Industrial valves · Характеристики материала клапана (A216/351/352/105/182)

Engineering Guide to Valve Materials According to ASTM Standards

This technical overview details the key material specifications according to ASTM standards used in the manufacture of valve bodies. The choice of technology — casting or forging — is a determining factor for the operational characteristics of the product. Cast bodies, obtained by pouring molten metal into specialized molds, are standard for valves with a nominal bore exceeding 2 inches. Forged bodies are manufactured by hot closed-die forging with subsequent precision machining, which ensures a denser metal structure. The main standards for cast bodies are ASTM A216 (grades WCA, WCB, WCC), ASTM A352 (LCB, LCC for cryogenic media), and ASTM A351 (CF8, CF8M for corrosion-resistant applications). For small diameter forged valves and products designed for high pressures, ASTM A105, A350, and A182 specifications are used.

Cast Steel Valves

The fundamental difference between cast and forged valve bodies lies in their manufacturing method, which directly affects their microstructure and mechanical properties. Casting technology is economically effective for producing large-sized items with complex geometries. At the same time, forging ensures the creation of a dense, homogeneous, and fine-grained metal structure, which is critically important for valves operating under extreme pressures and temperatures.

ASTM A216 WCA, WCB, WCC (Carbon Steel for High Temperatures)

ASTM A216 specifies requirements for three grades of carbon steel castings (WCA, WCB, WCC), intended for high-temperature service and possessing good weldability. These grades are fully compatible with pipelines according to ASTM A53, A106, and API 5L standards. All cast components manufactured by EV Group China undergo mandatory heat treatment (annealing or normalizing) to homogenize the structure and relieve internal stresses. Each casting is subjected to visual and instrumental inspection for the absence of unacceptable defects such as shrinkage cavities, cracks, and sand inclusions.

1. For each reduction of 0.01% below the specified maximum carbon content, an increase of 0.04% manganese above the specified maximum will be permitted, up to a maximum of 1.10%.
2. For each reduction of 0.01% below the specified maximum carbon content, an increase of 0.04% manganese above the specified maximum will be permitted, up to a maximum of 1.28%.
3. For each reduction of 0.01% below the specified maximum carbon content, an increase of 0.04% manganese above the specified maximum will be permitted, up to a maximum of 1.40%.

ASTM A352 LCB / LCC (Low-Temperature Carbon Steel)

ASTM A352 standard establishes norms for steel castings intended for service at low and cryogenic temperatures. Grades such as LCB and LCC are specially alloyed and heat-treated to ensure the required impact toughness properties at sub-zero temperatures, which prevents brittle fracture.

ASTM A351 CF8 / CF8M (Stainless Steel)

ASTM A351 standard covers austenitic iron-chromium-nickel alloy castings, developed for use in aggressive corrosive environments. The most sought-after grades are CF8 (a functional analog of AISI 304 stainless steel) and CF8M (an analog of AISI 316, alloyed with molybdenum for increased resistance to pitting and crevice corrosion). All castings from EV Group China under this standard undergo mandatory austenitization (solution heat treatment) followed by water quenching to fix a homogeneous austenitic structure and maximize corrosion resistance.

Forged Steel Valves

The bodies of EV Group China forged valves are manufactured by hot closed-die forging from solid steel blanks. This technology forms a directional fibrous macrostructure, which guarantees the absence of porosity and other casting defects. The result is exceptional strength, tightness, and reliability, essential for systems with extremely high pressure. The choice of body material is regulated by ASTM A105 (high-temperature carbon steel), ASTM A350 (low-temperature carbon steel), and ASTM A182 (alloy and stainless steels) standards.