Hot-Dip Galvanized Steel Pipe & Tube
We supply hot dip galvanized pipe, also called HDG pipe or hot dip GI pipe. Each length is dipped in molten zinc after forming, so the coat covers inside, outside and the weld. Sizes run from NPS 1/8" to 26", with larger LSAW / SSAW pipe up to OD 2000 mm dipped to order.
Zinc coating of 300 g/m² minimum, tested and printed on the certificate
BS 1387 / EN 10255 Light, Medium and Heavy, plus ASTM A53 Grade B
Threaded with BSP or NPT threads, or plain end
Round, square and rectangular HDG pipe & tube
Why Order HDG Steel Pipe From Us
01
Coating Weight in Numbers
We state zinc in g/m² and test every lot. Each lot is tested with a coating gauge or strip test, and the result goes on the mill certificate. You get the real figure, not "heavy coat".
02
Inside Coat Checked Too
Water pipe rusts from the inside first. We check the bore for bare spots and drips, not just the outside.
03
Clean Threads After Dipping
We cut, thread, couple and groove in house. Threads are cut after galvanizing, then capped. Fittings screw on without re-tapping.
04
White Rust Control
Fresh zinc can form white rust in a wet container. We oil or passivate the pipe and pack it dry.
05
8–12 Working Days Lead Time
Typical lead time is 8–12 working days. We keep 9,000 tons of galvanized pipe & tube in stock (out of 80,000 tons in total). Special walls take 2–3 weeks, depending on the order.
Hot Dip Galvanized Steel Pipe Protects Where Others Fail
A hot dip galvanized steel pipe gets the thickest zinc coat of any galvanized product. The zinc bonds with the steel and forms hard alloy layers. They resist knocks in handling and on site.
That is why water, fire and irrigation lines use hot-dip pipe. The bore stays protected, the weld is covered, and the cut ends are sealed. If the pipe will carry water, sit in soil or stand by the sea, this is the coat to choose.
Hot-Dip Galvanized Pipe & Tube Range
BS 1387 Hot Galvanized Pipe
Light, Medium and Heavy class, 1/2" to 6", with BSP threads and sockets. The standard water pipe for the Middle East and Africa.
ASTM A53 Hot Dipped Galvanized Steel Pipe
Grade B, Sch 40 and Sch 80, threaded and coupled or plain end. See Schedule 40 Galvanized Pipe.
Hot-Dip Square and Rectangular Tube
Box sections dipped after forming, for outdoor frames and solar mounts.
HDG Pipe for Fire and Irrigation
Grooved or threaded pipe to ASTM A795 and A135 for sprinkler and irrigation lines.
Specifications
| Item | Range |
|---|---|
| Size | NPS 1/8″ – 26″ (DN6 – DN650); round OD 12.7 – 610 mm; LSAW / SSAW up to OD 2000 mm |
| Wall | BS 1387 Light / Medium / Heavy; Sch 5 – Sch 160 / XXS (per size) |
| Base pipe | ERW / HFW, LSAW, SSAW or seamless; ASTM A53 Gr. A / B, API 5L Gr. B, EN 10255 S195T, EN 10219 S235JRH / S355J2H, Q195–Q355B, STK400 / STK500 |
| Zinc coating | 300 – 600 g/m², about 40 – 85 µm |
| Coating standards | EN 10240, ISO 1461, AS/NZS 4680, ASTM A53 |
| Ends | Plain, bevelled, threaded & coupled, grooved; flanged (fabricated) |
| Length | 5.8 m / 6 m / 12 m; 20 ft / 21 ft / 40 ft; or cut to length (e.g. 6.4 m) |
Hot-Dip vs Pre-Galvanized Pipe: Which One to Buy
Both are sold as galvanized pipe. Both look silver. But they are made in different ways, and they last very differently. Here is how to tell them apart and choose.
How Each One Is Made
Hot-dip pipe is made black first, then dipped in zinc at about 450°C. The zinc coats every surface, including the bore and the weld. Our hot-dip coat is 300–600 g/m², about 40–85 µm.
Pre galvanized steel pipe is made from zinc-coated coil. The tube mill forms and welds the coated strip. Only the outside weld gets a zinc spray. The bore weld and cut ends have little or no zinc. The strip carries 60–275 g/m² of zinc in total for both sides, about 4–19 µm per side.
How to Tell Them Apart
Hot-dip pipe has a duller, slightly rough surface. You may see drips at the ends. Pre-galvanized pipe is bright and smooth, with a visible seam line. On a tender, “GI” usually means hot-dip and “GP” means pre-galvanized. Ask for the coating weight to be sure.
When to Choose Hot-Dip
Choose hot-dip for anything that carries water, sits outdoors or goes underground. Choose it for fire lines, irrigation and coastal sites. Most water pipe standards, including BS 1387 and A53, call for hot-dip.
When Pre-Galvanized Is Enough
Pre galvanized pipe suits dry, indoor uses. Think furniture, shelving, greenhouse frames and fence rails. It costs less and looks better. Do not use it for water lines. The bore will rust within a few years.
Checking the Coat on Arrival
Use a magnetic coating gauge on the outside. Take readings at both ends and the middle of a few lengths. For the inside, look into the bore with a light. Bare patches and heavy drips mean poor dipping. The certificate should state the weight per lot, not a general value.
Schedule 40 and Other Walls
Hot dip galvanizing does not change the wall. A Schedule 40 hot dipped galvanized steel pipe has the same wall as black Sch 40, plus the zinc. Order the wall you need for pressure, then the coat you need for life.
Frequently Asked Questions
What is HDG pipe?
HDG stands for hot-dip galvanized. HDG pipe is black steel pipe dipped in molten zinc after it is made. HDG steel pipe has zinc on the inside, outside, weld and ends. It is the standard choice for water, fire and outdoor lines.
Is hot dipped galvanized GI pipe the same as hot dip galvanized pipe?
Yes. "Hot dipped galvanized GI pipe" and "hot dip GI pipe" are other names for the same product. GI comes from "galvanized iron". All three mean steel pipe coated in a zinc bath.
What is BS 1387 pipe?
BS 1387 is the British standard for steel water pipe, threaded or plain. It has three wall classes: Light, Medium and Heavy. EN 10255 replaced it, but many projects still name BS 1387. Medium is the most ordered class.
How thick is the zinc on hot galvanized pipe?
Our hot-dip coat is 300–600 g/m², or about 40–85 µm. Standards set a minimum. ASTM A53 and EN 10240 both define one. Send your spec, and we will match it.
Is pre galvanized pipe cheaper than hot-dip?
YesIt uses far less zinc. But it lasts much less outdoors. For water or outdoor lines, the extra cost of hot-dip pays back.
How much does hot-dip galvanized pipe cost?
Price depends on size, wall, coating weight and quantity. Zinc price moves it as well as steel. Send your list, and we will quote within 2–4 working hours. Quotes are valid for 3 days.
Request a Quote
We reply within 2–4 working hours with a price per ton, valid for 3 days.