Tubing is used as a fluid or liquid injection pipe.Usually pipe OD ≤ 2-1/16"（52.4mm）we called small-sizes tubing, which is mainly used for water injection, oil recovery and oil gas recovery.
(1) API: NU (Non-upset with coupling); EU (External upset with coupling); IJ (integral joint without Coupling)
（2）Non-API: CB-IJ (Changbao extreme-line without coupling); CB-FJ (Changbao extreme-line without coupling with gas sealed), etc.
API SPEC 5CT
API SPEC 5B
Ranking of joint OD size:EU＞NU＞IJ＞CB-IJ＞CB-FJ；
Ranking of joint ID size:CB-IJ=EU=NU＞CB-FJ＞IJ；
Ranking of joint connection strength:EU＞IJ＞CB-IJ＞NU＞CB-FJ；
(4) The performance of product depends on the size of the pipe body (OD, WT), Grade, etc.