TECTULby IMR

Fluid conveyance · Stainless steel pipe

TECHNICAL DATA SHEET

FT-TC-TUB-INOX-001

Issue date: July 22, 2026 · Rev. 001

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SKU VT-tubo-acero-inoxidable-sch40-sin-costura · seamless ASTM A312 stainless steel pipe, schedule 40S wall · 5.8 m lengths · made-to-order product: grade and diameters confirmed on quotation (Jul 2026)

1. TECHNICAL SPECIFICATIONS

General specifications

Dimensions and calculated allowable pressure by diameter (≤100 °F)

¹ Theoretical mass calculated with the 7.90 g/cm³ density of 1.4301/304 per EN 10088-1:2023; TP316L (1.4404, 8.00 g/cm³) weighs about 1.3% more.

² Allowable internal pressure calculated in the engineering section (Barlow, S per grade per ASME B31.3-2024 Table A-1, E = 1.00 seamless, −12.5% wall tolerance), rounded down. It is not a certified rating of the lot: read the calculations and the technical notice.

2. ENGINEERING CALCULATIONS

The allowable internal pressure is estimated with the Barlow formula, applying the manufacturing wall tolerance. Unlike carbon steel, here the allowable stress S depends on the certified grade: TP304 and TP316L do NOT share the same S. Every value used is declared below:

P = 2 · S · E · t_ef / D

Weld joint factor E by seam type — ASME B31.3-2024, Table A-1B for A312

Engineering consequence: at the same diameter, wall and grade, standard welded A312 pipe allows 15–20% less pressure than seamless (E = 0.85 or 0.80 versus 1.00), unless radiographed. Example: NPS 2″ TP304 double-butt welded: 156 bar × 0.85 ≈ 133 bar.

Worked example — NPS 2″ (DN 50)

1. Nominal 40S wall: t = 3.91 mm; outside diameter: D = 60.3 mm (ASME B36.19M-2022).
2. Effective wall: t_ef = 0.875 × 3.91 = 3.421 mm.
3. TP304: P = 2 × 137.9 MPa × 1.00 × 3.421 / 60.3 = 15.65 MPa ≈ 156 bar ≈ 2,269 psi.
4. TP316L: P = 2 × 115.1 MPa × 1.00 × 3.421 / 60.3 = 13.06 MPa ≈ 130 bar ≈ 1,894 psi.

Temperature derating — S(T) per ASME B31.3-2024, Table A-1

The allowable stress S — and with it the allowable pressure, proportionally — decreases with service temperature. Values for seamless ASTM A312 pipe:

Two code cautions. (1) For austenitic steels, several Table A-1 values above room temperature are based on the para. 302.3.2(d)(3) criterion — the lower of 2/3 of the specified minimum yield and 90% of the yield strength at temperature — and may exceed 2/3 of yield at that temperature; the code prints them in italics and does not recommend them for flanged joints or components where slight deformation can cause leakage (para. 302.3.2(e)). (2) Austenitics do not have carbon steel's graphitization limit: Table A-1 lists S values for TP304/TP316L up to 815 °C under creep criteria, but service above ~427 °C requires code analysis and, for sustained creep, the H grades (TP304H/TP316H). The project's design temperature and code edition govern.

3. CHEMICAL COMPOSITION AND MECHANICAL PROPERTIES (ASTM A312/A312M-25)

Chemical composition by heat analysis per ASTM A312/A312M-25, Table 1. Maximum values unless a range is shown:

Standard note: in A312 the L-grade carbon maximum is 0.035% — not 0.030% as in ASTM A240 plate — and it rises to 0.040% for tubes under 12.7 mm outside diameter or under 1.20 mm average wall, because of the multiple drawing passes (note D of Table 1, ASTM A312/A312M-25).

Minimum mechanical properties

TP316L's lower yield strength (170 versus 205 MPa) is the direct reason for its lower allowable stress in the calculations: S = 2/3 × 170 = 115.1 MPa, matching the 16.7 ksi conversion.

4. CORROSION RESISTANCE: PREN AND SENSITIZATION

PREN (Pitting Resistance Equivalent Number) is the standard index for comparing pitting corrosion resistance among stainless grades. The higher the PREN, the higher the resistance to chlorides. The formula, defined in ANSI/NACE MR0175/ISO 15156-3, is:

PREN = %Cr + 3.3 · %Mo + 16 · %N

The ranges are calculated with the composition limits of ASTM A312/A312M-25; since nitrogen has no requirement in these grades, the 16·%N term is taken as 0 (a conservative calculation — actual heat nitrogen can only raise the PREN). Engineering takeaway: TP316L's molybdenum gives it 2.6 to 9.9 PREN points over TP304, which is why it is the grade for chloride exposure: seawater and brines, food plants with chlorinated cleaning cycles, halide chemistry. In fresh water, air, clean steam and most organic acids, TP304 is sufficient and lower in cost.

Sensitization: why the L grade exists

Sensitization is the precipitation of chromium carbides at grain boundaries when an austenitic steel dwells between roughly 425 and 815 °C — for example, in the heat-affected zone of a weld — depleting the grain boundary of chromium and leaving it vulnerable to intergranular corrosion. The L grade fights it by composition: with carbon ≤0.035% there is very little carbon left to form carbides, so TP316L can be welded without post-weld heat treatment in most services. For standard TP304 (C up to 0.08%) welded for corrosive service, the alternative is to re-solution-anneal after welding (≥1,040 °C and quench, per A312) or verify susceptibility with ASTM A262 — the test A312 itself invokes in its supplementary requirement S7.

5. THERMAL EXPANSION OF AUSTENITIC STAINLESS

Austenitic stainless steel expands roughly one third more than carbon steel: a stainless line cannot be supported with carbon-steel criteria. Mean expansion coefficients per ASME B31.3-2024, Appendix C, Table C-1M:

Example: a 30 m straight run going from 20 to 80 °C elongates ΔL = α·L·ΔT = 16.2 × 30 × 60 / 1,000 ≈ 29.2 mm in stainless, versus ≈ 21.8 mm in carbon steel (+34%). Support implications: absorb that expansion with loops or flexible direction changes, use guides and sliding supports instead of rigidly anchoring both ends, and place anchors where the code flexibility analysis (ASME B31.3-2024, para. 319) dictates. In mixed carbon-stainless runs, the differential expansion between sections also generates stresses the design must absorb.

6. 40S DESIGNATION AND FINISHES

What does the “S” in schedule 40S mean?

The “S” identifies the wall thicknesses of ASME B36.19M-2022, the dimensional standard specific to stainless pipe, as opposed to ASME B36.10M for carbon steel pipe. In practice: from NPS 1/2″ to 6″ — the whole range of this data sheet — the 40S wall is identical to schedule 40; the series only diverge at large diameters (40S differs from 40 at NPS 12; 80S at NPS 10 and 12; 10S from NPS 14 to 22), where stainless standardizes thinner walls because it needs no corrosion over-thickness. That is why a schedule 40 fitting matches this pipe dimensionally across the published range.

Supply finishes

ASTM A312/A312M-25 furnishes pipe in two surface conditions: annealed and pickled (free of scale, matte gray surface) or bright annealed in a protective atmosphere (no subsequent pickling, reflective surface). Neither imposes a surface roughness (Ra) requirement: A312 is industrial process pipe. For sanitary service with controlled Ra and polished bore, the reference is ASTM A270 sanitary tubing, a separate data sheet in this catalog.

7. Application notes

8. Technical notice and limitation of liability