The Forming Process and Maintenance of Stainless Steel Elbows:
When stainless steel pipes need to change direction during layout, stainless steel elbows with angles such as 45° and 90° are used for connections. Below, I will guide you through the forming process of stainless steel elbows:
Push Bending is a commonly used method for bending stainless steel pipe fittings, primarily used for bending elbows. Based on the characteristics of the bending process, it can be divided into cold push bending and mandrel hot push bending.
1. Cold Push Bending: In this method, a bending device pushes the stainless steel pipe blank into a mold at room temperature using a bending chamber, forming the stainless steel elbow. Cold push bending is suitable for stainless steel elbows with a relatively small bend radius, with the minimum relative bend radius (r) being ≤ the pipe diameter (d). The ellipticity of the bend section is small (≤3% to ≤5%), and the outer pipe wall becomes thinner (≤9%). This method has a simple structure and does not require specialized equipment, resulting in high production efficiency. However, the relative thickness requirement of stainless steel pipes is typically (t) ≥ 0.06. Otherwise, the steel blank often loses stability due to poor rigidity, resulting in wrinkles or deformations inside the elbow.
2. Mandrel Hot Push Bending: This method involves axially pushing the mandrel hot push bending elbow through a mandrel with the help of axial thrust, causing the pipe blank to expand circumferentially and bend axially, so that a smaller diameter pipe blank is pushed into a larger diameter elbow.
The main material of stainless steel elbows is different from that of carbon steel elbows. The chemical composition of stainless steel itself allows the surface of the elbow to remain corrosion and rust-free for an extended period. However, this does not mean that stainless steel elbows do not require maintenance; stainless steel elbows still need maintenance. Here's how to maintain stainless steel elbows:
1. For long-term storage of stainless steel elbows, regular inspections are needed. They should be kept clean, and any exposed surfaces should be free of dirt. These elbows should be stored neatly in well-ventilated indoor locations, avoiding stacking or open-air storage. To maintain dryness and ventilation, stainless steel elbows should be stored following the correct storage methods.
2. During installation, stainless steel elbows can be directly mounted on the pipeline according to their usage location. In general, they can be installed at any point in the pipeline, considering ease of operation. Sealing should be ensured when installing stainless steel elbows to prevent extensive leakage that might affect the normal operation of the pipeline.
3. For stainless steel elbow ball valves, globe valves, and gate valves, they should generally be fully opened or fully closed and not used to adjust the flow rate. This is to prevent corrosion affecting the sealing surface and accelerating wear. Gate valves and globe valves with top threads are equipped with a backseat device and a top-fixed handwheel to prevent media leakage at the filling point.
4. Stainless steel elbows should be operated using handwheels. Levers or other tools should not be used to avoid damaging valve components. Turn the handwheel clockwise to close and counterclockwise to open.
5. The bolts on the gland of stainless steel elbow valves should be evenly tightened, without pressing them in a tilted state, which might lead to contact or hindrance of the valve stem's movement, resulting in leaks.
6. While using stainless steel elbows, cleanliness should be maintained as much as possible. If a fault is not found, usage should be stopped promptly.
