Steam Boiler: Material For Steam Boiler

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Forming Shape of Steel

Almost 100% except insulation and lagging, material in steam boiler construction is made from steel. Methods of forming shape are also described in requirement of ASME BPV Section I and Section II (American Society of Mechanical Engineer Boiler and Pressure Vessel.

The following below is the methods of forming shape of steel:

1. Casting

Casting is the method of forming steel by molten a metal in a certain place which has been designed and permit it to be solid shape

2. Forging

Forging is the method of forming steel by using pressure and impact to form steel as per design.

3. Rolling

Rolling is the methods of forming steel by roll process either cold roll or hot roll.

Requirement ASME for Material

ASME BPV stand for American Society of Mechanical Engineer Boiler and Pressure Vessel, it has requirements to set material will be used for steam boiler. ASME BPV Section I and Section II has important role to regulate the using of material. ASME BPV section II has four parts; each part explain about ferrous material specifications, nonferrous material specifications, specification for welding rods electrodes and filler metals, and explain about properties respectively.

The following below is summary sub chapter which can be known about material to be used in steam boiler:

# Material Specification, see ASME BPV Section II Part D
# Carbon Content for Cutting and Construction Process, see ASME BPV Section I sub chapter PW 5.2
# Welding Filler Metal and Electrodes, see ASME BPV Section I sub chapter PW 5.4
# Material Size Limits and Tolerance, see ASME BPV Section I sub chapter PG 5.4
# Plate Specifications, see ASME BPV Section I sub chapter PG 6
# Material Forging, see ASME BPV Section I sub chapter PG 7
# Material Casting, see ASME BPV Section I sub chapter PG 8
# Pipe, Tubes, and Pressure Containing Parts, see ASME BPV Section I sub chapter PG 9
# Material Identified with or Produced to a Specification Not Permitted by This Section, and Material Not Fully Identified, see ASME BPV Section I sub chapter PG 10
# Miscellaneous Pressure Parts, see ASME BPV Section I sub chapter PG 11
# Gage Glass Body and Connector Material, see ASME BPV Section I sub chapter PG 12
# Stays, see ASME BPV Section I sub chapter PG 13
# Material Steam Boiler which is Fabricated by Brazing, see ASME BPV Section I sub chapter PB
# Material for Water Tube Boilers, see ASME BPV Section I sub chapter PWT 5
# Material for Fire Tube Boilers, see ASME BPV Section I sub chapter PFT 5
# Material for Miniature Boilers, see ASME BPV Section I sub chapter PMB 5
# Material for Electric Boilers, see ASME BPV Section I sub chapter PEB 5
# Material for Organic Fluid Vaporizers, see ASME BPV Section I sub chapter PVG 5

Classification of Steel in Steam Boiler

The steam boiler is mainly constructed with steel material; include pressure part and non pressure part such as pipe, tube, plate, and structure. Steel can be classified by:

1. Manufacturing Method

Steel making method can be done by one of the following way: electric arc, acid open hearth, basic open hearth, basic oxygen, and acid bessemer.

2. Percentage of Carbon

Properties of steel are influenced by composition of carbon. Higher carbon will make steel has high tensile strength, hardness, fatigue resistance, and harden ability. Lower carbon composition in steel will make it low ductility, toughness, weldability, formability and machinability.

3. Percentage of Alloy

Alloying elements are added to obtain specific properties like corrosion resistance, elevated temperature strength, hardness, toughness, and so on. Alloying material that can be added are Cr, Al, Mn, Mo, Ni, St, W, V, S and Cu.

4. Grain Size

The steel can be classified based on coarsening of grain size. They are fine grained and coarse grained. Fine grained can generate higher yield and tensile strength than coarse grained.

5. Hardenability

Hardenability in material is influenced by percentage of carbon and alloy. Low carbon and no alloy will make steel is non hardenability, this material is usually used for welding and cold working. Medium carbon and low alloy will make material be shallow hardening steel. High carbon and high alloy will make material be deep hardening steel.

6. Amount of Deoxidation

Deoxidation process in manufacturing of steel is a process to reduce entrapped gasses such as CO in solid ingot that causes inconsistency of material and blow holes in steel. The result of deoxidation process will causes steel can be classified into three types such as rimmed steel, killed steel and semi killed steel.

Rules Regarding the Use of Material on Steam Boiler

All of materials used for construction of the steam boiler for best design should refer to ASME Code (American Society of Mechanical Engineers) because ASME Code takes high care to ensure the quality of the material. All of specification materials with classification of temperature design of material, allowable pressure, corrosion, manufacturing tolerance, erosion, wear and tear can be seen in ASME Boiler and Pressure Vessel (ASME BPV) Code Section II Parts A, B, C, and D. While for design and do calculation steam boiler refers to ASME BPV Section I.

ASME BPV Section II consists of four separate books:

1. ASME BPV Section II Part A: Ferrous Material Specifications

This code provides ferrous material specification that is safe for use on pressurized equipment.

2. ASME BPV Section II Part B: Nonferrous Material Specifications

This code provides nonferrous material specification that is safe for use on pressurized equipment.

3. ASME BPV Section II Part C: Specification for Welding Rod, Electrodes, and Filler Metals

This code provides filler metal procurement guidelines, specification for carbon, stainless and low alloy steel electrodes for shielded metal arc welding, specification for carbon and low alloy steel rods for oxyfuel gas welding, welding shielding gases, and so on.

4. ASME Section II Part D: Properties

This code provides properties of material such as stress tables, physical properties tables, chats and tables for determining shell thickness of components under external pressure.