304, 316 & 316L Stainless Steel Tube Supplier

TeCarve supplies 304, 304L, 316 and 316L stainless steel pipe and tube across 19 product lines, including seamless, welded, sanitary, capillary, heat-exchanger, coiled and shaped tubing. This page helps procurement teams and engineers match a required grade to the available tube form before reviewing dimensions, finishes and standards on the relevant product page.

304 vs 316 vs 316L: the essential differences

Grade 304 is a practical starting point for many general industrial, indoor architectural and low-chloride applications. Grade 316 adds 2–3% molybdenum, improving resistance to chloride-induced pitting and crevice corrosion. Grade 316L has the same molybdenum range as 316 but limits carbon to 0.035% maximum in ASTM A312 pipe (TP316L), compared with 0.08% for TP316. That lower carbon content helps reduce sensitisation risk in welded assemblies exposed to corrosive service.

As a practical guide drawn from TeCarve’s detailed grade-selection article, 304 is generally suitable below approximately 200 ppm chloride at ambient temperature, while 316 and 316L extend the practical range to approximately 1,000 ppm at ambient temperature. These are selection guides rather than universal limits: temperature, pH, flow conditions, fabrication and cleaning chemistry can materially change corrosion performance. Neither 304 nor 316/316L should be treated as a default material for continuous seawater immersion.

304 and 316 Stainless Steel Pipe to ASTM A312: Chemistry and Mechanical Properties

When engineering fluid handling, process lines, and pressure containment systems, procurement teams frequently specify 304 stainless steel pipe and 316 stainless steel pipe to ASTM A312/A312M-24b. This specification covers seamless, straight-seam welded, and heavily cold worked (HCW) austenitic stainless steel pipes intended for elevated-temperature and general corrosive service across nominal pipe sizes per ASME B36.19.

While generic commercial descriptions often treat 304, 304L, 316, and 316L interchangeably with ornamental or structural tubing, industrial pressure pipe ordered to ASTM A312 must comply with strict chemical composition limits, full solution annealing, standardized wall thickness tolerances, and mandatory individual non-destructive testing.

Chemical Composition of ASTM A312 TP304, TP304L, TP316, and TP316L

The table below summarizes the chemical requirements specified in ASTM A312/A312M Table 1 for the four primary austenitic piping grades. Values represent weight percent maximums unless indicated as a range.

Footnote D note: For small diameter or thin walls where many drawing passes are required, a maximum carbon content of 0.040% is permitted in Grades TP304L and TP316L. Small outside diameter pipes are defined as those less than 0.500 in. [12.7 mm] in outside diameter, and light wall pipes as those less than 0.049 in. [1.20 mm] in average wall thickness (0.044 in. [1.10 mm] in minimum wall thickness). Per Footnote E, phosphorus maximum is 0.045% for welded pipe.

Mechanical Properties and Solution Annealing

Per ASTM A312 Table 2, all four grades must be furnished in the solution-annealed condition: heated to a minimum temperature of 1900 °F [1040 °C] and quenched in water or rapidly cooled by other means at a rate sufficient to prevent re-precipitation of carbides, as demonstrable by the capability of passing ASTM A262 Practice E. Tensile and elongation properties tested per ASTM A370 must meet the minimum thresholds prescribed in Table 4.

Permissible Wall Thickness Tolerances and Mandatory Mill Testing

Dimensional tolerances for ASTM A312 pipe follow ASME B36.19. Under ASTM A312 Table 3, permissible variations in nominal wall thickness at any point are strictly bounded: for NPS 1/8 through NPS 2-1/2, the tolerance is +20.0% / −12.5%; for NPS 3 through NPS 18 with wall thickness to diameter ratio (t/D) ≤ 5%, the tolerance is +22.5% / −12.5% (+15.0% / −12.5% for t/D > 5%); and for NPS 20 and larger welded pipe, the tolerance is +17.5% / −12.5%. Across all pipe sizes, schedules, and product forms (seamless, welded, and heavily cold worked), the permissible under-thickness variation never exceeds −12.5%.

Furthermore, quality verification under Section 12.1 mandates that each individual pipe must undergo either a hydrostatic test or a nondestructive electric test. In addition, lot-based mechanical testing requires one tensile test per lot of 100 or fewer lengths (two tests for lots exceeding 100 lengths per Section 11.2) and flattening testing on 5% of lengths per Section 11.3.

304 Stainless Steel Pipe vs 304 Stainless Steel Tube

A critical engineering distinction exists between 304 stainless steel pipe and 304 stainless steel tube. Stainless steel pipe is designated by Nominal Pipe Size (NPS) and Schedule wall thickness per ASME B36.19, governed by ASTM A312 for fluid, gas, and pressure conveyance. In contrast, stainless steel tubing is specified by exact outside diameter (OD) and measured decimal wall thickness, governed by specifications such as ASTM A269 for general corrosion-resisting service or ASTM A249 for welded boilers, superheaters, and heat exchanger bundles. To review standard schedule wall thicknesses, dimensions, and weights for piping projects, consult the technical ASTM A312 pipe guide and the stainless steel pipe sizes and schedule weight chart.

Values per ASTM A312/A312M-24b.

When to move up to Duplex 2205

Duplex 2205 combines an austenitic-ferritic microstructure with higher chromium and molybdenum than 316L, giving it materially better resistance to chloride pitting, crevice corrosion, and chloride stress-corrosion cracking. It also has roughly double the yield strength of 304/316L, which can allow thinner walls for the same pressure rating. Duplex 2205 is the practical upgrade path when 316L is marginal for the chloride level, temperature, or mechanical stress involved — seawater and brine service, offshore and coastal environments, and chemical-plant tubing where 316L would be at or beyond its comfortable service range. It is not a universal upgrade: 2205 is more expensive than 316L, and for continuous high-chloride immersion at elevated temperature, super duplex grades or titanium may still be required. TeCarve supplies Duplex 2205 in seamless tube; contact us with your chloride level, temperature, and pressure requirements to confirm whether 316L, 2205, or a higher alloy is the right fit.

Which TeCarve product lines support each grade?

The grade ranges below reproduce the current Grades field on each TeCarve product page. Availability for a particular size, wall thickness, finish, standard or quantity should be confirmed when requesting a quotation.

How to choose a grade and product form

Start with the service environment, then select the tube form and manufacturing route.

• Choose 304 or 304L for many general indoor, architectural and low-chloride duties where the molybdenum addition in 316 would offer no practical benefit. Decoration, square, rectangular and special-shaped tubing provide several options for architectural and fabricated assemblies.
• Choose 316 or 316L when chloride exposure, coastal conditions, acidic cleaning media or other corrosive process conditions justify greater pitting resistance. Sanitary, heat-exchanger, capillary and coiled tubing are available in these grades.
• Prefer the low-carbon grade for corrosive welded service. Both 304L and 316L are intended to reduce sensitisation risk during welding. The final choice still depends on the applicable design code, fabrication method and service conditions.
• Confirm alternatives for severe chloride service. Where chloride exposure exceeds the practical range of 316/316L—or where continuous seawater immersion is involved—review higher-alloy or duplex options shown in the relevant product ranges.

Grade is only one part of a complete tube specification. An enquiry should also identify the product form, outside diameter or section dimensions, wall thickness, length, manufacturing route, surface finish, applicable standard, service medium, temperature and required documentation.

Request a grade-specific tube quotation

To identify the appropriate TeCarve product line, send the required grade together with your dimensions, quantity, finish, applicable standard and service conditions. The available grade, size combination and project documentation can then be confirmed before quotation.