DN 15–100 · black and galvanized · GOST 3262
Water and gas pipe
Water and gas pipe to GOST 3262 for water, gas and heating. Nominal bore 15–100, light, standard, heavy
St3sp · Q235B · DN 15–100 · Ø57–219 · zinc 60–80 µm · GOST 3262 · GOST 10704
Galvanized pipe
Welded and water-gas pipe with hot-dip galvanizing. Water supply, external networks, unpainted structures
GOST 3262-75GOST 10704-91GOST 10705-80GOST 9.307-89GB/T 3091-2015ASTM A53/A53MEN 10255EN 10240St2spSt3spQ195Q235BA53 Gr.B
Parameters
| Parameters | |
|---|---|
| Nominal bore, water and gas pipe | DN 15–100 per GOST 3262 |
| Outside diameter, welded pipe | 57–219 mm per GOST 10704 |
| Wall thickness | 2.5–6 mm |
| Length | random length 6–12 m; fixed length to specification |
| Steel grade | St2sp, St3sp; Q195, Q235B per GB |
| Coating | hot-dip galvanizing, 60–80 µm coating to specification; at least 30 µm per GOST 3262 |
| Ends | plain ends; threaded to specification |
Sizes and weight
| Size, mm | Weight, kg/m | Metres per tonne |
|---|---|---|
| 21.3×2.8 | 1.28 | 782.8 |
| 26.8×2.8 | 1.66 | 603.4 |
| 33.5×3.2 | 2.39 | 418.2 |
| 42.3×3.2 | 3.09 | 324.1 |
| 48×3.5 | 3.84 | 260.3 |
| 60×3.5 | 4.88 | 205.1 |
| 76×3.5 | 6.26 | 159.8 |
| 89×3.5 | 7.38 | 135.5 |
| 108×4 | 10.3 | 97.5 |
| 159×4.5 | 17.1 | 58.3 |
| 219×6 | 31.5 | 31.7 |
Theoretical weight at steel density 7.85 g/cm³. Actual batch weight is by scale and mill certificate.
Description
Galvanized pipe is black welded pipe that, after welding and cutting, has been hot-dip galvanized: the pipe is pickled, fluxed and immersed in molten zinc, and the layer forms both outside and inside. Small diameters go to GOST 3262-75 as galvanized water and gas pipe, medium diameters to the GOST 10704-91 size range with coating to GOST 9.307-89. At mills in China galvanized pipe is produced to GB/T 3091-2015, for export to ASTM A53/A53M in the hot-dipped galvanized version and EN 10255 with coating to EN 10240. Zinc protects the steel electrochemically: at a scratch down to the metal the coating corrodes, not the pipe, until the layer is used up.
The base steel grade is St2sp, St3sp or Q235B, as for black welded pipe; the difference is the coating. GOST 3262 requires a zinc layer of at least 30 µm; hot-dip galvanizing to GOST 9.307 gives a layer that depends on wall thickness and immersion time, and in the specification the bureau fixes a layer thickness of 60–80 µm as the agreed value, which the mill confirms by measurement. The weight of galvanized pipe exceeds the calculated weight of black pipe by the weight of zinc: under GOST 3262 it is taken as 3 % higher. Electro-galvanized pipe is a different product with a thin layer and is not taken for external networks; in the specification the galvanizing method is written in words: "hot-dip galvanizing".
During inspection at the mill, the zinc layer on galvanized pipe is measured with a magnetic thickness gauge at several points along the length and circumference of the sampled pipes; the coating is examined for bare areas, runs, white rust and zinc drops inside the pipe, and the cleanliness of the thread on threaded ends is checked. Outside diameter and wall thickness are measured with a micrometer and callipers at the pipe ends. The heat number in the marking is matched against the mill test certificate (MTC), which states grade, size, hydrostatic test and zinc layer thickness. The bundle tag and strapping are checked. Rejects recorded in the report are replaced; the replacement is supplied by the manufacturing mill under its contract with the bureau.
Applications
- external and internal water supply
- heating and hot water systems
- irrigation networks and water lines at agricultural enterprises
- unpainted outdoor fencing and structures
- lighting poles, road sign posts
- greenhouse and canopy frames
Packing and shipment
Bundles strapped with steel band over spacers so as not to damage the coating; threaded ends with protective caps; the bundle carries a mill tag with size, zinc thickness and heat number.
Grade equivalents
| GOST | GB (China) | ASTM | EN | Note |
|---|---|---|---|---|
| Steel 20 | 20# | A106 Gr.B | P235GH | Seamless pipes. Nearest equivalents by composition and strength; test requirements differ between the standards |
| Steel 45 | 45# | 1045 (A519) | C45 | Seamless pipes for machining, nearest equivalents. A519 is a standard for mechanical tubing; C45 under EN 10083 is a steel grade, tubes in it are made to EN 10297-1 |
| 09G2S | Q355B | A572 Gr.50 | S355J2H | Low-alloy steel, nearest equivalents. Before GB/T 1591-2018 the grade was designated Q345B; A572 is a standard for rolled products, not for pipe; S355J2H is a hollow section grade under EN 10219 |
| St3sp | Q235B | A53 Gr.B | P235TR1 | Welded pipes. A53 Gr.B is the nearest equivalent: its tensile strength is higher than that of Q235B |
| St3sp | Q235B | A500 Gr.B | S235JRH | Hollow sections. A500 specifies a higher yield strength than Q235B; structural design uses the standard stated in the specification |
| St2sp, St3sp | Q195, Q235 | A53 Gr.A | S195T | Water and gas pipes. GOST 3262 does not specify mechanical properties, so the grade comparison is nominal |
| K42 (GOST 20295) | L245 (GB/T 9711) | API 5L Gr.B | L245NB | Spiral-welded pipes. A strength class by tensile strength, not a steel grade |
| 08Kh18N10 | 06Cr19Ni10 | TP304 | 1.4301 | Stainless pipes. Austenitic 18-10 steel; 03Kh17N14M3 corresponds to TP316L and 1.4404 |
Equivalents are the closest match, not identical: chemistry and tolerances differ between standards. The exact grade and standard are written into the contract.
Related items
St3sp · Q235B · Ø57–530 · GOST 10704
Longitudinally welded pipe
Round pipe from strip with a high-frequency weld. Structures, fencing, low-pressure water and gas
St3sp · 09G2S · 15×15–300×300 · GOST 8639 · GOST 30245
Square hollow section
Closed square section for frames, trusses and fencing. Wall 1–12 mm, St3sp, 09G2S, Q235B, Q355B
Buyer questions
How to read a mill test certificate for pipe
The certificate (MTC) states the standard, steel grade, size, heat number, chemical composition by element, mechanical properties of the test specimens (yield strength, tensile strength, elongation), the hydrostatic test result and, for welded pipe, the result of non-destructive testing of the weld. The heat number in the certificate is matched against the marking on the pipe and the bundle tag: this is the only link between the document and the metal. The bureau checks this match at the mill before shipment and attaches the certificate to the inspection report.
How a seamless pipe differs from a welded one and when each is needed
A seamless pipe is rolled from a solid billet, it has no weld, and it goes where there is pressure, temperature or alternating load: boiler plants, steam, hydraulics, machine parts. A welded pipe is formed from strip and welded by high-frequency current; at the same size it is simpler to produce, and the weld passes a hydrostatic test and non-destructive testing. For structures, fencing, water lines and low-pressure gas lines a welded pipe does the job. The choice is fixed in the specification by the project, not by price.
How the tonnage of a pipe batch is calculated
The theoretical weight per metre of round pipe is calculated as 0.02466 · (D − t) · t, where D is the outside diameter and t the wall thickness in millimetres, steel density 7.85 g/cm³. For a hollow section: 0.0157 · t · (a + b − 2.86 · t). The actual weight is determined by weighing at the mill and is stated in the packing list. Whether settlement is by theoretical or actual weight is fixed in the specification before the order is placed: on thin walls the difference between them is noticeable.
What is checked during batch inspection of pipes at the mill
Outside diameter and wall thickness with a micrometer and callipers at both ends of the sampled pipes, ovality, wall-thickness variation, straightness, condition of the ends and bevel, the weld of welded pipe from outside and, where accessible, from inside, marking on every pipe, the bundle tag and matching of the heat number against the mill test certificate. The results are entered in a report with photo documentation. Rejects recorded in the report are replaced; the replacement is supplied by the manufacturing mill under its contract with the bureau.
What quantity can be ordered
The batch is sized to your quantity — send a specification with sizes, grades, acceptance standard and lengths. The manufacturing mill confirms the batch for a specific size range; the bureau agrees the inspection and acceptance procedure in the contract. Several sizes in one batch are sourced from one mill or from several if their size ranges differ.
Price request
Send your specification and we will quote your batch
Steel pricing depends on grade, size, tonnage and delivery terms on the day of contract. A number on the page would be wrong by the time you read it.
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