API 5L vs ASTM A53 steel pipe

In oil and gas long-distance pipeline projects, API 5L standard is preferred in high-pressure environments because of its higher requirements for chemical composition, mechanical properties and non-destructive testing; In general steam, water, air and structural piping, ASTM A53 occupies a wide range of application scenarios due to its wide coverage of welded and seamless types, low cost and relatively lenient inspection requirements. There are significant differences between the two in terms of application scope, product grade, performance testing and strength grade, etc. This article will conduct an in-depth comparison around these core elements.

The definitions of API 5L and ASTM A53

API 5L API 5L is the execution standard of the American petroleum Institute (API) for steel pipes used in transportation pipelines. It is mainly used in long-distance transportation systems of oil, natural gas and other pipelines, covering two major categories: seamless pipes and welded pipes (straight seam LSAW, spiral SSAW, ERW, etc.) It is divided into two product specification grades: PSL1 (General grade) and PSL2 (High Requirement grade). The latter has stricter requirements in terms of impact toughness, mechanical properties and non-destructive testing.

ASTM A53: ASTM A53 is the general specification of the ASTM international organization for carbon steel pipes (welded or seamless), applicable to the transportation of steam, water, air and general low-pressure fluids, and can also be used for mechanical or structural purposes. It covers NPS 1/8 to NPS 26 (nominal diameter 6 mm - 650 mm), including processes such as cold drawing and hot rolling.

Type and Grade

Standard	Type	Grade
API 5L	PSL1/PSL2	PSL1:Common steel grades L290 PSL2:X42-X80
ASTM A53	Type F Type E Type S	Grade A Grade B

Chemical composition comparison between API 5L and ASTM A53

API 5L:
PSL1 steel Grade (e.g. Grade B) : C ≤ 0.28%, Mn 0.9-1.2%, Si ≤ 0.45%.
PSL2 steel grades (such as X42 - X80) : In addition to meeting the requirements of PSL1, the control over elements like sulfur and phosphorus is more stringent, and the range of additional alloying elements and deoxidation state requirements must also be met.

ASTM A53:
C ≤ 0.30%, Mn ≤ 0.45%, P ≤ 0.035%, S ≤ 0.04%.
Grade B has A higher content of carbon and manganese than Grade A, which can significantly enhance the strength of the pipe.

Comparison of mechanical properties

Minimum yield strength: API 5LGradeB (PSL1) :241MPa, API 5L X Grade (PSL2) : 290-550MPa; ASTM A53 Grade A: 205MPa, ASTM A53 Grade B: 241MPa.
Minimum tensile strength: API 5LGradeB (PSL1) :415MPa, API 5L X Grade (PSL2) : 455-620MPa; ASTM A53 Grade A: 330MPa, ASTM A53 Grade B: 415MPa.

Comparison of inspection and testing

API 5L PSL1
Conduct a hydrostatic test and chemical composition inspection on each pipe.

API 5L PSL2
In addition to the hydrostatic test, 100% X-ray or ultrasonic testing is required. All steel grades except X80 were subjected to impact at -0 ℃, with longitudinal ≥101 J and transverse ≥68 J.

ASTM A53
Non-100% hydrostatic testing is allowed as a substitute; 100% non-destructive testing and impact testing are not required.

Comparison of application fields

API 5L
It is specifically designed for oil, natural gas and other transportation pipelines, especially suitable for long-distance and high-pressure environments.

ASTM A53
It is applicable to general low-pressure transportation (steam, water, air), mechanical structures and heat exchanger pipelines. It is also commonly found in building water supply and drainage as well as HVAC systems.

Summary

API 5L is designed for oil and gas pipelines and is divided into PSL1 (basic) and PSL2 (reinforced). Suitable for scenarios with high pressure, long distance and high toughness requirements. ASTM A53 is a general-purpose carbon steel pipe with various manufacturing methods, suitable for low and medium pressure transportation and structural applications; Moderate strength and high cost performance. When choosing pipe materials, a reasonable selection should be made based on factors such as fluid type, temperature and pressure environment, compliance with standards and economy.