Butt-weld Metal Seal Bi-directional Type Triple Offset Butterfly Valve

With the advancement of science and technology and the technological updates of products, the demand for industrial valves has significantly changed. The use of butterfly valves has evolved from low-pressure water supply to high-temperature, high-pressure, wear-resistant, corrosion-resistant and other fields. A large number of universal cut-off and regulating valves have been replaced by butterfly valves, which are suitable for various pipelines and are used for cut-off or regulating medium flow. Many working conditions require bidirectional sealing of butterfly valves. Therefore, based on absorbing and digesting advanced technologies at home and abroad, We,JUDU has developed a new generation product, the dual flow all metal hard seal three eccentric welded butterfly valve, which combines the floating valve seat of theball valve.

Its structural characteristics include: light weight, compact structure, quick opening, reliable sealing performance, lightweight and labor-saving, easy switch and long service life, frictionless switch, automatic compensation dual flow all metal hard seal, and easy maintenance. This butterfly valve is widely used in industries such as power, metallurgy, petroleum, chemical, gas, and urban heating.

Design principles and technical characteristics

Three dimensional eccentric opening and closing and floating valve seat sealing structure

The valve adopts a three-dimensional eccentric and floating seat structure. Three dimensional eccentricity refers to the eccentricity between the valve shaft and the sealing surface of the valve seat, namely axial eccentricity; the eccentricity between the valve shaft and the center of the pipeline, namely radial eccentricity; and the angular eccentricity between the sealing surface cone axis and the valve body axis. The function of three-dimensional eccentricity is to ensure that the butterfly sealing surface can quickly separate from the valve seat cone surface when opened, reduce the frictional torque force between the butterfly sealing surface and the valve seat sealing surface, and extend the service life; ⑵ Enable it to achieve excellent sealing performance of sealing upon closing contact and separating the sealing surface upon opening. When the valve shaft rotates clockwise, the butterfly plate moves in the closing direction. When the valve shaft rotates 90 ° clockwise, the sealing surface of the butterfly plate and the sealing surface of the valve seat are in a completely closed state (i.e. sealing state); Due to the principle of three eccentricities, the butterfly plate will become tighter and tighter under the pressure of the medium, thus achieving extremely high sealing performance. When the valve shaft rotates counterclockwise, the butterfly plate will immediately separate from the valve seat cone and move towards the opening direction. When the valve shaft rotates counterclockwise by 90 °, the butterfly plate is in a fully open state.
On the 360° circumferential surface of the butterfly plate, uniform sealing positive pressure can be ensured at all points, and the metal sealing ring can achieve zero leakage sealing effect without self deformation. The valve seat sealing ring and butterfly plate sealing ring of this valve are made of stainless steel material and welded STL hard alloy, which has the excellent characteristics of high hardness, strong corrosion resistance, good elasticity, reliable sealing performance, and no leakage after 100000 switches.

At the moment of opening, each point on the circumference of the butterfly plate can simultaneously complete the action of disengaging from the valve seat, so there is no relative friction between the butterfly plate and the valve seat, ensuring the high service life of the sealing pair, high operational flexibility, and consistent sealing effect with frequent opening and closing.
The butterfly plate and valve seat maintain a consistent sealing effect through "progressive style" self compensation, without clamping. After the friction of the sealing pair, it can be compensated by pushing the position of the butterfly plate.
There is no jamming or compression between the butterfly plate and valve seat during the full stroke of the switch, and the sealing performance of the valve is not affected by temperature changes.
The sealing performance and lifespan of this triple eccentric butterfly valve mainly depend on the reasonable design of structural parameters such as the cone angle, radial eccentricity, axial eccentricity, and angular eccentricity of the valve seat sealing surface; For valves of different diameters, these parameters are not exactly the same. Our company uses three-dimensional simulation to optimize the structural parameters of each diameter valve and adopts corresponding reasonable production processes to ensure the sealing performance and service life of the product.
The floating valve seat has an automatic compensation bidirectional pressure function: (see Figure 2) when applying pressure from left to right according to the diagram, using the principle of three-dimensional eccentricity, the butterfly plate and valve body become tighter as they close, thus achieving good sealing; When applying pressure from right to left according to the diagram, the automatic compensation valve seat will automatically push towards the butterfly plate under the thrust of the pressure. As the pressure increases, the automatic compensation valve seat will push towards the butterfly plate more tightly, resulting in better sealing; In long-term use, if there is wear or damage to the automatic compensation valve seat seal and butterfly plate seal, the automatic compensation valve seat will automatically push towards the butterfly plate under pressure. When the butterfly plate moves towards the arrow under reverse pressure, the automatic compensation valve seat will also move forward under pressure, thus achieving good automatic compensation function.

Body

The valve body is an A105 integral forging welding structure, and the valve body cylinder body is forged as a whole. The metal material of the body wall has good density and high strength, and there are no shell defects or leakage points. Fully automatic welding is used for the valve shaft head and tail (middle flange), followed by overall annealing treatment after welding.

Disc

The butterfly plate is made of integral stainless steel casting, and the front and back of the butterfly plate are designed with curved streamline shapes. The butterfly plate has a hollow structure with a turtle back, which not only has good compressive strength and rigidity, but also saves materials. The shape of the curved structure makes the medium flow smoother and the fluid resistance smaller

Shaft,Shaft Sleeve

The valve stem shaft sleeve adopts SKF self-lubricating bearings, which have a low friction coefficient with the valve stem and make the valve opening and closing more flexible.
The valve stem is a through shaft structure, effectively reducing the deflection deformation of the butterfly plate under pressure. The 17-4PH stainless steel valve stem has undergone appropriate precipitation hardening treatment, which greatly improves the strength and rigidity of the material, far exceeding general austenitic and martensitic stainless steels. It also has good wear resistance, strong corrosion resistance, and very high scratch resistance. The valve stem and butterfly plate are connected by offset pins, effectively reducing the weakening of the valve stem strength by the cylindrical pin and improving the shear resistance of the cylindrical pin. Under high pressure, it forms a whole with the butterfly plate, making the seal more reliable.

Packing seal dynamic load structure

The butterfly valve packing adopts a low leakage combination packing to ensure zero leakage at the packing point. And provide a dynamic load structure, that is, adding a disc spring structure on the packing compression bolt to ensure that the packing always maintains a stable compression force, so that the valve stem always maintains a reliable seal during rotation.