Pipe Categories
Seamless Pipes (SMLS):
Manufactured without a weld seam.
Preferred for high-pressure, high-temperature, and critical service (upstream, subsea, refineries).
Welded Pipes
• ERW (Electric Resistance Welded): Common for medium-pressure pipelines.
• LSAW (Longitudinal Submerged Arc Welded): Large diameter, long-distance pipelines.
• SSAW (Spiral Submerged Arc Welded): Economical for large diameters, lower pressure.
Standards & Codes
ASME B36.10M: Welded & seamless carbon steel pipes.
ASME B36.19M: Stainless steel pipes.
API 5L: Line pipe for oil & gas transmission (Grades A, B, X42–X80).
ASTM Standards: A106 (seamless carbon steel), A53 (welded/seamless), A312 (stainless steel).
1. Carbon Steel Pipes
ASTM A106 Grade B/C → Seamless carbon steel for high‑temperature service.
ASTM A53 Grade B → Welded/seamless carbon steel for general service.
API 5L Grades A, B, X42–X80 → Line pipe for transmission pipelines.
ASTM A333 Grade 6 → Low‑temperature carbon steel for cryogenic service.
2. Stainless Steel Pipes
ASTM A312 TP304 / TP304L → General corrosion resistance.
ASTM A312 TP316 / TP316L → Superior resistance to chlorides and sour service.
ASTM A312 TP310 → High‑temperature oxidation resistance.
ASTM A312 TP410 → Martensitic stainless, higher strength but less corrosion resistance.
3. Alloy Steel Pipes
ASTM A335 P11, P22, P91 → Seamless ferritic alloy steel for high‑temperature service (commonly used in refineries.
and power plants).
ASTM A213 T11, T22 → Seamless alloy steel boiler tubes.
ASTM A369 FP91 → Forged alloy steel for pressure piping.
4. Duplex & Super Duplex Pipes
UNS S31803 (Duplex 2205) → High strength + corrosion resistance, offshore seawater service.
UNS S32750 (Super Duplex 2507) → Superior resistance to pitting and crevice corrosion in aggressive environments.
5. Nickel & Specialty Alloys (for extreme service)
Inconel (Alloy 625, 825) → High strength, oxidation, and corrosion resistance.
Monel (Alloy 400) → Excellent resistance to seawater and acids.
Hastelloy (C22, C276) → Exceptional resistance to oxidizing and reducing agents.
Pipe Sizes & Schedules
• Nominal Pipe Size (NPS/DN): Standardized dimensions (e.g., DN 50, DN 150).
• NPS (inches): US standard designation (e.g. 2”, 6”).
• DN (mm): International metric designation (e.g., DN 50, DN 150).
• Schedules (Wall Thickness): Sch 10, Sch 20, Sch 40, Sch 80, Sch 160, XXS (Double Extra Strong).
• Thin wall: Sch 10/20 → low-pressure service.
• Standard wall: Sch 40 → general service.
• Thick wall: Sch 80, Sch 160, XXS → high-pressure, high-temperature service.
• Large Diameter: Up to 80" for transmission pipelines.