1) Why does planning for any type of pipeline project often begin years in advance of actual construction?

Pipeline planning is a complex process. It takes two or more years. A planning procedure includes marketing, pipeline designing, specifications preparing, route selection, environmental assessment, public discussion, land acquisition and permits obtaining.

2) What steps does the planning for a pipeline project include?

см. 1)

3) What are the main phases of pipeline construction?

Pipeline Construction is usually divided into three phases: pre-construction подготовительные строительные работы, construction and post-construction послепусковое обслуживание stage.

4) What pre-construction activities do you know?

I can name such pre-construction operations as

- Surveying and staking (геодезическая подготовка и разметка трассы)

- Preparing the right-of-way

- Trenching

- Pipe stringing the (трубоукладка)

5) What is the purpose of surveying and staking?

Pipeline surveying optimizes the pipeline route. It determines the construction workscope, machinery and corrosion protection needed and so on.

Staking marks the pipeline route. It is performed in accordance with engineering drawings.

6) What activities does the construction of a pipeline include?

These activities include

Pipe bending (гибка) necessary to follow the terrain contour

Special machines bend the pipe without destroying its cross section.

- Pipe joining by automated or manual arc welding. Welding is performed in several passes. Weld integrity is tested by X-ray or ultrasonic methods.

- Inside and outside

- Pipe coating which protects pipes against corrosion. Pipes are coated before construction. Welded joints are coated at the site.

- Pipe positioning, that is lowering the pipeline into the trench using sideboom bulldozers (трубоукладчик).

- Installing valves and fittings (монтаж арматуры) which takes place after the pipeline is in the trench.

- Backfilling the trench (обратная засыпка траншей) The pipeline is backfilled carefully not to damage pipe coating.

7) What should be done after backfilling the trench?

The post-construction activities include pressure testing and final cleanup.

- Pressure testing (опрессовка) controls pipeline integrity. It lasts for eight hours.

- Final cleanup (окончательное восстановление) is the right-of-way recovery. It includes top soil replacement and reseeding. Erosion control barriers are also constructed. If the pipeline passes through farmland, the right-of-way is seeded with crops (зерновые).

Text 2 Pipe Welding

The pipeline is placed above or along the trench. Welding is done with manual and automatic equipment. Welding machines are carried by trucks or pickups.

Pipeline joints are made by several welders: one welder makes the first pass and others make following passes. The number of passes depends on the wall thickness and characteristics. This number is mentioned in the construction plan. The first pass is critical for weld quality and should be carefully controlled.

To provide weld uniformity pipe ends are aligned. Line-up clamps (центровочный зажим) are used for this purpose.

Welding Processes Pipelines are welded by electric arc method, with filler metal and without pressure.

The types of welding include:

• Shielded metal arc welding. The method uses electric arc which melts a consumable electrode.

• Submerged arc welding. This method also uses electric arc and a consumable electrode. Besides, silicate flux (флюс) covers the weld. The arc melts this flux into liquid slag (шлак) that protects the weld against oxidation.

• Gas-metal arc welding. This process uses electric arc covered with inert gas - argon or helium and a consumable electrode.

• Gas-tungsten arc welding. This process also requires inert gas shield and tungsten non-consumable electrode.

• Electron beam welding is used for offshore pipelines.

Notes:

Submerged arc welding - дуговая сварка под флюсом

Gas-metal arc welding - дуговая сварка плавящимся электродом

Gas-tungsten arc welding - дуговая сварка вольфрамовым электродом в защитном газе

Electron beam welding - электроннолучевая сварка