Definition and core functions of spiral steel pipes for petrochemical transportation pipelines

Spiral steel pipes for petrochemical transportation pipelines are a type of welded steel pipe designed specifically for the petrochemical industry. They are made from strip steel coils and manufactured through spiral forming and double-sided submerged arc welding processes. They have high strength, corrosion resistance, high pressure resistance, and impact resistance, and are suitable for connecting long-distance transportation and storage facilities for crude oil, natural gas, and chemical media. Its core function is to ensure the safety, stability, and resistance to environmental erosion of petrochemical fluid transportation.

Technical characteristics and manufacturing processes

1. Material and structural design

Raw materials: Q235B, Q345B low-alloy steel or X70/X80 high-grade steel materials are used, and the strip steel is pre treated with leveling and edge cutting to ensure mechanical properties and processing accuracy.

Forming process: The strip steel is continuously formed by a spiral coiling machine, and the inner and outer double-sided submerged arc welding (automatic double wire welding) ensures the strength of the weld seam. The weld seam gap is strictly controlled within 1-3mm.

2. Anti corrosion and pressure resistance performance

Multi layer anti-corrosion technology: Targeting the corrosion characteristics of petrochemical media, 3PE (epoxy powder+adhesive+polyethylene) or hot-dip galvanizing process is used, with an acid and alkali corrosion resistance time of more than 30 years.

Pressure bearing capacity: The wall thickness range is 6-25mm, and the maximum pressure bearing capacity can reach 2.5MPa (such as DN1200 with a wall thickness of 12mm). The spiral weld disperses stress and increases the ability to resist geological disasters by 30%.

3. Performance advantages

High/Low Temperature Resistance: Suitable for temperatures ranging from -40 ℃ to 130 ℃, suitable for extreme environments such as oil fields and refineries.

Low flow resistance design: The inner wall is coated with epoxy resin or polyethylene coating to reduce medium flow resistance and lower transportation energy consumption.

Application scenarios and typical cases

Crude oil long-distance pipeline

Used for mainline transportation from oil fields to refineries, such as the Lianyungang oil pipeline which uses X70 steel grade spiral steel pipes, with a single pipe pressure of 2.0MPa, capable of transporting over 5 million tons of crude oil annually.

Chemical medium transportation

Acid and alkali resistant spiral steel pipes (such as 3PE anti-corrosion) are used for transporting corrosive fluids such as benzene and sulfides, and can withstand chemical environments with pH values ranging from 2 to 12.

Tank connection and port loading and unloading

The port oil loading and unloading pipeline adopts thick walled spiral steel pipes (wall thickness ≥ 15mm) to adapt to high-pressure pulse loads and mechanical impacts.

Typical case:

Zhongyuan Spiral Steel Pipe Petrochemical Project: X70 material spiral steel pipe is used for connecting storage tanks in a refinery, with a diameter of DN1400 and a wall thickness of 14mm. It has been running for 8 years without corrosion or leakage.

Quality Control and Industry Standards

Standard specifications

Material standards: comply with GB/T 9711 (Petroleum and Natural Gas Steel Pipe Standard) and SY/T 5037 (Spiral Welded Pipe Standard).

Anti corrosion standard: Implement SY/T 0413 (3PE anti-corrosion) or SY/T 0447 (epoxy coal tar anti-corrosion).