GOST 8732-78 Seamless Hot Worked Carbon Steel Pipes With Epoxy Coating For Oil And Gas

Material Overview

These pipes are seamless hot-worked (hot-finished) carbon steel pipes manufactured in accordance with GOST 8732-78, which specifies the dimensional range for general-purpose hot-deformed seamless steel tubes.

The base steel is typically non-alloy carbon steel such as grade 20 to GOST 1050, widely used for pressure and fluid service.

After hot manufacturing and heat treatment as per the relevant steel standard (e.g. GOST 1050 / GOST 8731), the pipes receive an external and/or internal epoxy (usually fusion-bonded epoxy, FBE) coating. This coating provides high-level corrosion protection for buried and subsea oil and gas pipelines, extending service life and reducing maintenance.

Specifications

1. Manufacturing and sizes (GOST 8732-78)

• Process: Seamless hot-worked (hot-rolled or hot-expanded)

• Outside diameter (typical standard range): 25–820 mm

• Practical industrial range supplied by many mills: approx. 32–426 mm OD

• Wall thickness: 2.5–75 mm

• Length:

  • Random (unmeasured) length: 4.0–12.5 m

  • Fixed (measured) or multiple lengths available within this range

• End finish: Plain end (PE) as standard; bevelled ends (BE) for welding on request

2. Epoxy / FBE coating

• Coating type:

  • External: Single- or dual-layer fusion bonded epoxy (FBE) or equivalent thermosetting epoxy system

  • Internal (optional): Epoxy flow-coat or FBE lining for reduced friction and additional corrosion protection

• Typical external coating thickness: 350–450 μm (single-layer FBE), with options up to ~750 μm for heavy-duty systems

• Typical internal lining thickness: commonly 200–500 μm depending on project specification

• Service temperature envelope (standard FBE):

  • Conventional range: approx. –30 °C to +80 °C

  • Special high-temperature FBE options: up to ~100–110 °C when specified and qualified

• Coating inspection:

  • Holiday detection (high-voltage spark testing) per NACE SP0490 / ASTM G62 or equivalent

  • Adhesion, impact, bend, and cathodic disbondment tests as per CSA Z245.20 / ISO 21809-2 or project specification

3. Delivery condition

• Pipe: Hot-finished, normalized or normalized-and-tempered depending on steel grade standard

• Coating: Fully cured, inspected, and visually free from pinholes, runs, blisters, and unbonded areas

• Ends: Plastic caps and suitable handling to avoid coating damage

Main Features

1. High integrity under pressure

   • Seamless hot-worked construction eliminates weld seams, giving uniform strength for high internal pressure and dynamic loads in oil and gas transmission systems.

2. Excellent corrosion protection with epoxy coating

   • FBE/epoxy forms a dense, strongly adhered barrier against soil moisture, chlorides, CO₂, and many chemicals, significantly slowing external and internal corrosion in pipelines.

3. Optimized for buried and subsea oil and gas pipelines

   • Designed to work with cathodic protection systems; FBE’s good adhesion and low cathodic disbondment reduce CP current demand and operating cost.

4. Stable performance over a wide temperature range

   • Base carbon steels such as GOST 20, ASTM A106 Grade B or API 5L Grade B offer reliable strength at typical oil and gas pipeline temperatures, while FBE maintains integrity from sub-zero conditions up to ~80 °C or higher with specialized systems.

5. Good weldability and field constructability

   • Low-carbon non-alloy steels ensure good weldability; compatible FBE and field joint coating systems (FBE, ARO, 3LPE/3LPP sleeves, viscoelastic tapes) support reliable joint protection.

6. Wide availability and cross-standard equivalence

   • Mechanical properties and chemistry align closely with common international pipe grades such as ASTM A106 Grade B, API 5L Grade B, EN 10216-1 P235TR1 and JIS G3454 STPG370, simplifying multi-standard projects.

Our Advantages

Below are typical concerns from oil & gas pipeline buyers, and how our GOST 8732-78 epoxy-coated seamless pipes address them.

1. “Will the epoxy coating really last in harsh oil and gas service?”

• We use high-performance FBE systems qualified against internationally recognized standards such as CSA Z245.20 and ISO 21809-2 for buried and submerged pipelines.

• Coating thickness is tightly controlled (typically 350–450 μm, with heavy-duty options up to ~750 μm) and monitored via continuous DFT (dry film thickness) checks.

• Every coated pipe undergoes visual inspection plus holiday detection using methods aligned with NACE SP0490 and ASTM G62 to find pinholes and thin spots before shipment.

2. “What about temperature limits and coating performance?”

• Standard FBE formulations are selected for a typical continuous service range of about –30 °C to +80 °C, which covers the majority of onshore transmission and gathering lines.

• For hotter applications, we offer high-glass-transition-temperature FBE options rated up to ~100–110 °C continuous service, based on manufacturer qualifications and long-term test data.

• Selection is made jointly with the client based on design temperature, soil conditions, and CP design, ensuring coating performance throughout the pipeline’s service life.

3. “Is the coating compatible with field joint coatings and rehab systems?”

• Our standard external coating is single- or dual-layer FBE, widely used and compatible with FBE-based field joint coatings, heat-shrink sleeves, and viscoelastic wraps designed for FBE/3LPE/3LPP systems.

• We can provide recommended field joint systems and application procedures that match the mainline coating specification and relevant ISO 21809 and company standards.

4. “How do these GOST pipes fit into our multi-standard project (API, ASTM, EN, JIS, GB)?”

• Base steel grades used with GOST 8732-78 (such as steel 20 to GOST 1050) are closely equivalent in chemical composition and mechanical properties to GB 20, EN 10216-1 P235TR1, and JIS G3454 STPG370.

• Our production and testing practice ensure that pipes can be cross-referenced to API 5L Grade B / ISO 3183 L245 and ASTM A106 Grade B where project specifications allow, simplifying design calculations and material approval.

5. “Can you provide full traceability and quality control?”

• Each pipe can be supplied with mill test certificates including heat analysis, mechanical test results and compliance with GOST 8731 / GOST 1050 and the selected international reference standards.

• Coating quality records (DFT logs, holiday test records, adhesion tests, curing temperature charts) are provided as part of the data book, supporting audits and asset integrity systems.

Chemical Composition 

Mechanical Properties 

Applicable Standards

GOST / Russian system

• GOST 8732-78 – Seamless hot-worked steel pipes – Range of sizes (defines OD, wall thickness, length).

• GOST 8731-74 – Seamless hot-deformed steel pipes – Technical requirements (manufacturing, testing).

• GOST 1050 – Carbon structural steels (e.g. steel 20).

ASTM / ASME

• ASTM A106 / ASME SA106 – Seamless carbon steel pipe for high-temperature service (Grade B commonly used as equivalent).

• ASTM A53 – General-purpose carbon steel pipe (often used for comparison).

• ASTM G62 – Holiday detection in pipeline coatings (coating QC).

API / ISO

• API 5L / ISO 3183 – Line pipe for oil and gas transportation (Grade B / L245 as key reference).

• ISO 21809-2 – External FBE coatings for buried/submerged pipelines in petroleum and natural gas industries.

EN (Europe)

• EN 10216-1 – Seamless steel tubes for pressure purposes – Non-alloy steel tubes with specified room temperature properties (P235TR1).

JIS (Japan)

• JIS G3454 – Carbon steel pipes for pressure service (STPG370 as equivalent grade).

GB (China)

• GB/T 8163 – Seamless steel pipes for liquid service (commonly using grade 20).

Coating-specific standards & guidelines

• DIN 30671 / DIN 30670 – Thermosetting and 3-layer polyolefin external coatings for buried and underwater steel pipes.

• CSA Z245.20 – Plant-applied external FBE coatings.

• NACE SP0490 – Holiday detection of FBE external pipeline coatings.

Application Fields

1. General application areas

Epoxy-coated GOST 8732-78 seamless carbon steel pipes are widely used in:

• Crude oil and refined product transmission pipelines

• Natural gas and gas-condensate pipelines

• Gathering systems and flowlines in upstream production

• Water injection and produced-water disposal lines

• Firewater, cooling water and industrial water lines

• Buried and subsea pipelines in corrosive soils or seawater environments

2. Typical uses within the oil and gas sector

1. Transmission pipelines (onshore and offshore)

   • Long-distance trunk lines carrying crude oil, natural gas or refined products.

   • External FBE coating provides primary corrosion barrier, working in conjunction with cathodic protection systems.

2. Gathering and flowlines in upstream production

   • Shorter pipelines from wellheads to manifolds and central processing facilities.

   • Epoxy-coated seamless pipes are preferred where internal CO₂ / H₂S levels and water cut require robust corrosion control, especially when combined with inhibitors or internal epoxy lining.

3. Water injection and disposal pipelines

   • High-pressure lines carrying injection water or treated produced water back into reservoirs or disposal wells.

   • External FBE reduces external corrosion risk; internal epoxy (if specified) helps mitigate internal pitting from oxygen and residual chemicals.

4. Station piping (pump stations, compressor stations, metering stations)

   • Aboveground and buried piping in compressor and pumping stations, manifolds, metering skids and pigging facilities.

   • Epoxy coating offers impact resistance and UV tolerance (when overcoated as required), easing maintenance in exposed installations.

5. Subsea tie-backs and risers (where design allows carbon steel)

   • Used for certain subsea spools, tie-in spools and short risers in combination with suitable cathodic protection, provided operating conditions and fatigue design are satisfied.

6. Cross-country water and utility pipelines in oil & gas complexes

   • Firewater, cooling water, and plant utility piping where hydrocarbon service is not involved but long-term corrosion protection is still critical.

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.

Q: Do you provide samples? is it free or extra ?

A: Yes, we could offer the sample for free charge but need pay the cost of freight.

Q: What is your terms of payment ?

A: Payment<=2000USD, 100% in advance. Payment>=2000USD, 30% T/T in advance ,balance before shippment.

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