What is the difference between Inconel 625 and 718?

Inconel 718 is a precipitation-hardenable alloy designed for even higher strength at elevated temperatures, whereas Inconel 625 achieves its strength through solid-solution hardening and offers superior corrosion resistance in many aqueous environments.

What is the maximum temperature for Inconel 625?

Inconel 625 retains excellent strength and oxidation resistance up to approximately 1800°F (982°C). It also maintains toughness at cryogenic temperatures.

Inconel 625 Pipes and Tubes

Q: What is Inconel 625 used for?

Inconel 625 is used in aerospace for engine exhaust systems, marine applications for seawater piping, chemical processing equipment, and pollution control systems due to its high strength and corrosion resistance.

Q: Can Inconel 625 be welded?

Yes, Inconel 625 has excellent weldability. It can be welded by all standard methods and does not require post-weld heat treatment to maintain its corrosion resistance, unlike many other high-strength alloys.

Table of Content

Introduction to Inconel 625 Superalloy
Inconel 625 vs Other High-Temperature Alloys
Alloy 625 Seamless Pipe vs Welded Pipe
ASTM B444 & ASME SB444 Specifications
Manufacturing Range & Dimensional Standards
Various Types of Inconel 625 Pipes & Tubes
Pipe Weight Chart (Common Sizes)
Applications & Industries Served
Quality Assurance & Testing
Export Destinations & Supply Chain
Frequently Asked Questions

Kalpataru piping produces and distributes Inconel 625 Pipes and Tubes (UNS N06625 / DIN 2.4856) in seamless welded form that is fully compliant to ASTM B444 and ASME SB444. The alloy 625 is a nickel-chromium-molybdenum-niobium superalloy that provides excellent strength, oxidation resistance, and corrosion resistance from cryogenic temperatures up to 982°C (1800°F). Our entire range of Inconel Products is available at /inconel-products/ to the entire family of Inconel alloy that we supply.

High-pressure aerospace ducting, subsea flowlines, desulfurization scrubber of flue gases or pharmaceutical heat exchanger, this page has every specification, dimension, grade condition, chemical composition, and application fact, you need to qualify and make purchase of Inconel 625 pipes and tubes with a confirmed Indian manufacturer.

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Inconel 625 Grade 1 vs Grade 2: Which to Specify?

ASTM B444 defines two condition grades for Inconel 625 seamless pipes and tubes. This distinction is frequently searched by procurement engineers and is a key content gap vs competitors:

Factor	Grade 1 (Annealed)	Grade 2 (Solution Annealed)
Heat Treatment	Annealed — lower temperature treatment	Solution annealed at higher temperature (~1150°C)
Primary Use	Moderate temperature service (up to ~593°C)	High-temperature service (593°C to 982°C)
Grain Structure	Fine-grained; higher tensile/yield strength	Coarser grain; better creep/rupture strength
Tensile Strength (min)	120 ksi (827 MPa)	100 ksi (690 MPa)
Yield Strength (min)	60 ksi (414 MPa)	40 ksi (276 MPa)
Elongation (min)	30%	30%
Typical Applications	Chemical processing, ambient/moderate temp piping	Aerospace, power generation, high-temp furnace components
ASTM Reference	ASTM B444 Grade 1	ASTM B444 Grade 2

Rule of Thumb: Specify Grade 2 for applications above 593°C or where creep resistance is required. Grade 1 is sufficient for most aqueous corrosion and moderate temperature chemical processing applications.

Inconel 625 Chemical Composition (UNS N06625)

The chemical composition of Inconel 625 per ASTM B444 / ASME SB444 is as follows. The high molybdenum content (8–10%) combined with niobium (3.15–4.15%) is the key differentiator from lower-alloy nickel grades:

Element	Symbol	Content (% by weight)	Role
Nickel	Ni	58.0% min	Base element — corrosion and oxidation resistance
Chromium	Cr	20.0 – 23.0%	Oxidation and high-temperature corrosion resistance
Molybdenum	Mo	8.0 – 10.0%	Pitting and crevice corrosion resistance; solid solution hardening
Niobium + Tantalum	Nb + Ta	3.15 – 4.15%	Weld stabilization; prevents sensitization; strengthening
Iron	Fe	5.0% max	Residual — kept low for corrosion performance
Cobalt	Co	1.0% max	Residual
Manganese	Mn	0.50% max	Residual
Silicon	Si	0.50% max	Residual
Carbon	C	0.10% max	Low carbon — minimizes carbide precipitation
Titanium	Ti	0.40% max	Residual
Aluminum	Al	0.40% max	Residual

Mechanical Properties of Inconel 625 Pipes and Tubes

Property	Grade 1 (Annealed)	Grade 2 (Solution Annealed)	Typical Value
Tensile Strength (min)	827 MPa (120 ksi)	690 MPa (100 ksi)	930 MPa typical
Yield Strength 0.2% (min)	414 MPa (60 ksi)	276 MPa (40 ksi)	517 MPa typical
Elongation (min)	30%	30%	42.5% typical (50mm gauge)
Hardness (max)	—	—	241 HB / 100 HRB
Density	8.44 g/cm³	8.44 g/cm³	0.305 lb/in³
Melting Point	1290 – 1350°C	1290 – 1350°C	2350 – 2460°F
Elastic Modulus	207 GPa (30.1 × 10³ ksi)	207 GPa	At room temperature
Poisson’s Ratio	0.278	0.278	—

Thermal and Physical Properties at Various Temperatures

Property	21°C (70°F)	204°C (400°F)	427°C (800°F)	538°C (1000°F)
Thermal Conductivity (Btu·in/h·ft²·°F)	68	87	109	139
Specific Heat (Btu/lb·°F)	0.098	0.109	0.122	0.118
Thermal Expansion (×10⁻⁶/°F)	—	7.3	7.6	7.7
Elastic Modulus (×10³ ksi)	30.1	28.7	26.9	25.7

Inconel 625 Equivalent Grades and Standards

Standard	Designation
UNS	N06625
DIN / Werkstoff Nr.	2.4856
EN	NiCr22Mo9Nb
JIS	NCF 625
BS	NA 21
GOST	ЭП718 (XH75MDT)
AFNOR	NC22DNb

ASTM B444 & ASME SB444 Specifications

All Inconel 625 pipes and tubes supplied by Kalpataru Piping are manufactured to the following international standards:

Standard	Scope	Product Form
ASTM B444 / ASME SB444	Seamless nickel-alloy (UNS N06625) pipe and tube — primary pipe standard	Seamless pipes & tubes
ASTM B705 / ASME SB705	Nickel-alloy welded pipe	Welded pipes
ASTM B446 / ASME SB446	Nickel-chromium-molybdenum-niobium alloy rod and bar	Round bar (for fittings)
ASTM B564 / ASME SB564	Nickel alloy forgings	Flanges & forged fittings
ANSI B36.19M	Stainless steel pipe dimensions (applied to nickel alloy)	Dimensional standard
ANSI B36.10M	Wrought steel pipe dimensions	Dimensional standard
API 5L	Line pipe specification	Oil & gas line pipe
EN 10216-5	Seamless pressure tubes — austenitic and duplex	European equivalent

Inconel 625 Pipe Dimensions, Schedules and Weight Chart

The table below covers standard Inconel 625 pipe dimensions per ANSI B36.19M and ASTM B444. Note: Alloy 625 has a higher density (8.44 g/cm³) than stainless steel (7.98 g/cm³), resulting in approximately 5.8% higher weight per metre.

Schedule 40 Weight Chart — Inconel 625 Pipes (Density 8.44 g/cm³)

NPS (in)	DN (mm)	OD (mm)	Schedule	Wall Thickness (mm)	Weight (kg/m)
1/2″	15	21.3	SCH 40	2.77	1.35
3/4″	20	26.7	SCH 40	2.87	1.80
1″	25	33.4	SCH 40	3.38	2.68
1-1/2″	40	48.3	SCH 40	3.68	4.33
2″	50	60.3	SCH 40	3.91	5.82
3″	80	88.9	SCH 40	5.49	12.06
4″	100	114.3	SCH 40	6.02	17.18
6″	150	168.3	SCH 40	7.11	30.20
8″	200	219.1	SCH 40	8.18	45.48

Full Schedule Range — Size and Wall Thickness Availability

Schedule	Wall Thickness Range	NPS Range Available	Typical Application
SCH 5S / 5	Light wall — 1.65mm to 2.77mm	1/2″ to 24″ NB	Low-pressure instrumentation, sampling lines
SCH 10S / 10	1.65mm to 4.19mm	1/2″ to 24″ NB	General process piping, offshore topsides
SCH 40S / 40	2.77mm to 15.09mm	1/2″ to 24″ NB	Standard process piping, chemical plants
SCH 80S / 80	3.73mm to 26.19mm	1/2″ to 24″ NB	High-pressure service, hydraulic systems
SCH 160	4.75mm to 40.46mm	1/2″ to 16″ NB	Very high-pressure or corrosive service
SCH XXS	7.47mm to 22.23mm	1/2″ to 8″ NB	Extreme pressure — subsea, downhole
Heavy Wall Custom	Up to 100mm wall	10mm to 600mm OD	Pressure vessels, thick-wall manifolds

Manufacturing Range Summary

Product Type	OD Range	Wall Thickness	Length	Standard
Seamless Pipe	1/8″ to 24″ NB (4mm to 610mm)	0.5mm to 20mm	Single/Double Random; Cut-to-Length up to 6m	ASTM B444
Welded / ERW Pipe	1/2″ to 24″ NB	1.0mm to 15mm	Up to 6 metres	ASTM B705
EFW Large Diameter Pipe	6″ to 48″ NB	1.5mm to 25mm	Up to 26 metres	ASTM B705
Heavy Wall Pipe	10mm to 600mm OD	2.5mm to 100mm	0.5 to 12 metres	Custom / ASTM B444
Instrumentation Tubing	1/16″ to 2″ OD (1.6mm to 50.8mm)	0.25mm to 9.5mm	Cut-to-length / Coil	ASTM B444

Pressure Ratings for Inconel 625 Pipes at Elevated Temperatures

The table below shows maximum internal working pressures (PSI) for selected Inconel 625 pipe sizes at various operating temperatures. Pressure ratings decrease at elevated temperatures — always consult our engineering team for project-specific pressure/temperature design.

Size (mm OD × WT)	38°C (100°F)	93°C (200°F)	204°C (400°F)	316°C (600°F)	427°C (800°F)	538°C (1000°F)
3 × 0.5	940 psi	940 psi	930 psi	921 psi	907 psi	888 psi
6 × 1	940 psi	940 psi	930 psi	921 psi	907 psi	888 psi
8 × 2	1,476 psi	1,476 psi	1,462 psi	1,447 psi	1,425 psi	1,395 psi
12 × 1	440 psi	440 psi	435 psi	431 psi	424 psi	415 psi
16 × 1	324 psi	324 psi	321 psi	318 psi	313 psi	307 psi

Alloy 625 Seamless Pipe vs Welded Pipe

Factor	Seamless Inconel 625 Pipe	Welded Inconel 625 Pipe
Manufacturing	Extruded or rotary-pierced from solid billet; no seam	Rolled plate/strip formed and longitudinally welded
Pressure Capability	Higher — no weld zone; preferred for critical high-pressure service	Slightly lower; weld zone is the design limit
Size Range	1/8″ NB to 24″ NB (standard)	Up to 48″ NB via EFW — unique advantage for large OD
Cost	Higher	More cost-effective for large diameter and long runs
Post-Weld Heat Treatment	N/A	Not required — Alloy 625 weld zone retains full corrosion resistance
Best Applications	Aerospace ducting, nuclear, subsea, high-pressure chemical	FGD scrubbers, offshore risers, large-bore chemical lines
Standard	ASTM B444 / ASME SB444	ASTM B705 / ASME SB705

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Applications and Industries Served

Aerospace and Gas Turbine

Aircraft ducting, engine exhaust and nacelle components, thrust-reverser systems.
Turbine shroud rings, fuel and hydraulic lines operating at 600–982°C.
Grade 2 (solution annealed) specified for creep-critical aerospace components.

Chemical Processing and Petrochemical

Reaction vessels, distillation columns, and transfer piping handling phosphoric acid, nitric acid, and alkali solutions.
SS 316L is often upgraded to Alloy 625 where chloride concentrations exceed 1,000 ppm.
Heat exchanger and condenser tubing in aggressive multi-phase chemical environments.

Marine and Offshore

Subsea flowlines, umbilicals, and wellhead piping where seawater exposure is constant.
Propeller shafts, submarine hull penetrations, and auxiliary propulsion motor shafts.
FPSO piping systems and offshore riser connections — both seamless and large-diameter welded.

Oil and Gas

Downhole tubing and wellhead components in sour service (H₂S environments) per NACE MR0175.
Refinery heat exchanger bundles — tube-side in overhead systems with chloride-rich condensates.
Saudi ARAMCO approved supplier — regularly supplied to major Gulf region oil and gas projects.

Pollution Control and Flue Gas Desulfurization (FGD)

Scrubber bodies, dampers, ductwork, and stack liners in coal-fired power plant FGD systems.
Resists corrosive sulfur dioxide and chloride-laden flue gas at elevated temperatures.
Large-diameter welded Inconel 625 pipes (EFW, 6″ to 48″ NB) used for main scrubber headers.

Power Generation

Boiler expansion joints, superheater piping, and heat recovery steam generator (HRSG) tubing.
Nuclear steam generator tubes and reactor coolant piping where stress-corrosion cracking resistance is critical.

Welding Inconel 625 Pipes — Process and Parameters

One of the most significant fabrication advantages of Inconel 625 is that it does NOT require post-weld heat treatment (PWHT) — unlike Inconel 718. The weld zone retains corrosion resistance equivalent to the base material, reducing fabrication cost and complexity.

Stage	Process / Consideration	Key Parameter
Pre-weld Cleaning	Remove all oils, marking inks, and surface contamination	Use acetone or alcohol; do NOT use chlorinated solvents
Fit-Up	Ensure proper alignment and root gap	Typical root gap: 1.6mm for GTAW backing pass
Preheat	Generally not required	Max 93°C (200°F) if preheat is applied
GTAW / TIG (root pass)	Preferred for root and thin-wall passes; highest quality	Filler: AWS ERNiCrMo-3; Shielding: 100% Argon
GMAW / MIG (fill & cap)	Higher deposition for fill passes on thicker sections	Filler: AWS ERNiCrMo-3; Argon/He mix shielding
SMAW / Stick (field repairs)	For on-site and maintenance welding	Electrode: ENiCrMo-3; DC Reverse Polarity
Submerged Arc (production)	Automatic/semi-automatic for large diameter pipe	High deposition; requires qualified flux
Post-weld cooling	Air cool naturally	Do NOT water quench
Post-weld inspection	Visual + NDT per applicable code	DP/PT, UT, radiography as required
Post-weld cleaning	Remove heat tint; passivate if required	Pickling paste or electropolish

Surface Finish Options for Inconel 625 Pipes

Finish Type	Description	Typical Application
Mill Finish	As-extruded or as-rolled; no further surface treatment	Structural and non-critical services
Annealed & Pickled	Heat treated; acid pickled to remove scale and restore passive layer	Standard for most corrosive process applications
Bright Annealed (BA)	Annealed in controlled atmosphere; smooth reflective surface	Pharmaceutical, food processing, clean room
Electropolished	Electrochemical surface removal; lowest Ra; best corrosion resistance	Semiconductor, biotech, ultra-pure fluid service
Polished (#4 / #8 Mirror)	Mechanical polishing to specified grit	Architectural, cleanroom, decorative
Sandblasted	Uniform matte; improves paint adhesion	Coated pipes, pre-treatment applications

Quality Assurance and Testing

Every Inconel 625 pipe and tube from Kalpataru Piping is subjected to a comprehensive quality programme conducted by an independent Quality Control department. We are a certified vendor to leading OEMs and our materials are Saudi ARAMCO compliant.

Test Type	Standard / Method	Purpose
PMI Testing	Positive Material Identification	Verify Ni (58% min), Cr, Mo, Nb content per heat
Chemical Analysis	Spectro / OES per ASTM E415	Confirm all elemental composition within ASTM B444 limits
Tensile Testing	ASTM A370	Verify tensile strength ≥ 827 MPa (Gr.1) / 690 MPa (Gr.2)
Yield Strength	ASTM A370	Verify 0.2% offset yield ≥ 414 MPa (Gr.1) / 276 MPa (Gr.2)
Intergranular Corrosion (IGC)	ASTM G28 Method A	Confirm sensitization resistance in weld-affected zones
Ultrasonic Testing (UT)	ASTM E213	Detect internal defects in seamless pipes
Hydrostatic Testing	ASTM A999	100% leak-proof pressure test on every pipe
Radiography (welded)	ASTM E94	100% weld seam integrity verification
Pitting Resistance	ASTM G48 Method A	Localized corrosion resistance assessment
Flattening / Flaring	ASTM E8 / E290	Ductility and weld quality assessment

Documentation Provided with Every Shipment

EN 10204 3.1 Mill Test Certificates (MTC) — Factory certificate with manufacturer’s declaration.
EN 10204 3.2 available — Third Party Inspection (TPI) by independent agencies on request.
NABL-approved laboratory chemical and mechanical test reports.
PMI test reports — elemental verification on each pipe.
Heat traceability records — raw material to finished product.
Hydrostatic and NDT test records.
Heat treatment charts (annealing / solution treatment records).
Fumigation certificate and Certificate of Origin for international shipments.
Commercial Invoice with HS Code 75071200 for customs clearance.

Export Destinations and Supply Chain

Kalpataru Piping exports Inconel 625 Pipes and Tubes to over 40 countries. Our logistics network ensures safe and timely delivery with full export documentation, ISPM-15 compliant fumigated wooden packaging, and seaworthy packing for ocean freight.

Region	Key Countries & Cities	Delivery (Air / Sea)
Middle East	Saudi Arabia (Riyadh, Jubail, Dammam), UAE (Dubai, Abu Dhabi), Qatar, Kuwait, Oman	Air: 3–5 days \| Sea: 15–20 days
Southeast Asia	Singapore, Malaysia, Indonesia, Thailand, Vietnam	Air: 2–3 days \| Sea: 10–15 days
Europe	Germany, UK, France, Italy, Netherlands, Norway, Spain	Air: 5–7 days \| Sea: 30–35 days
North America	USA (Houston, Los Angeles, New York), Canada (Calgary, Toronto), Mexico	Air: 7–10 days \| Sea: 45–55 days
South America	Brazil, Argentina, Chile, Colombia, Venezuela	Air: 10–12 days \| Sea: 50–60 days
Africa	Nigeria, South Africa, Egypt, Algeria, Kenya, Ghana	Air: 5–8 days \| Sea: 25–35 days
East Asia	Japan, South Korea, Taiwan, China	Air: 3–5 days \| Sea: 12–18 days

HS Code for Customs Clearance: 75071200 (Nickel tube or pipe fittings). Saudi ARAMCO Approved vendor — regularly supplied to major oil and gas EPC projects in the Gulf region.

Related Inconel 625 Products and Resources

Complete your Inconel 625 piping system with our full range of matching components. All products share the same UNS N06625 alloy and comply with applicable ASTM / ASME standards:

Inconel 625 Flanges → /inconel-625-flanges-supplier/
Inconel 625 Buttweld Fittings → /inconel-625-buttweld-fittings-supplier-exporters/
Inconel 625 Round Bars and Wires → /inconel-625-round-bars-supplier-exporters/
Inconel 625 Fasteners → /inconel-625-fasteners-supplier-exporters/
Browse our complete Inconel Products range → /inconel-products/
Not sure which Inconel grade to choose? Read our Inconel Grade Guide → /inconel-grades-for-industrial-applications/

Frequently Asked Questions

What is Inconel 625 used for?

Inconel 625 is employed in order to have a high strength, extreme corrosion resistance, and broad temperature range. The main uses are aerospace engine exhaust and ducting, subsea, offshore oil and gas piping, processing vessels and heat exchangers, flue gas desulfurization scrubbers and marine seawater piping. It is resistant to pitting, crevice corrosion and chloride stress-corrosion cracking and is therefore the standard alloy of chloride-rich and acidic service environments.

What is the difference between Inconel 625 and Inconel 718?

Inconel 625 is an alloy of solid-solution-strengthened alloy – it does not need heat treatment to be strengthened, and it does not need heat treatment after fabrication. Inconel 718 is a precipitation-hardened alloy, which is much higher tensile strength (up to 1,276 MPa), but requires solution annealing and aging heat treatment following welding, which adds complexity and high cost to fabrication. 625 is used in corrosion critical piping and 718 in high-strength mechanical components like gas turbine discs and shafts.

Can Inconel 625 be welded without post-weld heat treatment?

Yes, this is one of the greatest merits of Inconel 625 in comparison to other superalloys. Niobium addition (3.15-4.15%) is used to stabilize the alloy in respect to sensitization during welding. The heat-affected zone of the weld is corrosion-resistant like the base material free of post-weld heat treatment. The use of filler materials with ERNiCrMo-3 / ENiCrMo-3 is suggested.

What is the maximum service temperature for Inconel 625?

The maximum continuous service temperature range of Inconel 625 is 982°C (1800°F). In the case of intermittent service, exposures as high as 1093°C (2000°F) are acceptable. Grade 2 (solution annealed condition) is given at temperatures above 649°C (1200°F) since it has better creep and rupture resistance than Grade 1 (annealed condition).

What is the difference between Inconel 625 Grade 1 and Grade 2?

Grade 1 (annealed) has a service range of about 593°C and is more tensile and yield strength at room temperature. Grade 2 (higher temperature solution annealed) offers slightly lower tensile characteristics at room temperature, however, with better creep resistance and long-term mechanical integrity at elevated temperatures – it is the correct choice in aerospace, power generation, and high temperature chemical service.

What ASTM standard covers Inconel 625 seamless pipes?

ASME SB444 / ASTM B444 is the main criterion of Inconel 625 seamless pipes and tubes. ASTM B705 / ASME SB705 applies to welded pipes. Material supplied by Kalpataru Piping is of standard EN 10204 3.1 Mill Test Certificates although 3.2 Third Party Inspection upon request.

What is the UNS number and DIN equivalent for Inconel 625?

Inconel 625 is N06625 in the UNS nomenclature. Its European DIN / Werkstoff number is 2.4856. The designation of the EN is NiCr22Mo9Nb. These designations are synonymous and can be used interchangeably as a specification.

Do you supply Inconel 625 pipes for Saudi ARAMCO projects?

Yes. Kalpataru Piping is a nickel alloy pipes and tubes vendor that is approved by Saudi ARAMCO. Our pipes are made of Inconel 625 and follow the ARAMCO standards and are often supplied to large oil and gas projects in Saudi Arabia, UAE, Qatar and Kuwait. Complete ARAMCO-conformity documents such as Mill Test Certificates, PMI reports and third party inspection records are presented.

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