A106 is intended for seamless high-temperature process piping, while API 5L covers seamless and welded transportation line pipe. Compare their grades, PSL requirements, substitution limits and MTC checks before issuing an RFQ.
All pipes mentioned in this article are sold by our company.
A106 vs API 5L is a common material-selection question for EPC contractors, piping engineers and steel pipe buyers. Both specifications include Grade B carbon steel pipe, and their minimum strength values are close. However, they were developed for different systems.
ASTM A106 focuses on seamless pipe for high-temperature service. API 5L covers line pipe for transporting oil, gas and other fluids. Choosing between them requires more than comparing the grade name or tensile strength.
What Is ASTM A106 Pipe?
ASTM A106/A106M covers seamless carbon steel pipe for high-temperature service. According to ASTM, its standard size range extends from NPS 1/8 to NPS 48. Available material grades include A, B and C.
ASTM A106 Grade B is the most common purchasing grade. It is widely specified for refinery process lines, steam piping, boiler systems, power plants and chemical processing facilities.
The standard permits welding, bending, flanging and similar forming operations. However, it covers seamless pipe only. Welded pipe cannot be certified as ASTM A106.
A106 pipe is often used in systems designed under ASME B31.1 for power piping or ASME B31.3 for process piping. The material specification alone does not determine the safe operating pressure or temperature. Designers must also consider wall thickness, allowable stress, corrosion allowance and joint design.
What Is API 5L Pipe?
API Spec 5L covers seamless and welded steel line pipe used in petroleum and natural-gas pipeline transportation systems. Common manufacturing routes include seamless, HFW, SAWL and SAWH, depending on the diameter and project requirements.
The specification includes Grade A, Grade B and higher-strength X grades. For example, X42 and X52 indicate increasing specified minimum yield strength.
API 5L pipe is commonly used for gathering lines, onshore and offshore pipelines, and oil, gas or water transmission. These systems may be designed under ASME B31.4 for liquid pipelines or ASME B31.8 for gas transmission and distribution.
API 5L also separates products into PSL1 and PSL2. Buyers must state the required level in the RFQ because the two are not interchangeable purchasing descriptions.
A106 vs API 5L: Key Technical Differences
| Comparison | ASTM A106 | API 5L |
|---|---|---|
| Intended service | High-temperature process piping | Pipeline transportation |
| Manufacturing | Seamless only | Seamless or welded |
| Common grades | A, B, and C | A, B, and X grades |
| Product level | No PSL classification | PSL1 or PSL2 |
| Main design concern | Pressure, temperature, and process fluid | Strength, toughness, and pipeline environment |
| Common design codes | ASME B31.1 and B31.3 | ASME B31.4 and B31.8 |
| Inspection focus | Pipe body and material properties | Pipe body, weld seam, toughness, and traceability |
A106 Grade B has a minimum yield strength of 240 MPa and tensile strength of 415 MPa. API 5L Grade B, also called L245, has a specified minimum yield strength of 245 MPa.
These close values often cause confusion. However, chemical limits, manufacturing routes, delivery conditions and inspection requirements can still differ. Always check the editions named in the purchase specification.
The main question is not which pipe is generally “stronger.” Buyers should determine which standard matches the service conditions, design code, and project acceptance criteria.
A106 Grade B vs API 5L Grade B
A106 Grade B has a minimum yield strength of 240 MPa and a minimum tensile strength of 415 MPa. API 5L Grade B, also designated L245, has a specified minimum yield strength of 245 MPa.
These similar values explain why the two grades are frequently compared. However, similar minimum strength does not prove that the materials are equivalent.
The standards may apply different requirements to chemical composition, manufacturing route, delivery condition, dimensional tolerances, testing, and product marking. API 5L requirements can also vary according to the PSL, grade, pipe type, and standard edition.
Procurement teams should therefore compare the complete material requirements instead of relying on the words “Grade B.”
What Is the Difference Between API 5L PSL1 and PSL2?
PSL1 provides the baseline requirements for API 5L line pipe. PSL2 introduces tighter control over chemical composition, carbon equivalent, mechanical properties, delivery condition, and traceability.
PSL2 also includes additional or more clearly defined testing requirements. However, PSL2 should not be treated as automatically suitable for every critical pipeline.
For cold-climate, offshore, or sour-service projects, buyers may need to specify impact-test temperature, hardness limits, HIC testing, NDT coverage, and the applicable API 5L annexes. These requirements should be written into the purchase order.
Can API 5L Replace ASTM A106?
API 5L Grade B cannot automatically replace ASTM A106 Grade B. The same rule applies when A106 pipe is proposed for an API 5L pipeline.
Before approving a substitution, verify:
- Whether seamless construction is mandatory
- Whether the chemistry satisfies both standards
- Whether the mechanical properties are acceptable
- Whether dimensions and tolerances comply
- Whether the required delivery condition is documented
- Whether hydrostatic testing or permitted NDT has been completed
- Whether impact, hardness, or HIC testing is required
- Whether the governing code permits the material change
The project engineer or end user should approve the substitution in writing. This is particularly important for high-temperature, low-temperature, offshore, sour-service, and safety-critical systems.
When Should You Choose Each Standard?
| Project Condition | Recommended Starting Point |
|---|---|
| Steam or heated process fluid | ASTM A106 |
| Refinery or chemical process piping | ASTM A106 |
| Power plant pressure piping | ASTM A106 |
| Long-distance oil or gas transmission | API 5L |
| Large-diameter welded line pipe | API 5L |
| Pipeline requiring defined toughness | API 5L PSL2 with specified testing |
| One product must meet both standards | Verified dual-certified seamless pipe |
This chart is a selection guide rather than an engineering approval. Final material selection must follow the project specification and applicable design code.
What Does Dual Certification Mean?
Some seamless pipes can be supplied as ASTM A106 Grade B/API 5L Grade B dual-certified material.
Dual certification means the manufacturing process, chemical composition, mechanical properties, dimensions, and inspections comply with both standards. The Mill Test Certificate must identify both specifications and the applicable API 5L PSL.
Buyers should also verify the manufacturer, heat number, pipe size, wall thickness, test results, and product marking. The information marked on the pipe must match the MTC.
Adding a second specification to the stencil, invoice, or revised certificate does not create valid dual certification without supporting production and inspection records.
Procurement and Inspection Checklist
A complete RFQ should include:
- Standard edition, pipe material grade, and PSL
- Seamless or welded manufacturing route
- NPS or outside diameter
- Schedule or specified wall thickness
- Design pressure and temperature
- Transported medium and corrosion allowance
- Pipe length and end preparation
- External coating or internal lining
- Impact, hardness, HIC, and NDT requirements
- EN 10204 3.1 MTC requirements
- Third-party inspection requirements
During inspection, match the physical pipe marking with the MTC and packing list. Check the manufacturer, heat number, grade, PSL, dimensions, and test results.
Clear RFQ information reduces unsuitable quotations, repeated technical clarification, and the risk of material rejection after delivery.
Request A106 or API 5L Pipe from PANDAPIPE
The correct choice in A106 vs API 5L depends on the service environment, design code, manufacturing route, and inspection requirements.
PANDAPIPE supplies ASTM A106 seamless pipe and API 5L seamless and welded line pipe for international B2B projects.
Send us your pipe size, wall thickness, grade, PSL, quantity, transported medium, pressure, temperature, and testing requirements. We will review your RFQ and prepare a technically matched quotation with the required material documentation.
FAQs:
1. Is A106 Grade B equivalent to API 5L Grade B?
No. Their strength values overlap, but their scopes, manufacturing options, and technical requirements differ.
2. Is ASTM A106 always seamless?
Yes. ASTM A106 covers seamless carbon steel pipe. Welded pipe cannot be certified as ASTM A106.
3. Can API 5L pipe be seamless?
Yes. API 5L covers seamless pipe and several approved welded manufacturing routes.
4. Is API 5L Grade B the same as L245?
Grade B and L245 are corresponding grade designations used in API 5L. The applicable PSL and complete material requirements must still be specified.
5. Is PSL2 automatically suitable for sour service?
No. The purchase specification must define the applicable sour-service requirements, hardness limits, HIC testing, and relevant API 5L annex.
6. Can A106 pipe be used for a transmission pipeline?
Only when the governing design code and project specification permit it. Compliance with ASTM A106 alone does not establish compliance with API 5L.
7. What should buyers check on the MTC?
Check the standard and edition, grade, PSL, heat number, chemical composition, mechanical properties, dimensions, and inspection results.
8. Can one pipe meet both standards?
Yes. Its production and inspection records must demonstrate compliance with both specifications.
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