ASME Stainless Steel Torispherical Heads For Water Tank

Stainless steel 2B plate refers to stainless steel that has undergone cold rolling without any additional processing. It presents a matte effect with a certain luster but does not provide mirror-like reflection and cannot reflect human figures. The surface is smooth without obvious stripes or protrusions. The 2B finish is annealed or pickled, with a certain degree of surface oxidation, making it relatively dark.

The characteristics of stainless steel 2B plates include a typical surface thickness of under 3 mm. However, other thicknesses such as 5 mm, 6 mm, and 8 mm also exist, though they are relatively rare. Due to its excellent mechanical and processing properties, stainless steel 2B plate is widely used in fields such as stainless steel doors and windows, water tanks, shower rooms, electrical appliances, and kitchenware.

All stainless steel plates are divided into two types: 2B (cold-rolled) and No. 1 (hot-rolled). The thickness of 2B plates is ≤3.0 mm, while No. 1 plates are ≥3.0 mm. Compared with hot-rolled steel plates, cold-rolled steel plates have more precise thickness, a smooth and attractive surface, and superior mechanical properties, especially in terms of processing performance. Because cold-rolled raw coils are brittle and hard, they are not suitable for direct processing. Therefore, cold-rolled steel plates generally require annealing, pickling, and leveling treatments before being delivered to customers. The maximum thickness of cold-rolled steel is between 0.1 mm and 8.0 mm. For example, in most factories, the thickness of cold-rolled steel plates is less than 4.5 mm. The minimum thickness and width depend on each factory's equipment capacity and market demand.

Physical protection
Avoid bumps and scratches: During handling, positioning, welding, and other processes, Dingjin takes measures to prevent the surface of the steel plate from being bumped or scratched by hard objects.

Prevent iron-ion contamination: Avoid direct contact between stainless steel plates or heads and carbon steel. For example, during stamping, Dingjin uses materials free of iron ions to cover the surface of the steel plates.

Thermoforming high-temperature protection (if necessary)
When the thermoforming temperature is relatively high (for example, above 600°C), high-temperature-resistant paint or other protective measures should be applied to the surface of the torispherical head to prevent surface oxidation and contamination.

Control the heating temperature: Strictly control the initial and final heating temperatures.

Avoid mixed-furnace heating: It is prohibited to perform hot-forming heating of stainless steel and carbon steel heads in the same furnace.

1. Pickling Process
Objective: To remove surface oxide scale and rust, and to provide a basis for passivation.
Pickling solution: Typically, a mixture of nitric acid (10%–25%) and sodium fluoride (14%) is used.
Temperature: Controlled between 35°C and 50°C.
Time: Usually 10 to 20 minutes.

2. Passivation Process
Objective: To form a stable and dense passivation film on the stainless steel surface to enhance corrosion resistance.
Passivation solution: Typically, a mixture of nitric acid (10%–40%) and sodium dichromate (0.6%) is used.
Temperature: Controlled between 20°C and 40°C.
Time: Usually 20 to 30 minutes.

3. Cleaning and Neutralization
Cleaning: After pickling and passivation, thoroughly rinse with clean water to remove any remaining acid.
Neutralization: An alkaline neutralizing solution may be used to ensure that any residual acid on the surface is neutralized.
Final water quality: Deionized water with low halide content should be used to prevent halides from damaging the passivation film.
pH value: After cleaning, the surface pH should be controlled between 6.5 and 7.5.

4. Precautions for Operation
Strictly control the process parameters of each step, such as temperature, concentration, and time, during operation.
Prevent contamination by halides (such as chloride ions), as they can corrode the stainless steel passive film.