API 5L is normally used for both seamless steel pipes and welded steel pipes,but ASTM A106 is specially for seamless carbon steel pipes which can be used for high-temperature and high-pressures service.
API 5L steel pipes are derived from API Spec 5L specification for line pipe,and they are suitable for the transportation of gas,oil and water.API 5L are divided into two product levels:API 5L PSL1 and API 5L PSL2.PSL1 is a standard quality for line pipe where PSL2 contains additional chemical,mechanical properties,and testing requirements.Grades covered by API 5L specification are A25,A,B and “X” Grades X42,X46,X52,X56,X60,X65,X70, X80.The two digit number following the “X” indicates the Minimum Yield Strength (in 000’s psi) of pipe produced to this grade.
ASTM A106(S/A 106) steel pipes are the standard specification for seamless carbon steel pipe for high-temperature and high-pressures service,such as power generation. ASTM A106 steel pipes contain three grades: ASTM A106 Grade A, ASTM A106 Grade B, ASTM A106 Grade C.
API 5L is a relatively comprehensive specification,mainly developing line pipes for the oil and gas industry;the range of strength levels is much wider.While the lower strength grades A & B are comparable to ASTM A106,the strength of other grades are much higher (e.g. X42, X56, X60, etc.).In addition,the quality rating is more stringent when API 5L line pipe PSL2 is applied,the rolling rating is not acceptable and rework is not allowed.Moreover, particular attention is given to toughness and toughness tests for sour services and higher pressure/ temperature classes.