API 5L X46 is a line-pipe strength grade available in PSL 1 and PSL 2 and in permitted seamless and welded forms. Its corresponding SI designation is L320. Under the API 5L 46th-edition SI baseline, the minimum yield and tensile strengths are 320 MPa and 435 MPa respectively, subject to applicable table notes. LONGMA supplies round ERW and LSAW pipe. The order must identify the grade, PSL, process, delivery condition, dimensions and governing standard edition.
Overview of API 5L X46 Pipe Specifications
Chemical Composition and Mechanical Properties
Chemical requirements depend on PSL, manufacturing route, delivery condition and wall thickness. Compare the complete applicable chemistry table and its notes rather than apply one composition limit to all X46 products. Maximum values are acceptance limits, not target compositions. For sour service, ordinary PSL 2 chemistry does not replace the applicable material qualification and additional controls.
The following values summarize the API 5L 46th-edition SI strength baseline for X46. PSL 2 also has upper property limits and other applicable restrictions. API published the 47th edition in June 2026; the edition and amendments specified in the order govern acceptance.
| Property | Minimum Value |
| Minimum yield strength | 320 MPa SI baseline |
| Minimum tensile strength | 435 MPa SI baseline |
| Elongation | Calculated under applicable standard provisions |
Field weldability depends on chemistry, carbon equivalent, thickness, diffusible hydrogen, restraint and welding conditions. Apply the appropriate carbon-equivalent formula and limit under the specified standard. A single CEV value does not justify omitting preheat or heat treatment. The qualified welding procedure must define preheat, interpass temperature and other controls for the actual construction conditions.
Dimensional Standards and Manufacturing Processes
API 5L permits seamless and welded manufacturing routes for X46 within the standard’s provisions. High-frequency ERW pipe is generally formed from coil, while LSAW pipe is formed from plate, often using JCOE or UOE processes. Available OD, wall thickness and length depend on mill capability. These production ranges are not universal API 5L dimensional limits. Confirm the proposed mill can manufacture and inspect the exact ordered combination.
Outside-diameter and wall-thickness tolerances depend on dimensions and manufacturing route. Pipe-body and pipe-end requirements may differ. Check the applicable tables for OD, wall thickness, ovality, straightness and length; do not apply one percentage to every X46 welded pipe. For API 5L and ISO 3183 dual certification, compare the complete requirements of the specified editions.
PSL1 vs PSL2 What EPC and NOC Buyers Must Know
PSL 1 establishes basic chemical, mechanical, manufacturing and inspection requirements. PSL 2 adds controls including applicable impact testing, carbon-equivalent limits and restrictions on mechanical properties. Weld inspection is not exclusive to PSL 2. Sour-service hardness and environmental-cracking provisions must be identified separately where ordered; they should not be described as universal requirements for all PSL 2 pipe.
Key Advantages of API 5L X46 Pipes in Pipeline Applications
X46 can be selected where its strength and manufacturing options suit the approved pipeline design. Suitability for onshore, offshore or subsea service depends on dimensions, delivery condition, fracture-control requirements, corrosion protection and project supplements. The grade does not have a fixed operating-pressure category.
- Strength and design flexibility: X46 has a higher minimum yield-strength class than X42 and a lower one than X52. A grade change may affect calculated wall thickness, but substitution requires design approval. Do not reduce grade solely because an existing operating pressure appears modest.
- Weld quality: ERW and LSAW require controlled manufacturing and the applicable weld examination. Agree the permitted NDE methods, coverage, acceptance criteria and treatment of untested pipe ends. Hydrostatic testing verifies compliance with the specified test conditions and does not replace NDE.
- Coating options: External 3LPE, FBE, 3LPP or liquid-epoxy systems can be specified for the installation environment and temperature. Select the applicable coating standard and inspection scope separately. Internal flow-efficiency and internal corrosion-protection coatings have different functions and must be specified accordingly.
- Traceability: Specify the EN 10204 inspection document type and maintain links between the supplied pipe, material identity and test records. Third-party source inspection can be included in the inspection and test plan where required. The complete document package must meet the project’s requirements.
Assess material, fabrication, inspection, coating and delivery costs together. The approved technical specification should remain the basis for comparing suppliers.
Comparison API 5L X46 vs Other Pipe Grades
The table below compares nominal strength-class designations. It is not a pressure-rating table. SI grade numbers and the numbers in X designations represent corresponding strength classes; standard tables must be used consistently rather than replaced with direct unit conversions.
| X grade | Corresponding SI class | Relative strength class | Pressure selection |
| X42 | L290 | Below X46 | Approved design required |
| X46 | L320 | Between X42 and X52 | Approved design required |
| X52 | L360 | Above X46 | Approved design required |
| X65 | L450 | Above X52 | Approved design required |
X46 lies between X42 and X52 in the strength-grade sequence. Pressure capability depends on wall thickness, diameter and the governing design code as well as material properties. ASTM A106 Grade B is a seamless carbon-steel pipe specification for high-temperature service and is not automatically interchangeable with X46 line pipe. Product requirements and the approved service specification must be compared in full.
Procurement Considerations for API 5L X46 Pipes
Finding API 5L X46 pipe for a genuine project entails more than simply looking at costs. All of these activities – managing lead time, validating certificates and a supplier’s capabilities – directly impact fulfilling project deadlines.
The API 5L X46 line pipe pricing is based on the prices of hot-rolled coil and heavy plate. Volume pricing is possible for sales beyond 500 metric tons, but it has to be balanced against the expenses of transportation and warehousing management. Minimum order quantities (MOQs) vary wildly from one manufacturer to the next. Suppliers with enough completed materials in inventory may handle smaller spot orders, but custom-sized or heavy-wall orders normally need 30 to 45 days to produce.
Verify the manufacturing mill’s current API Monogram licence and scope where Monogram-marked pipe is required. The customer does not need a manufacturing licence to purchase pipe. Review the quality system, manufacturing range, traceability and inspection capability. EN 10204 defines document types; the contract determines whether Type 3.1 or 3.2 is required. UT and RT scope must match the applicable process and project, rather than a universal requirement for both methods on every weld.
Specify plain or bevelled ends and the applicable preparation standard in the order. Bevel angle, root face and any compound preparation depend on the selected standard, thickness and welding design. API 5L and ASME B16.25 should not be assumed to have identical end-preparation requirements. Agree end protection, export documentation and shipment arrangements with the supplier.
Conclusion
API 5L X46 specifies a strength grade, not a complete pipeline design. A reliable purchase specification also identifies PSL, manufacturing process, delivery condition, dimensions, testing and coating. Confirm the governing edition and required inspection documents before production. These details allow buyers to verify the supplied material against the approved design.
FAQ
What distinguishes API 5L X46 PSL1 from PSL2
PSL 2 contains additional controls for material properties and testing, including applicable CVN requirements and carbon-equivalent provisions. PSL 1 also has manufacturing and inspection requirements. The project design and material specification determine which PSL is acceptable; neither a third-party audit nor overseas destination alone determines the choice.
Can X46 pipe be used in sour service environments
Yes, where material qualification and the specified API 5L sour-service requirements are satisfied. Use the complete grade designation appropriate to the delivery condition and specified edition rather than an abbreviated X46S description. Agree hardness locations and limits, qualification and any HIC or SSC testing. Ordinary X46 PSL 2 compliance does not by itself establish sour-service suitability.
What welding process is used in the field for X46
SMAW, GTAW and GMAW can be used where supported by a qualified procedure for the actual joint and service conditions. Apply the construction code’s qualification rules; API 1104 or ASME Section IX may be specified as applicable. Preheat and interpass controls must come from the approved procedure and cannot be waived solely because the pipe is X46.
What coatings are available for X46 line pipe
Options include external 3LPE, FBE, 3LPP and liquid epoxy. Specify the system, standard, thickness and acceptance tests for the installation environment. Where DIN 30670 is selected for polyethylene coating, identify the applicable part and edition. Specify the purpose and technical requirements of an internal coating separately.
How is X46 pipe different from ASTM A106 Grade B
ASTM A106 Grade B covers seamless pipe for high-temperature service. API 5L X46 covers a line-pipe strength grade and permits seamless and specified welded routes. Their strength, manufacture and testing requirements differ. Neither specification alone makes a product suitable for every pressure or corrosion condition.
Request a Quote for API 5L X46 Pipe LONGMA
Since 2003, LONGMA has manufactured round ERW and LSAW steel line pipe. Our facility covers 230,000 square metres and annual output exceeds 500,000 tonnes. We can arrange the agreed inspection documentation and third-party inspection. Stock pipe may be available for dispatch within seven days and custom orders in around 45 days, subject to technical review and order confirmation. Send your grade, OD, wall thickness, PSL, quantity and service requirements to info@ilongma.com for a quotation.
