"HOT FINISH STEEL PIPE" refers to industrial seamless steel pipes whose main forming process is completed at high temperatures.

Seamless steel pipe

This type of steel pipe is made from a solid steel billet through a specific process, and the entire pipe wall has no welds or seams. This makes it usually have higher integrity and reliability than welded pipes (ERW, LSAW) when subjected to high pressure, high temperature or complex stress.

Hot rolling/Hot working

Core feature: The deformation process of the tube blank (such as piercing, rolling, and sizing) is carried out when the metal is in a state of being hot and above the recrystallization temperature.

Technological process (typical) :

Billet heating: Solid round steel billets are heated to high temperatures (usually above 1200°C, presenting a bright red/orange-yellow color).

Piercing: The most common technique is the "Mannesmann piercing method". The hot solid round billet is rotated and pushed between two inclined rolls and the core bar. Under strong pressure, the central part tears apart to form a hollow "rough tube".

Rolling (extension) : The rough tubes are rolled through multiple passes with the support of a series of rolling mills (such as continuous pipe rolling mills, automatic pipe rolling mills, and precision pipe rolling mills), aiming to reduce the wall thickness, decrease the outer diameter, and improve the uniformity of the wall thickness, thereby obtaining tubes that are close to the size of the finished product.

Sizing/reducing: When the pipe is in a hot state, it passes through a sizing (reducing) machine to further adjust the precise outer diameter size, and sometimes the wall thickness is slightly reduced. Heart sticks are usually no longer used at this stage.

Cooling and straightening: After rolling, the steel pipes are cooled (possibly involving controlled cooling), and then straightened to eliminate bending.

Finishing and inspection: Cutting to a fixed length, non-destructive testing (eddy current, ultrasonic), hydrostatic testing, inspection of dimensional accuracy, appearance, etc.

The meaning of "Finish" :

Here, "finish" emphasizes that the main and decisive forming processes (piercing, rolling, sizing) are completed in a hot state. This contrasts with the following processes:

Cold-rolled/cold-drawn seamless tubes: Further precision processing of hot-rolled tubes (as blanks) at room temperature (or close to room temperature) to achieve higher dimensional accuracy, surface finish and strength.

Hot-expanded seamless tubes: Although they also involve high temperatures (expansion after heating), the core forming method (expansion) is different from the traditional hot-rolling deformation (rolling).

Welded pipe: It is made by rolling and welding plates/strips.

The main characteristics of HOT FINISH STEEL PIPE
Medium geometric accuracy: Dimensional tolerances (outer diameter, wall thickness) and surface finish are usually not as precise as those of cold-drawn tubes, but generally better than those of hot-expanded tubes and some welded tubes. It can meet most industrial requirements.

Excellent mechanical properties

Strength and toughness: During the hot working process, metals undergo recrystallization and subsequent phase transformation (depending on the cooling rate), which can achieve excellent comprehensive mechanical properties (strength, toughness, and plasticity).

High-pressure/high-temperature applicability: Due to the absence of welds and uniform metal structure, it is highly suitable for pressure-bearing components (such as boiler tubes, superheater tubes), high-pressure oil and gas pipelines, structural parts subjected to mechanical stress, etc.

Wide range of wall thickness: Pipes with medium to relatively thick wall thicknesses can be produced. Thicker walls are easier to achieve through hot rolling.

Cost: Its production cost is usually between that of welded pipes and cold-drawn seamless pipes. It is more expensive than welded pipes, but less costly than cold-drawn pipes that require multiple cold processing passes.

Delivery condition: Normalizing treatment (heating to a specific temperature and then air-cooling to improve microstructure uniformity, relieve stress, refine grains, and enhance plasticity and toughness) may usually be carried out after hot rolling, or other heat treatments (such as quenching + tempering) may be performed as required.

Main application fields
Petroleum and natural gas: oil well casing, tubing, and transportation pipelines (especially in high-pressure and high-demand environments).

Boilers and pressure vessels: Boiler tubes (superheater tubes, reheater tubes, economizer tubes), pressure vessel cylinders (large containers), chemical equipment pipelines (subject to high pressure/corrosion).

Mechanical engineering: Hydraulic prop cylinder tubes, bearing housings, mechanical structural components.

Architecture and Structure: Pipe piles, special structural components (where strength and reliability are required).

Chemical industry: High-pressure conveying pipelines, reactor components.

Ships: Pressure-resistant pipes.

Common standards

This type of pipe usually complies with specific international or national standards according to different application fields, for example:
ASTM A106 (Carbon Steel Seamless Tubes for High Temperature)

ASTM A53 (General Carbon Steel Seamless Tubes)

API 5L (Pipeline Pipe)

ASTM A335 (Seamless Alloy Steel tubes for High Temperatures)

ASTM A312 (Austenitic Stainless Steel Seamless Tube)

DIN 2448 / EN 10216

GB/T 8163, GB 9948, GB 6479 (Chinese National Standards)

Summary

Simply speaking, a HOT FINISH STEEL PIPE is a seamless steel pipe in which solid billets are directly perforated and rolled into shape at high temperatures. It is a very important basic pipe material in the industrial field, renowned for its seamless structure, excellent mechanical properties and high reliability. It is widely used in key areas such as petroleum, chemical engineering, power, and mechanical manufacturing that need to withstand harsh working conditions. Its cost and performance lie between welded pipes and cold-drawn seamless pipes, making it a mainstream choice that strikes a balance in terms of comprehensive performance, production efficiency and cost.