Monel Tube Fittings Manufacturer
Nickel-copper alloy tube fittings for seawater, acids, alkalis, and sour gas service
- Monel 400, R405 or K500 fittings are available for your specific applications.
- Exceptional resistance to seawater, acids, and alkalis
- We supply Monel Tube Fittings in many forms including Compression Fittings, Union Fittings, Tee Fittings, Elbow Fittings and Adapter Fittings etc
Why NPTLOK for Monel Tube Fittings
We offer three Monel grades：
- Monel 400 – 65% Ni, 30% Cu. Excellent corrosion resistance in seawater, acids, and alkalis. Temperatures range from subzero to 1,000°F (538°C).
- Monel R405 – Free-machining version of Monel 400. Same corrosion resistance. Ideal for nuts and threaded bodies.
- Monel K500 – High-strength version with aluminum and titanium. Precipitation-hardened for extra hardness. For high-pressure applications.
What We Offer：
- All three Monel grades: 400, R405, and K500
- Compression fittings, unions, tees, elbows, adapters, bulkheads
- Sizes from 1/8“ to 1” OD
- NPT, BSP, or metric threads
- Silver-plated threads to prevent galling
Need Monel tube fittings for your project？ Contact us. We will help you select the right grade and configuration.
Double ferrule design. 6,000 psi rating. Monel 400, R405, or K500.
Connect two tubes end to end. Most common fitting in instrumentation systems.
Four tube connections. Distribute flow in three directions from a single point. For complex tubing layouts.
Features of Our Monel Tube Fittings
400, R405, or K500. Pick by your application.
Ideal for marine, offshore, and desalination.
Handles sour gas, caustic solutions, and more.
No galling. Smooth install and removal.
Monel 400 Tube Fittings vs Monel R405 Tube Fittings vs Monel K500 Tube Fittings
| Grade | Corrosion Resistance | Pressure Capability | Machinability | Strength / Hardness | Cost |
| Monel 400 Tube Fittings | Excellent seawater, acids, alkalis, sour gas | Standard (6,000 psi) | Good | Medium | Lowest (of the three) |
| Monel R405 Tube Fittings | Same as Monel 400 | Same as Monel 400 (6,000 psi) | Excellent best machinability | Similar to Monel 400 | Slightly higher than 400 |
| Monel K500 Tube Fittings | Same as Monel 400 | Higher (due to higher strength) | Good | Highest precipitation-hardened | Highest |
Where Are Monel Tube Fittings Used？
Marine Engineering
Monel tube fittings are used in seawater cooling systems, desalination plants, shipboard piping and offshore platforms. Monel has excellent resistance to corrosion by seawater and is particularly effective in resisting crevice corrosion and pitting. It is far better in these respects than 316LSS which would fail in a few months in such service.
Chemical Processing
Monel tube fittings are used in chemical processing for sour gas service, hydrofluoric acid service, sulfuric acid service, and in caustic service. In these extremely aggressive services, Monel tube fittings offer greater corrosion resistance and longer life than all stainless steels. They can be used in a variety of applications including well piping, heat exchangers, and other equipment where a high performance corrosion resistant alloy is required.
Oil & Gas Extraction
In this industry monel tube fittings are used in both offshore and onshore locations where high strength in corrosion resistant alloys are required.
Sour Gas Service
Natural gas with high hydrogen sulfide (H₂S) content. Monel tube fittings are qualified for sour gas service to NACE MR0175 and are also used for other corrosive service applications.
Nuclear Power
Monel tube fittings are used in cooling systems and instrumentation lines.
Laboratory & Research
Monel tube fittings are used in specialized equipment handling corrosive chemicals and high-purity media.
Need Monel tube fittings for your project？ Contact us with your grade, size, and quantity. We will help you select the right configuration.
What Tubing Should I Use with Monel Tube Fittings?
Monel tube fittings are used with Monel tubing.
Here is why.
Corrosion protection: the tube must be of the same alloy as the fitting to avoid galvanic corrosion. Monel 400, R405 and K500 fittings are used to connect Monel tubing of all grades.
Hardness of the tube material: The rear ferrule must ‘bite’ into the surface of the tube to assure a proper grip. A tube that is too hard will not allow the ferrule to ‘bite’. Typically, a tube with a hardness reading of less than 90 HRB is suitable for use with compression type fittings. And monel tubing has a hardness of approximately 75 HRB.
Tubing conditions: Tube with a constant wall thickness is better than tubing with varying wall thickness for higher working pressure. It is also recommended that the tubing be in the annealed condition so it can be more easily formed into the required shapes for an installation.
Tip1: K500 is a precipitation hardening alloy and is therefore much harder than 400 grade. Because of this higher hardness, 400 grade Monel tubing is the standard for use with all of the various types of compression type fittings. However, K500 tubing is stronger than 400 and is acceptable for use with Monel tube fittings, provided that the use is recommended by Special Metals Corporation, and that acceptable ferrules are available.
Tip2: 316 Stainless Steel Tubing is not recommended as it has a different hardness and corrosion characteristic than Monel tube fittings and ferrules and will not seat properly.
In conclusion, Use Monel 400 tubing with Monel tube fittings. Do not use stainless steel tubing. K500 tubing is not recommended for standard compression fittings, contact us if you need it.
Yes, Monel alloys are slightly magnetic. This is different from 316 stainless steel, which is non-magnetic. The magnetism does not affect corrosion resistance or performance.
Mark the nut at 6 o‘clock. Push the tube all the way in. Hand-tighten the nut. Then tighten with a wrench 1-1/4 turns – until the mark reaches 9 o’clock. No torque wrench needed.
10 pieces per size. You can start with a small order, test them in your application, and then scale up.
Yes. Monel 400 and R405 are suitable for temperatures up to 1,000°F (538°C). Monel K500 has similar temperature limits but is stronger at high pressures.
The fitting will not seal properly. Stainless steel tubing has different hardness and corrosion characteristics. The ferrule cannot bite into the tube surface. Always use Monel 400 tubing with Monel fittings.
