Copper-Nickel Brazing Fittings

What are Copper-Nickel Brazing Fittings?

Copper-Nickel or cupronickel, brazed fittings are alloys that contain copper and nickel as the primary strengthening agent with iron and manganese as other components. These fittings play a critical role in influencing the characteristics of fluid flow. They provide strength and corrosion resistance to different applications. The fittings are very ductile, allowing them to be shaped, formed, and subsequently brazed to correct specifications. The cupro-nickel brazed fittings cover 90-10% and 30-70% of copper and nickel content respectively.

Cuni 90/10 Braze Elbow and 70/30 Cupro Nickel End Feed Bend fittings accordance to BS EN1254-1

Copper-Nickel Brazing Fittings

Application of Copper-Nickel Brazing Pipe Fittings

Copper-Nickel braze fittings are suitable for hot and cold-water piping connection

Copper-Nickel brazing pipe fittings can use both oxygen-bearing and oxygen-free copper to produce the joint. These versatile fittings are a common feature in fire protection equipment, air-conditioning and refrigeration systems, marine environments, fuel gas distribution lines, and water supply systems.

How to braze copper nickel?

Copper-nickel brazing is done at temperatures in the range of 800 degrees F or above. The material is brazed by adding a filler material and heating it till its melts and binds the material grade together. The brazed grade has superior joint strength and can operate at extreme temperatures. For a successful brazing operation scarf, butt, and lap joints are used in connecting flat, round, tubular, or any irregular-sized cross-sections.

Brazing copper-nickel pipe

  • Mark the proper length of the tube and precisely cut it.
  • Prepare the joint area and remove any oxides.
  • Snug fit the pipe and leave room for capillary action.
  • Pre-heat both the joining sides. Heat one side till it becomes red hot.
  • Touch the filler metal to the hot surface to melt the grade.
  • Allow the metal to cool and clean the excess flux or oxides.

Some pipes like medical gas or ACR system may need to use inert gas to properly braze the material.

Copper Nickel Brazing fittings can be produced in various forms such as Coupling (Male/ Straight), Reducer, bend, Elbow, Tee (Equal/ Reduced), Stop End and Male Union

Brazing cupro-nickel

Cupro nickel grades can be readily brazed in different processes. Torch brazing is the most common process that relies on wetting the surface and joining the module. It requires absolute cleanliness and is cleaned with fluxes and solvents to ensure the brazed surface is strong and very reliable for long periods.

Brazing copper-nickel to stainless steel

Brazing of copper-nickel to stainless steel is extremely difficult and the subsequent product has very low structural strength. The first major issue in brazing both these components is that both these metals have a difference in melting point of nearly 315 degrees C. This makes the process difficult from the get go. The next issue is that there are chances of metallurgical mixing of two dissimilar metals. Since stainless steel is not fully soluble with cooper nickel due to its higher melting point, it will induce the formation of grain structure and solidify the material creating a weak bond. After all this hassle hot cracking may completely compromise the weld. The best solution to join both these materials would be taking expert help and utilizing the best machinery and hope for the best.

15 mm to 159mm Copper Nickel Braze Fittings for marine environments

Copper capillary tube size

A copper capillary tube is a throttling device that is utilized in air conditioning and refrigeration units. These tubes have a copper tube made up of a small internal diameter. The internal diameter of this model ranges between 0.5mm to 2.28mm and is usually 1-6 meters long. This tube can be coiled and occupies limited space. 

What is a capillary brazing elbow?

A capillary brazing elbow is a fitting that allows the flow of fluids to be changed in the piping system. The brazing elbow is joined using a tin or copper soft solder that allows the elbow to hold and transport fluids at 16 bar of pressure at -40 degrees C and 10 bar at 110 degrees C. The versatile grade can be brazed permanently or temporarily by melting a filler material that would bind the module using capillary action.

Brazing capillary tube fittings

Capillary brazing tube fittings are designed with a socket type end that is attached to the pipe. When the filler material is heated the fitting flows along with the capillarity and fills the space between the pipe and the socket to embed it in place. These fittings can be shaped in the form of elbows, tees, crosses, and other configurations to facilitate the movement of fluids and gases in the system.

How to braze copper hvac

AC lines contain high pressures and require brazed joints to hold them in place. Some AC lines have contracted ends and need to be expanded to fit them together. For a straight tubing process, a technician expands one end of the adjoining pipe to make it big enough to mate the pipe. The inside and exterior of the pipe are cleaned with brush or sandpaper and brush flux rosin is inserted between the pipe. The smaller pipe is then expanded, and brazing of the pipe takes place to put it in place. Following this, the pipe is cleaned and rubbed to give it an aesthetical outlook.

Brazing copper with oxy-acetylene

  • Oxy-acetylene is produced having precise brazed joints. Before initiating the process of brazing, the two pieces of steel are cleaned with an emery cloth to remove any grease or dirt from the module. After this flux is applied to the joint to protect the joint against oxidation and prevent the solder from flowing inside the joint.
  • After this, the area is preheated with an oxy-acetylene flame at a distance from the steel. The steel slowly warms up the two surfaces, which helps in evaporating the water in the flux.
  • The flame is focused at one end of the joint till the steel turns red hot. Here the brazing rod is placed in the joint with a filler material. The rod then proceeds along the joint to complete the brazing process.
  • After this, the steel is slowly cooled down and later cleaned.

 Brazing copper-nickel pipe

The brazing of copper-nickel 90-10 and the 70-30 grade is straightforward as the material is very ductile and can be easily formed. These pipes offer excellent machinability but require high levels of cleanliness compared to other steel grades. They can be easily brazed or welded using standard processes. 

The 70-30 consumables are recommended for both these alloys since they offer excellent deposition characteristics along with corrosion resistance. The silver brazed alloys should be utilized rather than phosphorous bearing components. The flux-coated wires have to be supplied with a small content of aluminium to avoid porosity. Post weld treatment of the material is not required, and any traces of spatter can be removed with a stainless steel brush or a flapper rotating wheel to give it an aesthetical appeal.

Brazed Copper Nickel Pipe Fittings are suitable for Navy, marine applications & shipyards

Brazing vs welding

Welding is a process where metal is joint by applying concentrated heat to the module to melt and fuse it together. Brazing, on the contrary, makes use of a filler metal that is melted on the material and fuses with the joint via the capillary actions. Welding can also use filler material, but brazing uses significantly lower temperatures to put the material in place.

A welded joint is permanent and may disturb the physical properties of the joint; however, brazing can be temporary or permanent and doesn’t distort or add any stress to the joint area. In the brazing procedure joints of dissimilar sizes can be easily joined and allow for easy realignment. The speed of joining parts via the welding process is slow in comparison to the fast-paced brazing process.

The capillary brazing fittings manufacturers in India can provide quality products at the most reasonable rates. The easy availability of raw materials due to the strategic location of the country helps in getting them to the vendor in a short time frame. India also bolsters vast resources in terms of labour. Due to the huge population of the country, labour for producing the material can be availed at cheap rates. Most vendors in the country have more than one outlets having good connection to roadways, waterways and airways, allowing for the movement of products easily and making transportation look simple and viable.