Description
Quick answer
Monel 400 stud bolts use UNS N04400, a solid-solution nickel-copper alloy known for marine service and resistance to selected reducing chemicals and alkalis. Alloy 400 is not precipitation hardenable; required strength comes from the specified product condition and cold work, which must be stated on the order.
Product specifications
| Material designation | Nickel-copper Alloy 400; UNS N04400; W.Nr. 2.4360/2.4361 |
|---|---|
| Material / bar reference | ASTM B164 rod, bar and wire in the ordered condition |
| Finished fastener reference | ASTM F468 for general nonferrous studs when the alloy, size and condition are covered |
| Stud configuration | Fully threaded stud bolts; custom double-end details by approved drawing |
| Inch threads | UNC, UNF and 8UN to ASME B1.1 as specified |
| Metric threads | Coarse or fine metric threads to ASME B1.13M / ISO requirements as specified |
| Dimensions | Diameter and length to flange bolting schedule, ASME B18.31.2 reference or approved drawing |
| Matching nuts | Compatible heavy hex or project-design nuts supplied after material and property review |
| Documentation | EN 10204 3.1 MTC, heat traceability and dimensional report; PMI/NDT/testing optional |
Why specify Monel 400 stud bolts?
Alloy 400 is considered for seawater pumps and valves, marine equipment, caustic solutions and properly controlled hydrofluoric acid service. It has a different corrosion profile from stainless steels and chromium-bearing nickel alloys, especially in oxidizing environments.
Corrosion resistance and material limits
The alloy performs well in flowing seawater and many reducing media, yet can be vulnerable in stagnant or polluted seawater and strongly oxidizing conditions. Dissimilar-metal contact and cathodic protection deserve review in marine bolted joints.
Engineering note: Material selection must be based on the complete process environment and governing design code. Product-page information is not a design allowable or a guarantee of service life.
Temperature and mechanical-property control
Temperature limits depend on environment, product condition, code allowables and relaxation requirements. Alloy 400 should not be selected for high-strength hot bolting solely because it retains general corrosion resistance.
Typical applications
- Marine pumps, valves and seawater piping
- Shipboard and offshore utility systems
- Hydrofluoric acid equipment under controlled conditions
- Caustic alkali and salt-production equipment
- Heat exchangers and chemical process connections
Standards, threads and flange fit-up
The material specification controls alloy chemistry, product form, heat treatment and mechanical tests. The finished-fastener specification controls stud manufacture and acceptance. The flange standard or bolting schedule controls diameter, thread and length. These documents perform different jobs and should all be identified at order review.
Cut threads and rolled threads can produce different dimensional, surface and residual-stress characteristics. State the required manufacturing method when it is a design requirement. Thread fit, end chamfers, nut engagement and exposed thread allowance must match the assembly procedure.
Matching nuts, lubrication and galling control
High-alloy studs should be purchased as part of an engineered bolting system. Nut material and proof strength must support the specified stud properties without creating an unacceptable corrosion couple. Clean threads, controlled surface finish and an approved lubricant reduce galling and torque scatter.
Torque values are not universal. Friction coefficient, coating or lubricant, nut condition, tightening sequence and reuse policy all affect achieved preload. Use a project-approved torque-tension or hydraulic-tensioning procedure.
Manufacturing, inspection and documentation
Production can include material verification, sawing, end preparation, thread machining or rolling, cleaning, dimensional inspection and permanent identification. Heat numbers remain traceable through manufacturing. Additional controls can include PMI, hardness, tensile tests, impact tests, microstructure examination, corrosion testing, ultrasonic testing or dye penetrant testing when specified.
Inspection documents should identify the ordered UNS grade, material specification and condition—not only a trade name. Third-party inspection, EN 10204 3.2 certification and customer hold points can be incorporated before production when agreed.
What to include in your RFQ
Define ASTM B164 condition and mechanical properties, F468 requirements, marine or chemical environment, thread, nut alloy, galvanic controls, PMI, cleanliness, marking and certification.
- Exact UNS designation and governing material specification/edition
- Finished-fastener and dimensional standard
- Diameter, thread series, pitch and overall length
- Required material condition and mechanical properties
- Nut and washer material, dimensions and quantity
- Design temperature, process environment and special service standard
- Testing, inspection, traceability and certificate type
- Lubrication, coating, marking, packing and delivery requirements
Authoritative material reference
Review Special Metals MONEL alloy 400 technical data together with the contractually required ASTM/ASME/ISO editions. Manufacturer literature supports material screening; the purchase order and governing code control supply.
Related stud bolt materials
Frequently asked questions
Is Alloy 400 suitable for seawater?
It is widely used in marine service, especially flowing seawater, but stagnant conditions, deposits, pollution, galvanic couples and cathodic protection must be reviewed.
Is Monel 400 precipitation hardened?
No. It is a solid-solution nickel-copper alloy. Mechanical properties depend on the supplied product condition and cold work.
Can Alloy 400 be used with stainless steel nuts?
Mixed-alloy bolting requires checks for strength, galvanic effects and galling. Use only the engineered nut material and installation procedure.
What thread systems are available?
UNC, UNF, 8UN and metric coarse or fine threads can be reviewed against diameter, length, material condition and the governing dimensional standard.
Trade names are used for material identification. INCONEL®, INCOLOY® and MONEL® are trademarks of Special Metals Corporation; HASTELLOY® is a trademark of Haynes International, Inc. SASA FLANGE supplies products to the specifications stated on the accepted order.
