The advantages of seamless steel pipes are high pressure resistance, good toughness, long pipe sections and few joints. The disadvantage is that it is expensive, easy to corrode, and thus has a short service life.

(1) Ordinary seamless steel pipe

Ordinary seamless steel pipes are rolled from ordinary carbon steel, high-quality carbon steel, low-alloy steel or alloy structural steel. Variety of specifications, high strength,

It is the most commonly used pipe material for pipelines and is widely used in pipelines with a working pressure below 1.6MPa. Such as heat pipelines, refrigeration pipelines, compressed air pipelines, oxygen pipelines, acetylene pipelines, and various chemical pipelines except for strong corrosive media.

(2) Stainless steel seamless steel pipe

Stainless steel seamless pipe is made of chromium-nickel stainless steel, and there are two kinds of hot-rolled and cold-rolled (cold-drawn) pipes. It is characterized by strong acid resistance and corrosion resistance, but it is expensive and is mainly used for chemical pipelines with special requirements.

(3) Welded steel pipes for low-pressure fluid transportation

Welded steel pipes for low-pressure fluid transportation are seamed pipes, generally made of Q215-A, Q235-A, Q255-A ordinary carbon steel. According to the surface quality, it is divided into two types: galvanized (white iron pipe) and stainless steel (black iron pipe); according to whether the pipe end is threaded or not, it can be divided into two types: threaded and unthreaded; according to the thickness of the pipe wall, there are ordinary and thickened two kinds.

Ordinary steel pipes can generally withstand 2.0MPa hydraulic test, and thickened pipes can withstand 3.0MPaz hydraulic test. Ordinary steel pipes and thickened pipes can generally be used for
Pipes with lower medium temperature for working pressure gauges. For example: Nominal diameter not more than 100mm can be used for indoor heating pipes, steam pipes and hot water pipes with a working pressure not exceeding 1.0MPa and medium temperature not exceeding 200°C; nominal diameter not greater than 65mm, used for working pressure not exceeding 0.8MPa Compressed air pipelines; nominal diameter not greater than 50mm can be used for gas or natural gas and clean water pipelines.

Galvanized steel pipe in hot water above 60°C and when the temperature is 60~120°C, zinc reverses the polarity. In fact, it does not prevent the corrosion of steel, but promotes the corrosion of steel, which quickly makes the water pipe rust and eventually lead to perforation.