Common Seamless Processing Methods for Stainless Steel Pipes
The seamless processing methods for stainless steel pipes are designed to eliminate weld seam defects, improve microstructure, and enhance both dimensional accuracy and surface quality. Different methods are selected based on pipe diameter, wall thickness, material grade, and performance requirements. At Ganyeah Group, we apply advanced seamless treatment technologies to ensure stainless steel pipes meet the demanding needs of industries such as petrochemical, energy, shipbuilding, and pharmaceuticals.
1. Hot Expansion Seamless Process
Hot expansion is the preferred method for large-diameter stainless steel welded pipes (DN200–DN1000). It integrates heating, expansion, and annealing to fully fuse the weld with the base material.
- Core Steps: Pre-treatment → Heating → Expansion → Annealing → Sizing & Straightening.
- Key Benefits: Eliminates welding stress, enhances toughness, and ensures reliable pressure resistance.
- Limitations: Higher energy consumption, moderate dimensional precision.
- Applications: Municipal water mains, chemical steam pipelines, and low-temperature service pipelines.
2. Cold Drawing Seamless Process
Cold drawing is the core method for small-diameter precision stainless steel pipes (DN10–DN150). By passing welded pipes through dies and mandrels multiple times, micro-defects are removed, grain structure is refined, and mechanical strength is increased.
- Core Steps: Pre-treatment → Multi-pass drawing → Sizing → Low-temperature annealing → Finishing.
- Advantages: High dimensional accuracy (±3%), excellent surface finish (Ra ≤ 0.8 μm).
- Limitations: Limited to small diameters, slower efficiency.
- Applications: Medical tubing, semiconductor ultrapure water systems, hydraulic pipelines.
3. Internal Weld Grinding
Internal weld grinding removes the inner weld bead, ensuring smooth internal surfaces that minimize fluid resistance and contamination risks.
- Advantages: Reduces fluid resistance by over 30%.
- Limitations: Does not improve weld microstructure, less effective for long pipes.
- Applications: Food-grade and pharmaceutical pipelines.
ASME B36.10 super duplex ASTM A790 PE seamless pipes
4. Internal Polishing
As an upgrade to grinding, internal polishing delivers mirror-like smoothness (Ra 0.2–0.8 μm). This ensures pipes meet strict hygiene standards in pharmaceutical and semiconductor industries.
- Advantages: Prevents microbial growth, supports fast cleaning (CIP).
- Limitations: High cost, limited to small diameters (DN ≤ 100).
5. Full Annealing
Annealing is an essential supporting process applied after hot expansion or cold drawing. It relieves residual stress, dissolves carbide precipitation, and improves corrosion resistance.
- Applications: Universal for all stainless steel grades, ensuring balanced mechanical performance.
6. Cold Rolling Seamless Process
Designed for thick-walled pipes (≥3 mm), cold rolling flattens the weld seam while strengthening the surface through cold working.
- Advantages: No material removal, enhances wear and pressure resistance.
- Limitations: Not suitable for thin-walled pipes.
- Applications: Hydraulic systems, structural supports.
7. Laser Cladding Seamless Process
Laser cladding applies alloy powders onto weld seams, creating a metallurgical bond that restores integrity and boosts corrosion resistance.
- Advantages: Excellent for extreme environments, resistant to H₂S and acid media.
- Limitations: High cost, lower efficiency.
- Applications: Offshore pipelines, high-temperature boilers, acid transportation.
Comparison of Main Seamless Processing Methods
| Method | Diameter Range (DN) | Wall Thickness (mm) | Key Advantages | Typical Applications | Relative Cost |
|---|---|---|---|---|---|
| Hot Expansion | 200–1000 | 3–12 | Large size, toughness | Water mains, steam pipes | Medium |
| Cold Drawing | 10–150 | 1–5 | Precision, strength | Medical, semiconductor | High |
| Internal Grinding | 50–800 | 2–10 | Smooth surface, low cost | Food, HVAC systems | Low |
| Internal Polishing | 10–100 | 1–5 | Ultra-clean surface | Pharma, ultrapure water | High |
| Cold Rolling | 50–300 | ≥3 | Strengthened surface | Hydraulic, structural | Medium |
| Laser Cladding | 50–200 | 2–8 | Extreme corrosion resistance | Offshore, acid pipes | Very High |
Ganyeah Group: Reliable Solutions for Seamless Stainless Steel Pipes
At Ganyeah Group, we understand that there is no one-size-fits-all seamless processing method. Our engineers analyze pipe diameter, material grade, operating conditions, and cost to recommend the most suitable seamless treatment for stainless steel pipes. Whether it is hot expansion for municipal systems, cold drawing for precision tubing, or laser cladding for extreme offshore conditions, we ensure that every pipe delivers consistent performance and long service life.
Contact Ganyeah Group today to discuss seamless stainless steel pipe solutions tailored to your project.