The most common method of laying oil pipelines

The laying of oil and gas pipelines is usually carried out by overhead, pipe trenches, and buried directly. According to the different laying methods, the insulation and outer protective layer materials used are also different.

1 . Directly laid

When the temperature is less than 100 °C, after the derusting of the steel pipe, apply anti-corrosion paint to the pipeline.

Insulation materials are mostly made of rigid polyurethane foam. The thickness of the insulation layer is generally 30 to 40mm , and a high-density polyethylene jacket is used for the protection layer.

When the temperature is greater than 100 °C, usually a layer of silicon ( such as microporous calcium silicate ) is placed between the steel pipe and the polyurethane foam , but this is only applicable to short distances and internal pipelines in the station.

2 . Pipe laying

It is widely used in stations or across pipe sections.

After the steel pipe is rusted, it is painted with rust-proof paint. Insulation materials often use cement perlite, microporous calcium silicate, compound aluminum silicate and rock wool or slag wool products. After the banding is fixed, an outer protective layer is added. The outer protective layer often uses asphalt felt glass cloth, asphalt glass cloth or epoxy coal pitch glass cloth structure.

3 . Overhead laying

Overhead paving is only applicable to station pipelines.

After the steel pipe is rusted and painted with rust-proof paint, heat-insulating materials are often made of rock wool products with relatively low density, slag wool products, composite silicate materials and products. The external protection uses galvanized iron sheet and aluminum alloy plate. In recent years, aluminum foil glass fiber reinforced plastic has also been widely used.

When transporting high-viscosity media ( crude oil, heavy oil ) , according to process requirements, thermal insulation and heat tracing structures are used, that is, steam or hot water heating pipes are arranged between the thermal insulation layer and the steel pipe, or the electric heating zone is used.

The requirements for insulation materials are as follows:

1 heat transfer coefficient is not greater than 0 . 12W / (m · K) ;

2 The density is less than 400 kg / m3 ;

3 hardness polyurethane foam compression strength should not be less than 0 . 29 MPa ;

4 The performance is stable under the use of temperature, the allowable use temperature of the insulation material products should be higher than the medium temperature;

5 flame retardant or non-combustible, small moisture content, low water absorption, no corrosion effect on gold shavings;

6 In the same temperature range, the thermal insulation materials used should have low thermal conductivity, low density, low manufacturing cost, local materials, and easy processing, and should be comprehensively compared and reasonably selected.

7 high-temperature medium pipe, can choose composite materials. Microporous calcium silicate and other composite structures are added between the anticorrosive steel pipe and the polyurethane foam.

This article was edited by China Rescue Equipment Network.