Introduction

A dual plate wafer check valve is compact, light, and suitable for installation between pipeline flanges, but its service life depends on more than the body material shown on a data sheet. The body, plates, hinge and stop pins, springs, seat, coating, and fasteners all face different combinations of pressure, temperature, corrosion, erosion, and cycling.

For water, oil, gas, cooling, fire protection, and general industrial systems, the correct material package should be selected from the actual medium and operating conditions. A WCB body may be appropriate for one line, while stainless steel, low temperature carbon steel, duplex steel, or a special alloy may be required for another. The seat choice is equally important because it controls shutoff performance and often sets the practical temperature limit.

Main Material Components

Body and Disc Material Selection

Carbon steel bodies such as ASTM A216 WCB are widely used in oil, gas, water, and general industrial service when corrosion is controlled and the temperature range is suitable. ASTM A352 LCC is commonly considered for lower temperature duties where impact properties and project requirements must be satisfied. Cast stainless steels such as CF8 and CF8M provide improved corrosion resistance, while duplex and nickel alloys may be considered for chloride-bearing or more aggressive media after a service-specific review.

The plate material does not have to match the body, but every material combination should be checked for galvanic compatibility, corrosion allowance, erosion resistance, and seat interaction. In large valves or high-velocity service, plate mass and closing impact also matter. A corrosion-resistant plate cannot compensate for an unsuitable spring, pin, seat, or body coating.

Soft Seat and Metal Seat Options

Selection by Service

· Water and wastewater: define water chemistry, solids, treatment chemicals, temperature, velocity, and whether an internal or external coating is required.

· Oil and refined products: identify the exact fluid, additives, aromatics, temperature, and required resistance of the elastomer or polymer seat.

· Natural gas and compressed gas: confirm pressure class, decompression behavior, seat permeability, fire-safe requirements, and fugitive-emission expectations where applicable.

· Seawater and chloride service: review pitting and crevice-corrosion resistance of the body, plates, pins, springs, and fasteners instead of specifying stainless steel generically.

· High temperature service: confirm the complete pressure-temperature rating and consider metal seating and suitable spring alloys when resilient seats exceed their qualified range.

Information to Send with an Inquiry

· Nominal size, pressure class, flange standard, and required face-to-face standard

· Medium composition, design and operating pressure, design and operating temperature

· Preferred body, plate, pin, spring, and seat materials or the governing piping specification

· Horizontal or vertical installation, flow direction, pump operating conditions, and expected cycle frequency

· Required shell and seat test standard, leakage acceptance, coating, NDE, certificates, and marking

· Any sour service, fire-safe, low-temperature, oxygen, potable-water, or project-specific approval requirement

Frequently Asked Questions

Is a stainless steel body always required for water service

No. Water chemistry, temperature, pressure, coating, maintenance, and project specification determine whether carbon steel, ductile iron, stainless steel, duplex steel, or another material is appropriate.

Can one seat material be used for water oil and gas

No. Seat compatibility must be checked against the exact fluid, concentration, temperature, pressure, and leakage requirement.

Does API 594 specify the complete material package

API 594 addresses design and performance requirements for applicable check valves, but the purchase specification and approved manufacturer design still need to define the required materials and service conditions.

What information is most important for a quotation

Provide size, pressure class, medium, pressure, temperature, flange standard, installation orientation, and required body and seat materials. These details prevent an unsuitable generic offer.