Grades & Chemical Composition

Grades

A total of 32 nickel alloy grades are included in ASTM B622. However, there are only 12 most commonly used grades among them. They contain most Hastelloy alloys. Additionally, Inconel 686 is the only Inconel alloy included in this standard.

A common feature of the grades in ASTM B622 is that most of these grades contain molybdenum. This is also one of the characteristics of Hastelloy alloy.

The molybdenum element brings an extremely strong resistance to reduction corrosion to the alloy. At the same time, molybdenum element plays a very good solid solution strengthening effect. Therefore, these alloys often have good comprehensive corrosion resistance and high strength.

In this standard, the Hastelloy B series are nickel-molybdenum alloys. They focus on reducing environmental resistance to extremes. Other Hastelloy alloys and Inconel 686 alloys are nickel-chromium-molybdenum alloys. They pay more attention to the comprehensive corrosion resistance of the alloy.

Chemical Composition

Inconel 686 (UNS N06686)

Hastelloy B (UNS N10001)

Hastelloy B-2 (UNS N10665)

Hastelloy B-3 (UNS N10675)

Hastelloy C-4 (UNS N06455)

Hastelloy C-22 (UNS N06022)

Hastelloy C-276 (UNS N10276)

Hastelloy C-2000 (UNS N06200)

Hastelloy G-3 (UNS N06985)

Hastelloy G-30 (UNS N06030)

Hastelloy G-35 (UNS N06035)

Hastelloy X (UNS N06002)

The supplier shall perform the chemical analysis of the alloy in accordance with ASTM B829.

Product Properties

Products in ASTM B622

Inconel 686
Seamless Pipe & Tube Hastelloy B
Seamless Pipe & Tube Hastelloy B-2
Seamless Pipe & Tube Hastelloy B-3
Seamless Pipe & Tube Hastelloy C-4
Seamless Pipe & Tube Hastelloy C-22
Seamless Pipe & Tube Hastelloy C-276
Seamless Pipe & Tube Hastelloy C-2000
Seamless Pipe & Tube Hastelloy G-3
Seamless Pipe & Tube Hastelloy G-30
Seamless Pipe & Tube Hastelloy G-35
Seamless Pipe & Tube Hastelloy X
Seamless Pipe & Tube

The product range of ASTM B622 is only seamless pipe & tube. Seamless pipes are a pipe / tube materials without welds. It is generally produced by cold rolling or cold drawing. Because there are no welds, it has a stronger pressure-bearing capacity than welded pipes. Due to the process, the wall thickness of the seamless pipes is generally not too thin.

The standard stipulates that the product with an outer diameter greater than 88.9mm is seamless pipe. And the product with outer diameter less than or equal to 88.9mm is seamless tube.

Mechanical Properties

The alloys in ASTM B622 are basically solid solution strengthened alloys. Because these alloys contain ideal solid solution strengthening elements such as molybdenum and tungsten, their strength is among the best among solid solution strengthening alloys. It is also true that these alloys are more difficult for the manufacture of seamless tubes. Therefore, their price will be much more expensive than other product forms.

Delivery State

According to the standard, seamless pipes of all materials need to be delivered in the state of solution treatment. This state is the most perfect balance of strength and toughness of the alloy. During use, the seamless pipe in the solution treatment state can achieve the best service life.

In addition, for most seamless pipes, they require surface treatment like pickling or polishing after heat treatment. This is to remove scale produced during heat treatment. Of course, if the material is heat-treated without oxygen, it no longer requires subsequent surface treatment.

Other Information

Dimension

ASTM B622 lists the size table (Pipe Schedules) of seamless pipes in the appendix. This size table is optional. That said, other dimensions than the table are also acceptable.

In fact, this size table is part of ASME B36.10. In practical applications, the size of the seamless pipe can be customized according to ASME B36.10 and ASME B36.19. Any other non-standard dimensions are also possible.

In addition, the dimensional tolerances of materials are not directly specified in the standard. However, ASTM B829 is mentioned in the standard. This means that in actual production, manufacturers should produce according to the tolerance requirements of ASTM B829.

Hydrostatic Test

The standard stipulates that each seamless pipe shall be hydrostatically tested according to ASTM B829. It may also be agreed between the purchaser and the manufacturer that hydrostatic testing be performed at pressures greater than 1000 psi.

Certification

The supplier should provide the corresponding Material Test Certificate before delivery to ensure the final quality of the product. The certificate needs to include customer & supplier information, chemical composition, mechanical properties, delivery status, heat number, reference standards and all other necessary information.