Monel K-500 Flanges Manufacturer in India

What is Monel K-500 (UNS N05500)?

---

Monel K-500 (UNS N05500, DIN 2.4375) is a precipitation-hardened nickel-copper alloy that combines the outstanding corrosion resistance of Monel 400 with significantly enhanced mechanical strength. By adding 2.3–3.15% aluminium and 0.35–0.85% titanium to the nickel-copper matrix, the alloy can be age-hardened to develop a fine dispersion of Ni₃(Al,Ti) γ'-precipitates, raising tensile strength to a minimum of 862 MPa — two to three times that of standard Monel 400 in the annealed condition.

Monel K-500 flanges are widely specified in offshore oil and gas, marine engineering, chemical processing, and seawater handling wherever both high mechanical strength and excellent corrosion resistance are simultaneously required. Unlike stainless steel grades, Monel K-500 is immune to chloride stress corrosion cracking and resists hydrofluoric acid, making it indispensable in alkylation units, sour gas systems, and subsea pipeline connections. Tesco Steel & Engineering manufactures UNS N05500 flanges per ASTM B564 / ASME SB564 in all standard types — WNRF, SORF, BLRF, SWRF, LJTF, THRF — from NPS ½ to 60, Class 150 to 2500.

Precipitation Hardening: What Makes K-500 Stronger Than Monel 400

---

The key differentiator between Monel K-500 and Monel 400 is the age-hardening (precipitation hardening) mechanism. The three-stage cycle transforms the alloy:

Important: Monel K-500 weld zones cannot be re-aged to full K-500 strength after welding. The heat-affected zone (HAZ) and weld metal remain in near-annealed condition. For load-bearing weld joints, specify a post-weld solution anneal + re-age cycle on the complete assembly before final machining.

Monel K-500 Chemical Composition (UNS N05500 / ASTM B564)

---

Element	UNS N05500 Range (%)	Role in the Alloy
Nickel + Cobalt	≥ 63.0 (balance)	Primary matrix; confers corrosion resistance and ductility
Copper	27.0 – 33.0	Reduces corrosion in HF acid and seawater; improves machinability
Aluminium	2.30 – 3.15	Forms Ni₃Al precipitates during ageing; primary strengthening element
Titanium	0.35 – 0.85	Co-precipitates with Al; refines precipitate size; controls grain boundary carbides
Iron	0.50 – 2.00	Solid solution strengthening; residual from raw materials
Manganese	≤ 1.50	Deoxidiser during melting; minor solid solution effect
Carbon	≤ 0.25	Limited to prevent Ti/Al carbide formation that would deplete strengthening elements
Silicon	≤ 0.50	Deoxidiser; limited to prevent embrittlement
Sulphur	≤ 0.010	Strictly controlled to prevent hot cracking during welding

Mechanical Properties — Monel K-500 vs Comparable Alloys

---

Property	K-500 Age-Hardened (UNS N05500)	K-500 Annealed (UNS N05500)	Monel 400 (UNS N04400)	Inconel 625 (UNS N06625)
UTS (MPa)	≥ 862	586	483 – 586	827 – 1034
Yield Strength (MPa)	≥ 655	241	172 – 345	414 – 758
Elongation (%)	≥ 20	35	35 – 45	30 – 40
Hardness (HRC / HRB)	25 – 33 HRC	75 – 85 HRB	70 – 85 HRB	20 – 30 HRC
Density (g/cm³)	8.44	8.44	8.83	8.44
Max Service Temp (°C)	480	480	480	980
Magnetic?	Slightly (μr < 1.005)	Non-magnetic	Non-magnetic	Non-magnetic
ASTM Flange Standard	B564 / SB564	B564 / SB564	B564 / SB564	B564 / SB564

Monel K-500 Flange Face Types Available

---

Type	Abbreviation	Description & Best Application
Weld Neck Raised Face	WNRF	Long tapered hub welded to pipe butt-end. Superior stress distribution; first choice for high-pressure, high-temperature, and vibrating service lines.
Slip-On Raised Face	SORF	Slides over pipe and double-fillet welded. Easier to align; lower material cost than WNRF; used in moderate-pressure systems up to Class 600.
Blind Raised Face	BLRF	Solid disc to permanently or temporarily close a pipe end or vessel nozzle. Used for line isolation, testing, and periodic access points.
Socket Weld Raised Face	SWRF	Pipe inserted into socket bore and fillet-welded. Suitable for small-bore piping NPS ½–2 in high-pressure Class 3000/6000 service.
Threaded (Screwed) Raised Face	THRF / SCRF	Internal threads engage directly onto threaded pipe end — no welding required. Used in low-pressure utility lines or where welding is prohibited.
Lap Joint (Van Stone)	LJTF	Used with a stub-end; flange rotates freely for bolt-hole alignment. Ideal for systems requiring frequent inspection, cleaning, or dismantling.
Ring Type Joint	RTJ	Machined groove accepts an octagonal or oval metallic ring gasket. Specified for Class 900, 1500, and 2500 high-pressure applications such as wellheads and subsea flanges.

Monel K-500 Grade Cross-Reference Table

---

Standard / System	Designation
UNS (Unified Numbering System)	N05500
ASTM / ASME (Flanges)	B564 Grade N05500 / SB564
DIN Material Number	2.4375
Trade Name	Monel® K-500 (Special Metals / Haynes International)
ISO	NiCu30Al / NW5500
EN (European Norm)	NiCu30Al (equivalent)
BS (British Standard)	NA18
AMS (Aerospace)	AMS 4676 (bar / forgings)
QQ (Mil-Spec)	QQ-N-286 (bar, rod, wire)
Filler Metal (GTAW/GMAW)	ERNiCu-7 (AWS A5.14)
Electrode (SMAW)	ENiCu-7 (AWS A5.11)

Monel K-500 Flange Specifications & Dimensions (ASME B16.5)

---

Monel K-500 Flange Dimensional Standards
Size Range	NPS ½" to 60" (DN 15 to DN 1500)
Pressure Classes (ASME B16.5)	Class 150, 300, 600, 900, 1500, 2500
Pressure Classes (ASME B16.47)	Class 75, 150, 300, 400, 600, 900 (Series A & B)
Bore Schedule	STD, XS, XXS, Sch 10–160
PN Rating	PN 6, PN 10, PN 16, PN 25, PN 40, PN 64, PN 100, PN 160, PN 250, PN 320, PN 400
Flange Standards	ASME B16.5, ASME B16.47, MSS SP-44, MSS SP-73, AWWA C207
Material Standard	ASTM B564 / ASME SB564 (UNS N05500)
Face Finish	125–250 μin Ra (AARH serrated), 63–125 μin (smooth), RTJ groove

ASME B16.5 Class 150 Raised Face — Representative Dimensions (Monel K-500 WNRF)

NPS	OD (mm)	Bolt Circle (mm)	No. of Bolts	Bolt Size	Raised Face Dia. (mm)
½"	89	60	4	M12	35
1"	108	79	4	M16	51
1½"	127	98	4	M16	73
2"	152	121	4	M16	92
3"	190	152	4	M20	127
4"	229	190	8	M20	157
6"	279	241	8	M24	216
8"	343	298	8	M24	270
10"	406	362	12	M27	324
12"	483	432	12	M27	381
16"	597	540	16	M30	489
20"	698	635	20	M30	597
24"	813	749	20	M30	711

* All dimensions per ASME B16.5. For custom sizes, Class 900–2500, or ASME B16.47 flanges NPS 26–60, contact us for certified drawings.

Welding Monel K-500 Flanges — Procedure & Best Practice

---

Parameter	Recommendation for UNS N05500
Filler — GTAW / GMAW	ERNiCu-7 (AWS A5.14) — Monel Filler Metal 60
Electrode — SMAW	ENiCu-7 (AWS A5.11) — Monel Electrode 190
Preheat	Not required; base metal temperature min 16°C (avoid welding on cold or damp surfaces)
Interpass Temperature	≤ 150°C — measure with contact pyrometer; excessive heat input increases hot-cracking risk
Shielding Gas	100% Argon (GTAW); Ar / 1–2% CO₂ (GMAW) — no nitrogen-containing gases
Heat Input	Low to moderate (0.5–1.5 kJ/mm); high heat input causes weld solidification cracking
Post-Weld Heat Treatment	Not mandatory for Monel 400 joints; for K-500 critical joints — solution anneal 980°C + age 593°C/16 h for maximum strength
Weld Zone Hardness (K-500)	Weld metal and HAZ remain in annealed condition (~75–85 HRB); full K-500 strength only restored by post-weld re-aging
Joint to Dissimilar Metals	ERNiCu-7 used for Monel-to-carbon steel or Monel-to-stainless transitions; buttering may be required for heavily restrained joints

Applications of Monel K-500 Flanges

---

International Standards for Monel K-500 Flanges

---

Category	Standard	Scope
Material (Forgings)	ASTM B564 / ASME SB564	Nickel alloy forgings — UNS N05500 chemical, mechanical, and heat treatment requirements
Material (Bar/Rod)	ASTM B865 / ASME SB865	UNS N05500 rod and bar for machined flanges and ring flanges
Pipe (for reference)	ASTM B165 / ASME SB165	UNS N04400 seamless tube/pipe (Monel 400 — basis for K-500 pipe connections)
Flange Dimensions	ASME B16.5	Flanges NPS ½–24, Class 150–2500, raised face, flat face, RTJ
Large Flanges	ASME B16.47 Series A & B	Flanges NPS 26–60; Series A (MSS SP-44), Series B (API 605)
Valve Flanges	MSS SP-44	Steel pipeline flanges — large diameter
Quality / MTC	EN 10204 Type 3.1	Material test certificates — chemical, mechanical, heat treatment records
NDE — PT	ASTM E165	Liquid penetrant examination of forgings
NDE — UT	ASTM A388 / ASME SA388	Ultrasonic examination of heavy steel forgings
Sour Service	NACE MR0175 / ISO 15156	Hardness limits and material selection for H₂S service environments
Welding Filler	AWS A5.14 / A5.11	ERNiCu-7 (GTAW/GMAW) and ENiCu-7 (SMAW) filler metal specifications
Mil Spec (Naval)	MIL-N-24106 / QQ-N-286	Monel K-500 bar and forging for US Navy and defence applications
DIN / EN	DIN 17752 / DIN 17754	European nickel alloy forging standards — material number 2.4375
JIS	JIS B2220 / JIS H4551	Japanese pipe flange and nickel alloy standards

Monel K-500 Flange Product Range — Tesco Steel & Engineering

---

Tesco Steel & Engineering supplies the complete range of Monel K-500 (UNS N05500) flanges: Weld Neck (WNRF / WNFF / WNRTJ), Slip-On (SORF / SOFF), Blind (BLRF / BLFF / BLRTJ), Socket Weld (SWRF), Threaded / Screwed (THRF), Lap Joint (LJTF), Long Weld Neck (LWNRF), Spectacle Blind, Plate Flanges and custom orifice flanges. All flanges are manufactured in the age-hardened condition per ASTM B564 unless annealed is specifically requested. Heat treatment records and material test certificates (EN 10204 3.1 MTC) supplied with every order.

For current stock availability, lead times, and pricing, click Ask for Quote or contact our technical sales team. Expedited export documentation (Mill Test Certs, Packing Lists, Country of Origin, Third-Party Inspection) available for all international shipments.

Frequently Asked Questions — Monel K-500 Flanges (UNS N05500)

---

What is Monel K-500 and how does it differ from Monel 400?

Monel K-500 (UNS N05500) is a precipitation-hardened nickel-copper alloy containing 2.3–3.15% aluminium and 0.35–0.85% titanium. These additions enable age hardening at 593°C (1100°F), raising minimum UTS to 862 MPa versus 483–586 MPa for Monel 400 (UNS N04400). Both alloys share virtually identical corrosion resistance in seawater, HF acid, and reducing environments, but K-500 offers 2–3× higher strength and hardness, making it the preferred choice for load-bearing flanges in high-stress marine and oilfield service.

What is the tensile strength of Monel K-500 flanges in the age-hardened condition?

In the age-hardened condition per ASTM B564, Monel K-500 flanges achieve minimum UTS 862 MPa (125 ksi), yield strength ≥ 655 MPa (95 ksi), and elongation ≥ 20%. In the annealed condition, UTS is typically 586 MPa with yield ≥ 241 MPa — confirming that full 862 MPa performance requires a complete solution-anneal + age-harden cycle.

What is the maximum service temperature for Monel K-500 flanges?

Monel K-500 flanges are rated for continuous service up to 480°C (900°F). Above this temperature, the Ni₃(Al,Ti) precipitate strengthening begins to dissolve, reducing hardness and strength toward annealed values. Below −100°C, K-500 retains excellent toughness, qualifying it for cryogenic pipeline flanges as well.

Which filler metal is recommended for welding Monel K-500 flanges?

ERNiCu-7 (AWS A5.14) is the standard filler wire for GTAW/GMAW of Monel K-500, and ENiCu-7 (AWS A5.11) for SMAW. Because the weld metal cannot be age-hardened to the same degree as the base metal, weld joints are inherently softer than the parent material. For critical applications, a post-weld solution anneal followed by a full age-harden cycle at 593°C for 16 hours is recommended to maximise joint strength.

Are Monel K-500 flanges magnetic?

Unlike Monel 400, which is non-magnetic, Monel K-500 exhibits slight ferromagnetic behaviour in the age-hardened condition due to ordered Ni₃(Al,Ti) γ'-precipitates. Permeability is very low (typically μr < 1.005) but measurable. For fully non-magnetic applications — such as minesweeping equipment or MRI-adjacent pipework — Monel 400 (UNS N04400) is the preferred grade.

What ASTM standard covers Monel K-500 flanges?

Monel K-500 flanges are produced to ASTM B564 / ASME SB564 (Nickel Alloy Forgings), designating UNS N05500. Dimensional standards include ASME B16.5 (NPS ½–24, Class 150–2500), ASME B16.47 Series A/B (NPS 26–60), and MSS SP-44. Material test reports (MTC 3.1 per EN 10204) must document heat treatment: solution anneal + precipitation harden, min UTS 862 MPa.

What is the chemical composition of Monel K-500 (UNS N05500)?

Per ASTM B564, Monel K-500 (UNS N05500) contains: Nickel + Cobalt ≥ 63.0%; Copper 27–33%; Aluminium 2.30–3.15%; Titanium 0.35–0.85%; Iron 0.50–2.00%; Manganese ≤ 1.50%; Carbon ≤ 0.25%; Silicon ≤ 0.50%; Sulphur ≤ 0.010%. The Al and Ti combination produces the Ni₃(Al,Ti) γ'-precipitate during ageing — the strengthening phase absent in Monel 400.

Can Monel K-500 flanges be used in seawater service?

Yes. Monel K-500 flanges exhibit uniform corrosion rates below 0.025 mm/year in flowing seawater. The alloy resists chloride pitting, crevice corrosion, and biofouling that degrade 316L stainless steel. The high strength (862 MPa UTS) further qualifies K-500 for subsea wellhead and pipeline flanges where standard austenitic grades would be inadequate. Cathodic protection is still recommended for stationary immersion service.

What is the density of Monel K-500?

The density of Monel K-500 (UNS N05500) is 8.44 g/cm³ (0.305 lb/in³). For comparison, Monel 400 has a density of 8.83 g/cm³. The slight reduction in K-500 is due to the aluminium addition (density 2.7 g/cm³) partially replacing nickel and copper in the alloy matrix.

What is the hardness of Monel K-500 in age-hardened condition?

In the age-hardened condition, Monel K-500 achieves a typical hardness of 25–33 HRC (approximately 260–340 HV). In the annealed condition, hardness is 75–85 HRB (approximately 130–170 HV). Standard age-hardening cycle: (1) solution anneal at 980°C for 1 hour + water quench; (2) age at 593°C for 16 hours; (3) air cool. For NACE MR0175 / sour service compliance, maximum hardness is 40 HRC — K-500 in normal age-hardened condition meets this limit.