What Is ASTM A420 WPL6?
ASTM A420 is the specification for wrought carbon steel and alloy steel fittings for low-temperature service. Grade WPL6 is the low-temperature counterpart of WPB — a notch-toughness tested carbon steel fitting used for ASME B16.9 buttwelding fittings in cold-climate and low-temperature piping.
Temperature Range
WPL6 is a low-temperature carbon steel grade; exact design-temperature limits follow the ASME B16.9/B16.5 pressure-temperature tables and your notch-toughness requirements (tested subzero impact values per ASTM A370). For colder-than-LF2 duty, specify nickel-alloy or austenitic stainless grades.
Material Group (per ASME B16.5)
WPL6 fittings pair with Group 1.1 low-temperature carbon steel flanges (e.g. A350 LF2) in ASME B16.5 systems.
Corrosion Resistance
Carbon-steel behavior per the Schweitzer tables: good in neutral, alkaline and dry service; not recommended in acids or corrosive aqueous media. Coat exposed fittings.
Typical Applications
- ASME B16.9 buttwelding fittings for winter and low-temperature pipelines
- Oil & gas and refrigeration-adjacent process piping
- Systems matched to A350 LF2 flanges and low-temperature pipe
Chemistry & Mechanical Properties
Composition, mechanical properties and Charpy impact acceptance values per ASTM A420 / A370 — consult the standard for exact limits. Impact test reports and 3.1 certificates ship with every order.
Related Standards
- ASME B16.9 — Buttwelding Fittings (NPS 1/2–48)
- ASME B16.5 — Pipe Flanges
- ASTM A350 LF2 — Low-Temperature Forgings
- ASTM A234 WPB — Carbon Steel Fittings
- Buttwelding Elbows
- Equal Tees
FAQ
What is WPL6 used for?
Low-temperature buttwelding fittings — elbows, tees, reducers and caps in cold-climate, refrigeration-adjacent and low-temperature process piping.
How is WPL6 different from WPB?
WPL6 adds Charpy V-notch impact testing for subzero toughness; WPB is general carbon-steel fittings for ambient to hot service.
What temperature limit applies to WPL6?
As a low-temperature carbon steel, its design envelope follows the ASME B16.9/B16.5 tables and your notch-toughness requirements; confirm with your engineer for the exact minimum.
Which flange pairs with WPL6 fittings?
A350 LF2 low-temperature flanges (Group 1.1) are the standard match.
Which fitting standard covers WPL6?
WPL6 buttwelding fittings are manufactured to ASME B16.9 (NPS 1/2–48), with notch-toughness tested low-temperature carbon steel.
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