Ball valves serve as shutoff valves on external pipelines (gas and oil pipelines, utility pipelines, pipelines in chemical explosive and fire hazardous industries, etc.). One of the varieties of a ball valve is a ball valve for welding.
It is used as a shut-off device in order to completely block the flow of circulating medium in the pipeline. Such a medium can be oil and its products, water, natural gas, air, alcohol products and other aggressive environments.
This type of valve is characterized by the fact that it is connected to the pipeline by welding. The ball valve for welding does not have detachable parts (flanges, couplings, etc.), and this ensures maximum joint density and minimizes leakage at the joints.
Classification
Welded ball valves are classified by type of drive:
- hand held;
- having an electric drive (made by special order taking into account the features of the pipeline);
- manual with gear;
- having a pneumatic drive (made by special order, taking into account the characteristics of the pipeline).
Usually a manual ball valve for welding is used for relatively small dimensions of the passages, with a low or medium pressure in the pipeline. If the pressure in the pipeline is above average, and the pipes themselves are large or medium diameter, it is better to use an electric valve or a pneumatic valve.
Also, the ball valve for welding can be full bore and partial bore (classified by type of passage).
Production and design of ball valve
The components of the body of ball valves are made by welding (so that the connection is strong and reliable). A free-floating ball is sealed with PTFE seats.
The production uses original technology. The principal feature of the devices is a steel non-separable case. During production, the locking mechanism is first assembled and then inserted into the housing. The pipes are neatly scalded.
The result is a non-separable design that does not require maintenance.
The ball- welded steel ball valve has a unique internal design. In the event of wear, this design itself compensates for the process. This is facilitated by free-floating balls, which are located between the springs having a seal. If one part wears out, then the spring is unclenched and the structure is still tightly connected. This ensures long-term tightness.
Operation and maintenance
1. The ball valve for welding should be operated at a temperature of at least 30 ° C.
2. The pressure in the pipeline can be 1.6 / 2.5 / 4 megapascals.
3. The circulating medium should also be appropriate temperature: range from -35 to +180 o C.
Regular maintenance and expensive maintenance are not required for these devices. You can add only a seal on the stem yourself. Design development does not include repair work or replacement of parts during the entire period of use.
Advantages and disadvantages of ball valves for welding
Advantages:
- low specific gravity;
- low cost;
- the crane opens simply and quickly;
- when using the crane stagnant zones are not formed in the area where the fluid flows;
- strong, reliable and simple design;
- tight shutoff of a stream of liquid;
- this crane is installed in the most critical and inaccessible places of the pipeline;
- no maintenance required.
Disadvantages:
- repair not possible;
- it is possible to install and change the crane only with welding work;
- the possibility of water hammer with a sharp opening of the crane;
- inconvenience when using due to the long lever to shut off the crane (when working in tight conditions).