Precision Rolling Pipe Manufacturer

Precision Rolling Pipe: The Complete Guide for Importers and Buyers

What You Need To Know About Precision Rolling Pipe

Precision rolling pipes are considered the best quality and one of the higher grades of seamless steel pipes.

One of the known characteristics of a precision rolling pipe is that it comes with greater precision and surface finish.

The quality requirement of seamless steel pipes for oil and gas processing applications are often higher compared to any other variety in the market.

Few domestic manufacturers of precision rolling pipes use a cold drawn pipe as the blank of fine rolling pipes.

On the other hand, most known precision rolling pipe manufacturers use the two-high cold rolling mills and three-high cold rolling mill in their production processes.

Taking from the current equipment conditions, the steel pipe industry provides the billet for precision rolled pipe through the cold technique.

Additionally, they use this to adopt more rational production processes. The product (when still in the form of a finely rolled pipe billet), can be used to produce the best quality seamless steel pipes.

Features of precision rolled pipe finishing.

Cold-rolled precision steel pipes have high tolerance dimension accuracy.

Accordingly, the product accuracy is often controlled at about +/- 0.05 mm (for good inner or outer wall finishing). Additionally, no oxidation layer is found on the surface of the pipes.

Cold-rolled precision pipes have an excellent comprehensive performance.

Additionally, the pipes are designed to withstand high pressure, cold processing, flattening, among other stress processes without cracking. The pipe can also withstand all types of mechanical processing ad sophisticated deformation methods.

Lastly, the promotion and applications of precision seamless pipes can be used to:

• Save steel;
• Improve the efficiency of the processing;
• Cut some cost related to processing procedures and equipment;
• Reduce machining hours to save on costs;
• Improve the capacity of production and increase the rate of utilizing materials and;
• Improve the quality of production to reduce related costs.

Process requirements

The initial cold drawing process is improved to ensure that qualified pipe billets for cold rolling and the requirements for finishing rolling pipe billets are met.

• Oblique holes are drilled in the pipe after heating to create conducive conditions for pickling and cleaning the steel pipes’ inner surface.
• After the acid cleaning, excellent cleaning is carried out repeatedly to ensure the steel pipe’s inner surface is clean enough and suitable for phosphating. At this phase, all defects, such as internal scratches caused by cold drawing, are significantly reduced.
• What follows is the adoption of multi-pass short mandrel drawing and conical internal mold. This process happens for the first time to increase the deformation of the finished steel pipe’s inner surface. For great results, you must ensure uniform deformation for both the steel pipe’s inner and outer surface.
• The heat treatment system changes the complete annealing for the intermediate heat treatment of the almost-finished product. Recrystallization annealing for the heat treatment of the final product is adopted. The processes are mostly adopted to ensure the surface finish and mechanical properties of the steel pipes are perfect.

Differences Between Precision Steel Pipe and Seamless Steel Pipe

Many features can be used to differentiate between precision steel pipes and seamless steel pipes.

However, the first thing you need to know is that precision seamless steel pipes are a cold-drawn or hot-rolled version of high precision steel pipes after undergoing treatment.

High precision, super finish, cold bending deformation, flaring, flattening without cracks, among other treatments, are often used to create pneumatic or hydraulic components of various materials made if seamless tubes.

These are all done to make the products withstand high pressures without any leakages when being used.

The chemical composition of precision seamless steel pipes is carbon, silicon, manganese, Sulphur, phosphorus, and chromium.

Other differences between precision steel pipes and seamless steel pipes include:

• Seamless steel pipes do no require welding but can withstand higher pressure. Additionally, seamless steel pipes are sometimes rough when still in the cast form or cold-drawn components.
• Precision steel pipes are mostly products within the hole with outer wall size harboring strict tolerance and roughness.

Characteristics of precision seamless steel pipes

• The tubes often have a small outer diameter;
• The pipe is made of more dense metal to improve its performance;
• The cross-sectional area of the pipe is more complicated;
• The pipe boasts of cold-drawn finish for higher precision and better surface quality;
• With high precision, one can expect small batch production.

Hot-rolled seamless steel pipes are categorized into:

1.General steel pipes;
2.Low, medium, and high-pressure boiler seamless steel pipes;
3.Alloy seamless steel pipes;
4.Stainless seamless steel pipes;
5.Petroleum cracking seamless steel pipes;
6.Geological seamless steel pipes, among many others.

On the other hand, cold drawn precision steel pipes can be categorized into:

1.General steel pipes;
2.Low, medium, and high-pressure boiler steel pipes;
3.Electric resistance welded steel pipes;
4.Alloy steel pipes;
5.Petroleum cracking steel pipes;
6.Carbon thin-walled steel pipes;
7.Ally thin-walled steel pipes.
8.Stainless thin-walled steel pipes and;
9.Special-shaped steel pipes.

Apart from production or manufacturing processes, other ways that can be used to differentiate between high precision rolling pipes and seamless steel pipes include;

• Accuracy

The accuracy of the two pipes is different. For instance, the outer wall of hot-rolled seamless steel pipes is mostly designed to have an outer diameter larger than 32 mm, with the thickness of the wall falling anywhere between 2.5 mm and 75 mm.

On the other hand, the outer diameter of cold drawn seamless steel pipes is often about 6 mm, with the thickness of the wall being 0.25 mm.

With this in mind, it is essential to note that cold drawn seamless steel pipes are designed with higher dimensional accuracy than hot rolled seamless steel pipes. This serves as the first reason why cold drawn seamless steel pipes are more costly compared to hot rolled seamless steel pipes.

• Hardness

Hot-rolled seamless steel pipes have higher free torsional rigidity compared to cold rolled seamless steel pipes.

Therefore, hot rolled seamless steel pipes have better torsional performance than cold drawn seamless steel pipes.

Since the inner and outer wall of precision cold drawn seamless steel pipes do not have an oxide layer, leakages cold deformation, flaring, or cracking, but rather high precision, high-pressure resistance, and better surface quality, they are mainly used in the manufacture of pneumatic and hydraulic products, such as cylinders and seamless tubes.

Some essential terms about precision rolling pipes:

• Annealing. This is the process of heating the precision cold drawn seamless pipe at the rig temperature, according to the varying holding time of the material and workpiece size before cooling it slowly.

The process is usually meant to make the internal structure of the metal reach equilibrium and achieve better process performance while preparing for further quenching.

• Normalizing. This term is used to describe the cooling of the precision cold drawn pipe to an appropriate temperature before cooling it in air. The outcome of normalizing is the same as that of annealing.

However, the final microstructure in normalizing is often fine as it is used to improve the cutting performance of the material. In some cases, normalizing is applied to less demanding components and is often the final heat treatment.

• Quenching. This is the process of rapidly cooling precision cold drawn pipes after quenching in water, oil or other inorganic salts, organic aqueous solutions, or any other quenching media. The process makes precision pipes harder and, in some cases, brittle.

Precision Pipe Features and Applications

a.Some precision pipes come with smaller diameters and highly accurate surface finish.
b.High precision pipes are designed to accept a small quantity of MOQ.
c.Cold drawn processes make these pipes more accurate and highly precise.
d.The transverse area of precision pipes is often more complicated.
e.Precision rolling pipes are made of dense materials to improve their performance.

The extern and internal diameter of precision pipes can be as small as 0.01 mm.

Additionally, the weight of precision pipes is much lighter if there is a guarantee for anti-bending strength and torque strength.

The pipes are widely used in the manufacture of precision machine components and engineering structures.

In some cases, they are used in the production of weapons, pump barrel, and plunger, shells, bearing, and ESP housing, among other parts that require accuracy.

Cold-rolled precision pipes are also used in the automobile industry and the manufacture of various pneumatic components and pressure boilers.

Precision Pipe Material Standards

Precision rolling pipes are mainly carbon, alloy, or stainless-steel pipes designed with higher precision sizes. Usually, the pipes are made through hot rolling or cold drawing processes.

In that way, precision rolling pipes are seamless pipes with different modifications.

The pipes are designed with various advantages, including strict less tolerance, smooth surface finish, no leaking, high-pressure tolerance, no oxide layer on inside or outside surface, no deformation during cold bending, no cracking during flaring and flattening tests.

The pipes are widely used in the manufacture of pneumatic components and hydraulic parts due to these advantages.

Precision pipes are manufactured following the internal standards for precision pipes, the DIN 2391, alongside the European standards.

Other steel pipes standards that can be applied in the manufacture of precision seamless steel pipes include DIN2445, EN10305, DIN1630, DIN1629, ASTM A106, ASTM A179, and JIS G3445.

Precision Pipe Manufacturing Processes

It is worth noting that the critical point in the manufacture of precision seamless steel pipes is doing the annealing of raw materials.

Precision steel pipe manufacturing flow chart:

The chart below represents the manufacturing process of precision seamless steel pipes:

The two most used processes in the manufacture of precision rolling pipes are cold drawing (cold rolling) and hot rolling. Cold rolling is often the most complex of the two manufacturing processes.

The pipe is required to undergo continuous rolling by three rollers. Still, the tests have to be precisely done after extrusion to ensure that they meet the quality of any precision pipe material.

Apart from hot rolling and cold drawing, precision seamless steel pipes can also be manufactured through the welding process. If this is done, the following key steps are taken:

• The pickling

Between 10% and 15% concentration of hydrogen sulphate is used at a temperature range of between 550C and 650C. Other components include ferrous content of 100g/l or less and a pickling time of about 30 minutes.

• Cleaning

This process entails multiple cleaning of the pipes to remove any residue.

Conical outer mold and cylindrical inner molds are sometimes used in cold drawing, while curved outer molds and conical inner molds are used after the manufacturing process is complete.

All internal molds of the precision seamless pipes (the final product) adopt a “metal infiltration internal mold.”

• Annealing

Full annealing heat treatment is adopted at an annealing temperature range of between 850 degrees Celsius and 880 degrees Celsius. This process takes about 15 minutes at most.

The finished product is then taken through a recrystallization annealing heat treatment and the removal of residues at an annealing temperature range of 630-670 ℃.

The time taken for this procedure is often 10 minutes. What follows is the performance of normal processes such as post-processing.

Precision Pipe Size Tolerances

• The tolerance of the outer diameter for hot-rolled precision steel pipes is +/- 0.1%.
• For cold drawn precision steel pipes, the tolerance is according to the following conditions.
• For diameters of between 6 mm and 10 mm, the normal tolerance condition is +/- 0.2%, while the premium tolerance condition is +/- 0.15%.
• For diameters of between 10 mm and 30 mm, the normal tolerance condition is +/- 0.4%, while the premium tolerance condition is +/- 0.2%.
• For diameters of between 30 mm and 50 mm, the normal tolerance condition is +/- 0.45%, while the premium tolerance condition is +/-0.3%.
• For all outer diameters above 50 mm, the normal tolerance condition is +/- 0.1%, while the premium tolerance condition is +/- 0.8%.

Check out the datasheet below for other size tolerance for precision cold-rolled steel pipes.

Data Sheet:

Dimension Range	280mm (OD)～14mm (ID)
Dimension Accuracy	±0.05mm
WT Tolerance	<0.35mm
Flatness	0.8μm
Straightness	<0.1mm/m
Ovality	<0.03mm

 

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