What Is an Angle Valve?

The angle valve is an angle globe valve. The angle valve is similar to a ball valve, and its structure and characteristics are modified by a ball valve. The difference from the ball valve is that the outlet of the angle valve and the inlet are at a right angle of 90 degrees. Angle valve is also called triangle valve, angle valve, angle water valve. This is because the pipe has a 90-degree corner shape at the angle valve, so it is called an angle valve, an angle valve, and a corner water valve.

Angle valve is also called triangle valve, angle valve, angled water valve. It is mostly used for water and electricity installation in the decoration industry. It is an important plumbing fitting.

What is the difference between quick opening triangle valve and ordinary triangle valve:

One is the rubber ring valve core, the other is the ceramic valve core. Quick opening is the latter, which can be done in only 90 degrees, commonly known as quick opening type. Angle valves are also commonly used on cookers for gas appliances.

Angle valve research background

More than 10,000 kitchen dishwasher installation brass angle valves produced by a bathroom products company

Figure 2 Deformation of the top of the screw

Partial cracking occurred after about 4 months. The angle valve is installed under the dishwasher, and the cracking position is at the nozzle of the PP-R joint. The angle valve is made of HPb58-2 brass, and the surface is chrome plated. Figure 1 shows the appearance of a cracked angle valve. There are severe deformation marks on the top of the screw teeth. The chrome plating layer is squeezed out to expose the copper substrate. This phenomenon is universal in cracked angle valves. See Figure 2.

Using fracture observation, chemical composition analysis, hardness test, metallographic inspection and other methods, the causes of cracking failure of brass angle valves are analyzed, and suggestions for improvement are provided to provide references for the production and reasonable use of brass angle valves.

Angle valve physical and chemical test

Figure 3 shows the macro morphology of a typical cracked angle valve fracture. It can be seen that the fracture is not obvious.

Fig. 4 Microstructure of the angle valve fracture

Deformation, the surface is covered with a layer of corrosion products, and the corrosion color of the inner wall surface is darker than that of the outer wall surface, which indicates that cracking starts from the inner wall, that is, the crack expands from the inside to the outside.

Figure 4 shows the micro-morphology of a typical angle valve fracture. It can be seen that the fracture has typical cleavage fracture characteristics. The X-ray spectrometer was used to analyze the corrosion product composition on the fracture surface. It was found that corrosive elements such as sulfur, oxygen, and chlorine could be detected in the corrosion surface of the fracture surface.

The above fracture analysis results show that there is no obvious macro deformation in the angle valve fracture, the crack source is on the inner surface, the fracture is microscopically cleaved, and the surface is corroded.

Figure 3 Macro morphology of the angle valve fracture

The corrosion products include corrosive elements such as sulfur, oxygen, and chlorine. These are typical stress corrosion cracking characteristics. This shows that angle valve cracking belongs to stress corrosion cracking.

Metallographic examination of the section near the cracked angle valve cross section shows that the crack is bifurcated. This is a typical feature of stress corrosion cracking, further indicating that angle valve cracking belongs to stress corrosion cracking.

Comprehensive analysis of angle valve

HPb58-2 brass has good mechanical properties, processability and corrosion resistance. It is widely used in the production of sanitary products, water supply and drainage pipes, medals, serpentine pipes, condensation pipes, cartridge cases, and various complex shapes of punched products and small hardware. Wait. Brass has good corrosion resistance, but it is more sensitive to stress corrosion cracking, especially brass with zinc content greater than 15% (mass fraction) has higher sensitivity to stress corrosion cracking. Therefore, after the brass is processed, stress relief treatment is required to reduce the stress corrosion cracking tendency. In terms of corrosive media, brass has a greater stress corrosion cracking sensitivity to sulfur-containing corrosion media, such as corrosive elements in the environment. The presence of sulfur, oxygen, and chlorine will accelerate the occurrence of stress corrosion cracking.

From the fracture analysis, metallographic examination and energy spectrum analysis results, we can see that no obvious macro deformation of the angle valve fracture, the crack source is located on the inner surface, the crack is bifurcated, the fracture microscopically shows cleavage brittle fracture characteristics, and the corrosion products on the fracture surface There are corrosive elements such as sulfur, oxygen, and chlorine. These characteristics indicate that cracking of angle valves belongs to typical stress corrosion cracking. Stress corrosion cracking needs to meet two conditions. One is the presence of a corrosive medium and the other is the effect of stress, especially tensile stress. Therefore, it can be concluded that there is a certain tensile stress inside these cracked angle valves. Some data point out that this tensile stress often comes from welding, cold working, heat treatment and assembly processes.

Angle valve failure is a typical stress corrosion cracking. Excessive assembly stress of the angle valve is the main reason for stress corrosion cracking. It is recommended to control the assembly force when assembling a brass angle valve to avoid leaving excessive internal stress in the angle valve and causing the early failure of the angle valve. ^[3]