ASTM B622

USED FOR:

Seamless nickel and nickel-alloy pipe.

B622 covers seamless nickel and nickel-alloy pipe manufactured from wrought alloys. It is used for corrosive and high-temperature applications where nickel-alloy materials are selected based on service requirements.

RELATED STANDARDS:

• Sibling specs: ASTM B619 covers welded nickel and nickel-alloy pipe, used where diameters or economics favor a welded route instead of seamless, generally for the same alloy families. ASTM B725 covers welded nickel-alloy pipe specifically for pressure applications requiring a defined weld joint efficiency system similar to A358, used when the welded product needs formal RT-class documentation for design credit. ASTM B829 and related tube specs (e.g., B163, B668) cover nickel-alloy tube rather than pipe, the pipe-vs-tube distinction here is just as easy to confuse as it is between A335 and A213.
• Design code that invokes it: ASME B31.3 (process piping) is the primary code referencing B622 for high-alloy, corrosion-resistant piping systems; ASME Section VIII references it for nickel-alloy nozzle and shell piping in pressure vessel applications, and NORSOK/offshore specs frequently invoke it directly for subsea and topside corrosive service piping.
• Dimensional standard that pairs with it:  Dimensional requirements are generally based on ASME B36.10M where applicable. Nickel-alloy pipe dimensions may also be specified by project requirements or manufacturer standards, since some nickel-alloy pipe sizes and wall thicknesses fall outside standard B36 schedules and are supplied to project-specific OD/WT combinations.

GRADE / TYPE RANGE:
B622 covers seamless pipe in nickel and nickel-alloy grades listed in the applicable ASTM B622 edition, including commonly used wrought nickel alloys such as UNS N02200/N02201, UNS N04400, UNS N06600, UNS N06625, and other specified alloys.

As alloying content shifts from pure nickel toward chromium-molybdenum-rich compositions, general corrosion resistance (particularly to chlorides, pitting, and crevice corrosion) and high-temperature oxidation resistance improve substantially, generally alongside a moderate increase in strength, though strength is rarely the primary selection driver here.

Alloy 400 is typically chosen for resistance to hydrofluoric acid and seawater;

Alloy 625 and C-276 are chosen for aggressive, high-chloride, or high-temperature acidic environments where even high-alloy stainless steels would suffer rapid attack;

Nickel-alloy grades such as Alloy 825 are selected for specific corrosive environments including applications involving acids, chlorides, and reducing/oxidizing conditions, based on corrosion evaluation and project requirements.

Selection among these grades is driven almost entirely by the specific corrosive species and temperature in the service environment rather than by mechanical property differences, which is a distinct mindset shift from carbon/low-alloy steel selection.

DESCRIPTION:
B622 covers pipe produced by hot working followed by cold finishing (cold drawing/cold rolling) as needed to achieve final dimensions, with mandatory solution annealing (or equivalent heat treatment appropriate to the alloy) to develop the corrosion resistance and mechanical properties required.

Testing requirements include tensile testing, flattening or flange test, hydrostatic or eddy-current/ultrasonic testing as alternatives, and grain size or microstructural checks for certain alloys where sensitization or precipitation behavior is a concern.

Given the cost of the base material, most projects specify very tight dimensional, surface finish, and NDE requirements beyond the base standard’s minimums, and heat/lot traceability is treated with a level of rigor closer to that seen for exotic alloy forgings than standard carbon steel pipe. Marking requirements identify manufacturer, alloy/UNS designation, heat number, and often require permanent marking methods that don’t compromise corrosion resistance (avoiding certain stamping practices that could initiate localized corrosion).

TYPICAL INDUSTRY USE:
Specified in offshore and subsea oil & gas production (particularly sour, high-chloride, or high-CO2 environments), chemical processing (acid production, pulp and paper), and high-temperature process piping where stainless steel grades under A312 don’t provide sufficient corrosion or temperature resistance.

IMPORTANT NOTES:

• We regularly see B622 confused with the welded equivalents (B619/B725) on procurement documents, If a welded nickel-alloy pipe product is required, the applicable welded pipe specification shall be selected instead of ASTM B622, which covers seamless pipe, even though the alloy grades overlap significantly.

• Additionally requirements commonly requested alongside B622 include additional requirements such as corrosion testing, grain size control, and PMI verification may be specified by the purchaser or project requirements depending on the alloy and service conditions;  given the significant cost difference between nickel alloys and the visual similarity of some alloys to stainless steel, we always recommend mandatory PMI on receiving inspection for B622 material, since a mix-up here is expensive and can be safety-critical.

• NACE MR0175/ISO 15156 sour service qualification is highly relevant for B622 material, since many of these alloys (particularly 625, 825, C-276) are specifically selected for sour, high-chloride environments,  however, qualification depends on the specific alloy, condition (annealed vs. cold-worked), and hardness, so we always verify the exact alloy and product form against the current NACE/ISO tables rather than assuming the alloy family alone qualifies it.

• Delivery times for B622 pipe are typically very long, and the supplier base is much smaller than for stainless or carbon steel pipe, we recommend mentioning this extremely early in project planning, since nickel-alloy pipe (especially higher-alloy grades like C-276) is frequently a schedule-driving long-lead item, sometimes with lead times measured in many months.

• Given the high material cost, we often see engineering pressure to substitute a “close enough” alloy for cost or availability reasons, this is a decision that should always go back through corrosion engineering rather than being made at the procurement level, since the alloy differences that look minor on paper can have a large real-world effect on service life in aggressive environments.