Description
Nickel-iron-chromium alloy industrial valve
Alloy 20 Wedge Gate Valve
A chemical-process valve material associated with sulfuric-acid, pickling and fertilizer duties. The wedge gate valve configuration is engineered for fully open or fully closed isolation with low open-position pressure loss.
What is a Alloy 20 Wedge Gate Valve?
A Alloy 20 Wedge Gate Valve combines a nickel-iron-chromium alloy containing copper and molybdenum, developed for resistance in sulfuric-acid and related chemical environments with a full-opening linear isolation design that raises a wedge out of a substantially straight flow path.
Alloy 20 selection must use concentration-temperature corrosion data and account for contaminants, aeration, velocity and crevices. A wedge gate valve is not normally used for throttling because partial opening can produce vibration and seat or guide damage.
Alloy 20 Wedge Gate Valve specifications
| Product | Alloy 20 Wedge Gate Valve |
|---|---|
| Valve construction | Bolted-bonnet outside-screw-and-yoke rising-stem gate valve with flexible or solid wedge |
| Nominal material | Alloy 20 |
| UNS / EN reference | UNS N08020; EN 2.4660 |
| Product forms | Wrought/forged ASTM B462 or ASTM A182 F20 as applicable; cast ASTM A351 CN7M; component specification controlled by design |
| Design standards | API 600 and ASME B16.34; API 602 for applicable compact forged designs |
| Pressure testing | API 598 or project-specified shell, backseat and closure testing |
| Pressure rating | ASME Class or PN rating verified against exact material, size, construction and design temperature |
| End connections | RF/RTJ flanged or butt-weld ends according to design |
| Operation | Handwheel, gearbox, electric, pneumatic or hydraulic actuator |
| Documentation | EN 10204 3.1 material records, pressure test report, GA drawing and project inspection records as ordered |
This is an engineered inquiry product, not a universal stock specification. Final availability depends on valve size, pressure class, material form, trim, seat system, operator, quantity and required code edition.
Alloy 20 material selection
| Selection point | Engineering guidance |
|---|---|
| Material profile | a nickel-iron-chromium alloy containing copper and molybdenum, developed for resistance in sulfuric-acid and related chemical environments |
| Why it is selected | Useful resistance to sulfuric acid and a range of chemical environments, with fabrication characteristics familiar to stainless-alloy shops. |
| Typical service | Sulfuric-acid processing, fertilizer, pickling, chemical transfer and pharmaceutical process systems. |
| Limitations to check | It is not a universal acid alloy. Hydrochloric acid, oxidizing contaminants and mixed acids can change performance significantly. |
| Specification route | Wrought/forged ASTM B462 or ASTM A182 F20 as applicable; cast ASTM A351 CN7M; component specification controlled by design |
| Verification | PMI for nickel, chromium, copper and molybdenum plus heat traceability and component-specific MTC review. |
Wedge Gate Valve design and standards
API 600
Common design basis for bolted-bonnet steel gate valves, including material, trim, testing and marking requirements.
ASME B16.34
General pressure-temperature and valve design requirements within scope.
API 598
Shell, backseat and closure pressure testing when specified.
API 624 / ISO 15848-1
Fugitive-emission qualification is specific to the packing system and qualified valve design.
Wedge flexibility, seat hardfacing, stem/packing system, body cavity drainage, thermal binding risk and operating thrust require service-specific review.
Fire-safe, fugitive-emission, sour-service, oxygen, cryogenic, chlorine and PED requirements apply only when explicitly defined and supported for the exact offered configuration.
Typical applications
| Industry | Material service context | Valve selection focus |
|---|---|---|
| Sulfuric-acid processing | Transfer, dilution and process systems within verified concentration-temperature limits | Full-open isolation, wedge/seat materials, thermal effects, packing emissions and operator thrust |
| Fertilizer | Acid and chemical handling systems after compatibility review | Full-open isolation, wedge/seat materials, thermal effects, packing emissions and operator thrust |
| Pickling | Selected acid circulation and transfer duties | Full-open isolation, wedge/seat materials, thermal effects, packing emissions and operator thrust |
| Pharmaceutical and fine chemical | Corrosive reagent and batch-process systems | Full-open isolation, wedge/seat materials, thermal effects, packing emissions and operator thrust |
Application examples are not a corrosion or design approval. The end user must verify process chemistry, contaminants, pressure, temperature, velocity, cycling, emissions and regulatory requirements.
Quality, testing and traceability
Heat-number traceability and EN 10204 3.1 records matched to the ordered component specifications.
PMI for nickel, chromium, copper and molybdenum plus heat traceability and component-specific MTC review.
API 598 or project-specified shell, backseat and closure testing, with acceptance and leakage criteria stated on the order.
GA drawing, dimensions, marking, operation, pressure test and specified NDE/third-party records.
RFQ checklist
- Valve design standard and required edition
- Nominal size and ASME Class or PN rating
- Exact material specifications for pressure boundary, trim, seats, packing and bolting
- Flexible or solid wedge, seat/hardfacing, stem arrangement, packing and operator requirements
- End connection, facing and face-to-face requirement
- Fluid composition, concentration, contaminants and solids
- Design and operating pressure/temperature
- PMI, corrosion testing, NDE, witnessing and document requirements
Frequently asked questions
Why is Alloy 20 used in sulfuric-acid service?
Its nickel, chromium, molybdenum and copper balance can provide useful resistance across selected sulfuric-acid conditions. Exact concentration, temperature and contaminants remain decisive.
What cast grade is commonly associated with Alloy 20 valves?
ASTM A351 CN7M is a commonly specified cast grade associated with Alloy 20-type service. Forged components use their applicable wrought specification.
Can Alloy 20 replace Hastelloy C276?
Not as a blanket substitution. The alloys have different chemistry, strength and corrosion behavior. Selection must follow actual process corrosion data and the piping material specification.
Can a wedge gate valve be used for throttling?
Normally no. It is intended for fully open or fully closed service; extended partial opening can damage the wedge, seats and guides.
What is the difference between flexible and solid wedges?
A flexible wedge can accommodate limited alignment and thermal effects, while a solid wedge is more rigid. Selection follows the design and service conditions.
Can Alloy 20 be used for every component in this wedge gate valve?
Not automatically. Pressure-boundary, trim, stem or shaft, seating, packing, gasket and bolting materials have different mechanical and corrosion duties. The complete bill of materials must be engineered for the service.
Related Alloy 20 valve products
Need a broader comparison? View the general stainless steel and alloy gate valves guide or browse all Gate Valves.
Request a Alloy 20 Wedge Gate Valve quotation
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