Comprehensive analysis of API 5L X46N seamless steel tube

1、 Definition and Standards

API 5L X46N seamless steel tube is a pipeline pipe for oil and gas transportation that meets the API SPEC 5L 46th edition standard. It belongs to the PSL1 (Product Specification Level 1) category and is suitable for medium and high pressure oil and gas transportation and acidic service environments. Its core standards include:

Material specification: X46N represents a minimum yield strength of 320MPa, and the suffix "N" represents suitability for acidic environments (such as media containing hydrogen sulfide).

Production range: Outer diameter 21.3mm~1020mm, wall thickness 2mm~130mm, supporting processes such as hot rolling, cold drawing, and hot expansion.

2、 Chemical and Mechanical Properties

Chemical composition (mass fraction,%)

Elemental carbon (C), manganese (Mn), phosphorus (P), sulfur (S), chromium (Cr), nickel (Ni)

Range ≤ 0.28 ≤ 1.40 ≤ 0.030 ≤ 0.030--

Note: The specific composition needs to be adjusted based on melting analysis and product analysis

Mechanical performance

Indicator parameters

Yield strength (Rt0.5) ≥ 320 MPa

Tensile strength (Rm) ≥ 435 MPa

Elongation rate (%) ≥ 40% (thickness ≤ 12.7mm)

Yield ratio ≤ 0.93

The data is based on the PSL1 standard and is applicable to seamless steel pipes

3、 Production process and testing

Manufacturing process

Hot rolling forming: Controlling wall thickness uniformity through multiple passes of rolling and eliminating internal stress through annealing.

Surface treatment: Acid washing is used to remove the oxide layer, and the surface roughness meets the requirement of Ra ≤ 0.4 μ m.

Testing requirements

Physical testing: tensile testing, hardness testing (Brinell/Rockwell), and impact testing.

Defect detection: Ultrasonic testing (UT) is used to screen for internal pores/cracks, and metallographic analysis is used to verify the uniformity of austenite grains.

4、 Core application areas

Oil and gas transportation

Long distance high-pressure natural gas/crude oil pipelines, suitable for land and shallow sea environments.

Acidic service

The transportation of corrosive media containing hydrogen sulfide (H ₂ S) must comply with NACE MR0175 standard.

Industrial structural components

Storage tanks, valves, and high-pressure equipment connections must comply with the TSG D7002 Pressure Pipeline Component Specification.

5、 Corrosion prevention and surface treatment

Coating type: 3PE (three-layer polyethylene), FBE (fusion bonded epoxy powder) or cement mortar coating to enhance corrosion resistance.

Applicable scenarios: high humidity, salt spray, or chemically corrosive environments (such as offshore platforms, chemical plants).