Stainless Steel Pipes & Fittings - Selection & Application in Water Supply/Gas Supply

Q1: What are the common types of stainless steel pipes, and how are they classified? A1: Common stainless steel pipes are classified by processing technology: 1. Seamless stainless steel pipes (made by extrusion or piercing, no welds, high pressure resistance, suitable for high-pressure gas supply and industrial pipelines); 2. Welded stainless steel pipes (made by welding stainless steel sheets, with welds, lower cost, suitable for low-pressure water supply and general industrial pipelines). They can also be classified by surface finish (bright pipe, matte pipe) and diameter (large-diameter pipe, small-diameter pipe).

Q2: Which grades of stainless steel are commonly used for water supply and gas supply pipes? A2: For water supply pipes (especially drinking water pipes), 304 and 316L are the most commonly used grades. 304 is suitable for ordinary tap water supply systems, and 316L is suitable for water supply systems in coastal areas (high salt content) or areas with high water quality requirements (such as hospitals, high-end communities). For gas supply pipes (natural gas, liquefied petroleum gas), 304 or 316 seamless stainless steel pipes are used, which have high pressure resistance and corrosion resistance.

Q3: What are the key parameters to consider when selecting stainless steel pipes? A3: Key parameters include: 1. Material grade (determines corrosion resistance and service life); 2. Pipe diameter (inner diameter, outer diameter, needs to match the pipeline system); 3. Wall thickness (related to pressure resistance, the higher the pressure, the thicker the wall thickness, usually expressed by SCH standard, such as SCH10, SCH20); 4. Pressure rating (must meet the working pressure of the pipeline system); 5. Surface finish (for drinking water pipes, a smooth surface with low roughness is required to avoid bacterial growth).

Q4: What are the common connection methods of stainless steel pipe fittings? A4: Common connection methods include: 1. Welded connection (argon arc welding, suitable for seamless pipes and high-pressure pipelines, firm connection but requires professional technology); 2. Compression connection (using compression fittings to fix the pipe, no welding, easy installation, suitable for low-pressure water supply pipes); 3. Threaded connection (suitable for small-diameter pipes, simple installation but low pressure resistance); 4. Flange connection (suitable for large-diameter pipes and equipment connections, easy to disassemble and maintain).

Q5: What are the advantages of stainless steel water supply pipes compared with plastic pipes (PPR, PVC)? A5: Compared with plastic pipes, stainless steel water supply pipes have the following advantages: 1. Better hygiene: no harmful substances (such as plasticizers) are released, and the smooth surface is not easy to breed bacteria, meeting drinking water safety requirements; 2. Longer service life: service life up to 70-100 years, while PPR pipes are about 50 years; 3. Higher temperature and pressure resistance: can withstand high temperatures up to 120°C and high pressure, suitable for hot water supply systems; 4. Recyclable and environmentally friendly.