The "family tree" of stainless steel pipes: from material to molding, how to accurately match the scene?

There are many types of stainless steel pipes, and choosing the right type is the key to unleashing their value. This article systematically sorts out the mainstream classifications and applicable scenarios:
Classification by material:
200 series (such as 201, 202): economical model, containing 3%-5% nickel, weak corrosion resistance, suitable for dry interior decoration (such as stair handrails, guardrails), but easy to rust in coastal areas. A community used 201 guardrails for 3 years and rusted, and was forced to replace it with 304 material;
300 series (such as 304, 316): all-round model, 304 steel pipe takes into account both rust prevention and processability, and is the first choice for food-grade pipes (such as milk delivery pipes, beer fermentation tanks). The inner wall is smooth and scale-free, and meets hygiene standards; 316 steel pipe contains molybdenum, and has outstanding resistance to sulfuric acid and seawater corrosion. The support pipes and chemical waste liquid pipes of deep-sea aquaculture cages are mostly made of this material;
400 series (such as 430, 410): nickel-free model, low cost but poor toughness, 430 steel pipe is suitable for washing machine drain pipes (resistant to weak acids and alkalis), 410 After quenching, the hardness of the steel pipe reaches HRC50, and it can be used as valve core and tool sleeve.
According to the forming process:
Seamless stainless steel pipe: formed by perforation hot rolling, seamless, pressure-resistant up to 10-30MPa, suitable for high-pressure scenes (such as boiler steam pipes, hydraulic oil pipes), a chemical plant's 10MPa reactor pipeline must choose seamless 316 steel pipe;
Welded stainless steel pipe: made of steel plate coil welding, divided into straight seam welding (suitable for low pressure) and spiral welding (slightly higher pressure), the cost is 40% lower than seamless pipe, urban tap water pipelines (below 1.6MPa) mostly use welded 304 steel pipes.