During the laying of highways in flooded and wetlands, pipeline ballasting is often used. For this purpose, several methods can be used. Each of them has certain characteristics, so you should familiarize yourself with the features of the application before starting work.
Tasks
Installation of the main pipeline in wetlands and flooded areas requires compliance with certain conditions. This is explained by the fact that the constant impact of waves leads to some displacement of the pipes. Moreover, in some cases, the flow can cause significant damage to the pipe. Thus, when analyzing the causes of failure of gravity lines, the experts came to the conclusion that most accidents were caused by the loss of stability of pipes.
It is possible to eliminate this problem by ballasting pipelines. During these works, the main pipeline is fixed and weighted with special devices. As a result, the pipe is given negative buoyancy.
Methods of ballasting pipelines
There are 3 methods of ballasting, each with its own means of solving the problem and different installation methods.
In order to give pipes negative buoyancy, products are used that are able to increase the weight of the pipeline due to their own. This category includes:
- framed and frameless soil-filled devices;
- weights saddle, ring, female.
For increased protection against mechanical damage and corrosion, a continuous concrete coating can be used.
Another possible option for ballasting the pipeline is the use of anchor devices. Of the features of the action is that the increase in the stability of the pipeline occurs due to the strength properties of the soil.
Types of weights
In the list of products that can give the pipeline negative buoyancy, several products should be noted:
- UBO. This abbreviation stands for a female concrete weight. Such a product is 2 blocks of reinforced concrete, which are fastened together with power belts. Most often, such products are used when laying oil and gas pipelines in difficult climatic conditions. UBO can be mounted one by one at an equidistant distance or grouped into several pieces.
- UBOM. This version of the weighting agents is a variation of the previous version, but differs in modification (this is indicated by the letter “m”). The design in this case is equippedgrooves and a metal rod with which this device is attached to the pipe. UBOM should be used when installing a closed circuit or when mass securing a load.
- 1UBKm. This weighting agent has a wedge-shaped structure. The design is presented in the form of two cylindrical surfaces that intersect with each other. The radius of the structure slightly exceeds the diameter of the main pipe. This method of ballasting the pipeline takes place in permafrost, wetlands and floodplains.
- UKT. These weighting agents are presented in the form of two half rings. They wrap around the pipe and are connected with nuts and studs.
- UBP. Belt concrete weighting agent is two blocks interconnected by a power belt.
Concrete pavement
This option is a concrete monolithic coating of the pipe throughout its entire length. This layer is applied by shotcrete. With its help, it is possible to both give negative buoyancy to the pipes and protect them from the effects of water.
To increase the bulk density, an aggregate in the form of barium sulfate is added to the concrete. To achieve high strength indicators, the coating is applied in the factory. On site during installation, only pipe joints are covered.
When choosing this method of weighting, you should pay attention to the type of material used.
Anchor devices
Another way to ballast subsea pipelines is to use different anchor devices. Their installation insummer time is taken after the laying of pipes, and in winter - during the development of the soil.
Anchors can have a different structure, and therefore the method of their installation also differs. This list includes anchors:
- drop-down;
- screw;
- frozen;
- shootable;
- injection;
- explosive.
Methods for installing weights
Specialized equipment is used to deliver ballasting elements and fix pipelines. The choice of a particular device depends on the size of the weighting agents, their type and working conditions. In this case, the following may be involved:
- pipelayers;
- amphibious cranes;
- marsh excavators;
- helicopters.
Ballast calculation
Calculation of pipeline ballast must be carried out at the planning stage. This takes into account a number of terrain features and operating conditions:
- The calculation of negative buoyancy depends on the pressure of the water flow and its speed. If these indicators can change along the way of laying the pipeline, measurements are taken at several sites at the planning stage.
- It is necessary to make calculations according to the maximum rate of water flow.
When choosing a weighting agent, it is also important to consider the type of device, the material used for its manufacture and density. During installation, you must strictly adhere tostep size for securing the load. Strict adherence to the rules is necessary for the reason that incorrect calculations can cause damage to the pipe.
