The Differences between Welded Steel Pipe and Iron Pipe

The following are the differences between the welded steel pipe and the iron pipe. Iron pipe are poured and molded with cast iron. Iron pipe is used for water supply, dewatering as well as gas transfer line. In addition, it includes cast iron straight pipe and pipe fittings. And it has smaller labor strength. And depending on the different casting process, the iron pipe has two different types: continuous iron pipe and centrifugal iron pipe. And the difference between iron pipe and welded steel pipe can be told from the lumen of the pipe. If there are apparent longitudinal threads which stand out, it is wedding collar. And we can recognize it as welded steel pipe, while if there are not, then it is seamless pipe or iron pipe.

In terms of material, iron pipe is cast by pig iron, which will break into lumps after oxidation as well as corrosion for a long time, and extrusion of external force. However, the welded steel pipe will only come off some scum or cracking on both sides of flattening after being flattened. And the welded steel pipe is made of materials that have corrosion resistant feature, so it has corrosion resistance. Therefore, it is used in corrosively environment or occasions that need high purity. And welded steel pipe is divided into spiral welded pipe with large diameter as well as straight welded pipe with small diameter , while iron pipe is generally non-pressure bearing pipeline which has large diameter and iron pipe is always used for manufacturing exhaust water pipes.

Longitudinal welded steel pipe has simple manufacturing technique, high production efficiency, low production cost as well as fast development and other advantages. Mild steel pipe with small bore adopts mainly straight welding, while welded steel pipe with large bore use partly spiral welding. Otherwise, the strength of spiral welded pipe is higher than that of longitudinal welded steel pipe. And it also can manufacture welded pipes with different diameter through processing blanks that have the same width. However, when compared with straight welded steel pipe, the length of welding line expand 30~100% with lower production rate. And welded steel pipe is connected with strip steel, so it has brief production technology. Thus, its price is not as expensive as that of the iron pipe.

The nominal caliber of the iron pipe is 80~2200mm. and compared with gray iron pipe, it has the characteristics of large intensity, good toughness, thin pipe wall, less metal dosage as well as higher pressure suffering ability. Thus, it becomes the development direction of cast iron pipe. What the iron pipe uses is low phosphorous and low sulfur cast molten iron with high quality produced by iron making shaft furnace. And mould into iron pipe through centrifugal casting, annealing process and centrifugal pipe casting machine that belongs to water cooling metal mold which are advanced in the world. And then carry out elaborately conducting of multiple working procedures such as annealing, finishing bell and spigot, hydrostatic test, packing block cement of inner walls, cement packing block to preserve nature, water mill cement liner, coating asphalt paint on outer surface, baking asphalt paint, rust prevention of mouthing, shipping mark as well as package, making it become iron skin with high intensity, high extension as well as corrosion resistance. Through the differences between the welded steel pipe and API carbon steel pipe, you will understand them better.