TECTULby IMR

Fluid conveyance · Steel pipe

TECHNICAL DATA SHEET

FT-TC-TUB-SCH80-001

Issue date: July 22, 2026 · Rev. 001

Check the current version

SKU VT-86936 · seamless carbon steel pipe, schedule 80 wall · sold by the meter, 6 m lengths

1. TECHNICAL SPECIFICATIONS

Dimensions and calculated working pressure per diameter

¹ Internal pressure calculated in the engineering section (Barlow, S = 137.9 MPa, E = 1.00, −12.5% wall tolerance), rounded down. It is not a certified rating for any given lot: read the engineering calculations and the technical notice. Dimensions and weights per ASME B36.10-2022.

General specifications

2. ENGINEERING CALCULATIONS

The allowable internal pressure is estimated with the Barlow formula, applying the manufacturing wall tolerance. Every value used is declared below — nothing is silently assumed:

P = 2 · S · E · t_ef / D

Worked example — NPS 2 (DN 50)

1. Nominal SCH 80 wall: t = 5.54 mm; outside diameter: D = 60.3 mm (ASME B36.10-2022).
2. Effective wall: t_ef = 0.875 × 5.54 = 4.848 mm.
3. P = 2 × 137.9 MPa × 1.00 × 4.848 / 60.3 = 22.17 MPa ≈ 221 bar ≈ 3,215 psi.

Derived allowable pressure per diameter (≤38 °C)

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

The allowable stress S — and with it, proportionally, the allowable pressure — decreases with service temperature. Values verified for seamless A106 Gr B / A53 Gr B / API 5L Gr B (identical series for all three grades):

Example: the NPS 2 line that allows 221 bar at ≤38 °C allows 221 × 0.895 ≈ 197 bar at 316 °C. Between 371 °C and 427 °C the allowable stress drops from 115.1 to 78.6 MPa: the line enters the creep range and keeps falling steeply above it — consult ASME B31.3-2024, Table A-1, and specify ASTM A106 Gr B, whose scope is high-temperature service. The project's design temperature and code edition govern.

3. SCH 80 VS SCH 40: WHEN THE EXTRA WALL IS JUSTIFIED

At the same nominal diameter, SCH 40 and SCH 80 share the outside diameter, the triple-certified allowable stress (S = 137.9 MPa) and the seamless factor E = 1.00: the only variable in Barlow's formula is the wall. The pressure gain is therefore exactly the wall-thickness ratio.

Allowable pressure SCH 40 vs SCH 80 (≤38 °C, same calculation method)

The trade-off: weight and bore

Bore = outside diameter − 2 × nominal wall; flow area falls with the square of the bore.

When it is justified — and when the code requires it

• When the code requires it for threading: ASME B31.3-2024, Table 314.2.1 (minimum schedule of components with external threads): in normal fluid service, a carbon steel component (a notch-sensitive material) with external threads at NPS ≤ 1-1/2 (DN ≤ 40) must be at least schedule 80; from NPS 2 to 6 the minimum is schedule 40, and above NPS 6 no minimum schedule is set. The exception is Category D fluid service (nonflammable, nontoxic fluid, not damaging to human tissue, at ≤ 1,035 kPa / 150 psi and between −29 °C and 186 °C), where no minimum schedule applies. In practice: an NPT-threaded pipe or nipple of 1/2, 3/4, 1 or 1-1/2 in on a process line must be SCH 80 even at low pressure — threading removes wall and the code compensates with thickness. Additionally, above NPS 2 a threaded joint on flammable or toxic fluid requires safeguarding (code Appendix G).
• When the pressure demands it: if the line's design pressure exceeds the SCH 40 column of the first table (e.g., more than 156 bar at NPS 2), schedule 80 raises it 35–42% with the same nominal-diameter fittings.
• When there is corrosion: the corrosion allowance c is subtracted from the effective wall. With c = 1.5 mm at NPS 2, SCH 80 keeps P = 2 × 137.9 × (4.848 − 1.5) / 60.3 = 15.31 MPa ≈ 153 bar, while SCH 40 falls to 87 bar: the extra wall is service-life reserve.
• When it is not justified: it costs +27–38% in weight (and steel) and takes 12–31% of the flow area. For low-pressure lines with no threading in normal service and no corrosion allowance, schedule 40 — or 10 — is usually enough; compare against its own data sheet.

4. JOINT QUALITY FACTOR E: SEAMLESS VS WELDED

The formula in the engineering section includes the quality factor E, which penalizes the pipe's longitudinal weld according to how it was manufactured. ASME B31.3-2024, Table A-1B, assigns:

That is why the same diameter and schedule in "welded" pipe allows less pressure at identical wall: an ERW NPS 2 SCH 80 would sit at 22.17 × 0.85 = 18.84 MPa ≈ 188 bar, versus the 221 bar of the seamless pipe in this sheet. When comparing quotations, check on the marking and the MTC whether the pipe is SMLS or ERW: they are not interchangeable in the calculation.

5. PIPE MARKING (STENCIL)

Each length arrives with the mill stencil along the pipe. The marking sections of ASTM A53, ASTM A106 and API 5L require identifying, at minimum:

• Manufacturer or registered brand of the mill.
• Certified standard(s) and grade: a triple-certified pipe lists all three designations, e.g. ASTM A106 GR B / ASTM A53 GR B / API 5L GR B. Whatever the stencil says must match the lot's MTC.
• Size and schedule (or wall thickness): e.g. 2" SCH 80.
• Manufacturing method: SMLS (seamless) — if it reads ERW, the E factor from the previous section drops to 0.85.
• Heat or lot identification, which links the length to the MTC tests (tensile, flattening, hydrostatic test or non-destructive examination, per the certified standard).

Field use and inspection: before installing, check stencil against MTC and against the purchase order; a length whose marking does not match its certificate is not traceable and must be set aside. The exact marking detail (position, paint or stamp, extra data such as test pressure) depends on the standard(s) the lot certifies and is confirmed on quotation. TECTUL delivers the pipe with the mill stencil intact and supplies the MTC upon request.

6. Application notes

7. Technical notice and limitation of liability