1. Carbon Steel Pipes (Standard Operation)

Used in parts of the boiler where the temperature does not reach critical oxidation levels, but the pressure is high.

• ASTM A106 Grade B: The worldwide standard for conveying steam and water at high temperatures. It is a seamless carbon steel pipe.

• ASTM A192: Specific standard for seamless carbon steel boiler tubes for high pressure. It has controlled mechanical properties to withstand the thermal cycle.

• Application: Water walls, economizers and saturated steam lines.

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2. Alloy Steel Pipes (Low Alloy - Molybdenum and Chromium)

When the temperature rises (above 400°C), ordinary carbon steel loses strength and undergoes "creep" (slow deformation under load). Chromium (Cr) is added for oxidation resistance and Molybdenum (Mo) for mechanical strength under heat.

• ASTM A213 (Grades T11, T12, T22): Known as "Chrome-Moly" tubing. These are seamless tubes for superheaters and reheaters.

• ASTM A335 (Grades P11, P22, P91): Used in main steam piping connecting the boiler to the turbine. Grade P91 is an advanced alloy that allows for thinner walls and greater efficiency in modern thermal power plants.

• Application: High-pressure superheaters and steam collectors.

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3. Stainless Steel Pipes (High Temperatures and Corrosion)

In areas of extreme heat or where the fuel generates highly corrosive gases.

• ASTM A213 (Grades TP304H, TP316H, TP347H): The "H" indicates a high carbon content, which provides greater resistance to creep failure at temperatures above 600°C.

• Application: Superheater tips where the steam reaches its maximum temperature before entering the turbine.