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Siddhgiri Overseas manufactures SS 316 stainless steel tube from our Mumbai facility, produced in seamless and welded (ERW) construction for applications where standard 304 stainless is not enough to withstand chlorides and aggressive chemical attack. The defining feature of the grade is molybdenum: SS 316 adds 2.0%-3.0% molybdenum to a chromium-nickel austenitic base, and that single alloying change materially improves resistance to pitting and crevice corrosion in marine and process environments. Produced to standards including ASTM A213, ASTM A249 and ASTM A269, our SS 316 tube is supplied to precise outside diameter and wall thickness tolerances, with the surface finishes, lengths and end configurations required for instrumentation, heat exchanger, hydraulic and high-purity process lines. Established in 1962, Siddhgiri Overseas backs every production lot with dimensional inspection, hydrostatic and non-destructive testing, and full material traceability before dispatch.
SS 316 tube is an austenitic stainless steel tube grade built on the same chromium-nickel foundation as SS 304, with one critical addition: 2.0% to 3.0% molybdenum. That single alloying change is what separates the two grades in practical service. Where 304 performs well in general atmospheric and mild process conditions, 316 is specified whenever chlorides enter the picture — seawater, salt-laden coastal air, chloride-bearing process fluids, or aggressive organic and mineral acids.
Like other tube products, SS 316 tube is specified by its actual outside diameter (OD) and wall thickness rather than the nominal bore and schedule system used for pipe. This gives the tighter dimensional control needed for instrumentation, heat-exchanger and precision mechanical applications, where consistent OD, wall thickness and internal bore finish directly affect system performance.
Siddhgiri Overseas produces SS 316 tube in seamless (SMLS), electric resistance welded (ERW), electric fusion welded (EFW) and cold-drawn welded (CDW) construction, in outside diameters from small capillary and instrumentation sizes up to large-diameter structural tubing, and wall thicknesses from thin-wall instrumentation gauges up to heavy-wall high-pressure sections. Every production lot is dimensionally checked before dispatch, and Mill Test Certificates are provided so buyers can verify chemistry and mechanical properties against the applicable standard.
SS 316 tube is manufactured to a tightly controlled chemical composition to ensure consistent corrosion resistance and mechanical performance across every batch:
|
Chromium (Cr) |
16.0% - 18.0% |
|
Nickel (Ni) |
10.0% - 14.0% |
|
Molybdenum (Mo) |
2.0% - 3.0% |
|
Carbon (C) |
0.08% max |
The molybdenum addition is what distinguishes 316 from 304. Molybdenum combines with chromium in the passive surface film to form a more stable chromium-molybdenum oxide barrier, one that resists breakdown by chloride ions far better than the chromium oxide film alone. This is the reason SS 316 resists localized pitting and crevice corrosion in marine, coastal and chloride-bearing chemical environments where standard grades would fail prematurely.
Mechanically, SS 316 tube is comparable to SS 304 rather than a higher-strength alloy — its value lies in corrosion resistance, not added strength:
|
Tensile Strength |
≥ 515 MPa (75 ksi) |
|
Yield Strength |
≥ 205 MPa (30 ksi) |
|
Hardness |
Rockwell B (HRB) ≤ 95, or Brinell (HBW) ≤ 217 |
To achieve these properties consistently, tubes are solution annealed in a controlled range between 1040°C and 1150°C and then rapidly water quenched, which stabilises the austenitic grain structure and restores the material's designed corrosion resistance after cold working. Every batch is verified through hydrostatic testing, eddy current or ultrasonic testing, and Positive Material Identification (PMI) to confirm alloy chemistry, including molybdenum content, before dispatch.
When specifying SS 316 tube for a fabrication project, particularly one involving significant welding, the carbon content of the grade becomes an important consideration:
For applications with minimal welding, standard SS 316 is a sound and economical choice. For assemblies involving heavy welding in marine or chloride-heavy service, SS 316L is generally the safer specification. Siddhgiri Overseas also stocks dual-certified 316/316L tube that meets both chemistry specifications simultaneously, giving buyers the weld-decay protection of 316L without giving up the higher strength retention of standard 316.
The chloride and pitting resistance of SS 316 tube, combined with reliable mechanical properties, makes it the preferred choice across a range of demanding industries:
Siddhgiri Overseas supplies SS 316 tube in round, square and rectangular profiles, in seamless and welded construction, tested and inspected before dispatch to suit these applications.
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.
SS 316 adds 2.0% to 3.0% molybdenum to the same chromium-nickel base used in SS 304. This molybdenum stabilises the passive oxide film and significantly improves resistance to pitting and crevice corrosion caused by chlorides, making 316 the correct choice for marine, coastal and chloride-heavy chemical environments where 304 would eventually pit.
SS 316 tube is specified by its actual outside diameter (OD) and wall thickness, unlike stainless steel pipe, which is sized by nominal bore and schedule. Tube sizing provides the tighter dimensional control required for instrumentation, heat-exchanger and precision mechanical applications.
Standard SS 316 carries carbon up to 0.08% and retains slightly higher base strength, making it suitable where welding is limited. SS 316L is a low-carbon version specifically intended for heavy welding, reducing the risk of weld decay in the heat-affected zone. For extensive field welding in marine or chloride service, SS 316L is generally preferred.
Our SS 316 tube is produced to standards including ASTM A213 for boiler and heat-exchanger tubes, ASTM A249 for welded austenitic tubing used in boiler and superheater applications, and ASTM A269 for general-service austenitic tubing, along with other applicable ASME and international specifications as required by the project.
We manufacture SS 316 tube in seamless (SMLS), electric resistance welded (ERW), electric fusion welded (EFW) and cold-drawn welded (CDW) construction, allowing buyers to select the option best suited to their pressure rating, dimensional tolerance and budget requirements.
Yes — this is the primary reason the grade exists. The molybdenum content in SS 316 specifically improves resistance to chloride-driven pitting and crevice corrosion, making it the standard stainless choice for marine and offshore equipment, subsea hardware and coastal installations.
We supply SS 316 tube in No.1 pickled (AP), 2B matte, bright annealed (BA), mechanically polished (MP) and electropolished (EP) finishes, selected according to the application — process and hygienic applications typically favour bright annealed or electropolished finishes, while general industrial use may call for a 2B or pickled finish.
Every batch undergoes dimensional inspection, hydrostatic pressure testing, eddy current or ultrasonic testing, Positive Material Identification (PMI) for chemistry verification, and visual examination, ensuring each tube meets the specified standard before it leaves our Mumbai facility. Mill Test Certificates are provided with every dispatch for full material traceability.
