ni 32-38%, Cr 19-21%, Mo 2-3%, Cu 3-4%, Nb stabilization verification) and traceability.

Casting/Forging: Valve body cast (CN7M) or forged to shape with strict temperature control.

Heat Treatment – Solution Annealing: Solution annealing at 925–1010°C followed by rapid cooling (water quenching) to dissolve carbides and restore properties.

Machining: CNC lathes and machining centers produce precise dimensions – ball cavity, stem bore, flange faces, bolt holes, and seat pockets.

Ball Machining & Polishing: Ball machined and polished to mirror finish (Ra ≤ 0.4μm) for bubble-tight shut-off.

Seat Machining: PTFE, RTFE, or PEEK seats machined to precise dimensions.

Stem Machining: Stem machined with anti-static spring grooves and blow-out proof shoulders.

Niobium Stabilization Verification: ASTM G28 intergranular corrosion test performed.

Assembly: Ball, seats, stem, seals, and body assembled in clean environment.

Testing: Hydrostatic shell test, high-pressure seat test, low-pressure air seat test (bubble test).

Marking: Laser engraved with size, pressure, material, heat number, API 6D, and fire-safe markings (if applicable).

Coating: External coating (epoxy or PTFE) for corrosion protection.

Pressure Testing: 100% hydrostatic shell test (1.5× rated pressure), high-pressure seat test (1.1× rated pressure), low-pressure air seat test (80 psi, bubble-tight).

Material Verification: PMI 100% for body, ball, stem – verification of Ni (32-38%), Cr (19-21%), Mo (2-3%), Cu (3-4%), Nb (stabilization).

Intergranular Corrosion Test: ASTM G28 – validates resistance to intergranular corrosion and niobium stabilization (mandatory for Alloy 20).

Dimensional Inspection: Face-to-face, flange dimensions, ball cavity, stem bore.

Sulfuric Acid Corrosion Test: ASTM G31 – weight loss in H₂SO₄ upon request.

Fire-Safe Testing: API 607 / ISO 10497 (upon request).

NACE Compliance: Documentation available (limited sour service).

Third-Party Inspection: SGS, BV, DNV, TUV, LR on customer request.

Sulfuric Acid Production & Handling: Sulfuric acid plant process isolation valves, acid cooler ball valves, acid piping system block valves, storage tank isolation, acid dilution system valves, spent acid recovery, metallurgical acid plant valves.

Phosphoric Acid Service: Phosphoric acid evaporator isolation valves, heat exchanger ball valves, fertilizer production equipment (DAP/MAP), wet-process phosphoric acid plant valves.

Nitric Acid Service: Nitric acid cooler isolation, heater block valves, ammonium nitrate production equipment isolation.

Pickling Plants (Stainless Steel): Pickling line isolation valves, acid recovery system ball valves, spent acid handling, steel mill pickling lines, titanium dioxide production.

Chemical Processing (Aggressive): Chemical reactor isolation valves, process vessel shutdown, organic acid processing (acetic, formic, citric), chlorinated hydrocarbon handling, chlor-alkali heat exchanger isolation.

Pharmaceutical: High-purity process line ball valves, API (Active Pharmaceutical Ingredient) reactor isolation, sterile transfer lines, clean steam systems, vitamin C production.

Metal Finishing: Acid bath isolation, recovery system valves, waste acid handling.

Marine Engineering (Chemical Tankers): Acid cargo piping ball valves, chemical tanker manifold valves (ABS/BV/DNV/LR certified).

1. How does Alloy 20 compare to 316L stainless steel for ball valves?
Alloy 20 offers significantly better resistance to sulfuric acid (H₂SO₄), phosphoric acid (H₃PO₄), and chloride stress corrosion cracking. For concentrated or hot sulfuric acid service where 316L would fail rapidly, Alloy 20 is required.

2. Is Alloy 20 resistant to hydrochloric acid (HCl)?
Limited. Alloy 20 has fair resistance to dilute HCl but is not recommended for concentrated or aerated HCl. For hydrochloric acid service, consider Hastelloy C276 ball valves.

3. Can Alloy 20 ball valves be welded without post-weld heat treatment?
Yes. Alloy 20 is niobium-stabilized, which prevents sensitization and intergranular corrosion after welding. This is a major advantage over non-stabilized grades, eliminating PWHT for most applications.

4. What is the maximum temperature for continuous service?
400°C (752°F) for general service. For sulfuric acid service specifically, limit to 150°C (302°F) depending on acid concentration.

5. Are Alloy 20 ball valves fire-safe certified?
Yes, API 607 / ISO 10497 fire-safe certification is available upon request. Fire-safe valves feature secondary metal seats and graphite stem packing.

6. What seat material is best for sulfuric acid service?

PTFE is standard for H₂SO₄ service up to 180°C. PEEK is recommended for higher temperature (up to 250°C). RTFE provides better wear resistance for high-cycle applications.

Complete Product Range: Floating, three-piece, top entry, V-port – all types available.

Strict Quality Control: ISO 9001:2015, API 6D, PED certified.

Niobium Stabilized: ASTM G28 intergranular corrosion tested.

Fire-Safe Certified: API 607 / ISO 10497 available.

100% Pressure Tested: Hydrostatic shell and seat tests on every valve.

Full Traceability: Heat number on body – traceable to raw material.

Flexible Customization: Special end connections, extended stem, locking device, gear operator.

Acid Service Expertise: Proven in sulfuric, phosphoric, and nitric acid plants worldwide.

Global Delivery: Exported to major chemical plants and acid handling facilities.

Small ball valves (≤2″): Individual poly bags in carton boxes with foam inserts.
Medium ball valves (2.5″–8″): Plywood cases with foam padding, each valve separated, flange protectors.
Large ball valves (≥10″): Wooden crates with protective wrapping, flange protectors, lifting lugs.

All shipments:

Plastic end caps for threaded/socket weld ends

Flange protectors for flanged ends

Individual tagging with heat number and grade

Complete documentation: MTR, PMI reports, ASTM G28 test reports, hydrostatic test reports

Tel / WhatsApp:
Victor: +86 15575100681
Jack: +86 18390957568

Website: www.womicstainless.com

E‑mail: info@womicstainless.com

Contact Womic Steel today for a competitive quote on Alloy 20 ball valves. We offer certified quality, niobium-stabilized material verification, ASTM G28 corrosion testing, fast production lead times, and reliable global delivery for your acid service and chemical processing projects.

Stock Examples (Floating Ball Valves – Class 150 Flanged – Alloy 20 – PTFE Seats – Sulfuric Acid Service):

Stock Examples (Threaded Alloy 20 Ball Valves – 3000 WOG – Three-Piece – Chemical Injection):

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