Basic Overview
API 5L Grade A longitudinal submerged arc welded (LSAW) pipe is the entry-level strength grade in the API 5L family, designed for low-pressure fluid transmission such as water, gas, and oil gathering lines. Grade A is a low-carbon steel with a minimum yield strength of 207 MPa (30,000 psi), providing a good balance of toughness and ductility at economical cost.
Mechanical Properties and Chemical Composition
| Property | Value |
|---|---|
| Minimum yield strength | 207 MPa (30,000 psi) |
| Minimum tensile strength | 331 MPa (48,000 psi) |
| Minimum elongation | 20 percent (in 200 mm) |
| Hardness | 187 HB maximum |
The chemical composition for Grade A PSL1 limits carbon to 0.28 percent, manganese to 1.20 percent, and phosphorus and sulfur to 0.03 percent each.
Manufacturing Process
LSAW pipe is formed from steel plate by UOE, JCOE, or roll bending processes, then welded longitudinally with submerged arc welding on the inside and outside. After forming and welding, the pipe may be mechanically expanded to precise dimensions, followed by non-destructive testing and hydrostatic testing. The process supports outside diameters from 323.9 mm to 1820 mm (12 to 72 in) with wall thicknesses from 5.0 to 50 mm, and lengths up to 18 m.
Grade A vs Grade B
Grade B has a minimum yield of 241 MPa (35 ksi) and a minimum tensile of 414 MPa (60 ksi), with a maximum carbon of 0.30 percent for welded pipe. Grade A is typically chosen for non-critical, low-pressure systems, while Grade B is the most common grade for general pipeline service. For higher pressure, X42 and above are used.
Testing and Inspection
API 5L Gr A LSAW pipe is verified by chemical analysis, tensile tests, flattening and bend tests, hydrostatic testing, and X-ray or ultrasonic examination of the weld seam. A mill test certificate to EN 10204 Type 3.1 is typically provided with full test results.
Applications
Common applications include low-pressure oil and gas gathering lines, water supply and irrigation pipelines, structural and piling applications, general utility piping, and low-pressure petrochemical process lines. For buried pipelines, coatings such as 3-layer polyethylene or fusion bonded epoxy are applied.
Frequently Asked Questions
Q: What is the yield strength of API 5L Grade A?
A: Grade A has a minimum yield strength of 207 MPa (30,000 psi) and a minimum tensile strength of 331 MPa (48,000 psi).
Q: What is the difference between Grade A and Grade B?
A: Grade B has a higher minimum yield of 241 MPa and tensile of 414 MPa, making it suitable for general pipeline service; Grade A is for low-pressure, non-critical systems.
Q: What sizes can LSAW Grade A pipe be made in?
A: Outside diameters from 323.9 mm to 1820 mm with wall thicknesses from 5.0 to 50 mm and lengths up to 18 m are available.
Q: What is the difference between LSAW and SSAW?
A: LSAW has a longitudinal weld along the pipe length; SSAW has a spiral weld. LSAW is preferred for heavy wall and high-pressure service, SSAW for very large diameters.
Q: Is impact testing required for Grade A?
A: Not for PSL1. Impact testing is mandatory for PSL2 grades, which is one reason Grade A is commonly specified as PSL1.
Q: What are the international equivalents of Grade A?
A> ISO 3183 L210 and GB/T 9711 L210 are the corresponding designations for the same strength level.
For API 5L Grade A LSAW pipe quotations with size, coating, and testing requirements, contact our sales team.
