API 5L X42 is a specification under the American Petroleum Institute (API) that defines standards for line pipes used in transporting oil, gas, and water in the oil and gas industry. The "X" designation signifies that the pipe is a high-strength grade, and the "42" refers to the minimum yield strength of 42,000 psi (290 MPa). API 5L X42 pipe is primarily used in conveying fluids in pipelines.

API 5L X42 Specification:

1. Chemical Composition:

The chemical composition of API 5L X42 pipe is regulated to ensure consistent mechanical properties.

Carbon (C): ≤ 0.22% max

Manganese (Mn): 1.40% max

Phosphorus (P): ≤ 0.025% max

Sulfur (S): ≤ 0.015% max

Silicon (Si): ≤ 0.45%

Additional alloying elements like niobium, vanadium, and titanium may be added to improve mechanical properties.

2. Mechanical Properties:

Yield Strength: Minimum 42,000 psi (290 MPa)

Tensile Strength: Minimum 60,200 psi (415 MPa)

Elongation: Depends on the thickness of the pipe; typically around 20%.

3. Physical Properties:

Density: 7.85 g/cm³

Modulus of Elasticity: 200-210 GPa

4. Manufacturing Process:

API 5L X42 pipes can be produced through different methods, including:

Seamless (SMLS)

Electric Resistance Welded (ERW)

High Frequency Induction Welded (HFIW)

Double Submerged Arc Welded (DSAW)

5. Application:

API 5L X42 pipes are used for the following:

Oil, gas, and water transmission pipelines.

Structural applications in the oil and gas industry.

Offshore and onshore piping systems.

6. PSL1 vs. PSL2:

API 5L X42 comes in two product specification levels (PSL1 and PSL2), which determine the quality and testing requirements:

PSL1: Basic requirements, fewer mechanical property tests.

PSL2: More stringent testing requirements for chemical composition, toughness, and non-destructive testing (NDT).

Applications:

Natural gas and oil pipelines.

Structural and pressure vessel applications.

Water transmission systems.

API 5L X42 is a widely used pipe grade due to its balance of strength, weldability, and cost. It is preferred for moderate-strength applications.