Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
Monel 400 Fittings - UNS N04400 Buttweld, Socket-Weld & Threaded
Monel 400 fittings (also Monel 400 buttweld fitting, Monel 400 socket weld fitting, Alloy 400 pipe fittings, UNS N04400 fittings, Nickel 400 fittings, Werkstoff 2.4360 fittings) are the wrought nickel-copper alloy pipe fittings family covering three end-prep groups: buttweld (BW) per ASTM B366 with ASME B16.9 dimensions, socket-weld (SW) and threaded (THD) per ASME B16.11. Sizes NPS 1/8 to 24, classes 2000 / 3000 / 6000 / 9000 on the forged side and schedules 10S through XXS on the buttweld side. Alloy is UNS N04400; chemistry matches B164 rod, B564 forgings and B127 plate. Used in HF alkylation piping, marine seawater systems, brackish-water coolers, caustic and sour-service lines. EN 10204 type 3.1 or 3.2 MTC, NACE MR0175 on indent. Monel® is a trademark of Special Metals Corporation.
Buttweld Fittings to ASTM B366 + ASME B16.9
Buttweld fittings are wrought-formed and annealed from seamless pipe, B564 forging or B127 plate blanks. Material grade is WPNC (wrought nickel-copper) per ASTM B366. Dimensional standard is ASME B16.9; bevel end preparation is ASME B16.25; the buttweld matches schedule of the connecting B165 seamless pipe. Form portfolio:
| Fitting | Dimensional standard | NPS range | Function |
|---|---|---|---|
| Long-radius elbow (LR 1.5D), 45 / 90 / 180 degrees | ASME B16.9 | 1/2 to 24 | Default direction change, center-to-end = 1.5 x NPS |
| Short-radius elbow (SR 1.0D), 90 / 180 degrees | ASME B16.9 | 1 to 24 | Tight-radius runs where space is fixed, center-to-end = 1.0 x NPS |
| Equal tee | ASME B16.9 | 1/2 to 24 | 90-degree branch off main run, same NPS run and branch |
| Reducing tee | ASME B16.9 | 1/2 to 24 | Branch smaller than run, reduces fitting count |
| Concentric reducer | ASME B16.9 | 1/2 to 24 | Pump suction transitions, centerlines aligned |
| Eccentric reducer | ASME B16.9 | 1/2 to 24 | Pump suction with flat-on-top to prevent vapour lock |
| Cap | ASME B16.9 | 1/2 to 24 | Pipe-end closure, alternative to a blind flange |
| Cross | ASME B16.9 | 1/2 to 24 | Two perpendicular branches on one fitting; on indent |
| Stub end (lap-joint) | ASME B16.9 | 1/2 to 24 | Mates with a backing flange, used where flange rotation is needed |
Wall schedule is matched to the run pipe: Sch 10S, 40, 40S, 80, 80S, 160, XXS. Hydrostatic test is by drawing; pneumatic test on indent. Heat treatment: annealed after hot forming, water-quenched, descaled by HNO3 / HF pickle.
Socket-Weld and Threaded Fittings to ASME B16.11
Forged fittings cover the small-bore high-pressure end of the system. ASME B16.11 sets socket bore, depth, pressure class and dimensions; material is forged ASTM B564 UNS N04400 to the B366 chemistry envelope. End preparation is socket bore for SW; NPT thread per ASME B1.20.1 for THD. Pressure class ratings:
| Class | Wall reference (socket-weld) | Wall reference (threaded) | Typical duty |
|---|---|---|---|
| Class 2000 | Sch 80 reference, threaded only on small NPS | Sch 80 | Light utility; rarely buttweld replaced |
| Class 3000 | Sch 160 reference | Sch XXS | Process plant standard; NPS 1/8 to 4 stocked ex Mumbai |
| Class 6000 | Sch XXS reference | Sch XXS plus | HF alkylation, sour service, NPS 1/8 to 2 stocked |
| Class 9000 | Above Sch XXS | Heavy bar-stock body | High-pressure pilot lines, on indent |
Forged form portfolio: full-coupling, half-coupling, reducing coupling, 90 elbow, 45 elbow, tee, cross, cap, union, plug (hex / square / round), bushing. Socket-weld joints require a 1.5 mm root gap per ASME B31.3 to absorb weld shrinkage; threaded joints use PTFE tape or anti-galling compound (galling note). Stamping covers heat number, spec B16.11, class, UNS N04400 and monogram.
Size Range NPS 1/8 to 24
Working envelope for Monel 400 fittings ex Mumbai stock. Larger sizes available on indent against forging blank capacity.
| End prep group | Standard | NPS range | Pressure class / schedule | Stock posture |
|---|---|---|---|---|
| Buttweld (BW) | ASME B16.9 | 1/2 to 24 | Sch 10S / 40 / 80 / 160 / XXS | NPS 1/2 to 12 ex stock; 14 to 24 on order |
| Socket-weld (SW) | ASME B16.11 | 1/8 to 4 | Class 3000, 6000 | Class 3000 ex stock; Class 6000 on order |
| Threaded (THD) | ASME B16.11 | 1/8 to 4 | Class 2000, 3000, 6000 | Class 3000 ex stock; rest on order |
| Stub end | ASME B16.9 (MSS-SP-43 short / B16.9 long) | 1/2 to 12 | Sch 10S / 40 / 80 | On order with backing flange |
Material Specification Stack
Three specs feed the Monel 400 fitting envelope; the right one depends on the form route from raw stock to finished part:
- ASTM B366 (wrought, WPNC). Primary specification for buttweld fittings hot-formed from pipe or plate blanks. Covers chemistry, mechanicals, hydrostatic, marking and certification. Grade WPNC = wrought nickel-copper = UNS N04400. Heat-treat condition is annealed.
- ASTM B564 (forged). Covers nickel-alloy forgings from which socket-weld and threaded fittings are machined. Chemistry and mechanicals match B127 plate and B164 rod. Hot-worked plus annealed. Used for B16.11 forged fittings and forged-blank B16.9 buttweld where size warrants forging route.
- ASTM B127 (plate cut). For large-diameter buttweld blanks cut and hot-formed into elbows, tees and reducers above NPS 12. Plate route is the only path on NPS 16 to 24 due to billet diameter limits. See Monel 400 plate.
Annealed mechanicals across the three specs: tensile 70 ksi (480 MPa) min, yield 28 ksi (193 MPa) min, elongation 35 percent, hardness 110 to 149 HBW. Sour service per NACE MR0175 capped at 35 HRC; annealed Monel 400 fittings clear the cap with margin.
Monel 400 Fitting Chemistry per ASTM B366 (UNS N04400)
Chemistry envelope is identical across B366, B564, B164 and B127. Detail on chemical composition.
| Element | UNS N04400 (wt %) | Role |
|---|---|---|
| Nickel (Ni) | 63.0 min | FCC matrix, sets corrosion behaviour |
| Copper (Cu) | 28.0 to 34.0 | HF and seawater passivation partner |
| Iron (Fe) | 2.5 max | Solid-solution strengthener |
| Manganese (Mn) | 2.0 max | Deoxidiser, sulphur tie-up |
| Carbon (C) | 0.3 max | Held low for weldability |
| Silicon (Si) | 0.5 max | Melt deoxidation |
| Sulphur (S) | 0.024 max | Capped for hot-working and weld soundness |
PMI by hand-held XRF on every fitting at receipt; verify Ni and Cu against the heat MTC. Free-machining Monel R-405 (N04405) at 0.025 to 0.060 percent S is bar only and never used for fittings (sour-service exclusion). See welding for ERNiCu-7 filler and procedure detail.
Companion Piping Components
A Monel 400 piping spool ties together five product families. All five trace to a single heat where possible:
- Run pipe - ASTM B165 seamless pipe, NPS 1/8 to 24, Sch 10S to XXS. Same B366 weld metal, same hydrotest.
- Flanges - ASME B16.5 (NPS 1/2 to 24) and B16.47 (NPS 26 to 60) in ASTM B564 forged Monel 400, class 150 to 2500. Welding-neck preferred for HF acid duty.
- Tubing - ASTM B163 / B165 seamless tubing for heat-exchanger bundles and instrument lines. Tube-to-tubesheet joint by ASME Section VIII Div 1.
- Bolting - ASTM F468 grade N04400 bolts and F467 nuts, K500 (N05500) on indent for higher strength. See stud bolts and hex bolts.
- Gaskets - spiral-wound Monel 400 strip with PTFE or flexible-graphite filler; ring-joint Monel 400 RTJ for class 900 plus.
Document control: spool number ties run pipe heat, fitting heat, flange heat, bolt lot and gasket lot on a single inspection record. EN 10204 type 3.1 on commercial, type 3.2 with TPI witness on nuclear, sour and NORSOK.
Applications for Monel 400 Fittings
Fittings ship where the fluid attacks stainless, carbon steel and copper alloys but stays inside the Ni-Cu passivation window:
- HF alkylation piping in refinery alkylation units per API RP 751. Reactor outlet, settler bottoms, acid regenerator overhead. Buttweld preferred; socket-weld on small-bore pilot lines. See HF alkylation and HF acid resistance.
- Marine seawater systems - sea chest piping, firewater rings, ballast lines, brackish-water coolers offshore. Crevice corrosion in stagnant seawater is the main wear vector; see seawater corrosion and marine applications.
- Sour-service gas-gathering lines per NACE MR0175 / ISO 15156-3. Annealed fittings clear the 35 HRC ceiling; see sour service applications.
- Caustic soda (NaOH) piping to 80 percent at 150 C. Branch tees and elbows on evaporator headers.
- Crude overhead condenser circuits handling fluoride and mixed-acid streams. Tube-side fittings tie to B163 / B165 tubing.
- Naval and submarine piping for non-magnetic compartments; permeability stays close to 1.0 above 51 C.
Frequently Asked Questions on Monel 400 Fittings
What are Monel 400 fittings? Wrought nickel-copper alloy pipe fittings to ASTM B366 grade WPNC, UNS N04400. Buttweld fittings (elbows, tees, reducers, caps, crosses) follow ASME B16.9 dimensions; socket-weld and threaded fittings (couplings, half-couplings, unions, plugs, bushings, elbows, tees) follow ASME B16.11 in classes 2000, 3000, 6000 and 9000. Annealed condition, hardness 110 to 149 HBW.
What is the dimensional standard for buttweld versus socket-weld Monel 400 fittings? Buttweld uses ASME B16.9 for center-to-end, center-to-face, wall and end bevel (B16.25 prep); socket-weld and threaded use ASME B16.11 for socket bore, depth and class rating. Material spec stays ASTM B366 (WPNC) for buttweld and ASTM B564 (forged UNS N04400) for socket-weld and threaded. Run pipe matches ASTM B165.
What material specification covers wrought Monel 400 fittings? Primary spec is ASTM B366 grade WPNC for wrought (hot-formed and annealed) fittings. Forged blank fittings - typical for socket-weld and threaded - run to ASTM B564 forgings. Plate-cut blanks for large-diameter buttweld run to ASTM B127. All three feed UNS N04400 chemistry with 63 percent min Ni and 28 to 34 percent Cu, annealed mechanicals at 70 ksi tensile / 28 ksi yield / 35 percent elongation.
What NPS sizes and pressure classes are available? Buttweld B16.9: NPS 1/2 to 24, Sch 10S through XXS. Socket-weld B16.11: NPS 1/8 to 4, class 3000 and 6000 stocked. Threaded B16.11: NPS 1/8 to 4, class 2000 / 3000 / 6000 / 9000. NPS 14 to 24 buttweld runs to order from plate-cut blanks per ASTM B127.
Related Pages
Forms: seamless pipe, tubing, flanges, plate, sheet, round bar, forging, wire. Standards: ASTM B164, B165, B163, B564, B127, F468, F467, NACE MR0175, DIN 17743. Properties: chemistry, mechanical, density, melting point, magnetic permeability, machinability, welding, heat treatment, corrosion, seawater, HF acid. Fasteners: bolts, nuts, hex bolts, stud bolts, washers. Applications: HF alkylation, sour service, marine, nickel-copper, what is Monel 400, UNS N04400, vs stainless, vs C276, vs K-500, data sheet, specifications, pricing, main reference.
Request a Quote. For Monel 400 fittings to ASTM B366 (WPNC) / ASME B16.9 (buttweld) / ASME B16.11 (socket-weld & threaded), UNS N04400, NPS 1/8 to 24, schedule 10S through XXS, class 2000 to 9000, EN 10204 type 3.1 or 3.2 MTC, NACE MR0175 on indent: send drawing, NPS list, schedule / class and quantity to info@torqbolt.com or WhatsApp +91-22-66157017. Heat-numbered MTC plus Mumbai ex-stock price within one working day. JNPT export worldwide.
References. ASTM B366 (Factory-Made Wrought Fittings, WPNC, N04400). ASME B16.9 (Factory-Made Wrought Buttwelding Fittings). ASME B16.11 (Forged Fittings, Socket-Welding and Threaded). ASME B16.25 (Buttwelding Ends). ASME B16.5 / B16.47 (Pipe Flanges). ASME B1.20.1 (NPT). ASTM B564 (Nickel-Alloy Forgings). ASTM B165 (Seamless Pipe, N04400). ASTM B127 (Plate, Sheet, Strip). NACE MR0175 / ISO 15156-3. EN 10204. API RP 751. ASME B31.3.
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