What is GI pipe?
GI (galvanized iron) pipe is ERW carbon steel pipe dipped in molten zinc after welding so that inside and outside surfaces carry 55–80 µm of zinc (400–600 g/m²). The zinc protects the steel for 20–40 years in fresh water and outdoor air, which is why GI pipe is the default for domestic and industrial water lines, fire-sprinkler mains, compressed air, fence posts, scaffold, greenhouse frames and electrical conduit. "Class B" and "Class C" are the old BS 1387 names for what EN 10255 now calls medium and heavy series.
We make it in Dilovası — strip from our own coil stock, HF welding, hydrostatic test, then hot-dip galvanizing, threading and socketing in one flow — so length, wall and end finish follow your order.
Pipe pages
For US-specification galvanized pipe (Grade B, sch 40, T&C) see the ASTM A53 pipe page.
Size chart — OD, wall and weight
Weights are for galvanized pipe (bare steel mass plus about 3–4% zinc). EN 10255 medium series is the standard for potable water and fire lines; the heavy series adds about 0.4–0.6 mm wall for pressure and threading depth. A 6 m bar of 1" medium (33.7 × 3.2 mm) weighs 14.5 kg.
| NPS | OD (mm) | Wall (mm) | kg/m | kg per 6 m |
|---|---|---|---|---|
| ½" | 21.3 | 2 | 0.95 | 5.71 |
| ¾" | 26.9 | 2 | 1.23 | 7.37 |
| ¾" | 26.9 | 2.5 | 1.5 | 9.02 |
| ¾" | 26.9 | 3 | 1.77 | 10.61 |
| 1" | 33.7 | 2 | 1.56 | 9.38 |
| 1" | 33.7 | 2.5 | 1.92 | 11.54 |
| 1" | 33.7 | 3 | 2.27 | 13.63 |
| 1¼" | 42.4 | 2 | 1.99 | 11.96 |
| 1¼" | 42.4 | 2.5 | 2.46 | 14.76 |
| 1¼" | 42.4 | 3 | 2.92 | 17.49 |
| 1½" | 48.3 | 2 | 2.28 | 13.7 |
| 1½" | 48.3 | 2.5 | 2.82 | 16.94 |
| 1½" | 48.3 | 3 | 3.35 | 20.11 |
| 2" | 60.3 | 2 | 2.88 | 17.25 |
| 2" | 60.3 | 2.5 | 3.56 | 21.38 |
| 2" | 60.3 | 3 | 4.24 | 25.43 |
| 2½" | 76.1 | 2.5 | 4.54 | 27.22 |
| 2½" | 76.1 | 3 | 5.41 | 32.45 |
| 3" | 88.9 | 2.5 | 5.33 | 31.96 |
| 3" | 88.9 | 3 | 6.36 | 38.13 |
| 4" | 114.3 | 3 | 8.23 | 49.4 |
EN 10255 M/H and EN 10219 dimensions; zinc per EN 10240 A1 (min. 55 µm); threaded and socketed or plain end.
Medium and heavy series (Class B and C)
| NPS | OD (mm) | Medium wall (mm) | Heavy wall (mm) | Medium kg/m | Heavy kg/m | Test pressure |
|---|---|---|---|---|---|---|
| ½" | 21.3 | 2.6 | 3.2 | 1.21 | 1.44 | 50 bar |
| ¾" | 26.9 | 2.6 | 3.2 | 1.56 | 1.87 | 50 bar |
| 1" | 33.7 | 3.2 | 4.0 | 2.41 | 2.93 | 50 bar |
| 1¼" | 42.4 | 3.2 | 4.0 | 3.10 | 3.79 | 50 bar |
| 1½" | 48.3 | 3.2 | 4.0 | 3.56 | 4.37 | 50 bar |
| 2" | 60.3 | 3.6 | 4.5 | 5.03 | 6.19 | 50 bar |
| 2½" | 76.1 | 3.6 | 4.5 | 6.42 | 7.93 | 50 bar |
| 3" | 88.9 | 4.0 | 5.0 | 8.36 | 10.30 | 50 bar |
| 4" | 114.3 | 4.5 | 5.4 | 12.20 | 14.50 | 50 bar |
| 5" | 139.7 | 4.5 | 5.4 | 15.00 | 17.90 | 50 bar |
| 6" | 165.1 | 4.5 | 5.4 | 17.80 | 21.30 | 50 bar |
Nominal masses for bare pipe per EN 10255; galvanized adds ~3–4%.
Zinc coating: EN 10240 A1 and ASTM A53
EN 10240 A1 requires a minimum local zinc mass of 400 g/m² (≈55 µm) inside and out with a smooth, continuous coating and no uncoated areas; threads are cut after galvanizing and protected with oil or a zinc-rich touch-up. ASTM A53 requires 550 g/m² (≈78 µm) on both surfaces by the same hot-dip process. Coating is checked by magnetic thickness gauge on every bundle and reported on the 3.1 certificate.
Threading, sockets and fittings
Ends are threaded BSPT to EN 10226-1 (taper) with one malleable-iron or steel socket per bar and plastic thread protectors; NPT to ASME B1.20.1 for A53 orders. Plain and bevelled ends for welded systems. Matching GI fittings — elbows, tees, sockets, unions, nipples — are supplied from stock to EN 10242 / ASME B16.3, so a water-supply order ships complete.
- BSPT (EN 10226-1) or NPT threads, socket per bar
- Plain or bevelled ends for grooved / welded systems
- GI malleable fittings EN 10242 class A, banded
- Grooved (roll-groove) ends for fire-fighting systems on request
Applications: water, fire-fighting, fencing, scaffold, conduit
Potable and irrigation water lines (EN 10255 M, WRAS-type approvals per market), fire sprinkler and hydrant mains (grooved or threaded, red-painted optional), compressed air, agricultural and greenhouse frames, fence and gate posts (42.4–60.3 mm), scaffold tube 48.3 × 3.2 (EN 39), sign posts and street-light columns, electrical conduit (EN 61386 on request). For structural outdoor frames see also pre-galvanized hollow sections.
GI pipe vs black (MS) pipe vs stainless
| GI (galvanized) | MS (black) | Stainless 304 | |
|---|---|---|---|
| Corrosion protection | Zinc 55–80 µm, 20–40 yr fresh water | None; paint or varnish | Inherent, 50+ yr |
| Use | Water, fire, fences, scaffold, conduit | Structures, low-pressure air, painted lines | Food, chemical, hot water, visible |
| Joints | Threaded, grooved, welded | Welded, threaded | Welded, press-fit |
| Price per ton | 1.20–1.30 | 1.00 | 4.5–5.5 |
| Weight | Same as MS + 3–4% | — | Thinner walls, lighter |
GI pipe price per ton
Indicative FOB Istanbul band from our weekly export list, EN 10255 medium series threaded and socketed, ½"–4", 6 m, full-container quantities. Zinc follows the LME price, so the band moves with it; heavy series and A53 with NPT add 4–8%.
Bands from our weekly export list (September 2026), FOB Istanbul, full-container quantities, excluding freight and certificates. Firm price per project on RFQ within one working day.
Export and packing
Hexagonal bundles of 300–1 200 kg, three straps, thread protectors, sockets fitted; no varnish needed. 6 m bars fit 20' and 40' containers. HS code 7306.30 (welded, galvanized).
| Term | Detail |
|---|---|
| MOQ | 1 × 20' (≈20 t) or 1 truck (22–24 t); sizes and fittings can be mixed |
| Incoterms | FOB Istanbul · CIF / CFR Gulf, Red Sea, Africa · DAP Iraq, Balkans, EU, Caucasus |
| Lead time | Stock 5–10 working days; mill run 2–3 weeks |
| Packing | Hex bundles 300–1 200 kg, 3 straps, thread protectors, socket per bar |
| Container / truck | 20' ≈ 20 t · 40' HC ≈ 24–25 t · truck 22–24 t |
| Documents | Invoice, packing list per bundle, EN 10204 3.1 (hydro + zinc), certificate of origin; SASO, SONCAP, COC, EAC on request |
| Payment | 30% advance, balance against B/L copy; L/C at sight via London office |
Certificates
EN 10204 3.1 with hydrostatic test, zinc thickness and thread inspection; certificate of origin; SASO/SABER (KSA water pipe), SONCAP (Nigeria), COC (Iraq), EAC (CIS) arranged before loading; potable-water conformity statements per market on request.
How to order
Send NPS, series (medium/heavy or A53 schedule), end finish (threaded + socket / plain / grooved), quantity in tons or bars, fittings if needed, and the port. Reply within one working day with price, bundle plan, gross weight and loading date.
Standards
- EN 10255 (medium / heavy series)
- EN 10240 A1 (hot-dip zinc coating of tubes)
- ASTM A53 Grade B Type E
- ASTM A123 / A53 zinc coating
- EN 10226-1 (BSPT threads)
- BS 1387 (legacy, Class B/C)
Grades
Grade data sheets (chemistry, mechanicals, equivalents) are on our reference site: S195T (EN 10255) · S235JR
Frequently asked questions
What is GI pipe made of?
Low-carbon ERW steel pipe (S195T to EN 10255 or Grade B to ASTM A53) hot-dip galvanized after welding with 55–80 µm of zinc inside and outside. "Iron" in the name is historical; the pipe is steel.
Class B (medium) or class C (heavy) — which GI pipe should I order?
Old BS 1387 classes: B = medium series (e.g. 1" at 3.2 mm wall), C = heavy series (1" at 4.0 mm). EN 10255 uses the same walls under the names M and H. Class C is chosen for higher pressure, deeper threads and longer life.
What is the price of a 25 mm (1") GI pipe?
A 6 m bar of 1" medium-series GI weighs about 14.5 kg; at the indicative band above that is roughly USD 12–13 per bar FOB Istanbul in full-container quantity, before freight and duty. Ask for the current price per bar or per ton on the RFQ form.
Is GI pipe suitable for drinking water?
Yes — EN 10255 galvanized pipe is the traditional potable-water pipe; several markets require a national conformity mark (SASO in KSA, WRAS-type in the UK) which we arrange. For hot water above 60 °C or aggressive water, stainless or PPR is preferred.
Do you make the GI pipe yourselves?
Yes. Welding, hydro test, hot-dip galvanizing, threading and socketing are done in our Dilovası plant from our own coil; that is why lengths, walls and end finishes can follow the order.
Can GI pipe be welded?
Yes, but the zinc must be ground back 20–30 mm from the joint and the weld re-protected with zinc-rich paint; fumes require ventilation. For welded systems order plain or bevelled ends; for fire systems grooved ends avoid welding altogether.
What sizes of GI pipe do you stock?
½" to 8" (21.3–219.1 mm OD) in medium and heavy series; 6 m standard, 5.8 m for 20' container optimisation on request. Larger diameters are supplied black and galvanized to order.
How much zinc is on the pipe?
Minimum 400 g/m² (about 55 µm) per EN 10240 A1 on both surfaces; typically 60–80 µm. ASTM A53 orders are coated to 550 g/m². Thickness is measured per bundle and recorded on the certificate.