Compression couplings are a type of fitting and allow you to quickly and efficiently install the pipeline without the use of welding or threaded connections. The use of this type of coupling gives a high tightness of the assembly, while maintaining the possibility of disassembling it if necessary.
Arrangement and design
Compression coupling includes the following structural elements:
- collet - central body threaded on both sides;
- external ferrule nuts;
- sealing collars;
- thrust rings.
Types of couplings
Compression couplings are divided into:
- Depending on the material from which the couplings are made: brass, bronze, steel (with anti-corrosion coating), plastic. Plastic fittings are most often made from low-density polyethylene (HDPE). There are also polypropylene products. The HDPE coupling is used to work with plasticpipes.
- By configuration: straight and angled (rotary).
- By purpose: connecting; transitional (for connecting elements of different diameters or different types of pipes); couplings for sanitary fittings.
Coupling selection
When selecting a compression coupling, first of all, they are guided by the conditions of its operation. So, metal fittings are used for heating systems, for hot water supply systems, as well as for communications located in the light. For units and systems located in basements and underground, HDPE couplings are used, since they are not subject to corrosion.
In addition, when choosing a coupling, it is desirable to select a material that matches the material of the pipe to be connected. Although the connection of polyethylene pipes with polypropylene couplings is acceptable.
Mounting Features
Installation of pipelines using this type of coupling is quite simple. For its implementation, in addition to the pipes to be connected and the fittings themselves, two adjustable wrenches of the appropriate size will be required. Their size must correspond to the diameter of the mounted compression sleeves.
Installation order of couplings and adapters:
- Cut off the required length of the workpiece, at the ends of which carefully deburr, both outside and inside.
- On the end of the pipe, put on the elements of the compression coupling in the following order: compression nut, sealing ring, thrust ring.
- Place onto the collet and screw on the compression nut by hand. At this stage, it is important to ensure that the nutdid not warp. It should clamp the ferrule and o-ring, forming a tight connection.
- Use a wrench to tighten the connection. In order to avoid damage to the fitting, as a rule, tighten the nut with one wrench, and fix the collet with the other.
Experienced craftsmen do not disassemble the coupling completely, but only slightly unscrew the compression nut, insert the workpiece with some effort and tighten the nut back. Due to the force applied when installing the workpiece into the coupling, the joint is sealed.
Advantages and disadvantages
The main advantages of using compression couplings compared to welded and threaded connections:
- quick and easy assembly of knots;
- tightness and reliability;
- durability - service life over 20 years;
- formation of detachable connections (with each assembly of the same connection, only seals are replaced);
- variety of fitting configurations.
The main disadvantages that limit the scope of compression couplings are:
- Max fitting diameter is 110mm.
- Use in systems with pressure not exceeding 1.6 MPa.
- For HDPE couplings and polyethylene couplings, there is such a disadvantage as low resistance to ultraviolet radiation. This limits their use in places where direct sunlight penetrates. Also, these materials have low heat resistance.
