API RP 5LT (R2024) PDF
The recommendations provided herein apply to the transportation of coated or bare line pipe in sizes 2 3/8 in. (60.3 mm) and larger, on trailer.
This recommended practice was developed and exists, to minimize transportation damage, including transit fatigue, for bare and coated line pipe of sizes 2 3/8 in. (60.3 mm) and greater.