What is a Monel 400 stud bolt?

A Monel 400 stud bolt is a threaded rod fastener made from UNS N04400 nickel-copper alloy and manufactured to ASTM F468. Two forms are common: full-thread studs (threads run end to end, used with two heavy hex nuts on either side of the flange) and double-end studs (a plain shank in the middle with threaded ends, used where one end taps into a blind hole). The alloy is corrosion-resistant in flowing seawater, hydrofluoric acid, and sour gas service at NACE MR0175 limits.

How does ASTM F468 compare to ASTM A193 Grade B7 for studs?

A193 B7 is a chromium-molybdenum alloy steel (AISI 4140 class) used for high-temperature flange bolting in clean service. F468 covers nonferrous bolting including Monel 400, used where B7 cannot survive: HF alkylation acid lines, seawater, hot caustic, and sour gas above NACE H2S thresholds. The geometry (continuous thread, double-end clamping, ASME B1.1 threads) is similar; the alloy and corrosion envelope are the operative difference.

Are Monel 400 stud bolts NACE MR0175 compliant?

Yes. ASTM F468 caps Monel 400 stud bolt hardness at 25 HRC across all diameters. NACE MR0175 / ISO 15156-3 sets the nickel-copper bolting ceiling at 35 HRC, so the F468 hardness gate clears NACE MR0175 by design. The full sour qualification still requires verifying H2S partial pressure and chloride concentration against ISO 15156-3 Annex A.4 for the specific service envelope. Shipments include EN 10204 type 3.2 plus the NACE compliance statement.

What nut and washer pair with a Monel 400 stud bolt?

Pair with Monel 400 heavy hex nuts to ASTM F467, equivalent in form to ASTM A194 grade 2H but in nickel-copper chemistry. Use Monel 400 washers (DIN 125 plain, DIN 9021 fender, DIN 127 spring) to match. Carbon steel or stainless nuts on a Monel stud creates a galvanic mismatch in the clamped joint and is rejected by NACE MR0175 for sour service.

What standard sizes are stocked at TorqBolt?

Metric M6 through M40 in DIN 975 full thread and DIN 939 double-end forms, in 1 m and 3 m mill lengths plus cut-to-length. Imperial 1/4 inch through 1-1/2 inch in ASME B1.1 UNC class 2A. Sizes M48 to M64 manufactured on indent through ASTM B564 forging stock with F468 Heavy Forged Equivalent mechanicals.

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Goujons Monel 400 — UNS N04400 / ASTM F468

Goujons Monel 400 (UNS N04400) selon ASTM F468 + format A193 B8M pour joints brides ASME B16.5 en HF, eau de mer et services chimiques réducteurs. Filetage traversant ou tige réduite.

Composition chimique

Élément	Plage (% en poids)
Nickel (Ni)	63 min
Copper (Cu)	28 - 34
Iron (Fe)	2.5 max
Manganese (Mn)	2.0 max
Silicon (Si)	0.50 max
Carbon (C)	0.30 max

Propriétés mécaniques

Propriété	Valeur (min)
Tensile / Zugfestigkeit / Carico rottura / Résistance traction	70 ksi / 485 MPa
0.2% yield	28 ksi / 195 MPa
Elongation	35%
Hardness HRB	60-80

Applications

Joints brides ASME B16.5
Boulonnage couvercles échangeurs
Boulonnage trous d'homme marins
Boulons récipients pression HF
Connexions échappement navales

Normes

ASTM F468
ASTM A193 B8M format
ASME B18.31.2
DIN 939 / DIN 938

Questions fréquentes

Devis en 24h avec certification EN 10204 3.1 ou 3.2.

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Goujons Monel 400 — UNS N04400 / ASTM F468

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