Galvanized Round Steel Pipe OD 88.9 mm — Size, Weight, Grades & Specification
Galvanized round steel pipe to EN 10255 / ASTM A53 — outside diameter and wall data, theoretical weight tables, tolerances, grades and threaded options.
Product Overview
Shandong Dayang Galvanized Round Steel Pipe with an outside size of OD 88.9 mm is a hot-formed hollow round section supplied in a hot-dip or pre-galvanized finish. It is manufactured from continuously cast, fully killed steel strip, formed and welded along the seam, then coated with zinc so that the finished tube resists atmospheric corrosion without any painting on site.
The OD 88.9 mm size is one of the most widely used sections in light structural work because it balances stiffness against weight — with a continuous circular wall, the closed profile resists both bending and twisting, which open sections of the same weight do not. It is produced in wall thicknesses from 3.0 mm to 4.5 mm, giving designers a continuous range of section properties from light frames through to load-bearing trusses and platforms.
This page gives the full engineering detail for this size: size range and theoretical weights, dimensional tolerances, steel grades and their international equivalents, chemical composition, mechanical properties, applicable standards, typical applications, and the practical problems buyers run into when sourcing galvanized round steel pipe from overseas mills — together with how we prevent each of them.
Specifications & Size Range
| Outside Diameter (mm) | Nominal Bore | Inch Designation | Wall t (mm) | Theoretical Weight (kg/m) | Weight per 6 m (kg) |
|---|---|---|---|---|---|
| 88.9 | DN80 | 3″ | 3.0 | 6.35 | 38.13 |
| 88.9 | DN80 | 3″ | 3.5 | 7.37 | 44.23 |
| 88.9 | DN80 | 3″ | 4.0 | 8.37 | 50.25 |
| 88.9 | DN80 | 3″ | 4.5 | 9.37 | 56.20 |
Theoretical weight is calculated on the EN 10255 / GB/T 3091 reference formula: W (kg/m) = (OD − t) × t × 0.02466, where OD is the outside diameter in mm and t is the nominal wall thickness in mm.
Standard lengths: 6 m standard; 5.8 m, 12 m, and threaded-and-coupled lengths available. Finish: Hot-dip galvanized (EN ISO 1461), typical zinc coating 275–500 g/m² double-sided.
Theoretical weight covers the bare steel section. A galvanized tube also carries a zinc coating mass — under EN ISO 1461 typically 275–610 g/m² double-sided depending on wall thickness — which adds roughly 3–6% to the weighed mass. Where a shipment is invoiced on actual weight that coating mass is included in the weighing; where it is invoiced on theoretical weight it is not. Please confirm which basis you require on the order.
Tolerances
| Parameter | Tolerance |
|---|---|
| Outside diameter | ±0.5 mm up to OD 48.3; ±1% above |
| Wall thickness t | ±10% of nominal |
| Length | 0 / +50 mm plain end; ±10 mm cut lengths |
| Straightness | ≤ 0.15% of total length |
| Ends | Plain end, bevelled, or threaded with couplings |
Tolerances follow EN 10219-2 unless another standard is specified on the order. ASTM A500 and JIS G3466 distribute the same allowances differently, so if your design assumes a particular set of limits, state the standard on the enquiry and we will confirm it in writing.
Steel Grades & International Equivalents
All grades below are supplied with a mill test certificate. The right-hand column shows the material type and the Chinese standard the grade is produced to; the middle columns give the nearest recognised equivalent in other national standards. Exact equivalence for a specific project should be confirmed on the enquiry.
| GB (China) | ASTM / AISI (US) | EN (Europe) | JIS (Japan) | DIN (Germany) | Type / Standard |
|---|---|---|---|---|---|
| Q235B welded pipe | A53 Gr.B / A500 Gr.B | EN 10219 S235JRH | STK400 (JIS G3444) | St37-2 | Welded steel pipe (ERW / LSAW) (GB/T 3091) |
| Q195 welded pipe | A53 Gr.A / A500 | EN 10255 (S195T) | SGP (JIS G3452) | St33 | Welded steel pipe (ERW) (GB/T 3091) |
| 20# seamless (A106 Gr.B equivalent) | A106 Gr.B / A53 Gr.B | P235GH (EN 10216-2) | STPG370 (JIS G3454) | St37.0 | Seamless carbon steel pipe (GB/T 8163 / GB/T 3087) |
Grade Notes
- Q235B welded pipe — Structural welded pipe for scaffolding, piling, water mains and building frames.
- Q195 welded pipe — General-purpose welded pipe for water, gas, heating and structural framing.
- 20# seamless (A106 Gr.B equivalent) — High-temperature service seamless pipe for steam, water and process lines. Supplied with mill test certificate.
Chemical Composition (%, ladle analysis)
Typical specification limits. Actual heat values are reported on the mill test certificate supplied with every shipment.
| Grade | C | Si | Mn | P max | S max | Other elements |
|---|---|---|---|---|---|---|
| Q235B welded pipe | ≤0.20 | ≤0.35 | ≤1.40 | ≤0.045 | ≤0.045 | — |
| Q195 welded pipe | ≤0.12 | ≤0.30 | 0.25–0.50 | ≤0.035 | ≤0.040 | — |
| 20# seamless (A106 Gr.B equivalent) | ≤0.30 | ≥0.10 | 0.29–1.06 | ≤0.035 | ≤0.035 | — |
Mechanical Properties
Minimum values at room temperature unless stated. ReL = yield strength; Rp0.2 = 0.2% proof stress; Rm = tensile strength; A = elongation after fracture.
| Grade | Yield (ReL) | Proof (Rp0.2) | Tensile (Rm) | Elongation A | Impact / others | |
|---|---|---|---|---|---|---|
| Q235B welded pipe | ≥235 MPa | — | 370–500 MPa | ≥26% | — | Test Pressure hydro-tested per spec |
| Q195 welded pipe | ≥195 MPa | — | 315–430 MPa | ≥33% | — | Test Pressure hydro-tested per spec |
| 20# seamless (A106 Gr.B equivalent) | ≥240 MPa | — | ≥415 MPa | ≥22% | — | — |
Standards & Documents
- EN 10255
- ASTM A53 Gr. A / B
- GB/T 3091
- JIS G3444
Every shipment is accompanied by a mill test certificate to EN 10204 3.1, traceable to the heat number of the supplied material. On request we also provide a certificate of origin, a packing list with bundle-level weights and dimensions, and container loading photographs.
Typical Applications
| Industry / Application | Typical use |
|---|---|
| Water and service lines | Low-pressure water, irrigation and utility piping in galvanized execution. |
| Scaffolding | Guard rails, braces and standards for modular scaffold systems. |
| Greenhouse and shade frames | Curved hoops and ridge pipes formed from round tube. |
| Fencing posts and railings | Chain-link posts, gate frames and roadside railing. |
| Handrails and stair rails | Balustrades where a round profile is specified. |
| General fabrication and OEM | Rollers, spacers, conveyor guards and machine protection. |
Common Problems Buyers Face — and How We Prevent Them
These are the issues that most often cause claims on steel imports. Each one is controlled in our process before shipment.
Diameter or wall thickness not per the ordered standard
Why it happens: Pipes are sometimes supplied to a different DN / wall combination than ordered, and the difference is only visible once you measure them.
Our control: We confirm outside diameter and wall against the order line by line and measure with a calibrated gauge before loading.
Threads that do not gauge
Why it happens: Threaded ends are only useful if they assemble on site; a badly cut thread stops the job at the first joint.
Our control: We check thread form and run a coupling test on the first piece of every batch supplied threaded.
Insufficient zinc coating
Why it happens: Coating mass decides corrosion life, and it is hard to see once the pipe is bundled.
Our control: Coating mass is stated in writing and can be sample-tested on request before shipment.
Bare patches or white rust after sea freight
Why it happens: Long sea transit in humid air can cause white rust on freshly galvanized surfaces.
Our control: We allow full curing before packing, keep bundles ventilated, and can wrap for long routes.
Mixed sizes in one bundle
Why it happens: Similar-looking diameters are easy to mix, and the error surfaces only at installation.
Our control: Each bundle is labelled with DN, outside diameter, wall and length, and loading photos are sent before the container closes.
Our Supply & Manufacturing Advantages
- Mill test certificates (EN 10204 3.1) traceable to the heat number of your order.
- Outside diameter, wall thickness and zinc coating verified in-house before shipment.
- Plain end, bevelled, or threaded-with-coupling — including thread gauging on request.
- Bundles labelled by DN / OD / wall / length, with loading photos before departure.
- Consolidation with angles, channels, plates and square tube in one shipment.
- Pre-shipment sample retained for any later claim.
Packaging, Delivery & Payment
- Packing: loose in bulk vessel, or bundled and containerised to your requirement. Galvanized and coated products get VCI paper, waterproof wrapping and edge protection. See our export packaging methods.
- Availability: both stock and custom production. Tell us the specification and we will confirm the route.
- MOQ: no strict minimum — one ton can ship.
- Lead time: stock dispatched to port within 3 days; orders needing export packaging about 1 week; custom production quoted per product.
- Payment: stock — 10% deposit, balance before shipment; custom production — 50% deposit, balance before shipment.
- Documents: EN 10204 3.1 mill test certificate with every shipment; third-party inspection (SGS / BV) on request.
Frequently Asked Questions
What is the difference between DN, inch size and outside diameter?
DN is a nominal bore designation and is not a dimension you can measure. A DN50 pipe has an outside diameter of 60.3 mm, and the same DN can be supplied in several wall thicknesses. Always order by outside diameter and wall thickness if the pipe has to fit an existing joint.
Is your galvanized pipe the same as ASTM A53?
ASTM A53 Gr. B is a widely used US standard for welded and seamless pipe. Our galvanized pipe is produced to EN 10255 / GB/T 3091, which set a similar but not identical set of requirements. Grade equivalence is approximate, so confirm the applicable standard against your specification.
Can I get threaded ends with couplings?
Yes. Pipe can be supplied plain end, bevelled, or threaded with couplings. Thread form and gauge are checked on the first piece of every threaded batch, so that on-site assembly is not held up by threads that will not run.
How is the pipe invoiced — actual weight or theoretical weight?
Both bases are used in the trade. Theoretical weight is calculated from the formula on this page; actual weight is the weighed mass including the zinc coating. The basis must be agreed before the order, because the difference on a full container is significant.
What zinc coating mass do you normally supply?
Typical hot-dip galvanized pipe carries 275–500 g/m² double-sided. If the destination is a high-corrosivity environment, specify a higher coating mass and we will confirm what the mill can achieve for the size you need.
Do you supply pipe suitable for water lines?
Yes, galvanized round pipe to EN 10255 / GB/T 3091 is used for low-pressure water and utility services. It is not intended for high-pressure or critical process duty — for those applications a seamless pipe to a pressure-rated standard should be specified instead.
Can several sizes be consolidated in one container?
Yes. Consolidation is normal for buyers who need a mixed programme. Each bundle is labelled with DN, outside diameter, wall thickness and length, and loading photographs are sent before the container closes so that you can verify the load.
Who supplies galvanized round steel pipe from China with mill test certificates?
Shandong Dayang supplies galvanized round pipe across the diameter and wall range shown on this page, with mill test certificates to EN 10204 3.1 issued against the heat number of the supplied material.
Request a Quotation for OD 88.9 mm
Send us the size, wall thickness, steel grade, length, coating requirement, quantity and destination port, and we will come back with a quotation and a loading plan. If you are unsure which grade or coating suits your project, send the project specification instead and we will map it for you.
Technical details on this page are given for guidance. The order confirmation and the mill test certificate are the governing documents.