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# API 5L X65 Line Pipe Applications and Specifications
API 5L X65 line pipes are engineered to provide both cost-effectiveness and safety when it comes to transporting oil and natural gas. Corrosion remains one of the primary causes of pipeline failures, and understanding how plastic deformation affects the mechanical properties of these pipes is crucial to preventing catastrophic failures.
## Understanding the Meaning of API 5L X65 Q PSL2 Levels
- **X65 Minimum Yield Strength**: The yield strength is 450 MPa (or 65,300 psi) for the pipe body.
- **Q Delivery Conditions**: This involves a combination of normalizing rolling (+N) followed by quenching and tempering (+Q). Quenching and tempering refer to a heat treatment process that enhances the material's strength and ductility.
- **PSL Level**: Product Specification Level (PSL) 2 provides a broader range of chemical compositions and mandates a higher minimum fracture toughness compared to PSL1.
### Delivery Conditions for API 5L X65 Line Pipes
| PSL | Delivery Condition | Pipe Grades |
|-----|-----------------------------------|-------------------------------------|
| PSL1| As-rolled, Normalizing Rolled | X42, X46, X52, X56, X60, X65, X70 |
| PSL2| Quenched and Tempered | BQ, X42Q, X46Q, X56Q, X60Q, X65Q, X70Q, X80Q, X90Q, X100Q |
| | Thermomechanical Rolled/Formed | BM, X42M, X46M, X56M, X60M, X65M, X70M, X80M |
## Chemical Composition for API 5L X65 PSL 1 Pipes (t ≤ 0.984")
| Steel Grade | C (%) | Mn (%) | P (%) | S (%) | V (%) | Nb (%) | Ti (%) |
|-------------|-------|--------|-------|-------|-------|--------|--------|
| X65 | ≤0.28 | ≤1.40 | ≤0.3 | ≤0.3 | f | f | f |
*Note: Unless otherwise agreed, NB + V = Ti ≤ 0.15%.
## Chemical Composition for API 5L X65 PSL 2 Pipes (t ≤ 0.984")
| Steel Grade | C (%) | Si (%) | Mn (%) | P (%) | S (%) | V (%) | Nb (%) | Ti (%) | Other (%) | CE IIW | CE Pcm |
|-------------|-------|--------|--------|-------|-------|-------|--------|--------|-----------|---------|---------|
| X65Q | ≤0.18 | ≤0.45 | ≤1.70 | ≤0.025| ≤0.015| g | g | g | h,l | ≤0.043 | ≤0.25 |
*Note: Unless otherwise agreed, Cu ≤ 0.50%, Ni ≤ 0.50%, Cr ≤ 0.50%, Mo ≤ 0.50%, and no intentional addition of B is permitted unless otherwise agreed, with residual B ≤ 0.001%.
## Mechanical Properties of API 5L X65
### Tensile Properties – Pipe Body of SMLS and Welded Pipes (PSL 1)
| Pipe Grade | Yield Strength (Rt0,5 PSI Min) | Tensile Strength (Rm PSI Min) | Elongation (Af % Min) |
|------------|--------------------------------|-------------------------------|-----------------------|
| X65 | 65,300 | 77,500 | c |
*Note: The specified minimum elongation, Af, shall be determined using a specific equation.
### Tensile Properties – Pipe Body of SMLS and Welded Pipes (PSL 2)
| Pipe Grade | Yield Strength (Rt0,5 PSI Min) | Tensile Strength (Rm PSI Min) | Ratio (R10,5IRm) | Elongation (Af % Min) |
|------------|--------------------------------|-------------------------------|------------------|-----------------------|
| X65Q, X65M| 65,300 | 77,600 | 0.93 | f |
*Note: The specified minimum elongation, Af, shall be determined using a specific equation.
### Bend Test
The bend test requires that no cracks appear in any part of the test piece, and the weld must not open during the test.
### Flattening Test
The acceptance criteria for the flattening test state that for EW pipes with D < 12.750 inches:
- For X60 with T ≤ 500 inches, the weld should not open until the distance between the plates is less than 66% of the original outside diameter.
- For all grades and wall thicknesses, the weld should not open until the distance between the plates is less than 50% of the original outside diameter.
- For pipes with D/t > 10, the weld should not open until the distance between the plates is less than 30% of the original outside diameter.
For other sizes, refer to the full API 5L specification.
### Charpy V-Notch Impact Test (PSL2)
Many PSL2 pipe sizes and grades require Charpy V-notch impact testing. Seamless pipes are tested in the body, while welded pipes are tested in the body, pipe weld, and heat-affected zone. Refer to the full API 5L specification for size and grade charts and required absorbed energy values.
### Surface Inspection
All surfaces are 100% visually inspected, and the surface condition complies with API 5L Annex E. The external surface of the pipe is coated with a layer of varnish.
### Non-Destructive Testing (NDT)
All pipes are ultrasonically tested on the pipe body and ends as per API 5L Annex E, Table E.2, and para E.3.3. Coverage includes 100% longitudinal coverage of the pipe surface, and pipe ends not scanned by an automatic ultrasonic system are inspected manually via ultrasonic testing or magnetic particle examination.
### Hydrostatic Test
The hydrostatic test pressure may not exceed 2970 psi, as per API 5L requirements. The holding time is a minimum of 5 seconds.
### Certification and Traceability
All dimensions come with a 3.2 certificate according to EN 10204, endorsed by a recognized and independent inspection agency. Marking is in SI units (X65), in compliance with API requirements and mill standards.
In conclusion, the API 5L X65 line pipe is a highly reliable option for transporting oil and gas, offering excellent mechanical properties and stringent quality control measures to ensure safety and durability.