Generally, the hardness of seamless steel pipes has three standards: Brinell Hardness, Rockwell Hardness and Vickers Hardness.   1. Brinell Hardness Brinell Hardness is the most common standard for seamless steel pipes, generally use diameter of indentation to represent the hardness of material, which is intuitive...

No matter how sophisticated the welding technique is, there still have some common defects on the welding parts of steel pipes. 1. Bubbles. Bubbles mainly occur in the center of the welding parts; the major reason is that the hydrogen is still existing in the metal weld seams in the form of bubbles. There are several measures...

There are some detailed matters need attention when welding stainless steel pipes. 1. Applied the vertical generator characteristic power, when using the direct current, apply the positive polarity (welding wire connect to negative polarity). Generally is suitable for welding thin plate about 6mm. When using this method,...

The uneven wall thickness of steel pipes is mainly represented as uneven spirally wall thickness, uneven straight wall thickness and the ends are too thick or too thin, even the grinding technique is one of the important factors. The following are the reasons to cause the uneven wall thickness and corresponding measures....

Seamless steel pipes are mainly used in oil pipeline and gas pipeline, but seldom used in oil pipelines with long-distance. Most long distance pipeline applied ERW pipes, SSAW pipes and LSAW pipes. Here are comparisons of technological features and performance of these pipes.    1. Electric Resistance Welding...

Generally, in terms of the surface treatment for stainless steel pipes, manufacturers have three methods, blenching treatment, polishing treatment and coloring treatment. However, it’s unavoidable to have some problems during the surface treatment, mainly are the following problems.   1. Defects of welding crevice....

Currently, the worldwide manufactures are attach great importance to study and research of anti-corrosion to pipes, and many new materials and technologies are emerging. 1. Double epoxy (double FBE). This material was invented by an American company named OBRIEN. The material combined the corrosion resistance and mechanical...

There are several methods of quenching the OCTG pipes, dipping, axial injection, laminar jet and laminar jet combined with axial injection. It will form the centrifugal force when quenching OCTG pipes and the centrifugal force will cause the deformation on pipes, which has serious influence on the quality and application...

There are some features about sulfate electro galvanizing technology.   1. Optimization of sulfate galvanizing The most important advantage of sulfate galvanizing is that the current efficiency can up to 100%, and has a fast deposition rate which is incomparable to other galvanizing technique. Since the crystalline...

With the constant development of industrial technology, the industrial equipment also has been developed rapidly. As a newly developed heat exchange tube with high efficiency, the nodes heat exchange tube has replaced the traditional ones. This new heat exchange tube has some unique advantages.   1. High coefficient...

According to the applications, seamless steel pipe can be classified into several major types.   1. GB/T8162-1999: structure seamless steel pipes. This type of pipe mainly used in general structure and mechanical structure. The representative materials are: carbon steel, steel of NO.20 and 45, alloy steel of Q345,...

This article introduces the extensive applications of ductile iron pipes in detail.    1. Fire protection Ductile iron pipes have three times of safety factor in design, not only can protect the whole fire protection system, the fire valves and fire hydrants are also completely made of ductile iron pipes which...