YB 4102 Welded Steel Tubes for Low- and Medium-Pressure Boilers

YB 4102-2000 covered electrically welded carbon steel boiler tubes in Grades 10 and 20. Historical references list outside diameters of 10–114 mm and nominal wall thicknesses of 1.5–6.0 mm in specified combinations. China’s standards registry lists YB 4102-2000 as withdrawn. If an existing boiler drawing calls for it, confirm the governing boiler code and obtain the responsible engineer’s approval of the material and manufacturing route before ordering.

Specifications

The OD and wall thickness ranges summarize a size schedule. Confirm the exact OD × wall combination and its acceptance limits before ordering.

Key Characteristics

• Grade 10 has a room-temperature tensile strength of 335–475 MPa, a minimum yield strength of 195 MPa, and a minimum elongation of 28% on the historical δ₅ basis.
• Grade 20 has a room-temperature tensile strength of 410–550 MPa, a minimum yield strength of 245 MPa, and a minimum elongation of 24% on the historical δ₅ basis.
• The former Chinese boiler regulation listed YB 4102 heating-surface tubes at a working pressure of up to 5.3 MPa and a calculated tube wall temperature of up to 300 °C. These were limits under that regulation. The allowable working pressure of a specific tube depends on the governing code, design temperature and minimum wall thickness.

Our Advantages

1. Material review for legacy drawings. If your drawing calls for YB 4102, include the drawing revision, design pressure, design temperature and governing code with your inquiry. Any proposed alternative can then be reviewed for grade, weld route, delivery condition and test requirements before the order is placed.
2. Fit requirements defined before production. For expanded tube ends, specify the tube sheet hole diameter, OD tolerance, ovality, minimum wall, end condition and internal weld bead limit. Put these values on the approved drawing so the mill and receiving inspector use the same acceptance criteria.
3. Inspection requirements agreed before purchase. Specify the required hydrostatic and nondestructive tests, including whether both are required, along with the method, coverage and acceptance criteria. Request a mill test certificate with heat and lot identification, chemistry, tensile results and the agreed inspection records.

Applicable and Reference Standards

Each standard below has its own scope and acceptance criteria. Any change of standard or manufacturing route requires project approval.

Application

Replacement second-pass smoke tube in a three-pass, wet-back fire-tube steam boiler. Match the original tube OD, minimum wall, installed length and tube sheet joint detail. Use the material and manufacturing route approved for the repair.

Chemical Composition

Values are in mass percent. Grades 10 and 20 are the historical YB grades. STB340, STB410 and STB510 are separate JIS grades shown for comparison. Each requires its own approval for substitution.

A dash indicates that the JIS heat-analysis table gives no limit for that element. JIS also allows the purchaser to specify 0.10–0.35% Si.

Mechanical Properties

These values apply at room temperature. The YB rows use the historical δ₅ elongation basis. The JIS rows show longitudinal elongation for OD ≥20 mm using a No. 11 specimen. Use the applicable JIS table for other diameters and specimen types, including No. 12 specimens on tubes with wall thickness below 8 mm.