A204 Grade B for Manufacturing Durable Pressure Vessels

ASTM A204 Grade B is used in fabricators serving industry, especially in the oil, gas and chemical supply markets. ASTM A204 specification covers molybdenum alloy steel plates, intended particularly for welded boilers and other pressure vessels.

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Product Description

1.For more information of A204 Grade B steel plates, please check them in following:

A204Grade B Chemicai Composition
Grade	The Element Max(%)
Grade	C	Si	Mn	P	S
A204Grade B	0.20-0.27	0.13-0.45	0.90-0.98	0.035	0.035

2.What is the difference between A204 Grade B and A36?

Property	A204 Grade B	A36
Standard	ASTM A204 (Pressure Vessel Plates)	ASTM A36 (Structural Steel)
Composition	Molybdenum (Mo) alloy, controlled carbon	Plain carbon steel, no alloying
Tensile Strength	485-620 MPa	400-550 MPa
Yield Strength	≥ 275 MPa	≥ 250 MPa
Operating Temp.	-30°C to 450°C (superior high-temp. performance)	Ambient (softens at high temps)
Primary Uses	High-pressure/temperature vessels, boilers, chemical equipment	Buildings, bridges, machinery bases

3. Advantages of A204 Grade B

(1) Superior High-Temperature & High-Pressure Performance

Molybdenum-enhanced: Mo improves high-temperature strength and creep resistance, ideal for sustained service up to 450°C.
Stability: Maintains integrity under thermal cycling/pressure fluctuations, unlike A36.

(2) Enhanced Corrosion Resistance

Resists sulfide stress cracking: Suitable for sour (H₂S) environments in oil/gas/chemical industries; A36 requires coatings.
Oxidation resistance: Slower scaling rate than A36 at elevated temperatures.

(3) Strict Manufacturing Standards

Mandatory UT inspection: Ultrasonic testing ensures internal soundness; A36 has no such requirement.
Heat treatment: Typically normalized for refined grain structure and improved toughness.

(4) Weldability & Fabrication

Pre-heating required: Prevents cold cracking but ensures stable post-weld properties.
A36 welds easily but loses strength faster in high-heat applications.