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Siddhgiri Overseas manufactures stainless steel seamless pipe from our Mumbai facility, in production since 1962. Seamless pipe is pierced and drawn from a solid round billet, so there is no weld seam anywhere along its length or circumference — the metal matrix stays uniform around the full cross-section, with none of the localized heat-affected zone or weak point that a welded seam creates. That construction makes seamless pipe the preferred choice for high-pressure fluid lines in oil and gas, chemical processing, and refinery piping, as well as for boiler and heat-exchanger tubing and severe chemical service in grades built for it. We supply seamless pipe from NB 15.875mm (1/2") up to 5" NB, across Schedule 40, Schedule 80, and Schedule 160 wall thicknesses, with dimensional checks carried out before dispatch.
Stainless steel seamless pipe is produced by piercing and drawing a solid round billet into a hollow tube, rather than rolling and welding a flat plate into shape. Because the pipe is formed from one continuous piece of metal, there is no weld seam running along its length or around its circumference at any point.
This matters structurally, not just cosmetically. A welded pipe carries a heat-affected zone along the weld line — a narrow band where the metal has been locally heated and re-solidified, and that behaves differently from the parent metal around it. Seamless pipe has no such zone: the metal matrix is uniform around the entire cross-section, end to end. That uniformity is the reason seamless construction gets specified wherever pressure rating and reliability matter more than cost, rather than being a marketing distinction between two otherwise identical products.
At Siddhgiri Overseas, seamless pipe is manufactured alongside our welded pipe range at our Mumbai facility, with dimensional checks carried out before dispatch on every order.
Stainless steel seamless pipe is supplied in the same core grades as our welded range, plus two grades produced specifically for seamless applications where higher temperature or higher corrosion resistance is required.
|
1.4301 |
X5CrNi18-10 |
TP304 |
|
1.4404 |
X2CrNiMo17-13-2 |
TP316L |
|
1.4845 |
X8CrNi25-21 |
TP310S (ASTM A213) |
|
1.4539 |
— |
Alloy 904L (UNS N08904) |
TP310S (1.4845) is rated for continuous service up to 1,100°C and is used for boiler and heat-exchanger tubes under ASTM A213. Alloy 904L (UNS N08904, EN 1.4539) is a super-austenitic stainless with added copper and higher nickel and molybdenum content than standard 316L, specified for the most aggressive acid and chloride environments — such as sulfuric acid handling — where 316L cannot reliably resist attack.
On standards: ASTM A312 covers both welded and seamless austenitic stainless pipe generally, and is the specification most seamless pipe in NB sizing is ordered against. ASTM A213 is a separate, narrower specification that covers seamless ferritic and austenitic tubing specifically for boilers and heat exchangers — a smaller-diameter, thinner-wall tube product rather than pipe. Mill Test Certificates (MTC, typically to EN 10204 3.1) are issued as standard documentation with each order.
Seamless pipe from Siddhgiri Overseas is available from NB 15.875mm (1/2") up to 5" NB.
Wall thickness is set by schedule: Schedule 40, Schedule 80, and Schedule 160 are supplied across this size range. The schedule number determines wall thickness and, with it, pressure rating — Schedule 160 carries the thickest wall and highest pressure rating of the three for a given NB, Schedule 40 the thinnest and lowest. Because seamless pipe has no weld seam to act as a limiting factor, its pressure rating at a given schedule and grade tracks the base metal's own rating directly, which is the practical advantage seamless construction offers over welded pipe at the same wall thickness.
Exact size and schedule availability by grade can be confirmed against a specific order requirement; dimensional checks are carried out before dispatch on every order.
Seamless pipe is specified wherever the absence of a weld seam is a real safety and reliability factor, not just a preference:
Across all of these, Schedule 40, 80, or 160 is selected to match the line's design pressure, and grade is selected to match the process fluid and operating temperature.
Siddhgiri Overseas is ISO certified for quality, occupational health & safety and environment management, and holds the import and export certification required to supply stainless steel pipe and tube to customers worldwide. Certificate copies are available on request for buyers who need them for their own compliance records.
Seamless pipe is pierced and drawn from a solid round billet, so it has no weld seam anywhere along its length or circumference. Welded pipe is formed by rolling a flat plate and welding the edge, which leaves a heat-affected zone along the seam where the metal behaves differently from the parent material around it.
At the same wall thickness and grade, yes — a welded pipe's seam is a localized point that a fully seamless cross-section does not have, so seamless construction is generally specified where pressure rating and reliability matter more than cost.
ASTM A312 covers both welded and seamless austenitic stainless pipe generally and is the specification most seamless pipe in standard NB sizing is ordered against. ASTM A213 is a separate, narrower specification covering seamless ferritic and austenitic tubing specifically for boilers and heat exchangers — a smaller-diameter, thinner-wall tube product rather than pipe.
We supply seamless pipe from NB 15.875mm (1/2") up to 5" NB, in Schedule 40, Schedule 80, and Schedule 160 wall thicknesses. The schedule number sets the wall thickness and therefore the pressure rating at a given size.
TP310S (1.4845) is used where continuous service temperatures run high — it is rated for continuous service up to 1,100°C and is produced under ASTM A213 for boiler and heat-exchanger tubes, a duty standard 304 or 316L are not rated for.
Alloy 904L (UNS N08904, EN 1.4539) is a super-austenitic stainless steel with added copper and higher nickel and molybdenum content than standard 316L. It is specified for the most aggressive acid and chloride environments, such as sulfuric acid handling, where standard 316L cannot reliably resist attack.
Yes. Mill Test Certificates (MTC), typically issued to EN 10204 3.1, are provided as standard documentation, and dimensional checks are carried out before dispatch on every order.
