Welding at the pipeline construction.

Welding is one of the most important phase in the pipeline construction process. The welding work quality determines the quality of pipeline performance, its ability to withstand temperature fluctuations and aggressive substances, remain longevity.

Welding work on gas and oil pipelines is very demanding and labour-intensive. In the implemented projects portfolio of BELTRUBOPROVODSTROY JSC there are projects for construction of a linear pipeline with the length of more than 100 kilometres, in conditions of hot climate and even in the Far North. Under such conditions it is very difficult to establish an efficient welding process, but thanks to our experienced specialists, the welding and installation work on our projects is always of high quality and reliability.

Welding methods at the pipeline construction.

The most efficient method used in long distance pipeline construction is arc welding. Automatic and semi-automatic submerged arc welding is used in 80% of welded joints on main pipelines. It is effective in welding steel pipes with diameters from 500 to 1420 mm.

Only for difficult and inaccessible joints can manual arc welding be used. Manual welding is not common technology used at BELTRUBOPROVOSDTROI facilities.

In some cases, in the construction of main pipelines, mechanised welding may be used, i.e. welding with flux-cored wire (for example, in our projects we often use Innershield). Using cored wire, an even welding seam geometry in different spatial orientations can be achieved. In addition its simple use and speed of execution, flux cored technology allows welding costs to be optimised during construction work.

The flux-cored wire welding process considerably increases welding efficiency, due to its high welding speed of 30-60 cm per minute, compared to an average arc welding speed of 10-20 cm per minute.

Welding phases.

Not depending on the type of welding process selected, there are three key steps in the welding process during pipeline construction:

• Preparatory. The stage concerns both preparation of a welder who will perform welding work (overalls, working safety) and preparation of the joint (straightening and facing the pipe end using various mechanical, hydraulic, pneumatic equipment, beveling of the pipe end for quality penetration and weld geometry formation, cleaning of the working area of the pipe from rust, paint and dirt – the cleaning method is selected on the basis of the type of dirt: special degreasing compositions, steel sheet, de-greasing compositions, etc.).
• The welding process itself. Method of working with an electrode and a tube depends on different factors – location of elements in space, basic material, qualification of a worker.
• Checking the quality and integrity of the welded joint. After the weld is completed, the slag formed must be levelled and then the quality of the resulting joint must be checked.

*the photos are for illustrative purposes only