1. Introduction and Overview

API Specification 5L, 46th Edition is the international standard for steel pipe used in pipeline transportation systems, published by the American Petroleum Institute (API). This standard covers seamless and welded steel pipes for the transportation of natural gas, oil, and other liquids in the petroleum and natural gas industries .

Effective Date: November 1, 2018

Scope: The standard specifies requirements for the manufacture of two product specification levels (PSL 1 and PSL 2) of seamless and welded steel pipes for pipeline transportation systems .

2. Key Changes in the 46th Edition

The 46th edition introduces several important technical updates that reflect industry consensus within API's Subcommittee on Tubular Goods :

1. Updated and expanded requirements for mill jointers:

• Differentiation between double-jointers and mill jointers

• Requirements to avoid welding consumables environmental contamination

• Qualification standards and new process testing requirements

• Clarified offset and undercut requirements

• Standardized marking requirements

• Reference to weld repair annex

2. Updated requirements for pipe end squareness

3. Updated hardness testing requirements:

• For API 5L PSL 2 pipes for sour environments

• For API 5L PSL 2 pipes for offshore environments

4. New annex for strain-based design requirements:

• PSL 2 pipe for applications requiring longitudinal plastic strain capacity

3. Product Specification Levels (PSL)

API 5L defines two product specification levels that determine manufacturing and testing requirements:

PSL 1 (Pipeline Specification Level 1)

• Basic requirements for standard pipeline applications

• Less stringent testing and quality control requirements compared to PSL 2

PSL 2 (Pipeline Specification Level 2)

• More rigorous requirements for critical applications

• Additional testing and quality control measures

• Special requirements for raw materials (must be fine-grain sedimented steel)

• Steel strip (coil) or plate used for PSL 2 pipe manufacturing shall not bear any tack welds

4. Steel Grade Classification

API 5L uses two parallel designation systems for steel grades:

Metric System (L + number)

The letter "L" followed by the specified minimum yield strength in MPa:

• L175, L175P, L210, L245, L290, L320, L360, L390, L415, L450, L485, L555, L625, L690, L830

Imperial System (X + number)

The letter "X" followed by the minimum yield strength in 1000 psi:

• X42, X46, X52, X56, X60, X65, X70, X80, X90, X100, X120

Grade Equivalents:

• Grade A = L210

• Grade B = L245

Important Note: L415/X60 or higher grades should not be used in place of L360/X52 or lower grades without the agreement of the purchaser .

5. Manufacturing Processes and Pipe Types

Welded Steel Pipe Types

1. CW Pipe: Process of forming a seam by heating the strip in a furnace and mechanically pressing the formed edges together

2. COWH Pipe: Tubular product having one helical seam produced by a combination of gas metal arc and submerged arc welding

3. COWL Pipe: Tubular product having one or two longitudinal seams produced by a combination of gas metal arc and submerged arc welding

4. EW Pipe: Tubular product having one longitudinal seam produced by low- or high-frequency electric welding

• HFW Pipe: EW pipe produced with welding current frequency ≥ 70 kHz

• LFW Pipe: EW pipe produced with welding current frequency < 70 kHz

5. LW Pipe: Tubular product having one longitudinal seam produced by laser welding

6. SAWH Pipe: Tubular product having one helical seam produced by submerged arc welding

7. SAWL Pipe: Tubular product having one or two longitudinal seams produced by submerged arc welding

Seamless Steel Pipe

• SMLS Pipe: Hot rolled seamless steel pipe and cold rolled seamless steel pipe

• Other processing methods include cold drawing, forging, etc.

6. Raw Materials

Acceptable raw materials for steel pipes include:

• Ingot

• Billet

• Strip (coil)

• Plate

Special Requirements for PSL 2:

1. Raw material must be fine-grain sedimented steel

2. Steel strip (coil) or plate shall not bear any tack welds

7. Special Application Pipe Types (PSL 2)

API 5L PSL 2 includes specific pipe types for special applications:

1. Resistance to Ductile Fracture Propagation (G)

2. Sour Service Condition Pipe (S)

3. Offshore Service Condition Pipe (O)

4. Requiring Longitudinal Plastic Strain Capacity Pipe

8. Pipe End Types

For PSL 1:

• Socket End

• Flat End

• Special Clamp Flat End

• Threaded End

Special Notes:

1. Socket ends, pipe ends for special clamps, and threaded pipe ends are for API 5L PSL1 only

2. L175 P/A25 P steel grade API 5L PSL1 steel pipe shall be machined with threaded ends

3. API 5L PSL1 steel pipe of other steel grades shall be machined with flat ends

For PSL 2:

• API 5L PSL 2 tubes shall be delivered with flat ends only

9. Testing and Inspection Requirements

API 5L specifies various testing and inspection requirements, including:

1. Appearance inspection for common defects

2. Dimensional inspection for dimensional deviations

3. Hardness testing (especially for sour service and offshore service pipes)

4. Impact testing with updated test piece size requirements

5. Tensile testing

6. Non-destructive testing (NDT) methods

10. Marking Requirements

The standard specifies detailed marking requirements including:

• Two marking options: ISO 3183 marking or API 5L with additional "ISO 3183" marking

• Specific purchase-order information requirements

11. Relationship with ISO 3183

ISO 3183:2019 is the international standard that supplements API Spec 5L, 46th edition (2018). The technical requirements of both documents are largely identical, with ISO 3183 including some supplementary content .

Key ISO 3183 supplements include:

• Annex A (formerly Annex M) for PSL 2 pipe ordered for European onshore natural gas transmission pipelines

• New Annex N addressing PSL 2 applications requiring longitudinal plastic strain capacity

12. Industry Implementation

IOGP JIP33 S-616 Specification:

• Defines minimum common requirements for procurement of line pipe according to API 5L 46th Edition

• Includes technical requirements specification, procurement data sheet, information requirements specification, and quality requirements specification

National Standards Equivalents:

• GB/T 9711-2011 (China): Steel pipes for oil and gas industry pipeline transmission system, prepared according to API 5L

13. Applications and Users

Primary Users:

• Pipeline manufacturers and mills producing seamless and welded steel line pipe

• Pipeline operators and EPC contractors specifying line pipe

• Procurement and quality teams

• NDT personnel, inspectors, and certification bodies

• Regulators and standards committees

14. Important Considerations

1. Carbon Equivalent Control: Strict control of carbon equivalent between different steel grades

2. Manufacturing Tolerances: Updated requirements for straightness, end squareness, and dimensional controls

3. Heat Treatment: Clarified requirements for weld seams

4. NDT Personnel Qualification: Reference to ISO 9712 for NDT personnel qualification

15. Procurement Guidelines

When procuring API 5L pipe:

1. Clearly specify PSL level (1 or 2)

2. Indicate steel grade requirements

3. Specify any special application requirements (sour service, offshore, etc.)

4. Define testing and inspection requirements

5. Ensure proper marking and documentation

6. Consider IOGP JIP33 S-616 specifications for standardized procurement

This comprehensive standard ensures consistent quality and safety in pipeline transportation systems worldwide, with the 46th edition reflecting the latest industry practices and technological advancements.