ASTM A333 Grade 6 Seamless Pipe — Factory Direct Supplier | Huaxia-Steel

ASTM A333 Grade 6 seamless pipe is the standard carbon steel pipe for low-temperature service, with guaranteed impact toughness down to −45 °C (−50 °F). Where ordinary A106 pipe loses toughness and becomes brittle in cold climates, A333 Gr6 retains Charpy impact properties that make it the specified material for LNG-adjacent systems, gas processing plants, Arctic pipelines and outdoor installations in cold regions. Huaxia-Steel supplies A333 Gr6 seamless pipe from NPS 1/8 to NPS 24 in all schedules, with full heat treatment, EN 10204 3.1 certificates and third-party inspection options.

Product Overview

ASTM A333/A333M covers seamless and welded carbon and alloy steel pipes intended for low-temperature service down to −150 °C depending on grade, with Grade 6 being the most widely used carbon grade. The pipe is made by hot finishing followed by mandatory heat treatment — Grade 6 is normalized at 870–900 °C or normalized and tempered at 620 °C minimum. This heat treatment, combined with fine-grain killed steel practice and restricted chemistry, is what delivers the notch toughness at low temperature that distinguishes A333 from standard line pipe and pressure pipe grades.

Compared with A106 Grade B — the same pipe people often substitute — A333 Gr6 carries a lower carbon ceiling (0.30 % vs 0.30 % max but with tighter Mn balance) and, critically, requires Charpy V-notch impact testing on every heat and lot. A106 has no impact requirement at all, so it cannot be certified for −45 °C service even when a mill claims “equivalent”.

Specifications and Dimensions

Item	Specification
Standard	ASTM A333/A333M Grade 6 (seamless)
Size range	NPS 1/8 – NPS 24 (DN 6 – DN 600)
Schedule	Sch 10, 20, 40, 80, 120, 160, XXS
Manufacturing	Hot finished seamless, then normalized (N) or normalized + tempered (NT)
Length	SRL 5.8 m / 6.1 m, DRL 11.6–12.2 m, random, or cut to order
Ends	Plain beveled (butt weld), plain, threaded + coupled per ASME B1.20.1
Test pressure	Hydrostatic per ASTM A999 or eddy current per ASTM E309/E426
Lowest test temperature	−45 °C (−50 °F) Charpy impact, 3 specimens

Chemical Composition (Grade 6)

Element	Requirement %
Carbon (C) max	0.30
Manganese (Mn)	0.29 – 1.06
Phosphorus (P) max	0.025
Sulfur (S) max	0.025
Silicon (Si) min	0.10

Mechanical Properties

Property	Requirement
Tensile strength min	415 MPa (60,000 psi)
Yield strength min	240 MPa (35,000 psi)
Elongation min (strip/bar)	30 % / 22 % (varies with size)
Charpy V-notch at −45 °C	≥ 13 J (10 ft·lbf) average of 3, min single 10 J
Hardness	No limit specified; typical 137–187 HB

Available Grades Within ASTM A333

Grade	Type	Min temp	Key feature
Grade 1	Carbon	−45 °C	Lower strength (170 MPa yield), thin sections
Grade 3	3.5 % Nickel alloy	−100 °C	Low-temp toughness for LNG/nitrogen service
Grade 6	Carbon, fine grain	−45 °C	Industry standard — best price/toughness balance
Grade 8	9 % Nickel alloy	−195 °C	LNG cryogenic service
Grade 9/10/11	Alloy variants	various	Specialized cryogenic niches

Applicable Standards and Companions

• ASTM A333/A333M: base product standard for pipe.
• ASTM A420: companion standard for butt-welding fittings (elbows, tees) in A333 Gr6 piping systems — order fittings to A420 WPL6.
• ASTM A350 LF2: companion forged flanges, forged fittings and valves for the same −45 °C class.
• ASME B36.10M: dimensional standard for the pipe sizes and schedules.
• ASTM A370: test methods including Charpy impact testing procedure.
• ASME B31.3: process piping code — assigns A333 Gr6 allowable stress for design below the ductile-brittle transition.

Typical Applications

• Natural gas gathering and processing plants in cold regions.
• LNG facility utility and auxiliary piping.
• Outdoor process piping in Canada, Russia, Northern China, Kazakhstan and Mongolia.
• Air separation and nitrogen/CO₂ refrigeration circuits.
• Compressed air systems with outdoor runs exposed to winter temperatures.
• Cold storage ammonia refrigeration piping.

Quality Assurance and Testing

Every heat and lot receives: chemical analysis; tensile test; Charpy V-notch impact testing at −45 °C with three specimens per lot (lots defined by heat treatment batch per ASTM A333); flattening test on sizes NPS 2 and under; hydrostatic or non-destructive electric test on the full length. We supply EN 10204 3.1 certificates as standard with actual Charpy values, and 3.2 certification with SGS, TÜV or BV witness testing on request. Optional extras include PMI, positive material traceability stamping, ultrasonic wall testing and full-length visual with gauge reports.

Packing and Shipping

Pipe is bundled with steel strapping on timber or steel cradles, ends fitted with plastic or steel caps, and threaded pipe protected with thread guards. Standard sea-worthy packing suits 20/40 ft containers (lengths cut to 5.8 m) or breakbulk for lengths above 6 m. Bundle tags show grade, size, schedule, heat number and length; each shipment includes the load plan, packing list and certificate package.

Size and Weight Reference

NPS / DN	OD mm	Sch 40 wall mm	Weight kg/m	Sch 80 wall mm	Weight kg/m
1″ / 25	33.4	3.38	2.50	4.55	3.23
2″ / 50	60.3	3.91	5.44	5.54	7.48
4″ / 100	114.3	6.02	16.1	8.56	22.3
6″ / 150	168.3	7.11	28.3	10.97	42.6
8″ / 200	219.1	8.18	42.6	12.70	64.6
12″ / 300	323.9	10.31	80.2	17.48	132.7
16″ / 400	406.4	12.70	123.3	21.44	203.6
24″ / 600	610.0	17.48	255.4	30.96	442.1

Weights are theoretical to ASME B36.10M and exclude mill tolerance; plan logistics on +10 % for Sch 40 and confirm bundle weights by scale for the VGM declaration.

How to Order

To receive an accurate quotation and production-ready order, specify:

• Quantity by NPS, schedule and length (SRL 5.8/6.1 m, DRL 11.8 m, or cut lengths).
• Heat treatment requirement: normalized (N) or normalized and tempered (NT).
• Impact test temperature if other than −45 °C (A333 covers down to −150 °C for alloy grades).
• End preparation: plain, beveled to ASME B16.25, or threaded per ASME B1.20.1.
• Certificate level: EN 10204 3.1 (standard) or 3.2 with named third-party inspector.
• Additional NDT: UT wall scan, PMI, hardness survey, or 100 % MT of the surface.
• Coating: bare oiled, FBE, 3LPE, or galvanized (galvanizing after impact testing).
• Destination port and per-container weight limit for the packing plan.

Frequently Asked Questions

Can A106 Grade B be substituted for A333 Grade 6?

No, in the reverse direction. A106 has no impact testing requirement and cannot be certified for −45 °C service, even if a mill’s chemistry looks favorable. A333 Gr6 can substitute for A106 Gr B in ambient service (its strength class matches), but the converse is a specification violation.

What fittings and flanges pair with A333 Gr6 pipe?

Butt weld fittings to ASTM A420 WPL6, forged flanges and fittings to ASTM A350 LF2 Class 1, and bolting to ASTM A320 L7 — the complete −45 °C material family. Mixing a standard WPB elbow into an A333 line breaks the low-temperature certification of the whole system.

Is A333 Gr6 available with galvanized finish?

Yes — hot dip galvanizing after impact testing is common for outdoor utility piping. Order pipe with the impact tests completed before galvanizing and require the galvanizer to avoid quench temperatures that would alter the heat treated condition (per ASTM A123 practice).

Documentation Package With Every Shipment

Each A333 Gr6 shipment includes: EN 10204 3.1 mill certificates per heat showing chemistry, tensile results and Charpy values at −45 °C; heat treatment charts for the lots supplied; dimensional and visual inspection reports; hydrostatic or NDT test records per length; the packing list with bundle weights for VGM; and the loading photo documentation set. For 3.2 orders, the third-party inspector’s endorsement and witness test report are added. Documentation is transmitted digitally at shipment and in hard copy inside container #1, so destination QC can start before the paper parcel arrives by courier.

Request a Quote

Send us your size list (NPS, schedule, length), quantity and destination port — Huaxia-Steel responds with a factory-direct quotation including latest mill test certificates within 24 hours. Samples and MTC verification available before order confirmation.