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Hot-dip galvanized conveyance pipe, heavy type (SCH 40)
TECTUL · Dispatch across Colombia · Exports to Central & South America
Carbon-steel pipe with schedule 40 wall, hot-dip galvanized with a minimum of 550 g/m² of zinc on each surface (ASTM A53), for conveying cold water, compressed air and non-corrosive gases in NPT-threaded lines. 6 m lengths, 12 sizes from 1/4″ to 6″. Dimensions per ASME B36.10-2022. Not suitable for steam or water above 60 °C (section 3).
Important: Before using these data in engineering, design or installation decisions on systems exposed to mechanical, pressure, rupture, fatigue, impact or water-hammer risk, it is essential to read the technical notice and limitation of liability at the end of this sheet.
VT-86944 · heavy-type SCH 40 galvanized pipe, threadable · 6 m lengths
1. Technical specifications
Dimensions and calculated working pressure by size
| NPS | DN | Outside Ø | SCH 40 wall | Weight (black pipe) | Allowable pressure at ≤38 °C¹ | ||||
|---|---|---|---|---|---|---|---|---|---|
| mm | in | mm | in | kg/m | lb/ft | bar | psi | ||
| 1/4″ | 8 | 13.7 | 0.540 | 2.24 | 0.088 | 0.63 | 0.42 | 335 | 4,864 |
| 3/8″ | 10 | 17.1 | 0.675 | 2.31 | 0.091 | 0.84 | 0.56 | 277 | 4,019 |
| 1/2″ | 15 | 21.3 | 0.840 | 2.77 | 0.109 | 1.27 | 0.85 | 266 | 3,869 |
| 3/4″ | 20 | 26.7 | 1.050 | 2.87 | 0.113 | 1.69 | 1.14 | 220 | 3,197 |
| 1″ | 25 | 33.4 | 1.315 | 3.38 | 0.133 | 2.50 | 1.68 | 207 | 3,010 |
| 1-1/4″ | 32 | 42.2 | 1.660 | 3.56 | 0.140 | 3.39 | 2.28 | 173 | 2,509 |
| 1-1/2″ | 40 | 48.3 | 1.900 | 3.68 | 0.145 | 4.05 | 2.72 | 156 | 2,266 |
| 2″ | 50 | 60.3 | 2.375 | 3.91 | 0.154 | 5.44 | 3.66 | 133 | 1,929 |
| 2-1/2″ | 65 | 73.0 | 2.875 | 5.16 | 0.203 | 8.63 | 5.80 | 144 | 2,102 |
| 3″ | 80 | 88.9 | 3.500 | 5.49 | 0.216 | 11.29 | 7.59 | 126 | 1,837 |
| 4″ | 100 | 114.3 | 4.500 | 6.02 | 0.237 | 16.07 | 10.80 | 108 | 1,566 |
| 6″ | 150 | 168.3 | 6.625 | 7.11 | 0.280 | 28.26 | 18.99 | 86 | 1,256 |
IMPORTANT
This data sheet is a reference guide to the properties of this product type. The measurements, dimensions and physical or geometric characteristics of the product actually supplied may vary by manufacturer and lot, and may even fall outside the cited standards. If any of these figures is critical to your design or build, it is essential to verify it with one of our advisors against the physical product, so you can be fully certain of what you are buying. · Original data sheet: tectul.com/en/conduccion-de-fluidos/tuberia/ficha-tecnica-tubo-galvanizado-tipo-pesado.html
¹ Internal pressure calculated in section 2 (Barlow, S = 137.9 MPa, E = 0.85 for ERW manufacture, −12.5% wall tolerance), rounded down. It is not a certified rating for any lot: read the calculation basis and the technical notice. Weight is that of plain-end black pipe per ASME B36.10-2022; zinc adds the mass calculated in section 3.
General specifications
| Product | Hot-dip galvanized carbon-steel pipe, schedule 40 wall (SCH 40) — the "heavy type" of the Colombian conveyance market |
| Material and grade | Carbon steel per ASTM A53. The calculations in this sheet use Gr B (yield ≥240 MPa / 35 ksi; tensile ≥415 MPa / 60 ksi); the certified grade of each lot appears in its mill test certificate (MTC) and is confirmed on quotation. |
| Manufacture | Electric-resistance-welded longitudinal seam, ERW (A53 Type E) — quality factor E = 0.85 per ASME B31.3-2024, Table A-1B. A seamless lot (Type S) carries E = 1.00, raising allowable pressure by 17.6%; manufacture type is confirmed on quotation. |
| Coating | Hot-dip zinc, minimum mass 550 g/m² (1.8 oz/ft²) on each surface — inside and outside — per ASTM A53/A53M-24, verifiable by ASTM A90/A90M testing (section 3) |
| Commercial class | "Heavy type" = schedule 40 wall (this sheet). The "light type" conveyance pipe is a thin-wall water pipe for medium and low pressure (certified in Colombia under NTC 5890) and has its own product page in the catalog. |
| Ends | NPT threaded (ASME B1.20.1) with plastic protector, or plain; confirmed on quotation (section 4) |
| Commercial length | 6 m lengths |
| Wall tolerance | Minimum wall at any point ≥ 87.5% of nominal (−12.5%), per ASTM A53/A53M-24 |
| Applicable standards | ASTM A53/A53M-24 (black and galvanized pipe) · NTC 3470:2021, Colombian equivalent of A53 · ASME B36.10-2022 (dimensions) · ASME B1.20.1 (NPT threads) · ASTM A90/A90M-21 (coating mass) · reference design code: ASME B31.3-2024 |
⚠ Important: this technical data sheet is a reference guide to the product's properties; it is not a quality certificate for the product you are buying. Heats vary from one another and may differ from the values stated here, or even depart from the standards. If your application requires compliance with a standard, always check the quality certificate (mill certificate) of the lot you are buying. If in doubt, ask one of our technical advisors →
2. Engineering calculations (allowable internal pressure)
Allowable internal pressure is estimated with the Barlow formula, applying the wall manufacturing tolerance and the weld-quality factor. Every value used is declared below — nothing is silently assumed:
P = 2 · S · E · t_ef / D
| S — basic allowable stress | S = 137.9 MPa (20.0 ksi) at ≤38 °C per ASME B31.3-2024, Table A-1, for ASTM A53 Gr B. If the lot certifies Gr A, S drops to 110.3 MPa (16.0 ksi) and the pressures in this sheet scale down accordingly. |
| E — quality factor | E = 0.85 for ERW welded pipe (A53 Type E) per ASME B31.3-2024, Table A-1B — the usual supply of galvanized conveyance pipe. This is why a welded pipe takes less pressure than the same seamless pipe: with E = 1.00 (Type S) the values rise 17.6% (at NPS 2″: 156 bar, the table in data sheet FT-TC-TUB-SCH40-001). |
| t_ef — effective wall | t_ef = 0.875 · t_nominal: the A53 manufacturing tolerance allows the wall to be up to 12.5% under nominal at any point, so the calculation uses the guaranteed minimum wall. Zinc thickness is not added: the coating protects, it does not carry pressure. No corrosion allowance is subtracted here (see Design, application notes). |
| D — outside diameter | Nominal outside diameter per ASME B36.10-2022 (table in section 1). |
IMPORTANT
This data sheet is a reference guide to the properties of this product type. The measurements, dimensions and physical or geometric characteristics of the product actually supplied may vary by manufacturer and lot, and may even fall outside the cited standards. If any of these figures is critical to your design or build, it is essential to verify it with one of our advisors against the physical product, so you can be fully certain of what you are buying. · Original data sheet: tectul.com/en/conduccion-de-fluidos/tuberia/ficha-tecnica-tubo-galvanizado-tipo-pesado.html
Worked example — NPS 2″ (DN 50)
- Nominal SCH 40 wall: t = 3.91 mm; outside Ø: D = 60.3 mm (ASME B36.10-2022).
- Effective wall: t_ef = 0.875 × 3.91 = 3.421 mm.
- P = 2 × 137.9 MPa × 0.85 × 3.421 / 60.3 = 13.30 MPa ≈ 133 bar ≈ 1,929 psi.
Derived allowable pressure by size (≤38 °C, E = 0.85)
| NPS | Effective wall | P (MPa) | P (bar) | P (psi) |
|---|---|---|---|---|
| 1/4″ | 1.960 mm | 33.54 | 335 | 4,864 |
| 3/8″ | 2.021 mm | 27.71 | 277 | 4,019 |
| 1/2″ | 2.424 mm | 26.68 | 266 | 3,869 |
| 3/4″ | 2.511 mm | 22.05 | 220 | 3,197 |
| 1″ | 2.958 mm | 20.76 | 207 | 3,010 |
| 1-1/4″ | 3.115 mm | 17.30 | 173 | 2,509 |
| 1-1/2″ | 3.220 mm | 15.63 | 156 | 2,266 |
| 2″ | 3.421 mm | 13.30 | 133 | 1,929 |
| 2-1/2″ | 4.515 mm | 14.50 | 144 | 2,102 |
| 3″ | 4.804 mm | 12.67 | 126 | 1,837 |
| 4″ | 5.268 mm | 10.80 | 108 | 1,566 |
| 6″ | 6.221 mm | 8.67 | 86 | 1,256 |
IMPORTANT
This data sheet is a reference guide to the properties of this product type. The measurements, dimensions and physical or geometric characteristics of the product actually supplied may vary by manufacturer and lot, and may even fall outside the cited standards. If any of these figures is critical to your design or build, it is essential to verify it with one of our advisors against the physical product, so you can be fully certain of what you are buying. · Original data sheet: tectul.com/en/conduccion-de-fluidos/tuberia/ficha-tecnica-tubo-galvanizado-tipo-pesado.html
Temperature derating — S(T) per ASME B31.3-2024, Table A-1
The allowable stress of A53 Gr B steel barely drops within the galvanized service range; the ceiling is set by the zinc coating, not the steel:
| Temperature | S | Factor vs. 38 °C | Galvanized service? | |
|---|---|---|---|---|
| MPa | ksi | |||
| ≤38 °C · 100 °F | 137.9 | 20.0 | 1.000 | Yes |
| 93 °C · 200 °F | 137.9 | 20.0 | 1.000 | Dry fluids only (in water >60 °C zinc reverses its potential — section 3) |
| 149 °C · 300 °F | 137.9 | 20.0 | 1.000 | Dry fluids only, up to 200 °C |
| 204 °C · 400 °F | 137.2 | 19.9 | 0.995 | No — exceeds the coating's 200 °C limit |
IMPORTANT
This data sheet is a reference guide to the properties of this product type. The measurements, dimensions and physical or geometric characteristics of the product actually supplied may vary by manufacturer and lot, and may even fall outside the cited standards. If any of these figures is critical to your design or build, it is essential to verify it with one of our advisors against the physical product, so you can be fully certain of what you are buying. · Original data sheet: tectul.com/en/conduccion-de-fluidos/tuberia/ficha-tecnica-tubo-galvanizado-tipo-pesado.html
Above 200 °C of continuous exposure the outer free-zinc layer peels from the zinc-iron alloy layers (American Galvanizers Association). For higher-temperature service specify black pipe: data sheet FT-TC-TUB-SCH40-001.
3. Zinc coating: mass, service life and limits
Hot-dip galvanizing protects steel in two ways: as a barrier — zinc exposed to the atmosphere passivates into a basic zinc carbonate patina that slows its own corrosion — and as a sacrificial anode — zinc is anodic to steel in the galvanic series, so at cuts, scratches and edges it corrodes before the substrate does (American Galvanizers Association).
| Minimum zinc mass | 550 g/m² (1.8 oz/ft²) on each surface, inside and outside, per ASTM A53/A53M-24. |
| Equivalent thickness | ≈77 µm per surface: 550 g/m² ÷ 7.14 g/cm³ (zinc density, CRC Handbook) = 77.0 µm. Real coatings usually exceed the minimum; each lot's value appears in its test report. |
| Measurement | ASTM A90/A90M-21: the reference gravimetric method of A53 — the coating of a specimen is stripped and the mass difference weighed. |
| Zinc melting point | 419.5 °C (CRC Handbook); the useful service limit of the coating is far lower: 200 °C (see below). |
Minimum zinc mass per meter of pipe (calculated)
With the A53 minimum mass per surface and B36.10 dimensions, zinc mass per meter is m = 0.550 kg/m² × π × (D_out + D_in):
| NPS | Inside Ø | Min. zinc mass | Vs. black-pipe weight |
|---|---|---|---|
| 1/4″ | 9.22 mm | 0.040 kg/m | +6.3% |
| 3/8″ | 12.48 mm | 0.051 kg/m | +6.1% |
| 1/2″ | 15.76 mm | 0.064 kg/m | +5.0% |
| 3/4″ | 20.96 mm | 0.082 kg/m | +4.9% |
| 1″ | 26.64 mm | 0.104 kg/m | +4.1% |
| 1-1/4″ | 35.08 mm | 0.134 kg/m | +3.9% |
| 1-1/2″ | 40.94 mm | 0.154 kg/m | +3.8% |
| 2″ | 52.48 mm | 0.195 kg/m | +3.6% |
| 2-1/2″ | 62.68 mm | 0.234 kg/m | +2.7% |
| 3″ | 77.92 mm | 0.288 kg/m | +2.6% |
| 4″ | 102.26 mm | 0.374 kg/m | +2.3% |
| 6″ | 154.08 mm | 0.557 kg/m | +2.0% |
IMPORTANT
This data sheet is a reference guide to the properties of this product type. The measurements, dimensions and physical or geometric characteristics of the product actually supplied may vary by manufacturer and lot, and may even fall outside the cited standards. If any of these figures is critical to your design or build, it is essential to verify it with one of our advisors against the physical product, so you can be fully certain of what you are buying. · Original data sheet: tectul.com/en/conduccion-de-fluidos/tuberia/ficha-tecnica-tubo-galvanizado-tipo-pesado.html
Coating service life by atmospheric environment (ISO 9223)
Quotient estimate: life ≈ minimum thickness (77 µm) ÷ first-year zinc corrosion rate per corrosivity category (ISO 9223:2012, Table 2). It is a linear, conservative projection: the zinc rate decays after the first year as the patina consolidates (American Galvanizers Association).
| ISO 9223 category | Typical environment | Zinc rate, 1st year | Estimated life of minimum coating (77 µm) |
|---|---|---|---|
| C2 (low) | Dry rural, minimal pollution (SO₂ < 5 µg/m³) | 0.1–0.7 µm/yr | over 110 years |
| C3 (medium) | Urban with medium pollution (SO₂ 5–30 µg/m³) or coastal 1–30 km from the sea | 0.7–2.1 µm/yr | 36 to 110 years |
| C4 (high) | Industrial, or coastal under 1 km from the sea | 2.1–4.2 µm/yr | 18 to 36 years |
| C5 (very high) | Heavily polluted industrial; jetties and offshore structures | 4.2–8.4 µm/yr | 9 to 18 years |
| CX (extreme) | Marine splash zone; extreme industrial | 8.4–25 µm/yr | 3 to 9 years |
Coating life is the time until zinc is locally exhausted on the outside surface exposed to the atmosphere (maintenance criterion: ~5% red rust). The inside surface is governed by the fluid's chemistry — hardness, oxygen, temperature — not by this table.
Temperature limits — and why not in steam or hot water
200 °C of continuous exposure is the maximum recommended by the American Galvanizers Association: above it, diffusion between the outer free-zinc layer and the zinc-iron alloy layers creates voids that peel the coating off; between 200 and 250 °C the alloy layers still protect, but peeling accelerates and continued exposure worsens it.
In water between 60 and 82 °C containing dissolved oxygen and bicarbonates, potential reversal occurs: zinc passivates, becomes cathodic to the steel and stops protecting it — attack then concentrates as pitting of the exposed steel (American Galvanizers Association). That is why galvanized pipe is not specified for steam, condensate return or hot water: a steam line also exceeds the coating's thermal limit. For those services use black pipe (data sheet FT-TC-TUB-SCH40-001).
4. NPT threading, touch-up and installation
Galvanized conveyance pipe is joined by threading, not welding: the arc burns the coating in the heat-affected zone — leaving bare steel exactly where corrosion concentrates most — and releases zinc oxide fumes (metal fume fever). If a joint does require welding, the area must be restored per ASTM A780/A780M-20.
NPT thread per ASME B1.20.1
| Sizes | Threads per inch | Pitch |
|---|---|---|
| 1/4″ and 3/8″ | 18 | 1.411 mm |
| 1/2″ and 3/4″ | 14 | 1.814 mm |
| 1″ to 2″ | 11½ | 2.209 mm |
| 2-1/2″ to 6″ | 8 | 3.175 mm |
IMPORTANT
This data sheet is a reference guide to the properties of this product type. The measurements, dimensions and physical or geometric characteristics of the product actually supplied may vary by manufacturer and lot, and may even fall outside the cited standards. If any of these figures is critical to your design or build, it is essential to verify it with one of our advisors against the physical product, so you can be fully certain of what you are buying. · Original data sheet: tectul.com/en/conduccion-de-fluidos/tuberia/ficha-tecnica-tubo-galvanizado-tipo-pesado.html
Taper thread, 1:16 on diameter (3/4 in per foot), 60° flank angle (ASME B1.20.1). Threading cuts into the wall: the pressure in section 2 is at full wall — check the remaining wall under the thread on demanding lines. The schedule 40 wall is what makes the "heavy type" threadable.
Touch-up of exposed thread and damaged areas (cold galvanizing)
The cut thread is left uncoated. After assembly, touch up every exposed flight per ASTM A780/A780M-20 with zinc-rich paint: metallic zinc content in the dry film of 65–69% or above 92%, minimum thickness 50 µm (2 mils), over a clean, dry surface. For larger repairs, A780 also allows zinc thermal spraying or hot-applied zinc-alloy stick.
Galvanic couple: do not connect galvanized pipe directly to copper or brass: in the galvanic series zinc sacrifices itself at an accelerated rate against those metals. Insert dielectric unions and avoid water flowing from copper toward the galvanized run.
5. Application notes
Feasibility
Choose the heavy type (SCH 40) when the line is threaded and pressurized: cold water, compressed air, irrigation and non-corrosive gases. At NPS 2″ the calculated pressure is 133 bar at ≤38 °C — far above ordinary networks (≤16 bar); that margin is consumed by internal corrosion, water hammer and the thread. The thin-wall light type is for medium and low pressure where cost and weight dominate.
Installation
Join with NPT-threaded galvanized fittings of the same size and a sealant compatible with the service. Do not weld: thread — and touch up every exposed thread with cold-galvanizing compound per ASTM A780 (section 4). Against copper or brass, insert a dielectric union. Support the line with hangers selected per MSS SP-69; outdoor galvanized pipe benefits from supports that do not trap water against the surface.
Design
Galvanizing protects while zinc remains: size the line's life with the section 3 table for the site's ISO 9223 category. The thermal ceiling belongs to the coating (200 °C; in water, 60 °C), not the steel. For an aggressive internal fluid, subtract a corrosion allowance c from the effective wall: with c = 1.5 mm at NPS 2″, t_ef = 3.421 − 1.5 = 1.921 mm and P drops to 74 bar. The calculation covers internal pressure only; the design code adds combined loads, water hammer and fatigue.
6. Technical notice and limitation of liability
The pressures, dimensions, weights, coating masses and service lives in this sheet are theoretical calculation values obtained from nominal properties published in the standards cited (ASME B36.10-2022, ASME B31.3-2024, ASTM A53/A53M-24, ASTM A90/A90M-21, ISO 9223:2012). They guide selection; they are not a certificate of conformity for any given lot. Coating service lives are statistical estimates per environment category: the site's actual corrosivity and the fluid's chemistry modify them.
The actual behavior of each lot varies with manufacturing — wall tolerance (up to −12.5%), actual zinc mass deposited, out-of-roundness, residual stresses — and with the raw material — chemical composition within the ranges the standard allows, heat-to-heat differences. To certify a lot, the tests defined by its product standard are required: tensile test, flattening test, hydrostatic test and coating-mass verification per ASTM A90/A90M, documented in the manufacturer's mill test certificate (MTC), which TECTUL supplies upon request; testing of the lot in an independent laboratory can also be arranged.
These values must not be used as the sole criterion in critical or safety applications, or wherever failure of the line may compromise people, property or the environment: in such cases the design belongs to the project's responsible engineer under the applicable code (ASME B31.3, B31.1 or the one governing the installation), with the design temperature, corrosion allowance and load cases of the actual service. Before deciding with these data, consult our technical team.
Sources
- ASTM A53/A53M-24 — Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and Seamless (masa mínima de zinc 1,8 oz/ft² [550 g/m²] por superficie; tolerancia de espesor −12,5%; propiedades Gr A/Gr B)
- NTC 3470:2021 — Tubos de acero soldados y sin costura, negros y recubiertos de cinc por inmersión en caliente (equivalente colombiano de ASTM A53)
- ASTM A90/A90M-21 — Standard Test Method for Weight [Mass] of Coating on Iron and Steel Articles with Zinc or Zinc-Alloy Coatings
- ASTM A780/A780M-20 — Standard Practice for Repair of Damaged and Uncoated Areas of Hot-Dip Galvanized Coatings
- ASME B36.10-2022 — Welded and Seamless Wrought Steel Pipe (dimensiones y pesos)
- ASME B31.3-2024 — Process Piping: Tabla A-1 (esfuerzo admisible S) y Tabla A-1B (factor de calidad E)
- ASME B1.20.1 — Pipe Threads, General Purpose (Inch): rosca NPT, conicidad 1:16, hilos por pulgada
- ISO 9223:2012 — Corrosion of metals and alloys. Corrosivity of atmospheres: Tabla 2, tasas de corrosión del zinc en el primer año por categoría C1–CX
- American Galvanizers Association — «Galvanized Steel’s Performance in Extreme Temperatures» (límite de 200 °C y mecanismo de desprendimiento) y «Performance of Hot-Dip Galvanized Steel in Water Environments» (inversión de potencial del zinc en agua a 60–82 °C)
- CRC Handbook of Chemistry and Physics — densidad del zinc 7,14 g/cm³ y punto de fusión 419,5 °C
This data sheet is the property of TECTUL, part of the Industrias IMR group. Reproduction without attribution is prohibited. Original document and updates: tectul.com/en/conduccion-de-fluidos/tuberia/ficha-tecnica-tubo-galvanizado-tipo-pesado.html.