How to Calculate the Yield of Seamless Tube Production?

What is the Yield of Seamless Tube Production?

The yield of seamless tube production refers to the proportion of the weight of the final qualified product to the total weight of the raw materials (pipe billet/steel billet) input during the production process. Yield is a core indicator for measuring the technical level, management level, and economic efficiency of a seamless tube production line. A higher yield indicates less scrap and loss during production, and lower production costs.

How to Calculate the Yield of Seamless Tube Production?

The formula for calculating the yield of seamless tube production is:


Where:
* Total Weight of Raw Materials: The total weight of the tube blanks or steel billets used in production (usually calculated based on theoretical weight or actual weighing weight).
* Weight of Qualified Products: The total weight of seamless steel tubes that have passed inspection and are ready for delivery to customers.

For Example: 

A seamless tube production line inputs 100 tons of tube blanks. After processes such as piercing, rolling, sizing, heat treatment, and finishing, the final qualified finished product weighs 91 tons. The yield rate for this batch is:

91 ÷ 100 × 100% = 91%

Industry Reference:
Hot-rolled seamless tube production line: Yield rate is generally between 85% and 92%;
Cold-rolled/cold-drawn precision tube production line: Yield rate is generally between 75% and 85% (due to multiple processing steps and higher losses);
Advanced production line (such as continuous rolling mill): Yield can reach 92%-95%.

Main Loss Factors in Seamless Tube Production:

When calculating yield, losses occur at the following stages:

Loss Stage	Cause of Loss	Typical Loss Rate
Piercing and Cutting	Irregular portions removed from both ends of the tube blank after piercing	3%-5%
Rolling Burn-in	Oxidation and scale formation on the metal surface during heating	1%-2%
Pickling Loss	Slight corrosion on the metal surface during pickling to remove scale	0.5%-1%
End and End Cutting	Removal of unqualified portions from the tube ends during finishing stage	2%-4%
Scrap Loss	Scrap due to defects (cracks, internal folds, uneven wall thickness, etc.)	2%-5%
Sampling and Testing	Destructive sampling for mechanical properties, metallographic examination, etc.	0.1%-0.3%

How to Improve Seamless Tube Production Yield?

To improve the yield of seamless tubes, considering the characteristics of seamless tube production, the following measures can be taken:

1. Optimize billet quality control:
Select high-quality continuously cast billets with no surface cracks and no internal segregation.
Perform surface cleaning and flaw detection on the billets, removing billets with obvious defects.
Control the accuracy of billet cutting length to reduce length allowance.

2. Precisely control the heating process:
Use a walking beam furnace to control heating temperature and holding time.
Reduce oxidation loss; use protective atmosphere heating when necessary.
Avoid wall thickness deviation caused by uneven temperature.

3. Improve rolling accuracy:
Use high-precision piercing mills and continuous rolling mills to reduce wall thickness unevenness.
Optimize die design to improve metal deformation efficiency.
Detect wall thickness and outer diameter online and adjust rolling parameters in a timely manner.

4. Optimize head and tail cutting control:
Use online ultrasonic detection to accurately locate defects.
Automatically optimize head cutting length based on detection results to reduce waste.
Grade the cut tube ends; some can be converted into short-length tubes for sale.

5. Strengthen Quality Process Control
Implement full-process quality tracking and establish a quality file for each steel pipe.
Classify and determine defective steel pipes; those that can be repaired should not be directly scrapped.
Regularly analyze the causes of scrap and improve processes accordingly.

6. Equipment Maintenance and Management
Regularly calibrate the rolling mill roll gap to ensure dimensional accuracy.
Maintain key equipment such as heating furnaces, piercing mills, and sizing mills.
Reduce intermediate product losses caused by unplanned downtime.

7. Employee Training and Assessment
Improve operators' ability to control process parameters.
Incorporate yield indicators into team performance assessments.
Encourage employees to propose reasonable suggestions for cost reduction and efficiency improvement.

Through the implementation of the above measures, the yield of seamless tube production can be effectively improved, production efficiency increased, and production costs reduced.

Read more: Seamless Steel Pipe Sizes and Weights or Seamless Pipe Manufacturing Process