A gas pipeline is an engineering structure, each element and node of which solves an important specific functional task and is responsible for the safety, quality and uninterrupted operation of the network. Various gas fittings and equipment differ in the complexity of execution, in the material of manufacture, in purpose and in type.
Gas pipeline fittings are a wide class of fixtures and fittings that are mounted on gas pipelines, as well as on devices. With their help, switching off / on, changing the direction, quantity, pressure of the gas flow or complete removal of gases are carried out. A wide range of these parts is classified, making it easy to understand the issue of classifying gas fittings.
Purpose of Gas Fittings and Equipment
Gas fittings and gas equipment are intended for installation on pipelines used for transportation, supply and distribution of blue fuel. With the help of these mechanisms, the supply, pressure, quantity, direction of the gas flow is switched on and off. The valve has such basic characteristics as nominal pressure (nominal) and nominal diameter.
Under the nominal pressure, the maximum pressure is taken at a temperature of 20 degrees, at which long-term service of various connections of elements and assemblies with the pipeline is guaranteed. Nominal size (DN) is a characteristic that is used in pipeline networks as a general parameter of the connected parts.
Classification of Fittings for Gas Pipelines
All existing types of gas fittings, depending on their purpose, can be divided into:
- shut-off. Fittings usually used for periodic shutdowns of individual sections of the gas pipeline, instruments, equipment. This type includes gas taps, gate valves;
- Serving to prevent the risk of gas pressure rise above the established norms. This type of fittings includes a relief safety valve;
- Designed to change and maintain pressure within specified limits. These are dampers, gate valves, etc.;
- reverse action. To prevent a change in the direction of gas movement;
- emergency and cut-off. For quick auto – stop of gas movement towards the emergency section in case of violation of the preset mode. This type includes a safety shut-off valve;
- condensate drain. The one that automatically removes condensate accumulating in condensate collectors and in the lower sections of pipeline networks;
- Determines the pressure of the passing mass, temperature, etc.
According to the control method, the valves can be of two types: controlled and automatic. First one is driven by manual manipulation or by means of a drive: pneumatic, hydraulic, electromagnetic, electric.
The manual process is marked by a lot of effort and wasted time. The more drive is often installed and the possibility of emergency control remains in case of emergencies. And the second one works with the help of automatic actuation devices. The gas fitting should be done by plumber gas fitter experts who get the gas fitter online courses with practical experience.
Gas Valve Symbols
Commonly fittings used in the gas industry are standardized. Each detail must have a code consisting of 4 parts.
The first 2 digits of the code are the type of fittings:
- 11 – valves for pipelines;
- 14,15 – shut-off valves;
- 16 – lift check valves;
- 17 – safety valves;
- 19 – rotary check valves;
- 25 – control valves;
- 30, 31 – shut-off valves;
- 32 – gates.
Condensate Traps and Expansion Joints
Condensate traps are installed to collect and remove water and condensate at the lower levels of gas pipelines. They can be of different capacities: a large capacity is necessary if the transported gas has a high humidity, a smaller one is suitable for transporting dry gas. In addition, depending on the pressure of the working medium passing through, the condensate collectors differ into devices of low, medium, high pressure.
Low pressure devices are a container with an inch tube led out under the gas carpet. The tube ends with a sleeve and plug. Condensate is removed through it, the pressure is measured, the gas pipeline is blown through.
Medium and high pressure devices are additionally equipped with another protective tube and a valve on the internal riser. There is a hole at the top of the riser for equalizing the pressure of the working medium in the case and in the riser. Without a hole, condensate would fill the riser under gas pressure, which could lead to its rupture at low temperatures.