ASTM A333 covers seamless and welded carbon and alloy steel pipe intended for use at low temperatures. This specification is essential for applications in cryogenic service, LNG facilities, offshore platforms, and cold climate operations where materials must maintain toughness at temperatures as low as -195°C.

Quick Specifications

Grades: Grade 1, 3, 4, 6, 7, 8, 9, 10, 11
Product Forms: Seamless and Welded Pipe
Temperature Range: -45°C to -195°C (depending on grade)
Applications: LNG, LPG, offshore, petrochemical, cryogenic service

Chemical Composition (ASTM A333)

Element	Grade 1 (%)	Grade 3 (%)	Grade 6 (%)	Grade 8 (%)	Grade 9 (%)
Carbon (C), max	0.30	0.19	0.30	0.13	0.20
Manganese (Mn)	0.40 - 1.06	0.31 - 0.64	0.29 - 1.06	0.90 max	0.40 - 1.06
Phosphorus (P), max	0.025	0.020	0.025	0.015	0.025
Sulfur (S), max	0.025	0.020	0.025	0.015	0.025
Silicon (Si)	-	0.18 - 0.37	0.10 - 0.35	-	-
Nickel (Ni)	-	3.18 - 3.82	-	8.0 - 9.0	2.03 - 2.57
Copper (Cu)	-	-	-	-	0.75 - 1.25

Mechanical Properties

Property	Grade 1	Grade 3	Grade 6	Grade 8	Grade 9
Tensile Strength, min (MPa)	380	450	415	680	435
Yield Strength, min (MPa)	205	240	240	450	315
Elongation, min (%)	30	30	30	22	30

Low Temperature Service Ratings

Grade	Material Type	Min. Temp. Service (°C)	Typical Application
Grade 1	Carbon Steel	-45°C	General low-temp service
Grade 3	3.5% Nickel Steel	-100°C	LNG, offshore
Grade 4	1.5% Nickel Steel	-75°C	Moderate cryogenic
Grade 6	0.2% Molybdenum Steel	-45°C	Most common LTCS
Grade 7	2% Nickel Steel	-60°C	Moderate cryogenic
Grade 8	9% Nickel Steel	-195°C	LNG storage tanks
Grade 9	3% Nickel Steel + Cu	-75°C	Pipe within LNG facilities

Available Products (ASTM A333)

Grade 6 (Most Common) Seamless Pipe

Size Range: 1/2" - 48" (OD 21.3mm - 1219mm)
Wall Thickness: SCH 20 - SCH XXH
Length: Random or Fixed lengths
Surface: Black painted, FBE coated, or bare

Grade 3 Seamless Pipe

Size Range: 1/2" - 24" (OD 21.3mm - 610mm)
3.5% Nickel content for enhanced low-temp toughness
Used in LNG and offshore applications

Grade 8 Seamless Pipe (9% Nickel Steel)

Size Range: 1/2" - 48" (various)
LNG storage and transport applications
Requires specific heat treatment

Welded Pipe Options

Available for Grades 1, 3, 4, 6, 7, 9
SAW or ERW process
Heat treatment required for welded pipe

Key Features

Impact Toughness: Guaranteed Charpy V-notch impact values at minimum service temperature
Ductility: Maintains formability at low temperatures
Weldability: Good weldability with proper preheat and post-weld heat treatment
Toughness Testing: 100% impact testing available per ASTM A333 requirements

Charpy Impact Requirements

Grade	Test Temp. (°C)	Min. Avg. Impact (J)	Min. Single Value (J)
Grade 1	-50	13	10
Grade 3	-107	18	14
Grade 6	-50	18	14
Grade 8	-196	20	16
Grade 9	-75	18	14

Heat Treatment Requirements

Grade	Seamless Pipe	Welded Pipe
Grade 1	As rolled, normalized, or normalized & tempered	Normalized or normalized & tempered
Grade 3	Normalized or normalized & tempered	Normalized or normalized & tempered
Grade 6	Normalized or double normalized	Normalized (or as rolled with tests)
Grade 8	Quenched & tempered	Quenched & tempered

Applications

LNG (Liquefied Natural Gas) Industry

LNG storage tanks and piping
LNG carrier cargo holds
Regasification terminals
Grade 8 (9% Ni) is the preferred material for LNG tanks

Offshore Oil & Gas

Platform piping in cold climates
Subsea pipeline systems
FPSO vessels

Petrochemical & Refining

Low-temperature process streams
Cryogenic separation units
Ethylene and propylene plants

General Industrial

Cold storage facilities
Air separation plants
Industrial gas distribution

Welding Guidelines

Preheat and PWHT Requirements:

Grade 1, 6: Preheat 50-100°C for thick sections; PWHT optional based on service
Grade 3: Preheat 100-150°C; PWHT may be required
Grade 8: Preheat 150°C minimum; PWHT at 580-620°C

Recommended Filler Metals:

Grade 1, 6: Use matching or over-matched filler (e.g., E7018, E8018)
Grade 3: Use Ni-bearing fillers (e.g., ENiCrMo-3, ENiCrFe-2)
Grade 8: Use over-matched 9% Ni fillers or Inconel fillers

Testing Requirements

Tensile Test: One per heat/lot
Flattening Test: Seamless pipe - one per end from each heat
Bend Test: Welded pipe - one per heat/lot
Charpy Impact Test: Required for low-temp service verification
Hydrostatic Test: 100% of pipes
Visual Inspection: Surface defects, dimensional compliance

Dimension Tolerances (Per ASTM A999)

Parameter	Tolerance
Outside Diameter	±0.4% (min ±0.15mm, max ±3.2mm)
Wall Thickness	+15% / -12.5%
Weight	+10% / -3.5%
Length	+6mm / -0mm

Related ASTM Standards

ASTM A334 - Seamless and Welded Carbon Steel Tube for Low-Temperature Service
ASTM A420 - Wrought Carbon Steel Fittings for Low-Temperature Service
ASTM A350 - Forgings for Low-Temperature Service
ASTM A694 - High-Strength Pipe Fittings

Frequently Asked Questions (FAQ)

Q: What is the most common ASTM A333 grade?

A: Grade 6 is the most commonly used ASTM A333 grade, accounting for approximately 80% of LTCS pipe applications. It offers good low-temperature toughness at -50°C with excellent cost-effectiveness.

Q: What grade of ASTM A333 is used for LNG applications?

A: For LNG service (-160°C), Grade 8 (9% Nickel Steel) is preferred for storage tanks and critical piping. Grade 3 (3.5% Ni) is used for supporting piping at -100°C. Grade 9 is also specified for certain LNG facilities.

Q: Can ASTM A333 Grade 6 be used at -50°C?

A: Yes, Grade 6 is certified for service down to -50°C with Charpy impact testing at -50°C. However, for temperatures below -45°C, you need to verify the specific test temperature with the manufacturer.

Q: What is the difference between ASTM A333 and ASTM A334?

A: ASTM A333 covers pipe (4" and larger typically), while ASTM A334 covers tube (under 4" OD). Both are for low-temperature service with similar grade requirements.

Q: Are impact tests required for all ASTM A333 pipe?

A: Charpy impact tests are required when specified for low-temperature service. For Grades 1, 3, 6, 7, and 9, impact tests are commonly specified. Grade 8 typically requires 100% impact testing due to the critical LNG service.

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