DongWu Machinery (DWMC) API 526 safety valves, pilot valves, breathers and OEM parts

Supply ASME UV/NB stamped spring-loaded safety valves, pilot-operated relief valves, cryogenic LNG/LH2 safety valves, API 2000 tank breathers, changeover blocks and genuine springs/bellows from DongWu Machinery (DWMC).

DWMC Spring-Loaded Safety Relief Valves (API 526 / ASME Section VIII UV & NB)

Wujiang Dongwu Machinery (DWMC) manufactures direct spring-loaded safety and relief valves engineered to API 526, API 520, API 527, ASME Section VIII (UV & NB stamped) and ISO 4126-1 for overpressure protection across gas, vapor, steam and liquid services.

Conventional closed-bonnet, balanced-bellows (backpressure-compensated) and open/packed lifting-lever styles
Standard API 526 orifice sizes from D through T across pressure ratings Class 150 to Class 2500
Precision-lapped Stellite 6 metal-to-metal seats and bubble-tight soft-seat (O-ring / PCTFE) options
Spare parts: calibrated springs (50CrVA, Inconel X-750), balanced bellows (316L / Inconel 625), discs, nozzles

DWMC Nuclear Island Class 1, 2 & 3 Safety & Relief Valves

Certified for civil nuclear safety equipment design and manufacture (Nuclear Class 1, 2 and 3), DWMC supplies Main Steam Safety Valves (MSSV), pressurizer safety valves and auxiliary loop relief valves for third-generation nuclear power plants including Hualong One.

Nuclear Class 1, 2 and 3 spring-loaded and pilot-operated safety valves per ASME Section III / RCC-M
Qualified under seismic, LOCA, thermal-aging and full-flow saturated steam bench testing
High pop stability and repeatable reseating pressure for reactor coolant and secondary steam systems
Spare parts: nuclear-certified bellows, spring packs, lapped discs, nozzles and stem position indicators

DWMC API 2000 Pressure/Vacuum Breather Valves & Tank Venting Devices

DWMC tank protection devices engineered to API 2000 and ISO 28300 safeguard atmospheric storage tanks, chemical vessels and cryogenic LNG flat-bottom tanks against overpressure rupture and vacuum implosion during filling, emptying and thermal breathing.

Weight-loaded, spring-loaded and pilot-operated pressure/vacuum relief valves (vent to atmosphere or pipe-away)
Optional integrated flame arresters and steam-jacketed bodies to prevent condensate freezing on pallets
Emergency pressure/vacuum relief manways (gauge hatches) and nitrogen blanketing regulator valves
Spare parts: FEP/PTFE pallet diaphragms, flame arrester bank elements, calibration weights, soft seals

DWMC High-Performance Steam Safety Valves for Power Boilers & Turbines

DWMC high-capacity steam safety valves engineered to ASME Section I and Section VIII protect utility power boilers, superheaters, reheaters and main steam headers under high-temperature supercritical conditions.

Flexible thermo-disc design compensates for thermal distortion and ensures tight reseating on high-pressure steam
Open yoke/bonnet construction isolates the alloy spring from radiant heat and vents escaping steam safely
Body materials in WC6, WC9 and C12A (P91) Chrome-Moly alloys rated for steam temperatures up to +600 °C
Spare parts: Stellite-faced thermo-discs, guide bushings, upper/lower blowdown adjusting rings, high-temp springs

DWMC Threaded, Socket-Weld & Flanged Thermal Relief Valves (US & GB Series)

DWMC compact portable and thermal relief valves (1/2" to 2", NPT threaded, socket-weld or flanged) protect blocked-in liquid pipelines, heat exchangers, cryogenic lines and pump casings against hydraulic thermal expansion.

Prevents overpressure damage in liquid-full piping sections isolated between two closed block valves
Barstock and forged bodies in A105, LF2, F304, F316L, Duplex F51/F53, Monel 400 and Hastelloy C276
Anti-chatter trim geometry suitable for both incompressible liquids and compressible gas/vapor relief
Spare parts: replaceable nozzle inserts, soft/metal discs, calibration springs and cap seal gaskets

DWMC Steam & Thermal-Oil Jacketed Safety Relief Valves

DWMC jacketed safety valves feature welded or cast heating jackets enveloping the inlet nozzle and body cavity, preventing solidification, crystallization or polymerization in viscous media such as molten sulfur, bitumen, asphalt, phthalic anhydride and polymers.

Continuous steam or hot-oil circulation around the nozzle and discharge chamber prevents plugging
Available with shielded balanced bellows to protect convolutions from viscous buildup and backpressure
Flanged or threaded jacket connections engineered to ASME B16.5 and customer piping layouts
Spare parts: jacketed nozzle assemblies, shielded bellows, lapped discs, high-temperature springs

DWMC Pilot-Operated Safety Valves (POSV) & Ultra-Cryogenic Valves (-250 °C)

DWMC Pilot-Operated Safety Valves (POSV) in pop-action and modulating-action designs utilize system line pressure to hold the main valve seat tight up to 98% of set pressure, eliminating simmering in high-pressure gas, LNG (-196 °C) and liquid hydrogen (-253 °C) systems.

Ultra-cryogenic pilot and spring safety valves validated on specialized low-temperature helium/nitrogen test benches
Unaffected by high variable superimposed or built-up flare header backpressure; compact low-profile envelope
Available with backflow preventers, pilot supply filters, remote unloading and field test connections
Spare parts: complete pilot valve cartridges, main piston/diaphragm soft Goods kits (PCTFE, PTFE, Kalrez)

DWMC Interlocked Changeover Valves for Dual Safety Valve Assemblies

DWMC three-way changeover (selector) valves connect two safety relief valves (one active, one standby) to a single vessel nozzle, enabling online safety valve removal, calibration and maintenance without plant shutdown.

Mechanical interlock guarantees one flow path remains fully open at all times during switching
Streamlined y-pattern flow geometry maintains inlet pressure drop well below the API 520 3% limit
Available as inlet-only selector valves or mechanically synchronized inlet-and-outlet tandem combinations
Spare parts: changeover obturator plugs, Stellite seats, synchronization chains/gearboxes, bleed valves, packings

Safety valve identification and DWMC / Neway nameplate verification

Wujiang Dongwu Machinery Co., Ltd. (DWMC), founded in 1954 and part of Neway Group since 2011, is a specialized manufacturer of safety relief valves holding ASME Section VIII (UV Stamp), National Board (NB) and civil nuclear Class 1, 2 and 3 licenses.

To request replacement safety valves or genuine OEM spare parts, provide the nameplate Serial Number, valve model code, inlet/outlet sizes, API 526 orifice letter (D through T), set pressure, cold differential test pressure (CDTP), backpressure and fluid temperature.

Verifying the factory sizing sheet and serial record guarantees exact spring rate, bellows effective area and nozzle orifice geometry.

API 526 spring-loaded safety relief valves (conventional & balanced bellows)

DWMC direct spring-loaded safety valves protect pressurized vessels, distillation columns and pipelines in oil refining, chemical processing and gas plants.

Available in conventional closed-bonnet, balanced-bellows (for variable superimposed or built-up backpressure) and lifting-lever designs across Class 150 to Class 2500.

We supply calibrated springs (50CrVA, Inconel X-750, 17-4PH), multi-ply 316L / Inconel 625 balanced bellows, Stellite-faced discs, nozzles and soft-seat O-ring/PCTFE kits.

Pilot-operated safety valves (POSV) and ultra-cryogenic relief (-250 °C)

DWMC pop-action and modulating pilot-operated safety valves (POSV) use process pressure to keep the main seat bubble-tight up to 98% of set pressure, eliminating product loss and high-backpressure instability.

Cryogenic pilot and spring safety valves are tested in-house with liquid nitrogen (-196 °C) and helium for LNG terminals, air separation units and liquid hydrogen (-253 °C) facilities.

We provide replacement pilot cartridges, backflow preventer kits, main piston seals, PCTFE cryogenic seats and Elgiloy spring-energized lip seals.

Nuclear island Class 1/2/3 safety valves and supercritical steam valves

DWMC manufactures Main Steam Safety Valves (MSSV), pressurizer safety valves and nuclear Class 1, 2 and 3 relief valves deployed on third-generation nuclear reactors including Hualong One.

For thermal power stations, DWMC high-capacity open-bonnet steam safety valves with flexible Thermo-discs operate on WC6, WC9 and C12A (P91) headers up to +600 °C.

We supply nuclear-grade bellows, Stellite thermo-discs, full-nozzle inserts, guide bushings and blowdown adjusting rings.

API 2000 tank breather valves, flame arresters and emergency manways

DWMC tank venting equipment engineered to API 2000 (ISO 28300) protects atmospheric and low-pressure storage tanks against overpressure rupture and vacuum implosion.

Product lines include weight-loaded, spring-loaded and pilot-operated pressure/vacuum relief valves, combination flame-arrester vents, nitrogen blanketing valves and emergency relief manways.

We deliver non-stick FEP/PTFE pallet diaphragms, stainless steel flame arrester elements, calibration weights and jacketed breather bodies.

Thermal expansion relief valves, steam-jacketed valves & changeover blocks

Compact threaded and flanged thermal relief valves (US & GB series, 1/2"–2") safeguard liquid-full piping sections against solar or ambient thermal expansion.

Steam and hot-oil jacketed safety valves prevent solidification in molten sulfur, bitumen, asphalt and polymer lines.

Three-way mechanically interlocked Changeover Valves connect active and standby safety valves to a single vessel nozzle for uninterrupted online maintenance with less than 3% inlet pressure drop.

Full-flow steam, gas, liquid and cryogenic test center in Suzhou

DWMC operates an advanced 30,000 m² manufacturing and testing facility in Wujiang, Suzhou, equipped with high-pressure steam boilers, nitrogen/helium gas benches, liquid loops and cryogenic test cells.

Every valve is calibrated for pop pressure, blowdown and API 527 seat tightness prior to shipment.

Certified test certificates, ASME UV / NB data reports and EN 10204 3.1/3.2 mill certificates accompany all deliveries.

Turnaround spare parts kits and set-pressure recalibration springs

During plant turnarounds, replacing fatigued springs, corroded bellows and lapped disc inserts restores safety valves to as-new performance.

When process operating pressures change, we supply factory-calculated replacement springs and conversion trim kits matched to your existing valve serial number.

We also assemble 2-year operational spare parts packages for greenfield LNG, refinery and chemical projects.

Global project procurement, tandem safety blocks and export delivery

We coordinate international supply of complete DWMC safety relief valves, tandem changeover valve skids and genuine OEM spare parts.

Our engineering team assists with API 520 orifice sizing verification, material selection and export sea/air logistics.

Send your safety valve datasheet, tag schedule or nameplate photo to receive a prompt technical and commercial proposal.

Sizing calculations, lead times and pricing for DongWu Machinery safety valves and spare parts are determined individually upon engineering inquiry. Scope of supply, ASME/NB certification and delivery terms are defined in the contract.