Everything You need to Know about ASTM B444
Overview
ASTM B444 is a very commonly used standard for nickel alloy seamless pipes. The standard mainly includes Inconel 625 (UNS N06625) and two other materials. The main products are seamless pipe & tube. In this article, we will detail the important requirements mentioned in ASTM B444. This will allow you to better control the quality when ordering.
Grades & Chemical Composition
Grades
Three grades are included in the ASTM B444 standard.
Nickel-chromium-molybdenum-niobium alloys: Inconel 625 (UNS N06625), UNS N06852.
Nickel-chromium-molybdenum-silicon alloy: UNS N06219.
Among them, Inconel 625 is the most commonly used. Compared with nickel-chromium alloy, Inconel 625 alloy is added with molybdenum element to further improve the comprehensive corrosion resistance of the alloy. Inconel 625 also contains a certain amount of niobium. Higher strength is obtained by solid solution strengthening.
Chemical Composition
Inconel 625 (UNS N06625)
625
Si
C
Al
Ti
Co
Ta
Mo
Fe
Cr
Ni
Suppliers shall perform chemical analysis of the material in accordance with ASTM B829.
Product Properties
Products in ASTM B444
ASTM B444 mainly specifies the technical requirements for seamless pipe & tube. Among them, the materials with an outer diameter of 127mm or less are defined as seamless tubes. Materials with an outer diameter of 127mm or more are seamless pipes.
Mechanical Properties
| Condition and Diameter or Distance Between Parallel Surfaces, in. (mm) |
Tensile Strength min, ksi (MPa) |
Yield Strength (0.2% offset) min. ksi (MPa) |
Elongation in 2 in. or 50 mm (or 4D), min, % |
|
|---|---|---|---|---|
| Inconel 625 (UNS N06625) | ||||
| Grade 1 (annealed) | 120 (827) | 60 (414) | 30 | |
| Grade 2 (solution annealed) | 100 (690) | 40 (276) | 30 | |
| UNS N06219 | ||||
| All (solution annealed) | 96 (660) | 39 (270) | 30 | |
| UNS N06852 | ||||
| All (solution annealed) | 85 (586) | 35 (241) | 30 | |
Delivery State
In ASTM B444, UNS N06852 and UNS N06219 are only specified for delivery in solution treated state.
For Inconel 625 (UNS N06625), the standard specifies the following two states:
Grade 1 (annealed): Grade 1 is the annealed state, which is stronger and suitable for use at temperatures up to 1100°F (593°C). In most cases, Inconel 625 will be used at this temperature. Therefore, grade 1 is the default delivery state for the Inconel 625 seamless pipe & tube.
Grade 2 (solution annealed): Grade 2 requires the material to be delivered in a solution annealed state. When the material is used above 1100°F (593°C). The Grade 2 state helps to improve the creep properties and fatigue properties of the alloy. Therefore, if you need Inconel 625 seamless pipe & tube to be used at higher temperature, you should choose grade 2.
Other Information
Dimension
For small-diameter tube and light-wall tube, the standard additionally specifies tolerances for outer diameter, wall thickness and length. For other seamless pipes & tubes, tolerances should refer to ASTM B829.
| Nominal Outside Diameter, in. (mm) |
Permissible Variations | Thickness of Specified Minimum Wall, % | ||||
|---|---|---|---|---|---|---|
| Outside Diameter, in. (mm) |
Thickness of Specified Nominal Wall, % |
Plus | Minus | |||
| Plus | Minus | Plus | Minus | |||
| Over 0.400 (10) to 5/8 (16), excl | 0.005 (0.13) | 0.005 (0.13) | 15.0 | 15.0 | 30 | 0 |
| 5/8 (16) to 1 1/2 (38), incl | 0.0075 (0.19) | 0.0075 (0.19) | 10.0 | 10.0 | 22 | 0 |
| Over 1 1/2 (38) to 3 (76), incl | 0.010 (0.25) | 0.010 (0.25) | 10.0 | 10.0 | 22 | 0 |
| Over 3 (76) to 4 1/2 (114), incl | 0.015 (0.38) | 0.015 (0.38) | 10.0 | 10.0 | 22 | 0 |
| Over 4 1/2 (114) to 6 (152), incl | 0.020 (0.51) | 0.020 (0.51) | 12.5 | 12.5 | 28 | 0 |
| Over 6 (152) to 6 5/8 (168), incl | 0.025 (0.64) | 0.025 (0.64) | 12.5 | 12.5 | 28 | 0 |
| Over 6 5/8 (168) to 8 5/8 (219), incl | 0.031 (0.79) | 0.031 (0.79) | 12.5 | 12.5 | 28 | 0 |
| Over 8.625 (219) to 14 (356), incl | 0.062 (1.57) | 0.031 (0.79) | 15.0 | 12.5 | 30.0 | 0.0 |
| Over 14 (356) to 24 (610), incl | 0.125 (3.18) | 0.031 (0.79) | 15.0 | 12.5 | 30.0 | 0.0 |
| Nominal Outsider Diameter, in. (mm) |
Permissible Variations | |||||
|---|---|---|---|---|---|---|
| Outside Diameter or Inside Diameter, in. (mm) |
% of Thickness of Specified Nominal Wall |
% of Thickness of Specific Minimum Wall |
||||
| + | - | + | - | + | - | |
| 3/4 (19) to 1 1/2 (38), incl | 0.015 (0.4) | 0.031 (0.8) | 12.5 | 12.5 | 28.5 | 0 |
| Over 1 1/2 (38.1) to 4 (102), incl | 0.031 (0.8) | 0.031 (0.8) | 12.5 | 12.5 | 28.5 | 0 |
| Over 4 (102) to 9 1/4 (235), incl | 0.062 (1.6) | 0.031 (0.8) | 12.5 | 12.5 | 28.5 | 0 |
| Nominal Outsider Diameter, in. (mm) |
Permissible Variations | |||||
|---|---|---|---|---|---|---|
| Outside Diameter, in. (mm) |
Thickness of Specified Nominal Wall, % |
Thickness of Specified Minimal Wall, % |
||||
| Plus | Minus | Plus | Minus | Plus | Minus | |
| 1 (25) to 1.900 (48), incl | 0.015 (0.40) | 0.031 (0.79) | 16.0 | 12.5 | 28.5 | 0 |
| over 1.900 (48) to 4 1/2 (114), incl | 0.031 (0.79) | 0.031 (0.79) | 16.0 | 12.5 | 28.5 | 0 |
| over 4 1/2 (114) to 6 1/2 (165), incl | 0.047 (1.2) | 0.047 (1.2) | 16.0 | 12.5 | 28.5 | 0 |
| over 6 1/2 (165) to 9 1/4 (235), incl | 0.062 (1.6) | 0.062 (1.6) | 16.0 | 12.5 | 28.5 | 0 |
| Outside Diameter, in. (mm) | Cut Length, in. (mm) | |
|---|---|---|
| Over | Under | |
| Under 2 (50.8) | 1/8 (3.2) | 0 |
| 2 (50.8) and over | 3/16 (4.8) | 0 |
| Specified Outside Diameter, in. (mm) | Outside Diameter | Inside Diameter | Wall Thickness, % | |||
|---|---|---|---|---|---|---|
| Plus | Minus, in. (mm) |
Plus | Minus | Plus | Minus | |
| Under 3/32 (2.4) | 0.002 (0.05) | 0 | 0 | 0.002 (0.05) | 10 | 10 |
| 3/32 to 3/16 (2.4 to 4.8), excl | 0.003 (0.08) | 0 | 0 | 0.003 (0.08) | 10 | 10 |
| 3/1 6 to 1/2 (4.8 to 12.7), excl | 0.004 (0.10) | 0 | 0 | 0.004 (0.10) | 10 | 10 |
| 1/2 to 1 1/4 (12.7 to 31.8), incl | 0.005 (0.13) | 0 | 0 | 0.005 (0.13) | 10 | 10 |
| Length, ft (m) | Tube Size, in. (mm) | Permissible Variations, in. (mm) | |
|---|---|---|---|
| Over | Under | ||
| Under 1 (0.30) | up to 1.250 (31.8), incl | 1/32 (0.8) | 0 (0) |
| 1 to 4 (0.30 to 1.22), incl | up to 1.250 (31.8), incl | 1/16 (1.6) | 0 (0) |
| Over 4 to 10 (1.22 to 3.0), incl | up to 1.250 (31.8), incl | 3/32 (2.4) | 0 (0) |
| Over 10 (3.0) | up to 1.250 (31.8), incl | 3/16 (4.8) | 0 (0) |
Hydrostatic Test
Each pipe or tube with an outside diameter 3mm and larger and with wall thickness of 0.38 mm and over shall be tested in accordance with Specification ASTM B829.
For Inconel 625, the test pressure for grade 1 is 30,000 psi (207 MPa). Grade 2 is tested to 25,000 psi (172 MPa).
Test pressures for UNS N06219 and UNS N06852 are 24,000 psi (165 MPa) and 21,000 psi (145 MPa), respectively.
The results of the hydrostatic test shall be reflected in the material test certificate.
Certification
Supplier should issue material test certificate corresponding to the material before shipment. The certificate should include supplier information, customer information, product form and state, heat number, chemical composition, mechanical properties, smelting method, hydrostatic test result and other necessary information.
Conclusion
ASTM B444 is mainly used for seamless pipe & tube of nickel-chromium-molybdenum-niobium alloy and nickel-chromium-molybdenum-silicon alloy. Among them, Inconel 625 seamless pipe & tube is the most commonly used material in the standard. Suppliers shall manufacture this material strictly in accordance with ASTM B444.
We produce Inconel 625 seamless pipe & tube according to ASTM B444 standard by default. If you have corresponding needs, please do not hesitate to contact us.
