Is carbon steel pipe a welded steel pipe?

Is carbon steel pipe a welded steel pipe?

Carbon steel pipe is not welded steel pipe. Carbon steel pipe refers to the specific material of steel pipe is carbon steel, which refers to iron-carbon alloy with carbon content Wc less than 2.11%. In addition to carbon, it generally contains a small amount of silicon, manganese, phosphorus, sulfur and other impurities. and other trace residual elements. In addition, this carbon steel pipe has a wide range of applications, mainly used in construction, bridges, railways, vehicles, ships and various machinery manufacturing industries.

Carbon steel pipes can be divided into carbon steel welded pipes and carbon steel seamless pipes according to the manufacturing process.

Carbon steel welded pipes can be divided into three types: straight seam submerged arc welded steel pipes, spiral welded steel pipes, and high-frequency straight seam welded steel pipes according to the forming method of the weld seam.
Longitudinal welded pipe: The weld is in a straight line, so it is called straight seam welded pipe.
Spiral welded pipe: The weld seam is in a spiral shape, which is called spiral welding.

The three welding methods have their own advantages and disadvantages, and which one to use depends on the design requirements. Carbon steel welded steel pipe can be applied to many fields, such as water supply and drainage projects, piling projects, sewage pipelines, oil and gas transmission, structural pillars and other projects. The current welding method of carbon steel welded steel pipe is mainly double-sided submerged arc welding. This welding method has high efficiency, high weld quality and smooth surface.

Carbon steel seamless pipe production method:

Carbon steel seamless pipes are divided into two types: hot-rolled (extruded) seamless steel pipes and cold-drawn (rolled) seamless steel pipes due to their different manufacturing processes. Cold drawn (rolled) tubes are divided into two types: round tubes and special-shaped tubes.

1. Hot-rolled (extruded) carbon steel seamless steel pipe: round tube billet → heating → piercing → three-roll cross rolling, continuous rolling or extrusion → tube removal → sizing (or reducing) → cooling → straightening → water Pressure test (or flaw detection) → marking → storage

The raw material for rolling seamless carbon steel pipe is round tube billet, and the round tube embryo should be cut by cutting machine to grow billets with a length of about 1 meter, and transported to the furnace by conveyor belt. Billet is fed into the furnace to heat, the temperature is about 1200 degrees Celsius. The fuel is hydrogen or acetylene. The temperature control in the furnace is a key issue. After the round tube is out of the furnace, it must be pierced through a pressure piercer. Generally, the more common piercer is the cone roll piercer. This kind of piercer has high production efficiency, good product quality, large perforation diameter expansion, and can wear a variety of steel types. After piercing, the round tube billet is successively cross-rolled, continuous rolled or extruded by three rolls. After extrusion, the tube should be taken off for sizing. Sizing by high-speed rotary cone drill holes into the billet to form a tube. The inner diameter of the steel pipe is determined by the length of the outer diameter of the drill bit of the sizing machine. After the steel pipe is sized, it enters the cooling tower and is cooled by spraying water. After the steel pipe is cooled, it will be straightened. After straightening, the steel pipe is sent to the metal flaw detector (or hydraulic test) by the conveyor belt for internal flaw detection. If there are cracks, bubbles and other problems inside the steel pipe, they will be detected. After the quality inspection of steel pipes, strict manual selection is required. After the quality inspection of the steel pipe, paint the serial number, specification, production batch number, etc. with paint. And hoisted into the warehouse by crane.

2. Cold drawn (rolled) carbon steel seamless steel pipe: round tube blank→heating→perforation→heading→annealing→pickling→oiling (copper plating)→multi-pass cold drawing (cold rolling)→blank tube→heat treatment→ Straightening→hydrostatic test (flaw detection)→marking→warehousing