API 5L PSL1 and PSL2 refer to different levels of specifications for steel pipes used in the oil and gas industry. X52 and X65 are specific grades within the API 5L specification.

An ERW (Electric Resistance Welded) steel pipe is a type of pipe that is manufactured by forming flat steel into a cylindrical shape and then welding the edges together using electrical resistance. It is commonly used for various applications, including building structures.

API 5L PSL1 and PSL2 standards define the requirements for the chemical composition, mechanical properties, manufacturing processes, and testing procedures of steel pipes. PSL1 pipes have lower requirements compared to PSL2, especially in terms of impact toughness and nondestructive testing.

X52 and X65 are both high-strength grades within the API 5L specification. X52 has a minimum yield strength of 52,000 psi (360 MPa), while X65 has a minimum yield strength of 65,000 psi (450 MPa). These grades offer excellent strength and toughness properties, making them suitable for demanding applications in building structures.

In summary, API 5L PSL1 and PSL2 X52 and X65 ERW steel pipes are specifically designed for use in building structures. They meet stringent industry standards and provide high-strength and reliable performance for structural applications in the oil and gas industry.