Seamless GI Pipes: 40mm, 80mm NB Sizes, S&S Types, and Threading Info

 

Seamless GI Pipes: 40mm & 80mm NB Sizes, S&S Types, and Threading Info
Explore seamless galvanized iron (GI) pipes with precise 40mm & 80mm nominal bore (NB) sizes, socketed & screwed (S&S) options, threading details, and industrial applications.

Seamless GI pipes in 40mm and 80mm NB sizes are widely used in high-pressure plumbing, industrial water lines, and compressed air systems. They come in Screwed & Socketed (S&S) or Plain End types, with BSP threading commonly used for jointing.

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📏 Standard GI Seamless Pipe Sizes & Specs

NB Size (mm)	OD (mm)	Wall Thickness (mm)	Type	Threading
40mm	48.3	3.2 – 4.0	S&S / Plain End	BSPT / NPT (Optional)
80mm	88.9	4.0 – 5.5	S&S / Plain End	BSPT / NPT

• OD = Outside Diameter
• S&S = Screwed & Socketed
• BSPT = British Standard Pipe Thread
• NPT = National Pipe Thread

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🔧 S&S Type vs Plain End – What's the Difference?

Feature	S&S Type	Plain End
Threaded Ends	Yes	No
Socket Attached	Yes	No
Joining Method	Threaded joint (no welding)	Welding or flange connection
Common Use	Plumbing, temporary pipelines	Fabrication, heavy-duty installations

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🧰 Threading Info for GI Seamless Pipes

• Type: BSPT (Tapered), NPT (American Standard), or Metric
• Common Threading Standard: IS 554 for BSPT
• Thread Length:
  • For 40mm NB: ~19–20 threads per inch (TPI)
  • For 80mm NB: ~14–16 TPI

🛠️ Seamless pipes are typically machine-threaded for leak-proof installation and paired with GI sockets or unions.

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🏗️ Industrial Applications

• 🚰 High-pressure plumbing lines
• 🏭 Factory compressed air & gas lines
• 🔥 Steam and boiler installations
• 🌆 Urban water distribution
• 🧯 Fire sprinkler lines (due to high pressure tolerance)

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⚙️ Benefits of Seamless GI Pipes

• No weld seam – stronger under pressure
• Superior zinc coating for corrosion resistance
• Longer lifespan in harsh environments
• Reliable for underground or exposed pipelines

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💡 Tips for Industrial Buyers

1. Always check for IS:1239 or IS:3589 compliance.
2. Specify “S&S” or “Plain End” when placing orders.
3. Ask for threading tolerance and zinc coating micron levels.
4. Use teflon tape or pipe dope for threaded joints.
5. Avoid using welded GI pipes for high-pressure jobs.

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📦 Top Brands Offering Seamless GI Pipes

Brand	Strength	Availability
Jindal (Hisar)	Heavy-duty seamless & S&S GI pipes	Pan-India
Maharashtra Seamless	Superior seamless technology	Bulk orders
Tata Pipes	ISI-marked, premium GI pipes	Urban infrastructure
Surya Roshni	Zinc-rich GI S&S pipes	Large-scale civil jobs

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❓FAQs

Q1: Are seamless GI pipes available in threaded form?
Yes, seamless GI pipes can be supplied with BSPT or NPT threading upon request.

Q2: What pressure can a 40mm GI seamless pipe handle?
Typically up to 25–40 bar, depending on wall thickness and material grade.

Q3: Is 80mm seamless GI pipe good for compressed air lines?
Absolutely. It provides high flow and durability under continuous air pressure.