Monel K-500 Blind Flanges — UNS N05500 Age-Hardened Blind Manufacturer
Tesco Steel & Engineering forges Monel K-500 blind flanges — ASTM B865, UNS N05500, EN 2.4375 — to ASME B16.5 Class 150–2500 from ½″ to 24″ NB and to ASME B16.47 up to 60″. Take Monel 400's century of nobility — seawater, brine, HF acid, no passive film to break — and add the superalloy trick: aluminium and titanium precipitates (gamma-prime, the same Ni3(Al,Ti) that powers jet engines) formed by age hardening, tripling the yield to 690 MPa — the strongest grade in our entire blind range. The metal of subsea bolting, pump shafts and oil-tool hardware, here as the closure for line classes that specify it — with NACE MR0175 hardness control on request. Static duty without the stress case: Monel 400 serves it cheaper. Facings: BLRF, BLFF or BLRTJ. Every lot with EN 10204 3.1/3.2 MTC. ISO 9001:2015, made in Mumbai, India — exported to 50+ countries.
Monel K-500 · ASTM B865 · UNS N05500EN 2.4375 · NiCu30Al · QQ-N-286Age-Hardened: 965/690 MPaStrongest Grade in Our Blind RangeMonel Chemistry · Fastener-Class StrengthNACE MR0175 Hardness ControlASME B16.5 ½″–24″ · Class 150–2500EN 10204 3.1 / 3.2 · ISO 9001:2015
Monel K-500 Blind Flanges — Specifications at a Glance
What is a Monel K-500 Blind Flange?
The strong Monel. A solid forged disc of age-hardenable nickel-copper alloy (ASTM B865 / UNS N05500 / EN 2.4375) with no bore — the Monel 400 base plus Al 2.30–3.15% and Ti 0.35–0.85%, precipitation-hardened to 965/690 MPa, triple the 400's yield. The corrosion franchise carries over: seawater, brine, HF acid, caustic — nobility, not a breakable film. Subsea, offshore, oil-tool and pump/valve line classes; NACE MR0175 aged-hardness control (≤35 HRC) on request. Dimensions per ASME B16.5 / B16.47 in RF, FF and RTJ facings; EN 10204 3.1 certified.
Also searched as: Monel K500 blind flange, K-Monel blind, N05500 blind, 2.4375 blind flange, NiCu30Al blind, QQ-N-286 blind flange, age-hardened Monel blind — all refer to the product on this page. See also its soft sibling Monel 400 blind flanges, the Monel flanges hub, the strength rivals F53 super duplex / Inconel 718, and the facing pages BLRF / BLFF / BLRTJ.
The Superalloy Trick on the 1905 Base
Gamma-Prime Precipitates
Aluminium and titanium dissolve at solution temperature, then a controlled ~600°C ageing precipitates billions of sub-microscopic Ni3(Al,Ti) particles that lock the crystal planes. Yield: 172 → 690 MPa, no cold work. The K in K-500 marks the founding member of the whole age-hardened nickel family.
Nobility Untouched
The copper-nickel matrix does the corrosion protecting, and the precipitates live inside it — so seawater, brine, HF and caustic carry over from the 400 page nearly unchanged. Same enemies too: oxidising media and hot sulphur stay off the menu.
Machined and Bolted, Never Welded
Welding re-solutions the precipitates and leaves an un-ageable soft zone — so industry treats K-500 as a machined, bolted material. A flanged closure is exactly that: it delivers K-500's properties through bolting alone, asking nothing of an arc.
The aluminium-titanium pair is the entire difference from Monel 400 — the age-hardening agents. Note the impurity caps tightened across the board (sulphur at a quarter of 400's limit): a precipitation-hardened structure is less forgiving of tramp elements. Still no chromium, no molybdenum — the nobility mechanism is unchanged. Our PMI reads the Ni-Cu-Al signature on every piece.
Mechanical Properties & The Service Span
Property
ASTM B865 N05500 Requirement (Age-Hardened)
Tensile Strength
≥ 965 MPa (140 ksi) — the strongest grade in our blind range
Yield Strength (0.2%)
≥ 690 MPa (100 ksi) — four times annealed Monel 400, more than double super duplex
Elongation
≥ 20%
Hardness
Surveyed & documented; aged to ≤35 HRC where NACE MR0175 sour service applies
Condition
Precipitation (age) hardened — ageing charts on the certificate; unaged supply against specification
Service Span
Sub-zero marine duty upward; strength retained to ~480°C; the working world is chemical-plus-mechanical — seawater, HF, oil-tool stress
The natural companion of K-500's high-pressure classes — ring softer than groove
Monel K-500 Blind Flange Specifications
Monel K-500 / UNS N05500 Blind Flanges are available in the following specifications:
Material Grade
Monel K-500 — ASTM B865 (UNS N05500); QQ-N-286 heritage spec; EN 2.4375 / NiCu30Al designation where required
Heat Treatment
Precipitation (age) hardened — ageing charts certified; NACE-limited hardness or unaged condition against specification
Size
1/2"NB to 24"NB per ASME B16.5; 26"–60" per ASME B16.47; EN 1092-1 to order
Class
150#, 300#, 400#, 600#, 900#, 1500#, 2500#
Facings
Raised Face (BLRF), Flat Face (BLFF), Ring Type Joint (BLRTJ) with groove per B16.20
Service Span
Seawater, brine & HF chemistry under mechanical duty — subsea, offshore, oil-tool; state cathodic-protection regime and sour-service status at enquiry
Surface Finish
Pickled or natural machined — no paint; segregated alloy handling throughout
Modifications
NPT-tapped centre (machined before ageing), lifting provisions — machined & certified at the works
Testing
Tension & chemistry per heat — Al/Ti windows verified; hardness survey; PMI routine
Certification
EN 10204 3.1 (standard) / 3.2 witnessed
Why Monel K-500 Blind Flanges Are Specified
The Line Class Lives at the Strength Limit
Class 900–2500 seawater and injection systems, compact weight-critical offshore assemblies, completion hardware matched to drill-string metallurgy — where the stress case wrote the specification, K-500 is the only Monel that answers.
One Certificate, Stud to Closure
Systems built around K-500 pumps, valves and fasteners keep a single alloy trail across the assembly — the closure matches the metallurgy the designers already qualified.
Monel Chemistry, Kept
The stagnant-service crevice immunity, the HF franchise, the caustic tolerance — everything the 400 page claims carries over at four times the yield.
Bolted by Design
An alloy the industry refuses to weld is a natural flange material — the closure delivers full aged properties with no arc, no soft zone, no re-ageing question.
Three details buyers miss.Hydrogen embrittlement under cathodic protection: subsea K-500 bolting on CP systems has a documented brittle-failure history — hydrogen generated by the very protection scheme; control aged hardness, mind the CP potential, and state the regime at enquiry — it is a design input, not a detail. NACE MR0175 caps the hardness: sour-service N05500 must stay ≤35 HRC while meeting strength minimums — the ageing window is deliberately steered and the hardness survey joins the MTC; say “sour” explicitly on the order. Don't overspecify: for ordinary static isolations Monel 400 delivers the same chemistry at a fraction of the cost — K-500 is for the closures where the stress analysis, not the corrosion table, wrote the line class.
How Our Monel K-500 Blind Flanges Are Manufactured
1
Forging — cut billet of the spectro-verified N05500 heat — nickel floor, copper window and the Al/Ti pair confirmed — is hot-forged into the solid disc blank with full heat traceability and segregated alloy handling.
2
Solution treatment — dissolving the hardening elements into the matrix and softening the blank for machining; furnace charts retained against the heat number.
3
Machining & facing — faces, OD, drilling and any NPT taps cut in the softer unaged state to ASME B16.5 / B16.47; RF serrations, flat face or RTJ groove gauged per B16.20.
4
Age hardening — the controlled ~600°C precipitation cycle that forms the gamma-prime and triples the strength — steered to the NACE hardness window where sour service is declared; ageing charts certified.
5
Testing & finishing — tension test and chemistry against the heat; hardness survey on the aged piece; PMI reads the Ni-Cu-Al signature; pickled and marked with standard, grade, size, class and heat number.
6
Certification & packing — EN 10204 3.1 MTC (3.2 witnessed on request) including heat-treatment records; faces protected, palletised or crated sea-worthy — no carbon-steel contact in transit.
Where Monel K-500 Blind Flanges Are Used
Where Monel chemistry meets mechanical duty: subsea and offshore injection and completion systems, oil-tool and drilling assemblies, naval engineering to QQ-N-286 heritage, pump and valve circuits with K-500 shafts and trim, HF-alkylation hard points. Production below:
8″ Class 300 Blind Flange — Machined at Our WorksForged Blind Flanges — Ready for Dispatch
Monel K-500 Blind Flange Dimensions
Blind dimensions are class-governed — identical across material grades. Full charts:
Five elements — the condition and service declarations are the K-500-specific ones:
1
Size & standard — e.g. 3″ NB ASME B16.5, or the B16.47 series for 26″ and above.
2
Pressure class & facing — Class 150–2500; RF, FF or RTJ (with ring number) to match the mating flange.
3
Grade & condition — ASTM B865 UNS N05500 (Monel K-500), age-hardened (our standard) or unaged; QQ-N-286 or EN 2.4375 designation where the specification requires it.
4
Service declarations & certification — sour service (NACE MR0175 ≤35 HRC) and cathodic-protection regime stated explicitly; NPT tap size if a test blind; PMI or 3.2 witnessing as specified; EN 10204 3.1 standard.
A Monel K-500 blind flange is a solid forged disc of age-hardenable nickel-copper alloy — the Monel 400 base with aluminium and titanium added, certified to ASTM B865 as UNS N05500, EN 2.4375 — drilled to the standard bolt pattern with no bore. It carries Monel's century-proven seawater, brine and hydrofluoric-acid chemistry at roughly triple the strength: 965 MPa tensile, 690 MPa yield in the age-hardened condition. The metal of subsea bolting, pump shafts and oil-tool hardware, supplied here as the closure for line classes that specify it. Dimensions follow ASME B16.5 from ½ inch to 24 inch and ASME B16.47 beyond, in raised face, flat face and ring joint facings.
How does age hardening triple Monel's strength?
By the same trick that powers the jet-engine superalloys. Aluminium and titanium dissolve into the nickel-copper matrix at solution temperature; a controlled ageing treatment around 600°C then precipitates them as billions of sub-microscopic gamma-prime particles — Ni3(Al,Ti) — that lock the crystal planes against slip. Yield strength climbs from Monel 400's 172 MPa to 690 MPa minimum with no cold work, and the corrosion chemistry is barely touched because the copper-nickel nobility lives in the matrix, not the precipitates. The K in the name marks the founding member of that whole age-hardened nickel family.
Monel K-500 or Monel 400 — when is each specified?
By whether the component works for its living mechanically. Monel 400 is the default for static wetted parts — piping, vessels and most closures — soft, weldable, forgiving and cheaper. K-500 earns its premium where stress is the design driver: shafts, stems, springs, fasteners, drill collars, and the high-class or compact closures of subsea and oil-tool line classes. The corrosion franchise is essentially shared, so the honest rule is: specify 400 unless the stress analysis or the line class says otherwise — and when it does, K-500 is the only Monel that answers. We supply both.
What is the chemical composition of Monel K-500 (UNS N05500)?
Nickel 63.0% minimum, copper 27.0-33.0%, aluminium 2.30-3.15%, titanium 0.35-0.85%, iron ≤2.0%, manganese ≤1.5%, carbon ≤0.18%, silicon ≤0.5%, sulphur ≤0.010%. Two readings matter: the aluminium-titanium pair is the entire difference from Monel 400 — they are the age-hardening agents — and the impurity caps are tighter across the board (sulphur at 0.010 against 400's 0.024) because a precipitation-hardened structure is less forgiving of tramp elements. Still no chromium and no molybdenum: the nobility mechanism is unchanged.
What are the mechanical properties of Monel K-500 blind flanges?
In the age-hardened condition per ASTM B865: tensile strength 965 MPa (140 ksi) minimum, yield strength 690 MPa (100 ksi) minimum, elongation 20% minimum — the strongest grade in our entire blind range, four times the yield of annealed Monel 400 and more than double super duplex. The two-condition subtlety matters to buyers: K-500 is machined most economically in the softer unaged state and then hardened, so the purchase order should state the delivery condition — our standard for flanges is fully age-hardened, certified with the ageing charts.
Why is K-500 certified to ASTM B865 and not B564?
Because the age-hardening chemistry gets its own standard. B564 covers the solid-solution nickel-alloy forgings — Monel 400 among them — while B865 is written specifically for the precipitation-hardening nickel-copper-aluminium alloy N05500, with its solution and ageing heat treatments, both delivery conditions and their distinct mechanical tables. The military heritage spec QQ-N-286, still cited in naval and oil-tool procurement, covers the same metal. A purchase order citing B564 for K-500 mixes the families — the certificate that exists reads B865, and ours do.
Does K-500 keep Monel 400's corrosion resistance?
Essentially yes — that is the point of the alloy. Seawater, brine, hydrofluoric acid, caustic and the rest of the film-free franchise carry over nearly unchanged, because the noble copper-nickel matrix does the protecting and the strengthening precipitates sit inside it. Differences are at the margin: the aged structure is slightly more susceptible to localised attack in a few stagnant chloride cases and to the stress-related mechanisms that high strength always invites. The dislikes are identical: strongly oxidising media — nitric acid, ferric salts, wet chlorine — and hot sulphur-bearing gases remain off the menu.
What is the hydrogen embrittlement caution with K-500?
The famous one, learned offshore. High-strength alloys absorb atomic hydrogen, and subsea K-500 bolting connected to cathodic-protection systems — which generate hydrogen on the very surfaces they protect — has a documented history of brittle failures. The industry's response is written into practice: control the aged hardness, mind the CP potential, and qualify the combination. For a bolted closure the exposure is usually milder than for a stressed stud, but any K-500 hardware living under cathodic protection deserves the same review. State the CP regime at enquiry — it is a design input for this alloy, not a detail.
Is Monel K-500 acceptable for NACE MR0175 sour service?
Yes, with a condition attached to its hardness. NACE MR0175 / ISO 15156 lists N05500 for sour environments but caps the aged hardness at 35 HRC — precisely because the strength that makes K-500 useful also makes it sensitive to sulphide stress cracking if pushed harder. Compliant material is aged to meet the strength minimums while staying under the hardness ceiling, and the certificate documents both. If the enquiry says sour service, say so explicitly: the heat-treatment window is deliberately steered, and the hardness survey becomes part of the MTC.
Can Monel K-500 be welded?
Reluctantly, and the industry mostly declines. Welding locally re-solutions the precipitates, leaving a soft zone that cannot be re-aged without heat-treating the whole assembly, and the aged base metal is crack-sensitive beside an arc. Practice therefore treats K-500 as a machined, bolted material — exactly what a flanged closure is — and where a welded joint is unavoidable, Monel 400 or filler-metal 60 territory takes over with the strength penalty accepted. This is genuinely a point in the blind flange's favour: it delivers K-500's properties through bolting alone, asking nothing of an arc.
Where does K-500's strength actually matter on a blind flange?
In the line classes that already live at the strength limit. High-rating closures in Class 900-2500 seawater and injection systems; compact and weight-critical offshore assemblies where a thinner, lighter closure pays for itself topside; oil-tool and completion hardware where every component matches the drill-string metallurgy; and systems specified around K-500 pumps, valves and fasteners, where a matching closure keeps one alloy certificate across the assembly. For ordinary static isolations, Monel 400 remains the honest recommendation — and we will say so on the quotation.
What facings are Monel K-500 blind flanges made with?
All three: raised face (BLRF) — the default — flat face (BLFF) for mating lined and composite systems, and ring type joint (BLRTJ), the natural companion of the high-pressure classes where K-500 earns its keep, the ring chosen softer than the groove. Each facing has its own page on this site. The aged hardness deserves one note: gasket and ring materials are selected to seat against it properly, and NPT-tapped test blinds are machined before ageing and certified at the works.
Where are Monel K-500 blind flanges used?
Where Monel chemistry meets mechanical duty: subsea and offshore hardware — injection systems, completion equipment, high-class seawater circuits; oil-tool and drilling assemblies alongside K-500 collars and instruments; naval and marine engineering built to QQ-N-286 heritage; pump and valve circuits with K-500 shafts and trim; and HF-alkylation hard points where strength joins the acid brief. K-500 blinds close those systems as isolations, spare-nozzle blanks and tapped test points — one alloy certificate from stud to closure.
Which standards cover Monel K-500 blind flanges?
The material standard is ASTM B865 (UNS N05500) — the precipitation-hardening nickel-copper-aluminium specification — with QQ-N-286 as the military-heritage companion still cited in naval and oil-tool procurement, and EN 2.4375 / NiCu30Al as the European designation. Dimensions follow ASME B16.5 for ½"-24" and ASME B16.47 for 26"-60". A complete specification reads: 'Blind Flange, RTJ, 3", ASME B16.5 Class 1500, ASTM B865 UNS N05500 (Monel K-500), age-hardened' — and our EN 10204 certificates state it exactly that way, ageing treatment and hardness included.
Who manufactures Monel K-500 blind flanges in India?
Tesco Steel & Engineering is an ISO 9001:2015 certified flange manufacturer based in Mumbai, India, forging Monel K-500 / ASTM B865 / UNS N05500 / EN 2.4375 blind flanges from ½" to 24" NB per ASME B16.5 in Classes 150-2500 and to 60" per ASME B16.47 — precipitation hardened with documented ageing charts, hardness surveyed (NACE MR0175 limits on request), pickled, PMI-verified with the nickel-copper-aluminium signature read on every piece, certified to EN 10204 3.1/3.2 on every lot — in raised face, flat face and ring joint facings, alongside Monel 400, copper-nickel, Alloy 20, Hastelloy and Inconel blinds. Exported to more than 50 countries.
