B983 covers precipitation-hardened or cold-worked high-strength nickel alloy pipe (Hastelloy C-22HS, Inconel 725, Inconel 740H); B444 covers annealed or solution-annealed Inconel 625 pipe. B983 delivers yield strengths of 100,000-120,000 psi (690-827 MPa); B444 delivers 40,000-60,000 psi (276-414 MPa). If your application requires high strength plus corrosion resistance, such as sour gas wells or A-USC boilers, B983 is the correct specification. If you need standard-strength Inconel 625 for chemical processing or marine service, B444 is appropriate.
ASTM B983 High-Strength Nickel Alloy Seamless Pipe & Tube Standard
ASTM B983 is a standard specification published by ASTM International that covers high-strength, seamless nickel alloy pipe and tube produced by precipitation hardening or cold working. It was developed specifically for the oil & gas and advanced power generation industries, where standard annealed nickel alloys like Inconel 625 (ASTM B444) or Hastelloy C-276 (ASTM B622) lack the yield strength required for ultra-deep sour wells, high-pressure subsea systems, and advanced ultra-supercritical (A-USC) boiler tubing.
The specification covers three primary UNS-designated alloys: N07022 (Hastelloy C-22HS), N07725 (Inconel 725), and N07740 (Inconel 740/740H). Products are supplied in one of three conditions: cold worked, cold worked plus precipitation hardened, or solution annealed plus precipitation hardened and descaled.
This guide covers every section of ASTM B983. This includes the three primary alloys, their chemical compositions, mechanical properties by condition type, heat treatment protocols, dimensional tolerances, testing requirements, and key application sectors. With this, engineers and procurement teams can specify the right high-strength nickel alloy pipe for extreme-service environments.
ASTM B983 PDF Free Download
ASTM B983 PDF Free Download
What Is ASTM B983?
ASTM B983 is the Standard Specification for Precipitation Hardened or Cold Worked, Seamless Nickel Alloy Pipe and Tube. It falls under ASTM Committee B02 on Nonferrous Metals and Alloys, Subcommittee B02.07 on Refined Nickel and Cobalt and Their Alloys. General requirements for material under this specification conform to ASTM B829.
A conventional annealed Inconel 625 casing at 40,000 psi yield cannot withstand the collapse pressures in a 25,000-ft sour gas well. B983-grade material at 120,000 psi yield changes that design equation entirely. Existing nickel alloy pipe specifications, like B444 (Inconel 625), B622 (Hastelloy C-family), and B167 (Inconel 600/601), only cover material in the annealed or solution-annealed condition. These conditions deliver yield strengths in the 40,000-60,000 psi (276-414 MPa) range. Deep sour gas wells and A-USC boilers demand yield strengths of 100,000-140,000 psi (690-965 MPa) while retaining the same level of corrosion resistance. B983 fills that gap.
The specification covers pipe and tube in two strength-building routes: (1) cold working (where controlled deformation during drawing increases dislocation density and strength), and (2) precipitation hardening (where controlled ageing precipitates gamma-prime (γ′) or gamma-double-prime (γ″) phases that block dislocation movement). Some alloys use both methods together.
Each pipe or tube is tested by the manufacturer using either hydrostatic testing or non-destructive electric testing per ASTM B829. The ASME Boiler and Pressure Vessel Code references for these alloys are covered under their respective ASME Code Cases.
Chemical Composition of ASTM B983
ASTM B983 defines separate chemical composition limits for each alloy in the table given below. The compositions reflect each alloy’s primary function: N07022 maximises Mo for reducing-acid resistance, N07725 balances Cr/Mo/Nb for broad corrosion resistance with age-hardening capability, and N07740 adds Co for high-temperature creep strength.
| UNS Designation |
Standard (Pipe) |
C | Mn | P | S | Si | Ni | Cr | Mo | Cu | Fe | Ti | Al | Co | Other |
| N07718 | B983 | 0.08 | 0.35 | 0.015 | 0.015 | 0.35 | 50.0-55.0 | 17.0-21.0 | 2.8-3.3 | 0.30 | BAL | 0.65-1.15 | 0.2-0.8 | 1.0 | B:≤0.006; Nb+Ta 4.75-5.5 |
| N07022 | B983 | 0.01 | 0.50 | 0.025 | - | 0.08 | - | 20.0–21.4 | 16.0–18.0 | - | 1.5–3.0 | - | - | 1.0 | - |
| N07725 | B983 | 0.03 | 0.35 | - | - | 0.20 | - | 19.0–22.5 | 7.0–9.5 | - | Bal (5–9) | 1.0–1.7 | 0.35–0.75 | - | - |
| N07740 | B983 | 0.005–0.08 | 1.0 | - | - | 1.0 | - | 23.5–25.5 | 0.1–1.0 | - | 0.7 | 0.5–2.5 | 0.2–2.0 | 15.0–22.0 | - |
Note: Nickel is the balance element for N07022 and N07740. For N07725, Ni is specified as 55.0-59.0% with iron as the balance. One chemical analysis test per lot (one heat) is required. Product analysis variations follow ASTM B829. The cobalt content in N07740 (15-22%) is the signature differentiator. It provides the matrix strengthening needed for A-USC steam temperatures above 1300°F (700°C).
Mechanical Properties of ASTM B983
The defining feature of ASTM B983 is strength. Every alloy and condition listed in this specification delivers yield strengths at or above 100,000 psi (690 MPa), which is two to three times the yield strength of the same alloys in their standard annealed condition. The trade-off is lower elongation (10-20% vs 30-45% for annealed material), but ductility remains adequate for the intended applications.
The table below lists the minimum mechanical property requirements per ASTM B983.
| Alloy | Condition / Type | Tensile Min, ksi (MPa) | Yield Min, ksi (MPa) | Elong. Min, % | Hardness, HRC max |
| N07718 | Solution Ann + prec hard | 150 (1034) | 125 (862) | 20 | 40 |
| N07022 | Type 1: Cold Worked | 140 (965) | 110 (758) | 10 | 40 |
| N07022 | Type 2: Cold Worked + Aged | 140 (965) | 120 (827) | 10 | 40 |
| N07725 | Type 1: Solution Annealed + Aged | 140 (965) | 120 (827) | 18 | 40 |
| N07725 | Type 2: Cold Worked | 140 (965) | 110 (758) | 10 | 40 |
| N07740 | Solution Annealed + Aged | 140 (965) | 100 (690) | 15 | — |
Note: All values are minimum requirements. Yield strength uses the 0.2% offset method. Elongation is measured in 2 in. (50 mm) gauge length or 4D for round specimens. For N07022 and N07725, hardness is capped at 40 HRC to satisfy NACE MR0175/ISO 15156 sour service requirements.
ASTM B983 Tolerances
Dimensional tolerances for ASTM B983 include the various sizes, diameters, thicknesses, and lengths of the seamless pipes and tubes in the cold-worked and cold-drawn conditions.
| STANDARD | OD(D) | TOLERANCE(MM) | THICKNESS(S) | TOLERANCE | LENGTH | TOLERANCE |
| MM | COMMON HIGH | MM | MM | MM | ||
| B983 (Cold-Worked Tube) |
D<12.7 | +0.13/0 | ave. ±12.5% | min: +25.0%/0 | OD<50.8: +3.2/-0 OD≥50.8: +4.8/-0 Details refer to B829 |
- |
| 12.7≤D≤15.9 | ±0.13 | |||||
| 15.9<D≤38.1 | ±0.13 | ave. ±10.0% | min: +20.0%/0 | |||
| 38.1<D≤76.2 | ±0.25 | ave. ±12.5% | min: +22.0%/0 | |||
| B983 (Hot-Finished Tube) |
19≤D≤38 | +0.4/-0.8 | for nominal wall: ±12.5% | for min wall: +28.5%/0 | - | - |
| 38.1<D≤102 | ±0.8 | |||||
| 102<D≤235 | +1.6/-0.8 | |||||
| 235<D≤305 | ±2.8 | for nominal wall: ±12.5% | - | |||
| B983 (Hot-Worked Pipe) |
25≤D≤48 | +0.40/-0.79 | for nominal wall: +16%/-12.5% |
for min wall: +28.5%/0 | - | - |
| 48<D≤114 | ±0.79 | |||||
| 114<D≤165 | ±1.2 | |||||
| 165<D≤235 | ±1.6 | |||||
| 235<D≤356 | ±3.05 | for nominal wall: +16%/-12.5% |
- | |||
| 356<D≤610 | ±5.08 |
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ASTM B983 Grades
ASTM B983 covers three primary alloys, each targeting a different extreme-service environment. Hastelloy C-22HS uses cold work for high strength in corrosive oil casings. Inconel 725 uses precipitation hardening for sour gas well completions. Inconel 740/740H uses precipitation hardening for A-USC power plant tubing rated above 1300°F (700°C). The table below summarises all three alloys with their types, strengthening mechanisms, and primary applications.
| UNS | Trade Name | Alloy System | Strengthening | Types | Primary Application |
| N07022 | Hastelloy C-22HS | Ni-21Cr-17Mo | Cold work + optional aging | Type 1, Type 2 | Ultra-deep sour gas well casings |
| N07725 | Inconel 725 | Ni-21Cr-8Mo-3.5Nb-1.5Ti | Precipitation hardening (γ″) | Type 1, Type 2 | Sour gas completions, marine fasteners |
| N07740 | Inconel 740/740H | Ni-25Cr-20Co-2Nb-1.8Ti | Precipitation hardening (γ′) | — | A-USC superheater/reheater tubing |
UNS N07022
UNS N07022 is the only precipitation-strengthened alloy in the Hastelloy family. The alloy contains 20.0–21.4% Cr and 15.5–17.4% Mo, giving it broad acid resistance. It is NACE MR0175/ISO 15156 approved for sour service. This alloy is used for ultra-deep downhole casings, production tubing, and wellhead components exposed to H₂S, CO₂, and chlorides at high pressures and temperatures.
UNS N07725
The UNS N07725 (Inconel 725) is the age-hardenable evolution of Inconel 625, with roughly double the strength at equivalent corrosion resistance. It shares the same Ni-Cr-Mo-Nb corrosion resistance matrix as ASTM B444 but adds 1.0-1.7% titanium and 0.35% max aluminium. Because strength comes from precipitation hardening rather than cold work, ductility and toughness remain high. This is a critical advantage for large-diameter or non-uniform sections that cannot be strengthened by cold working. Inconel 725 is approved under NACE MR0175/ISO 15156 and specified for sour gas hangers, landing nipples, side pocket mandrels, polished bore receptacles, and high-strength marine fasteners.
UNS N07740
The UNS N07740 (Inconel 740H) is engineered for the next generation of coal-fired power: advanced ultra-supercritical (A-USC) boilers operating above 1300°F (700°C). It is a nickel-chromium-cobalt alloy strengthened by gamma-prime (γ′) precipitation. With 25% Cr, 20% Co, 2% Nb, and 1.8% Ti, it maintains creep rupture strength at steam temperatures of 1400°F (760°C) and pressures above 5,000 psi (34.5 MPa) conditions, where all existing power plant tube materials (T91, T92, stainless TP347H) fail. Applications include superheater tubes, reheater tubes, steam header piping, and high-pressure steam lines in next-generation 760°C-class coal power plants.
Heat Treatment Requirements for ASTM B983
The heat treatment is the most critical step in ASTM B983 production. It determines whether the alloy achieves its specified strength level while retaining adequate ductility and corrosion resistance. Each alloy follows a distinct heat treatment protocol matched to its strengthening mechanism.
N07022 (Hastelloy C-22HS) Heat Treatment
Type 1 (Cold Worked): Material is cold worked at 30-65% reduction to achieve the target yield strength. No ageing is performed. The high dislocation density from cold work provides the strengthening.
Type 2 (Cold Worked + Aged): After cold working, the material is heated at approximately 1300°F (704°C) for 16 hours, furnace cooled to 1125°F (607°C), held for 32 hours, then air cooled. This two-step ageing cycle precipitates fine intermetallic phases that interact with cold-work dislocations to increase yield strength beyond cold-work-alone levels.
N07725 (Inconel 725) Heat Treatment
Type 1 (Solution Annealed + Aged): Material is solution annealed at approximately 1900-1975°F (1038-1080°C) followed by rapid cooling. Then a two-step ageing is applied: first age at 1350°F (732°C) for 8 hours, furnace cool at 100°F/hour (56°C/hour) to 1150°F (620°C), hold at 1150°F (620°C) for 8 hours, then air cool. This precipitates γ″ (Ni₃Nb) and γ′ (Ni₃(Al, Ti)) phases uniformly throughout the matrix.
Type 2 (Cold Worked): Material is cold worked to the specified reduction to achieve the target strength without ageing. This route is used when ageing furnace access is limited or when the application does not require the full ductility of the aged condition.
N07740 (Inconel 740/740H) Heat Treatment
Material is solution annealed at approximately 2050-2125°F (1120-1163°C) followed by rapid cooling. Then heated at approximately 1470°F (800°C) for 4-16 hours to precipitate gamma-prime (γ′) phase. The ageing time depends on the target grain size and the specific 740 vs 740H variant. The 740H modification adjusts the Ti/Al/Nb ratio to improve long-term creep ductility and reduce the tendency for eta phase formation.
ASTM B983 Tolerances
Dimensional tolerances for ASTM B983 include the various sizes, diameters, thicknesses, and lengths of the seamless pipes and tubes in the cold-worked and cold-drawn conditions.
Testing and Inspection Requirements
ASTM B983 requires chemical analysis, tension testing, and either hydrostatic or non-destructive electric (NDE) testing on every lot. These tests are supplemented by the general requirements of ASTM B829.
Chemical Analysis
One test per lot (one heat). Product analysis, if requested by the purchaser, must conform to the specification with the check analysis tolerances from ASTM B829.
Tension Test
One tension test per lot. A lot consists of material from the same heat, same condition and processing, same nominal size (excluding length). Testing follows ASTM E 8. Full tubular specimens are preferred. If two additional specimens are required (retest), both must meet the specified requirements.
Hydrostatic or NDE Test
Every pipe or tube must be tested by either: (1) a hydrostatic test at an internal pressure not exceeding 1,000 psi (6.9 MPa) calculated per P = 2St/D, or (2) a non-destructive electric test (NDE) per ASTM B829. Any piece showing leaks or NDE indications above the acceptance threshold is rejected. The NDE option is increasingly specified for high-strength pipe because cold-worked material can develop micro-defects that hydrostatic testing alone may not detect.
Product Marking
Each piece must be marked with: alloy designation (UNS number), ASTM specification and type, condition (cold worked, aged, etc.), heat number, and size. Bundles and shipping containers carry additional details per ASTM B829.
Frequently Asked Questions
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What is the Difference Between ASTM B983 and ASTM B444?
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What is NACE MR0175 and Why Does It Matter for B983 Alloys?NACE MR0175/ ISO 15156 is the international standard that defines which materials are acceptable for use in sour (H₂S-containing) oil and gas production. Both N07022 (C-22HS) and N07725 (Inconel 725) are approved under NACE MR0175 for sour service, with hardness limits of 40 HRC maximum. This approval is mandatory for any pipe used in sour gas wells. Non-approved materials risk sulfide stress cracking (SSC) and hydrogen embrittlement, both of which can cause catastrophic failures.
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What Temperature Range Does Inconel 740H Cover?Inconel 740H (N07740) is designed for continuous service at steam temperatures up to 1400°F (760°C) and pressures above 5,000 psi (34.5 MPa). Under these conditions, this value is based on published EPRI A-USC research data and is not a property specified within ASTM B983 itself. This is sufficient for A-USC boiler superheater tubing. No other commercially available tube material can match this creep strength at 760°C.
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Can ASTM B983 Alloys Be Welded?Yes, all three B983 alloys are weldable, but each requires a specific post-weld heat treatment (PWHT) protocol. For N07725, the preferred process is GTAW with ERNiCrMo-3 filler, followed by a full solution anneal and re-ageing to restore precipitation-hardened properties in the HAZ. For N07022, PWHT depends on whether the cold-worked or aged condition is used. For N07740, a matching filler (similar to 740H composition) and a full solution anneal plus ageing cycle are required. (Note that filler selection must follow the applicable welding procedure specification and NACE MR0175 requirements.)