Now that you understand steel fundamentals and manufacturing processes, let’s explore the types of steel pipes and their applications.
1. Major Pipe Classifications
Steel pipes are categorized based on manufacturing method, application, and industry usage.
Here are the key classification methods:
(1) Classification by Manufacturing Method
| Pipe Type | Description | Examples | Main Applications |
|---|---|---|---|
| Seamless Pipe | Made by extruding billets, no weld seam | API 5L, API 5CT, ASTM A106 | High-pressure, high-temperature, oil & gas, boiler, nuclear |
| Welded Pipe | Made by rolling and welding steel plates or coils | API 5L, ASTM A53 | General piping, construction, structural applications |
| ERW Pipe (Electric Resistance Welded Pipe) | Welded using high-frequency electric current | API 5L Gr. B, ASTM A53 | Water supply, gas pipelines, structures |
| LSAW Pipe (Longitudinal Submerged Arc Welded Pipe) | Straight seam welded with submerged arc welding | API 5L X70 | Large-diameter oil & gas pipelines |
| SSAW Pipe (Spiral Submerged Arc Welded Pipe) | Spiral welded from steel coils | API 5L X52, X60 | Offshore and transportation pipelines |
✅ Seamless pipes have higher strength, while welded pipes are more cost-effective.
(2) Classification by Application
Each industry requires different mechanical properties, sizes, and corrosion resistance for pipes.
A. Piping Pipes (Fluid Transport)
- Purpose: Transport of fluids (water, gas, oil, chemicals)
- Common Standards:
- API 5L (Oil & gas pipelines) → X42, X52, X60, X70
- ASTM A53 (General piping) → Grade A, B
- ASTM A106 (High-temperature piping) → Grade B, C
✅ Piping pipes are mainly made using welded methods (ERW, LSAW, SSAW).
B. Structural Pipes
- Purpose: Buildings, bridges, towers, steel structures
- Common Standards:
- ASTM A500 (Structural round & square pipes)
- EN 10219 (European structural pipe standard)
✅ Square and round pipes are used in construction.
C. OCTG (Oil Country Tubular Goods)
- Purpose: Drilling, production, and transport of oil & gas
- Common Standards:
- API 5CT (Casing & tubing for drilling) → J55, K55, N80, L80, P110
- API 5L (Transmission pipelines) → X42 ~ X80
✅ Requires high strength and corrosion resistance for extreme conditions.
D. Boiler & Heat Exchanger Pipes
- Purpose: Power plants, petrochemical plants, industrial boilers
- Common Standards:
- ASTM A192, A209, A210 (High-temperature boiler pipes)
- ASTM A213, A335 (High-alloy boiler tubes)
✅ Alloy steel (with Cr, Mo) is used for high-temperature & high-pressure environments.
E. Stainless Steel Pipes
- Purpose: Chemical plants, food processing, sanitary applications
- Common Standards:
- ASTM A312 (General stainless steel pipes) → TP304, TP316
- ASTM A269 (Chemical processing tubes)
✅ Excellent corrosion resistance for chemical and food industries.
2. Pipe Standards & Marking System
When selecting a steel pipe, you must check the standard, outer diameter (OD), wall thickness (WT), and grade.
(1) Pipe Standard Example
Example: API 5L X52 PSL2 12” SCH 40
- API 5L → Standard
- X52 → Strength grade (52 ksi = 52,000 psi yield strength)
- PSL2 → Product Specification Level (higher quality requirements than PSL1)
- 12” → Outer diameter (OD, 12 inches)
- SCH 40 → Schedule (wall thickness)
✅ Each industry requires different strength and specifications, so understanding markings is essential.
3. Industry-Specific Pipe Applications
| Industry | Main Pipe Type | Common Standards |
|---|---|---|
| Construction & Structures | Structural pipes | ASTM A500, EN 10219 |
| Water & Gas Supply | Piping pipes | ASTM A53, A106 |
| Oil & Gas | Transmission & OCTG | API 5L, API 5CT |
| Power Plants & Boilers | High-temp, high-pressure pipes | ASTM A192, A335 |
| Chemical & Food | Stainless steel pipes | ASTM A312, A269 |
✅ Pipe applications vary by industry, and selecting the correct specification is crucial.
🔹 Summary of Lesson 3
- Pipes are categorized based on manufacturing method (Seamless vs. Welded).
- Pipes are classified by application, including piping, structural, OCTG, boiler, and stainless steel pipes.
- Each industry requires different specifications, so understanding pipe markings is essential.