Galvanized Steel Pipe
Galvanized steel pipe is a steel pipe that has been coated with zinc. This coating protects the steel from corrosion. It is most commonly used for outdoor construction like fences and handrails, or for some interior plumbing. It is also sometimes called galvanized iron pipe.
To create galvanized steel pipe, steel materials are placed into a molten bath of zinc. This process is also called hot dip galvanization. The two metals are chemically bound to one another in this process, and will therefore never separate, resulting in a more resistant and longer lasting version of steel.
Galvanized steel pipe is generally connected by threads on either end of a length of pipe. A small amount of adhesive is typically placed on the threads before screwing them together, in order to reinforce the connection. If no threads are available, the pipes and fittings can be welded together.
Cold galvanized, electro-galvanized, galvanized the amount of small, only 10-50g/m2 of its own resistance to corrosion than hot dip galvanized pipe a lot of difference. Regular galvanized pipe manufacturers, in order to ensure the quality, most do not use electro-galvanized (cold-plated). Only those small-scale, outdated equipment and small businesses with electric galvanized, of course, their prices are relatively cheap. The Ministry of Construction has formally below, cold galvanized pipe to eliminate backward technology, the future not be allowed to cold galvanized pipe for water, gas pipes.
Hot Dipped galvanized pipes are ideal for jobs that require long-term protection in all weather and all conditions. It is suitable for various pipeline-related applications. Hot Dipped galvanized coating can be used on the inner and outer surfaces, the minimum coating weight is 300g/sq.m.
OD | 1/2”-10” (21.3mm-273mm) |
Wall Thickness | 1.5mm-14mm |
Length | 1m-16m |
Steel material | S195GT/235GT/355GT; Q195; Q235; Q345 |
Standard | EN10255; ASTM A53; BS1387:1985 |
Surface | Hot-dipped Galvanizd/Painted/Oiled |
Section Shape | Round |
Application | Fluid tube, With 100% hydro-test |
Zinc coating | Normal AVG: 280g/m2(40um), Max.70um |
Pipe End Treatment | Plain/Threaded/Grooved/Bevelded |
Galvanized steel tube is divided into hot galvanized and electric galvanized galvanized two methods, hot galvanized galvanized layer thick, low cost of electric galvanized, the surface is not very smooth.
Chemical composition and mechanical properties of BS1387 galvanized steel tubes
Chemical composition (ladle) | Mechanical properties at room temperature | |||||
C
max. | Mn
max. | P
max. | S
max. | Tensile strength, Rm | Yield strength, Re(min.) | Elongation on gauge length（min） Lo = 5.65 ÖSo A |
| % | % | % | % | N/mm2 | N/mm2 | % |
0.20 | 1.20 | 0.045 | 0.045 | 320 to 460 | 195 | 20 |
Heat treatment of BS1387 galvanized steel tubes
Tubes shall be supplied in the annealed or normalized condition, the as-welded condition, the as-welded condition with the weld zone heat treated, or after a hot finishing process
Surface treatment of BS1387 galvanized steel tubes
Tubes shall be supplied varnished unless it is specifically requested by the purchaser in his enquiry or order that the tubes shall be supplied self colour or with a hot-dip zinc coating.
Packing of BS1387 galvanized steel tubes
In loose or in bundles
Product show of BS1387 galvanized steel tubes
Zinc layer thickness ≥500g/㎡ according to customer requirements
JIS G3452 hot dipped galvanized steel pipes for ordinary piping shall be classified into only one grade symbolized by “SGP”. Pipes shall be manufactured by electric resistance welding and butt welding. There are two finishing methods under this specification, hot-finished and cold-finished. However, the cold-finished pipes shall be annealed after manufacturing. If the purchaser intends for hot dipped galvanized pipes, the “SGP-ZN”must be listed in the order between the buyer and seller. But it need not to mark on the pipes.
Specification
Outside diameter:10.5-508.0mm
Wall thickness: 2-50mm or according to clients request.
Length: 6m 12m or random length
Packing: The tubes are supplied in packages with hexagonal diameter with having weight of 500KG to 2000KG. From 1/8” to 8”steel pipes are tied with steel strip. 9” and upper size will be in loose. Pipes both end will be protected by plastic or metal cap. Bundled or each piece with knitted plastic bag, wooden cases or Ply-wooden Case /Iron Case/ Bundle or as per customers’ requirement.
Transportation: By container vessel, our experienced driver drives forklift to load steel pipes into container.
Appearance
The appearance of pipes shall be as follows,
1. Pipes shall be almost straight with the both ends perpendicular to the pipe axis.
2. The inside and outside surfaces of pipes shall be well-finished and free from defects that are detrimental to practical use. Especially, the inside and outside surfaces of white pipes shall be smooth.
3. The surface of all repaired parts shall blend smoothly into the contour of the pipe.
4. Upon the agreement between the purchaser and manufacturer, pipes shall be coated zinc on the outside and inside surface.
Inspection
Inspect the size, length and zinc coating layer of the tubes before shipment.
Galvanized seamless steel tube used to transport require relatively clean medium, such as: water, clean air. Threaded pipe connection is a common way to connect, pipe end with threaded and non- threaded. In order to improve the corrosion resistance of steel tube, normally seamless steel tube will be galvanized. Galvanized seamless steel tube is divided into hot galvanized and electro-galvanized two, thickness galvanized galvanized, electro-galvanized low cost, the surface is not very smooth.
Specification
Steel Pipe Type | Galvanized seamless steel tube |
Outside Diameter | 10-900mm |
Wall Thickness | 1.5-60mm |
Length | 5-12m as per clients’ requirements |
Standard | API 5L, ASTM A106, ASTM A53, ASTM A179/A192/A213/A210 GB5310-2009,GB3087-2008,GB6479-2013,GB9948-2013, GB/T8163-2008, GB8162-2008,GB/T17396-2009 |
Material | 10#, 20#, 45#, A53A, A53B, A106A,A106B, A106C, API 5L B, API 5L X42, API 5L X46, API 5L X52, API 5L X56, API 5L X60, API 5L X65, API 5L X70 ST37.0, ST35.8, St37.2, St35.4/8, St42,St45, St52, St52.4 STPG38, STPG42, STPT42, STB42, STS42, STPT49, STS49 |
Surface | Black painting, varnish paint, anti rust oil, hot galvanized, cold galvanized, 3PE, etc. |
Certificates | API 5L, ISO 9001:2008, TUV, SGS, BV, etc |
Packaging | Loose package, Packaged in bundles (3Tons Max), bundled pipes with two slings at the both end for easy loading and discharging, End with Plastic caps or as per requirement |
Application | 1. Fluid pipe 2. Power Plant 3. Structure pipe 5. Seamless pipe /tube for petroleum cracking 6. Conduit pipe 7. Scaffolding pipe pharmaceutical and ship, building etc. |
Pipe standard: ASTM A53 Gr.A
Tensile strength (min): 330 MPa
Yield strength (min): 205 MPa
External coating: 0.9 oz/ft2 zinc coating with a chromate passivation coating and a clear polymer film
Internal coating: high corrosion resistance paint
Nominal Size | Outside Diameter | Wall Thickness | Weight | |
inch | inch | inch | Kg/ft | lb/ft |
1” | 1.315 | 0.133 | 0.76 | 1.68 |
1-1/4” | 1.660 | 0.140 | 1.03 | 2.27 |
1-1/2” | 1.900 | 0.145 | 1.23 | 2.72 |
2” | 2.375 | 0.154 | 1.66 | 3.65 |
BS1139 Galvanized Scaffolding Pipe
Tensile strength: 340-480MPa
Yield strength (min): 235MPa
OD Tolerance: +/- 0.50 mm
Length Tolerance: -0, +5 mm
Thickness Tolerance: -10%, +not specified
Weight Tolerance: -8.0%, +12.0%
External Coating: 40 micron zinc coating
Internal Coating: high corrosion resistance paint
Nominal Size | Outside Diameter | Wall thickness | Pipe end | Length | Weight | Packing | |||
mm | Max mm | Min Mm | mm | meter | Kg/m | Kg/ft | lb/ft | Piece/bundle | |
48.3 | 48.8 | 47.8 | 3.2 | plain | 6 | 3.58 | 1.09 | 2.39 | 61 |
4.0 | plain | 6 | 4.37 | 1.33 | 2.94 | 61 | |||
JIS G3444 Galvanized Scaffolding Pipe
Tensile strength: 290 to 540 MPa
Yield strength (min): 235 to 390 MPa
Length Tolerance: -0, +5 mm
Thickness Tolerance: +/- 0.3mm (wall thickness <3mm)
+/- 10% (3mm<wall thickness<12mm)
Designation of grade: STK290, STK400, STK490, STK500, STK540
Surface option: Galvanized finish
Nominal Size | Outside Diameter | Wall thickness | Pipe end | Length | Weight | Reference | Packing | ||||
max | min | Cross section area | Geometric moment of inertia | Modulus of section | Radius of gyration of area | ||||||
mm | mm | mm | mm | meter | Kg/m | cm2 | cm4 | cm3 | cm | Piece/bundle | |
21.7 | 21.95 | 21.45 | 1.2 1.5 1.6 2.0 | plain Plain Plain Plain | 6 6 6 6 | 0.607 0.747 0.793 0.972 | 0.773 0.952 1.010 1.238 | 0.407 0.488 0.513 0.607 | 0.375 0.450 0.473 0.560 | 0.726 0.716 0.713 0.700 | 217 217 217 217 |
48.6 | 48.85 | 48.35 | 2.3 2.5 2.8 3.2 | plain Plain Plain Plain | 6 6 6 6 | 2.630 2.840 3.160 3.580 | 3.345 3.621 4.029 4.564 | 8.990 9.650 11.800 | 3.700 3.970 4.360 | 1.640 1.630 1.620 1.610 | 91 91 91 91 |
ASTM A795 standard specification for black and hot dipped zinc coated (galvanized) welded and seamless steel pipe for fire protection use
Classification of ASTM A795 galvanized steel pipe
Type F-Furnace-butt welded, continuous welded
Type E-Electric-resistance-welded
Type S-Seamless
Quantity | pieces, feet, lengths, tons |
Name of material | Galvanized steel pipe |
Type | F, E or S |
Grade | Grade A, Grade B |
Size | NPS or outer diameter, weight class or wall thickness |
Finish coating | galvanized |
Length | 3m, 5.8m, 6m, 10m, 11.8m, 12m, specific or random |
End finish | Plain end, square cut, bevel, grooved, threaded, coupling |
Chemical composition
Grade | Composition, max, % | |||
C | Mn | P | S | |
Type E & Type S | ||||
Grade A | 0.25 | 0.95 | 0.035 | 0.035 |
Grade B | 0.30 | 1.20 | 0.035 | 0.035 |
Type F | ||||
– | – | 0.050 | 0.045 | |
Packing for ASTM A795 galvanized steel pipe
5” and below: In bundles by steel strip, each bundle has 2pcs of lifting belts,
6″ and up: in loose, 2pcs of cotton ropes wrapped around both ends for protection.
All pipe’s ends are covered by plastic caps. Non-woven bag for packing
Pre galvanized steel pipe refer to steel pipes that are galvanized in sheet form, and therefore before further manufacturing. After the sheet is sent to the rolling mill for galvanizing, it is cut to a certain size and rewinded.
One of the advantages of pre galvanized steel pipe over hot-dip galvanized steel pipe is its better appearance. Pre galvanized materials can be used in a variety of products, including catheters, lips and open channels.
Pre galvanized steel pipes are widely used as Scaffolding pipe, Structure pipe, Fence/Door pipe, Furniture, Low Pressure fluid pipe for water oil or gas, Boiler pipe.
Zinc coating: 40~275 g/sq.m.
Ends type: plain ends (Square cut), bevel ends, thread ends, grooved
Packing: in bundles with steel strip, plastic end caps, woven packing for each bundle
BS1387 standard specification— For pre galvanized steel pipe
Type Thickness(mm) | Outer diameter(mm) | Weight(kg/m) Plain ends | |||||||||
Max | Min | ||||||||||
A | B | C | A | B | C | A | B | C | A | B | C |
2 | 2.6 | 3.2 | 21.4 | 21.7 | 21.7 | 21 | 21.1 | 21.1 | 0.947 | 1.21 | 1.44 |
2.3 | 2.6 | 3.2 | 26.9 | 27.2 | 27.2 | 26.4 | 26.6 | 26.6 | 1.38 | 1.56 | 1.87 |
2.6 | 3.2 | 4 | 33.8 | 34.2 | 34.2 | 33.2 | 33.4 | 33.4 | 1.98 | 2.41 | 2.94 |
2.6 | 3.2 | 4 | 42.5 | 42.9 | 42.9 | 41.9 | 42.1 | 42.1 | 2.54 | 3.1 | 3.8 |
2.9 | 3.2 | 4 | 48.4 | 48.8 | 48.8 | 47.8 | 48 | 48 | 3.23 | 3.57 | 4.38 |
2.9 | 3.6 | 4.5 | 60.2 | 60.8 | 60.8 | 59.6 | 59.8 | 59.8 | 4.08 | 5.03 | 6.19 |
3.2 | 3.6 | 4.5 | 76 | 76.6 | 76.6 | 75.2 | 75.4 | 75.4 | 5.71 | 6.43 | 7.93 |
3.2 | 4 | 5 | 88.7 | 89.5 | 89.5 | 87.9 | 88.1 | 88.1 | 6.72 | 8.37 | 10.3 |
3.6 | 4.5 | 5.4 | 113.9 | 114.9 | 114.9 | 113 | 113.3 | 113.3 | 9.75 | 12.1 | 14.5 |
— | 5 | 5.4 | — | 140.6 | 140.6 | — | 138.7 | 138.7 | — | 16.6 | 17.9 |
— | 5 | 5.4 | — | 166.1 | 166.1 | — | 164.1 | 164.1 | — | 19.7 | 21.3 |
Galvanized steel pipes can be made into a strong plumbing or tubing material — one that resists corrosion from exposure to water or the elements. It has been used used for water-supply pipes or as a strong tubing for outdoor applications.
Galvanized pipe has been coated with a layer of zinc. The zinc provides a barrier against corrosion so that the pipe may be exposed to the outdoor environmental elements. The protective barrier proves equally effective against damage from indoor humidity.
Related standard of galvanized steel pipe
ASTM A123/A123M, ASTM A53/A53M, ASTM A795/A795M, ASTM A865, BS1387……
ASTM A53: seamless and welded black and hot-dipped galvanized steel pipe
There are 3 types in ASTM A53 standard.
Type F—Furnace-butt-welded, continuous welded Grade A
Type E—Electric-resistance-welded, Grades A and B
Type S—Seamless, Grades A and B
| Composition, % | Type S(SMLS), Type E(ERW) | Type F(furnace-welded) | |
| Grade A | Grade B | Grade A | |
| C, max | 0.25 | 0.30 | 0.30 |
Mn, max | 0.95 | 1.20 | 1.20 |
| P, max | 0.05 | ||
| S, max | 0.045 | ||
| Cu, max(1) | 0.40 | ||
| Ni, max(1) | 0.40 | ||
| Cr, max(1) | 0.40 | ||
| Mo, max(1) | 0.15 | ||
| V, max(1) | 0.08 | ||
| Tensile strength, MPa, min | 330 | 415 | 330 |
| Yield strength, MPa, min | 205 | 240 | 205 |
(1) The total composition for these five elements shall not exceed 1.00 %.
Description of ASTM A53 galvanized steel tube
Galvanized steel tube ordered under the specification shall be coated with zinc inside and outside by the hot-dip process.
The weight of zinc coating: not less than 0.55kg/m2 on average
not less than 0.49kg/m2 for either of speciments
Process of hot galvanizing of ASTM A53 galvanized steel tube
black part inspection——bridging——degrease——rinsing——pickling——cleaning——plating assistant dipping——dry by hot air——HDG——cooling——passivation & rinsing——unloading——inspection and repair——packing
Zinc coating thickness grade of ASTM A53 galvanized steel tube
| coating grade | mils | oz/ft2 | μm | g/m2 |
| 35 | 1.4 | 0.8 | 35 | 245 |
| 45 | 1.8 | 1.0 | 45 | 320 |
| 50 | 2.0 | 1.2 | 50 | 355 |
| 55 | 2.2 | 1.3 | 55 | 390 |
| 60 | 2.4 | 1.4 | 60 | 425 |
| 65 | 2.6 | 1.5 | 65 | 460 |
| 75 | 3.0 | 1.7 | 75 | 530 |
| 80 | 3.1 | 1.9 | 80 | 565 |
| 85 | 3.3 | 2.0 | 85 | 600 |
| 100 | 3.9 | 2.3 | 100 | 705 |
Remark: The value in μm are based on the coating grade. The other values are based on conversions using the following formulas: mils=μmX0.03937; oz/ft2=μmX0.02316; g/m2=μmX7.067.
