The Advantages and Disadvantages of Using Both Hot-rolled and Cold-drawn Seamless Pipes

Written by

A seamless pipe is a circular pipe with no seams or joints and a hollow section. Alloy steel, carbon steel, stainless steel ingot, or solid tube blank are the materials you can use to make this kind of pipe. These pipes typically use hot rolling, cold rolling, or cold drawing. In addition, you can process seamless steel pipes using monolithic steel billets, ensuring that the pipes have intrinsic mechanical strength and perform more efficiently than welded pipes.

As per the assembling strategy, the seamless pipes can be isolated into two segments that are hot-rolled seamless steel pipes and cold-drawn seamless steel tubes. Remember that there are two types of cold-drawn tubes: circular and shaped.

Pipes made of hot-rolled seamless steel:

Cold-rolling is superior to hot-rolling. It is because you can start cold rolling at the rolling’s recrystallization temperature, while hot rolling is higher than the rolling’s.

Advantages of employing hot rolled SMLS pipes:

To improve the mechanical properties of the steel organization compacting, the hot-rolled seamless pipe can damage the steel ingot’s cast microstructure, refine the steel’s crystal grains, and eliminate the microstructure flaws.

The steel is no longer, to some extent, isotropic due to this change, which you will notice while you roll the pipes in a specific direction. The most common occurrences you will notice when manufacturing welded pipes are cracks, bubbles, and osteoporosis, which result from high temperatures and pressure.

Disadvantages of using hot rolled seamless pipes:

In the hot rolling process, you will need to press the non-metallic inclusions in a steel interior that includes silicate, sulfides, and oxides primarily. The weld shrinkage interlayer tear may indicate a significant decline in the steel layering in the thickness direction due to the pull performance. Local strain caused by welding shrinkage frequently reaches multiple times the yield point strain. Therefore, the strain is much greater than the load causing it.

You should also remember that uneven cooling results in residual stress, a significant disadvantage in this process. In the absence of an external force, the stress of internal self-phase equilibrium is the focus of the residual stress. Such residual stress exists in various cross-sectional hot-rolled steel seamless pipes and tubes. The residual stresses typically increase the significance of the steel’s sectional dimension.

Thickness and edge width are challenging to control in hot-rolled steel products. You must already be well-versed in the concepts of thermal expansion and contraction. Even if the hot-rolled pipes’ initial length and thickness are standard, cooling will have some adverse effects. Because of this negative difference, you will see that the edges of the pipes get broader and thicker.

Therefore, no law requires steel edge width, thickness, length, angle, or sideline to be too precise for large steel.

Cold-drawn steel seamless pipes:

Cold-rolled seamless pipes are more precise than ot-rolled seamless steel pipes. You need these pipes for hydraulic and machinery applications, and they have a good finish on the surface. The cold rolling process is the technique you can employ to transform the steel billets into different sorts of steel items by cold working cycles such as cold drawn processes and cold bending.

General steel pipes, boiler steel pipes with low and medium pressure, high-pressure boiler steel pipes, petroleum cracking steel pipes, stainless steel pipes, and alloy steel pipes are all examples of cold-rolled seamless tubes. However, special-shaped, stainless, alloy and carbon steel pipes with thin walls are also examples of cold-rolled seamless steel pipes. The outer dimension of hot-rolled seamless pipes typically exceeds 32 mm, and the wall thickness ranges from 2.5 mm to 75 mm. The cold-rolled seamless tubes typically have a wall thickness of fewer than 0.25 millimeters and an outer diameter of fewer than 6 millimeters.

Additionally, thin-walled pipes typically have a wall thickness of less than 0.25 mm and an outer diameter of less than 5 mm. Therefore, the dimensional accuracy of cold-rolled pipes is typically higher than hot-rolled pipes.

Benefits of using cold-rolled SMLS pipes:

You can rest assured that the high-speed molding and efficiency won’t harm the coating that you use. In addition, you can manufacture various shapes using the cold-rolled method to suit different conditions. Most of the time, this process makes your seamless pipes and tubes have a higher yield point.

You may choose cold rolling to give steel products a compact finish and enhance their mechanical properties. In this process, you can eliminate steel ingots’ casting structure, refine steel products’ grain, and eliminate microstructure defects.

Steel products are no longer, at least to some extent, non-isotropic bodies due to this improvement, which can be observed primarily along the rolling direction. Additionally, this procedure addresses the high-temperature and high-pressure casting-induced shrinkage, cracks, and bubbles. So, you end up with pipes that are more durable, long-lasting, and withstand pressure better than hot-rolled pipes.

Disadvantages of cold-drawn SMLS Pipes:

Cold-rolled steel pipes typically have a relatively low free torsion stiffness. When bent, you will notice that the steel easily twists. When you roll the steel, the flexural-torsional buckling is quick in these pipe manufacturing types. The resistance to torsion is relatively low.

The cold-rolled seamless pipes have a wall thickness lower than the hot-rolled pipes. However, the connecting plates at the corners are thick enough. As a result, the partially concentrated load has limited bearing capacity.

Key takeaway:

Only a few reputable manufacturers have an integrated manufacturing unit where both processes are carried out to produce all kinds of seamless pipes and tubes that you may require while working in various industries.

Global Seamless Tubes & Pipes (GSTP) is a fabricator with skilled technocrats with extensive industry experience to oversee and carry out the entire manufacturing process with utmost precision. As a result, customers from different parts of the world always see the integration of the cold-drawn and hot-finishing processes in the same unit as a distinct advantage. If you want to know more about GSTP, visit our website: https://www.globalseamless.com/.

Article Categories:
Business

Leave a Reply

Your email address will not be published. Required fields are marked *