Characteristics of Carbon Steel Tee Pipe Fittings and Precautions for Opening Stainless Steel Tee Pipe Fittings:
I. Characteristics of Carbon Steel Tee Pipe Fittings:
Carbon steel tee pipe fittings are generally used for valve adjustments and drainage. Concentric tees facilitate fluid flow with minimal disruption to the flow pattern due to changes in diameter. Therefore, seamless tee pipe fittings use concentric pipes of different diameters for gas and vertical liquid flow pipelines. As one side of the different diameter pipes is flat, it aids in the discharge of liquids and facilitates startup and maintenance, making them suitable for liquid pipelines with different diameters in horizontal installations.
Different diameter pipes, also known as reducing tees, have different diameters at both ends and are used to connect pipes or flanges of varying diameters. In concentric and eccentric pipe fittings, the center of the circles at both ends lies on the same axis. When the pipe diameter changes, if the orientation of the pipe is calculated using the axis, the pipe's orientation angle remains unchanged. This is typically used to alter the diameter of gas or vertical liquid pipelines. Eccentric pipe fittings with different diameters cut the circumferential circumference and are generally used in horizontal liquid pipelines.
Welded tee pipe fittings are formed by hot pressing or forging steel, and they are directly welded to the steel pipe. The main manufacturing standards for welded tee pipe fittings include GB/T 12459, GB/T 13401, ASME B 16.9, SH 3408, SH 3409, HG/T 21635, HG/T 21631, and SY/T 0510. Welded tee pipe fittings come in various types, including equal tee pipe fittings and reducing tee pipe fittings, and they are made from carbon steel, alloy steel, and stainless steel.
The corrosion resistance of stainless steel tee pipe fittings depends on the alloying elements in the steel, with chromium being a fundamental element. When the chromium content in the steel reaches around 1.2%, it reacts with oxygen in corrosive media, forming a very thin oxide film (passivation film) on the steel's surface. This film prevents further corrosion of the steel. Common alloying elements used in addition to chromium are nickel, molybdenum, titanium, niobium, copper, and nitrogen, meeting the structural and functional requirements of concentric and eccentric pipe fittings for various applications.
Choosing the right production process for concentric and eccentric reducers is crucial to ensure outstanding performance and effectiveness during production and processing.
II. Precautions for Opening Stainless Steel Tee Pipe Fittings:
Deformation in stainless steel tee pipe fittings during extrusion is a form of stretching deformation. When ε (strain) is large, it can cause necking at the edge of the hole and subsequent rupture. Therefore, avoiding edge cracking is the primary concern in extrusion forming. The maximum degree of deformation in a single extrusion is mainly limited by the elongation of stainless steel data.
Precautions to be taken when opening stainless steel tee pipe fittings include the following:
1. The stainless steel tee pipe fitting ball valve should be in the closed position, where the ball valve is under the mechanical pressure of the valve stem, and the seat pressure is tight.
2. When turning the handwheel counterclockwise, the stem of the stainless steel tee pipe fitting ball valve moves in the opposite direction, causing the flat bottom surface of the stem to lift the ball off the seat.
3. The stem is continuously pulled out and colored with a guide pin in the stem's helical groove, ensuring that the ball head is not twisted due to friction.
4. Before reaching the fully open position, the stem is pulled to the extreme angle, and the ball reaches the fully open position.
These precautions are essential for the safe and efficient operation of stainless steel tee pipe fittings when opening them.
