GOST 550-75 Alloy Seamless Steel Tubes For Oil transportation
GOST 550-75 Alloy Seamless Steel Tubes for Petroleum Processing and Petrochemical Service
Although this product is often marketed as “for oil transportation,” GOST 550-75 is technically a seamless steel tube specification for petroleum processing and petrochemical industry equipment and piping, rather than a long-distance transmission line pipe standard. Under GOST 550-75, tubes are supplied in Group A and Group B, with Group A covering fixed-length tubes and tighter dimensional requirements, while the standard itself was later superseded by GOST 550-2020 in current interstate standardization.
GOST 550-75 seamless tubes are intended for refinery and petrochemical duty where buyers care about elevated-temperature strength, controlled chemistry, dimensional reliability, hydrostatic integrity, and traceable heat-treatment condition. The standard covers both carbon and alloy grades, including Cr-Mo and Cr-W-V heat-resistant steels used in demanding process piping and equipment circuits.
Specifications
| Item | Specification |
|---|---|
| Material | Carbon steel and alloy steel; alloy grades commonly include 12МХ, 12Х8, 1Х2М1, 15Х5М, 15Х5ВФ |
| Standard | GOST 550-75 |
| Steel grade examples | 20, 12МХ, 12Х8, 1Х2М1, 15Х5ВФ |
| Outside diameter | 19–219 mm |
| Wall thickness | 1.5–25.0 mm |
| Length | Group A fixed lengths according to Table 1, typically 4.0–12.2 m; custom 1–12 m is feasible by agreement |
| Tolerance range | Group A: cold/warm tubes of steels 10 and 20 to GOST 9567; OD up to 30 mm: ±0.2 mm, above 30 mm: ±0.3 mm; hot-finished OD: +0.5% / -1.25%; cold/warm WT: ±8%; hot-finished WT ≤15 mm: ±12.5%, WT >15 mm: ±10% |
| Straightness | Group A local bow not over 1.5 mm per 1 m; total bow not over 8 mm |
| Length tolerance | +10 mm for tubes up to 6 m; +15 mm for tubes over 6 m or OD above 152 mm |
| Surface condition | Free from folds, cracks, laps, shelling and hairlines; local dressing permitted within minimum wall tolerance |
| Heat treatment | Tubes are supplied in heat-treated condition; hot-finished tubes of steels 10, 20 and 10Г2 may be supplied from rolling heat |
| Testing | Hydraulic test to GOST 3845, pressure up to 30 MPa, holding time not less than 10 s; NDT may be agreed as an alternative to hydrotest |
Main Features
- Refinery-grade alloy seamless construction: no weld seam, reducing the weld-zone risk in elevated-temperature hydrocarbon service. GOST 550-75 specifically targets refinery and petrochemical equipment and piping.
- Controlled size envelope: OD 19–219 mm and WT 1.5–25.0 mm, suitable for small and medium process lines, heater circuits, and plant equipment connections.
- Tight Group A dimensional control: cold/warm tubes of steels 10 and 20 can be supplied at ±0.2 mm OD up to 30 mm and ±0.3 mm above 30 mm, with ±8% wall tolerance for cold/warm tubes.
- Straightness control for fabrication: ≤1.5 mm/m local curvature and ≤8 mm total curvature for Group A supports easier fit-up during spool fabrication.
- Mandatory heat-treated delivery condition: the standard requires heat-treated supply, with only limited exceptions for hot-finished 10, 20, and 10Г2 from rolling heat.
- Pressure integrity verification: hydraulic testing is required up to 30 MPa, with a minimum 10-second hold, and NDT can be specified as an equivalent integrity route.
- Process-grade Cr-Mo and Cr-W-V options: grades such as 12МХ, 1Х2М1, 15Х5М, and 15Х5ВФ support higher-temperature refinery service than plain carbon grades.
Our Advantages
1. “Can you actually hold refinery-critical dimensions, or only nominal mill tolerances?”
A professional buyer usually checks OD, wall, straightness, and fixed-length tolerances before approving a refinery tube source. GOST 550-75 already defines measurable controls for Group A, including ±0.2 / ±0.3 mm OD, ±8% wall tolerance for cold/warm tubes, ≤1.5 mm/m straightness, and +10 / +15 mm length tolerance. This means supply can be aligned to fabrication-shop expectations rather than vague “commercial tolerance” language.
2. “How do I reduce the risk of tube rejection after arrival at site?”
Experienced buyers focus on surface quality, hydrotest/NDT, and batch traceability. GOST 550-75 requires tubes to be free of folds, cracks, laps and similar defects, mandates hydraulic testing, and defines lot acceptance rules by size, heat-treatment regime, and in several alloy grades even by heat. That structure materially improves inspection traceability during incoming QA.
3. “Is the offered grade really suitable for elevated-temperature refinery duty?”
This is the core technical question. GOST 550-75 includes not only carbon steels but also Cr-Mo and Cr-W-V heat-resistant grades such as 12МХ, 1Х2М1, 15Х5М, and 15Х5ВФ, and it sets minimum tensile, yield, elongation, impact, and hardness values by grade and supply condition. In practice, that allows the buyer to specify a grade around service temperature and process severity instead of buying a generic seamless tube and hoping it performs.
Execution Standards
| System | Brief reference |
|---|---|
| GOST | GOST 550-75 for seamless tubes for petroleum processing and petrochemical industry; current successor is GOST 550-2020 |
| ASTM | Closest elevated-temperature alloy reference: ASTM A335/A335M for seamless ferritic alloy-steel pipe for high-temperature service |
| EN | Closest pressure-tube reference: EN 10216-2 for seamless non-alloy and alloy steel tubes with specified elevated-temperature properties |
| JIS | Closest alloy high-temperature pipe reference: JIS G 3458 for alloy steel pipes |
| GB | Closest Chinese petrochemical reference: GB/T 9948-2025 for seamless steel tubes and pipes for petrochemical and chemical facilities |
Application Field
Specific application: seamless alloy tube for crude distillation unit heater outlet piping spools in refinery service, where elevated temperature, pressure tightness, and stable dimensional control are more important than generic fluid-transport pipe pricing. This application fits the refinery and petrochemical process scope of GOST 550-75 much better than cross-country pipeline service.
Chemical Composition
| Grade | Standard source | C | Si | Mn | Cr | Mo | W | V | Ni | P | S |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 20 | GOST 1050 | 0.17–0.24 | 0.17–0.37 | 0.35–0.65 | ≤0.25 | — | — | — | ≤0.30 | ≤0.035 | ≤0.040 |
| 12МХ | GOST 20072 | 0.09–0.16 | 0.17–0.37 | 0.40–0.70 | 0.40–0.70 | 0.40–0.60 | — | — | ≤0.30 | ≤0.030 | ≤0.025 |
| 12Х8 | GOST 550-75 / GOST 20072 family | ≤0.12 | 0.17–0.37 | 0.30–0.60 | 7.5–9.0 | — | — | — | ≤0.40 | ≤0.035 | ≤0.030 |
| 1Х2М1 | GOST 550-75 | 0.08–0.13 | 0.17–0.37 | 0.30–0.60 | 2.0–2.5 | 0.9–1.1 | — | — | ≤0.50 | ≤0.035 | ≤0.035 |
| 15Х5ВФ | GOST 20072 | ≤0.15 | 0.30–0.60 | ≤0.50 | 4.5–6.0 | — | 0.4–0.7 | 0.4–0.6 | ≤0.60 | ≤0.030 | ≤0.025 |
Mechanical Properties
| Grade | Supply condition in GOST 550-75 | Tensile strength, MPa | Yield strength, MPa | Elongation, % | Reduction of area, % | Impact toughness KCU, J/cm² | Hardness, HB max |
|---|---|---|---|---|---|---|---|
| 20 | Hot-finished | ≥431 | ≥255 | ≥22 | ≥50 | ≥78 | ≤156 |
| 12МХ | Hot-finished | ≥412 | ≥245 | ≥21 | ≥45 | ≥69 | ≤156 |
| 12Х8 | Cold- or warm-deformed | ≥392 | ≥216 | ≥22 | — | — | ≤170 |
| 1Х2М1 | Hot-finished | ≥441 | ≥265 | ≥20 | ≥45 | ≥98 | ≤227 |
| 15Х5ВФ | Hot-finished | ≥392 | ≥216 | ≥22 | ≥50 | ≥118 | ≤170 |
Q: Are you trading company or manufacturer ?
A: manufacturer,also can do trading.
Q: How long is your delivery time?
A: Generally speaking,it is 10-15 days if the goods are in stock,or it is 30-40 days if the goods are not in stock, it is according to quantity.
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A: Yes, we could offer the sample for free charge but need pay the cost of freight.
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A: Payment<=2000USD, 100% in advance. Payment>=2000USD, 30% T/T in advance ,balance before shippment.
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