Insulation of pipelines - a necessary and important action aimed at protecting the pipeline from adverse environmental factors. Thermal insulation not only reduces heat loss but also increases the quality of highway operation.
Insulation materials for pipeline
Insulation for surface gas pipes made with different materials, which meet the following requirements:
- Insulating insulation must go uniformly over the entire surface of the pipe.
- It should have a high degree of waterproofing and UV protection.
- Resistant to chemical agents.
- He must protect the surface of the pipeline by mechanical action, ie be resistant to damage.
These requirements must be observed so as pipelines transporting gas under pressure with elevated operating loads. Surface damage or workmanship lead to great difficulties in the system transporting gas.
Types and characteristics of insulators
The main types of insulation materials for the pipeline include:
- Bituminous mastics. They are plastic, mineral, rubber. They represent the residues of the oil industry viscous consistency. The additive composition is introduced to the carbon mineral oils, atactic polypropylene, dolomite, crumb rubber. To increase the elasticity of bituminous mastics add special additives that enhance protection against cracking.
- Belt. They are made of PVC and polyethylene. They have an adhesive surface on one side which is mounted on the pipe surface.
Each type has its advantages, but only insulate the pipe at the factory.
application technology
Prior to applying the insulator surface previously cleaned of rust, scale and smelting residues. After the tube is primed to increase corrosion protection and better adhesion to the tape materials. Further applied bituminous mastic or adhesive tape is wound of polyethylene. Both operations are carried out with a special machine.
After applying the insulating material pipe subjected to careful inspection for defects, cracks, roughness. Verification is carried out by special instruments.
The thickness of the coatings was monitored by tolschemerov. For each type of coverage has its own density level indicators:
- For bituminous mastic coating this figure corresponds to from 7.5 to 9 mm.
- For PVC adhesive tapes active index from 1.8 to 3 mm.
- Polyethylene tape thickness ranges from 2.5 mm do3,5.
To enhance the insulation gas system material is applied in multiple layers: the first - primer 2-3 further layer of polyethylene tape, the top - the wrapping. Such coating is capable of withstanding high loads and at a pressure to maintain their function at temperatures from 45 to - 35 degrees. Typically the tape is applied at the factory, but the insulation is applied by hand to a complex configuration of pipelines.
In field conditions, when the required application directly to difficult weather conditions, the tape can not be used, use bituminous mastic. Manual work is permitted only to isolate the pipe joints, repair works on the surface.
Technology insulation coating using the bituminous mastics during repair work includes the following steps:
- Conducting cleaning insulated area. To do this, use metal brushes and sandpaper.
- Treat the ends adjacent to the treated site. For this it is necessary to cut the material at a distance of 1.5 cm.
- Dried and heated in the winter butt.
- Is applied to the prepared surface of the bituminous mastic brush or roller.
- Preheat adjacent joints gas burner.
- Mastic is applied to the preheated reinforcing material or glass wool.
- Then placing another layer of hot bitumastic.
Every action should be done with great care, since we are talking about working with chemical material and the use of heating appliances.
Especially insulation of underground pipelines
Insulation for underground gas pipelines needed to protect the pipeline against corrosion processes due to increased soil moisture, as well as to eliminate the effects of stray currents.
The impact of stray currents detrimental effect on metal pipes. They are able to bring down the pipeline within the first year of operation. Currents are formed in places the passage of electricity, motorways and railways. If the pipeline is laid alongside the likes Communications to apply special protection. Best insulator in this case is a polyurethane foam (PUR).
The advantages of this insulator include:
- Low thermal conductivity.
- Low density material.
- Stability to temperature and pressure fluctuations.
- Increase the service life of the pipeline.
- Ease of installation during renovation work.
For isolation using PUF is used two ways of application:
- Application of the product in the factory.
- Protection of communications after the installation of the pipeline.
Pipes with polyurethane foam insulation, applied in the factory, are regulated by GOST №30732. According to this norm produces two types of pipes: normal and enhanced performance. They are characterized by technologically advanced features and performance characteristics. pipe production technology with polyurethane foam insulation is as follows:
- Upper shell is made of polyethylene using extrusion technology. For its production using special press machine, in which liquid is supplied under pressure polyethylene, and then it solidifies. After complete solidification shell insert and take out the inside of the pipe.
- The gap between the pipe wall and the inner surface of the shell is filled with liquid polyurethane foam which then solidifies.
Insulating the pipes in the factory is considered more reliable and durable. To enhance the protection against moisture penetration from the top is covered with polyethylene sheath.
In this isolation has another advantage - the ability to install electronic monitoring sensors for the gas pipeline. It allows to detect the slightest fault in the system and quickly resolve them.
During installation, the pipeline ends of the pipe are covered with asbestos cloth to protect the coating from damage during heating. To connect the pipe ends is best to use heat-shrink sleeve. They are not inferior in performance indicators PPU and will perfectly protect the whole system.
