Product Introduction
Copper nickel inner weld flange, also known as copper nickel alloy butt weld flange, is a pipe flange product made of copper nickel alloy, also called cupronickel, and connected by welding through the inner bore.
The main material grades include CuNi 90/10（B10, C70600）and CuNi 70/30（B30, C71500）. Among them, 90/10 copper nickel alloy contains approximately 10% nickel, along with small amounts of iron and manganese. It offers an excellent balance between corrosion resistance and cost-effectiveness, making it the most widely used grade.
"Inner weld" refers to the welding method in which the weld seam is located on the inner side of the flange neck when the flange is connected to the pipe. Common forms include weld neck flange（WN） and socket weld flange（SW）.
Weld neck flanges are preferred in copper nickel piping systems because of their rigid neck structure, low welding deformation, and excellent sealing performance. They are suitable for applications with relatively high pressure ratings, such as Class 150 to Class 900 and PN 6 to PN 100.
Product Specifications
| Material | C70600, C71500 and other copper nickel alloy materials |
| Size | DN15—DN600, customized according to drawings available |
| Pressure Rating | PN6, PN10, PN16, PN25, or according to project standards |
| Sealing Face Type | Flat face, raised face, male and female face, etc. |
| Connection Type | Inner weld connection, butt weld matching connection, bolted flange connection |
| Connection Method | Socket Weld |
| Working Temperature | -196℃ to 450℃ |
| Standards | GB, marine standards, DIN, JIS, ANSI, EN and other relevant standards; customized processing according to customer drawings is also available |
Product Performance Advantages
1.Excellent Corrosion Resistance
Copper nickel alloy naturally provides outstanding resistance to seawater corrosion and marine biofouling, ensuring a long service life.
2.Reliable Connection
The inner weld structure, including butt weld and socket weld types, offers excellent rigidity and sealing performance, making it suitable for a wide range of applications.
3.Complete Standards
Products can meet American, German, European, Chinese and other standard systems. Available sizes cover DN20 to DN500.
4.Mature Manufacturing Process
The product is manufactured through integrated forging, precision machining, and strict welding quality control, ensuring stable and reliable quality.
5.Wide Application Range
Copper nickel inner weld flanges have mature application cases in various industries, from shipbuilding and offshore engineering to petrochemical systems, and from normal operating conditions to high-temperature and high-pressure environments.
Product Display
Application Fields
Shipbuilding
Used in seawater cooling piping systems, ballast water pipelines, and fire-fighting systems.
Marine Engineering
Suitable for offshore platform piping systems and seawater desalination equipment.
Petrochemical Industry
Used for process pipelines conveying corrosive media.
Power Industry
Applied in condensers and cooling water pipelines of nuclear power plants and thermal power plants.
Pharmaceutical and Food Industries
Suitable for medium transportation pipelines requiring cleanliness and hygiene.
| Type | Welding Method | Strength | Installation Difficulty | Application Scenario |
| Inner Weld Flange | Socket weld | High | Relatively low | Small-diameter high-pressure systems |
| Weld Neck Flange | Butt weld | Very high | Relatively high | High-temperature and high-pressure systems |
| Slip-on Flange | Double-sided fillet weld | Medium | Easy | Low-pressure systems |
| Threaded Flange | Threaded connection | Medium | Easiest | Applications where welding is prohibited |
| Blind Flange | No welding | - | Easy | Pipeline sealing and closure |
