Metinox Overseas supplies ASTM A420 WPL6 low-temperature carbon steel butt weld fittings for pressure piping and pressure vessel service where impact toughness at -50°F (-45.6°C) is specified. The range includes elbows, tees, reducers, caps, stub ends and crosses manufactured to applicable dimensional standards such as ASME B16.9 and ASME B16.28. Each order can be supplied with EN 10204 3.1 / 3.2 documentation, Charpy impact test reports and radiography records for fusion-welded butt joints where applicable.
With over two decades of manufacturing experience, we export to industrial projects across 65+ countries in the Middle East, Asia-Pacific, Europe, the Americas, and Africa. Our facility combines hot-forming, forging, and precision machining to produce fittings that meet ASTM A420/A420M requirements. Incoming material is verified by PMI testing, and all welded joints undergo radiographic examination per the specification.
Request a quote now!ASTM A420 WPL6 identifies wrought carbon steel pipe fittings for low-temperature service. WPL6 is selected where the design requires carbon steel fittings with verified Charpy V-notch impact toughness at -50°F (-45.6°C). It is commonly specified with ASTM A333 Grade 6 pipe and ASTM A350 LF2 flanges in low-temperature piping systems.
The designation breaks down as: WP = Wrought Product, L = Low Temperature, 6 = Grade designation. This grade is required whenever operating temperatures fall below the range suitable for standard carbon steel (ASTM A234 WPB) or when the project piping specification mandates mandatory impact testing for fracture safety.
| Specification Parameter | Details |
|---|---|
| Material Standard | ASTM A420 / ASME SA420 / SA420M |
| Grade | WPL6 (Wrought Product Low Temperature Grade 6) |
| Dimensional Standards | ASME B16.9, ASME B16.28, MSS-SP-75 |
| Size Range – Seamless | 1/2" NB to 24" NB (DN15 to DN600) |
| Size Range – Welded | 26" NB to 48" NB (DN650 to DN1200) |
| Schedule / Thickness | SCH 10, 20, 30, 40, STD, 60, 80, XS, 100, 120, 140, 160, XXS |
| Wall Thickness | 2 mm to 150 mm (custom thickness available on request) |
| Bending Radius | R=1D, 1.5D, 2D, 3D, 5D, 6D, 8D, 10D, or custom |
| Manufacturing Type | Seamless; Welded (ERW/SAW); Fabricated |
| End Finish | Beveled End, Plain End, Threaded End |
| Surface Treatment | Black painted, varnish coated, galvanized, 3PE coated |
| Impact Testing | Charpy V-notch at -50°F (-45.6°C) – mandatory per ASTM A420/A420M |
| Additional Inspection | Radiography (fusion-welded butt joints); UT, PT/MPI, PMI, hydrostatic test – when specified in PO |
| Certification | EN 10204 3.1 / 3.2; NABL-accredited lab test reports; NACE MR0175/ISO 15156 review available on request |
| Element | Composition (%) | Purpose |
|---|---|---|
| Carbon (C) | 0.30 max | Provides strength; kept low to maintain low-temperature toughness |
| Manganese (Mn) | 0.60 – 1.35 | Enhances strength and impact resistance |
| Phosphorus (P) | 0.035 max | Controlled to prevent embrittlement |
| Sulfur (S) | 0.040 max | Minimised to improve ductility and weldability |
| Silicon (Si) | 0.15 – 0.40 | Deoxidiser; improves strength |
| Nickel (Ni) | 0.40 max | Optional; enhances low-temperature toughness |
| Chromium (Cr) | 0.30 max | Improves corrosion resistance |
| Molybdenum (Mo) | 0.12 max | Enhances strength retention |
| Copper (Cu) | 0.40 max | Improves corrosion resistance |
| Vanadium (V) | 0.08 max | Grain refinement; improves toughness |
Note: Chemical composition must remain within the limits specified by ASTM A420/A420M and the purchase order. Heat number, ladle analysis and product analysis records are checked against the supplied MTC before dispatch. Verify Columbium/Niobium (Cb/Nb) content against the applicable standard revision if required by the project specification.
| Property | Specification | Testing Method |
|---|---|---|
| Tensile Strength, min | 415 MPa (60 ksi) | ASTM E8 / ASTM A370 |
| Yield Strength (0.2% offset), min | 240 MPa (35 ksi) | ASTM E8 / ASTM A370 |
| Elongation in 2", min | 22% (Longitudinal) / 12% (Transverse) | ASTM E8 |
| Hardness | Verify against controlled ASTM A420/A420M and order MTC | ASTM E10 |
| Impact Test Temperature | -50°F (-45.6°C) | ASTM A370 / ASTM E23 |
| Charpy V-Notch – Full-size 10×10 mm specimen – Average of three | 13 ft-lb (17.6 J) minimum | ASTM E23 (Charpy V-Notch) |
| Charpy V-Notch – One specimen without retest | 10 ft-lb (13.6 J) minimum | ASTM E23 (Charpy V-Notch) |
| Hydrostatic Test | Not a mandatory requirement of ASTM A420; available when specified in PO | As per purchase order |
Critical Note: Every lot of ASTM A420 WPL6 fittings must undergo Charpy impact testing at -50°F (-45.6°C). The mandatory impact test distinguishes this grade from standard carbon steel grades such as ASTM A234 WPB. The values above are subject to the applicable ASTM/ASME revision and purchaser requirements; always reconcile against the MTC before acceptance.
| NPS (Inches) | DN (mm) | Outside Diameter (mm) | Centre to End (mm) | Approx. Weight SCH 40 (kg) |
|---|---|---|---|---|
| 1/2" | 15 | 21.3 | 38 | 0.05 |
| 3/4" | 20 | 26.7 | 48 | 0.08 |
| 1" | 25 | 33.4 | 57 | 0.13 |
| 1-1/4" | 32 | 42.2 | 64 | 0.21 |
| 1-1/2" | 40 | 48.3 | 73 | 0.28 |
| 2" | 50 | 60.3 | 92 | 0.50 |
| 2-1/2" | 65 | 73.0 | 105 | 0.76 |
| 3" | 80 | 88.9 | 127 | 1.15 |
| 4" | 100 | 114.3 | 152 | 1.95 |
| 6" | 150 | 168.3 | 229 | 4.95 |
| 8" | 200 | 219.1 | 305 | 9.50 |
| 10" | 250 | 273.0 | 381 | 16.80 |
| 12" | 300 | 323.9 | 457 | 26.30 |
| 16" | 400 | 406.4 | 610 | 52.60 |
| 20" | 500 | 508.0 | 762 | 95.70 |
| 24" | 600 | 610.0 | 914 | 154.50 |
Note: Dimensions and weights are approximate and provided for reference. For tees, reducers, caps, stub ends and crosses, share the required NPS/DN, schedule, dimensional standard and quantity. Metinox will confirm applicable dimensions and approximate weights in the quotation sheet.
Metinox Overseas manufactures ASTM A420 WPL6 pipe fittings in accordance with multiple international standards to ensure global project compatibility:
| Comparison Factor | ASTM A420 WPL6 | ASTM A234 WPB | WPL3 / WPL8 |
|---|---|---|---|
| Primary Application | Low-temperature service piping | General carbon steel – moderate temperatures | Lower design temperature service |
| Minimum Impact Test Temperature | -50°F (-45.6°C) | Impact testing not required by ASTM A234 | Below -50°F – verify with project engineer |
| Impact Testing | Mandatory per ASTM A420 | Not required unless specified | Mandatory – temperature per grade |
| Tensile Strength | 415 MPa (60 ksi) min | 415 MPa (60 ksi) min | Verify against applicable ASTM standard |
| Material Cost | Moderate | Lower | Moderate to higher depending on grade |
| Typical Industries | LPG/NGL systems, cold-climate process lines, offshore modules, pressure-vessel connections | General refinery, power plants, moderate-temp process piping | Sub-zero process piping per project code |
| Weldability | Excellent | Excellent | Excellent |
| Availability | Good | Excellent | On order – confirm lead time |
Selection guidance: Use ASTM A420 WPL6 when the project specification requires low-temperature carbon steel fittings with Charpy impact testing at -50°F (-45.6°C). Use ASTM A234 WPB for general carbon steel butt weld fittings where low-temperature impact toughness is not specified. Use WPL3 or WPL8 when lower design temperatures are specified and approved by the piping engineer.
ASTM A420 WPL6 fittings are specified for low-temperature process piping, LPG and NGL handling systems, cold-climate pipeline stations, petrochemical utility lines, pressure vessel connections and offshore modules where the design temperature is within WPL6 impact qualification at -50°F (-45.6°C).
Note: For liquid LNG service at approximately -162°C, materials with lower-temperature impact qualification are required. Consult the project design code and piping engineer for material selection in true cryogenic liquid service.
Manufacturing route depends on fitting type, size and seamless or welded construction. Fittings may be formed by pressing, bending, welding or machining from qualified bars, plates, seamless pipe or fusion-welded tubular products. Heat treatment condition must match ASTM A420/A420M and the purchase order, and all welding must be completed before final heat treatment where required.
Lloyd's Register (LR), Bureau Veritas (BV), DNV GL, TUV, SGS, Intertek, ABS
Metinox Overseas exports ASTM A420 WPL6 pipe fittings to industrial projects across 65+ countries worldwide.
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ASTM A420 WPL6 fittings are specifically designed for low-temperature service and require mandatory Charpy V-notch impact testing at -50°F (-45.6°C). ASTM A234 WPB is a standard carbon steel grade for moderate-temperature applications and does not require impact testing unless specifically called for. Choose A420 WPL6 when the project specification mandates impact-tested carbon steel fittings for sub-zero service.
"WPL6" stands for Wrought Product, Low temperature, Grade 6. It identifies a specific grade within the ASTM A420 specification developed for low-temperature service through controlled chemistry and mandatory impact testing.
Yes, Charpy V-notch impact testing at -50°F (-45.6°C) is mandatory per the ASTM A420/A420M specification. For full-size 10×10 mm specimens, the minimum accepted value is 13 ft-lb (17.6 J) as an average of three specimens, with one specimen permitted down to 10 ft-lb (13.6 J) without retest, subject to the applicable standard revision and purchaser requirements.
ASTM A420 WPL6 fittings are specified for low-temperature service with Charpy impact testing at -50°F (-45.6°C). Suitability for service at any temperature below that threshold must be approved through the project design code, material specification and project-specific impact test requirements.
ASTM A420 WPL6 fittings are intended primarily for low-temperature service and are not optimised for elevated-temperature duty. For high-temperature applications, alloy steel grades such as ASTM A234 WP11, WP22 or WP91 are generally recommended based on the design temperature and applicable code.
ASTM A333 Grade 6 is the pipe material typically paired with ASTM A420 WPL6 fittings in low-temperature carbon steel piping systems. Both are impact tested at -50°F (-45.6°C) and share compatible chemistry and mechanical requirements, making them a natural system pairing alongside ASTM A350 LF2 flanges and ASTM A352 LCB valves.
Share fitting type, NPS/DN, schedule, seamless or welded construction, quantity, inspection requirement, MTC requirement (3.1 or 3.2) and delivery location. Metinox will confirm availability, applicable documentation and dispatch timeline.
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