Gas condensate collectors on the gas pipeline: structure and purpose of the condensate collector + nuances of installation and maintenance

Vasily Borutsky
Checked by a specialist: Vasily Borutsky
Author: Kristina Veklich
Last update: September 2019

Are you going to gasify your house? Perhaps you are setting up an autonomous gas supply system with a gas holder? In this case, you need to know about gas condensate traps.

They will help to avoid many problems in the use of gas and extend the life of the equipment consuming gas, as well as the gas pipeline and chimneys. A correctly selected and installed condensate collector significantly improves the quality of the gas and ensures the safe functioning of the entire system.

In this article we will tell you what functions condensate collectors perform on a gas pipeline, what settles in them, what they are and how they differ, what is the principle of operation of this valve, how to install and maintain them.

Why do we need a condensate collector on a gas pipeline?

Both methane and liquefied propane-butane mixtures need additional purification. This is caused by storage and use conditions, imperfection of gas distribution systems.

Impurities in gases are various:

  1. Water can get into the gas pipeline during its construction, inspection and purge, as well as through the smallest openings or cracks. It contributes to the corrosion of steel and destroys the chimney
  2. Butane (liquid) can be condensed from a propane-butane mixture. It does not evaporate and does not rise through the gas pipeline at low temperatures, in frost. Liquid butane in a gas burner forms a torch, and in the boiler provokes a stop or explosion.
  3. Fine particulate matter may enter the gas from the tanks and piping of the system, especially if they are not new and the corrosion process has started inside. Because of them, nozzles get clogged.

Each of these types of impurities is dangerous in its own way.Water, liquid butane in a gas burner forms a torch, and in the boiler provokes an explosion; solid particles clog nozzles.

The condensate collector is involved in the filtration, accumulation and removal of foreign matter.

Condensate collector with liquid
The condensate collector consists of the following components: 1) gas pipeline; 2) pressure equalization line; 3) shutoff valves; 4) a purge pipe; 5) condensate drain; 6) a condensate collector installed under the gas pipeline

Everything heavy is collected in the condensate collector, including liquid butane, preventing dangerous situations that it can provoke.

The structure and principle of the collection

Low pressure condensate collectors are fundamentally different from valves designed for operation with a medium or high pressure gas pipeline.

This is a vertical cylindrical tank with a convex or cone-shaped bottom, on the upper part of the walls of which pipes are welded on both sides for connection to the gas pipeline, and through the cover a pipe is brought out to the ground surface, under a special peak - a carpet, for pumping out condensate.

Gas passes through the top of the glass from one nozzle to another, and all liquid or solid impurities from it settle to the bottom. In such systems, the gas pressure is not enough to push the liquid through the unit’s tube, and it must be pumped out, similar to how you drink a drink from a glass through a straw.

Overhead condensate collector
In elevated condensate collectors, sometimes a discharge pipe is located below, and the condensate simply drains when the tap is opened under gravity

Medium and high pressure coders are expansion tanks in which the gas settles, as it were. Due to a significant increase in the cross-sectional area, compared with gas pipes, the flow rate drops, and all heavy liquid and solid particles have time to settle.

The main part of the unit - the collection - is a cylindrical tank with convex extremities, like a tank. Two branch pipes are diverted from above from above: through the first, condensate flows by gravity from the pipeline, and through the second, the gas entering the condenser along with the liquid is returned to the pipeline.

A purge pipe for condensate removal in medium or high pressure devices is necessarily equipped with a tap - and not a stopper, as in the first embodiment. In some cases, the gas pressure in the system may be sufficient to remove all condensate when opening the valve. More often this happens with condensate traps installed on the surface of the earth.

In underground tanks, only at a pressure of at least 15-20 kPa, the accumulated liquid independently rises through the discharge pipe and splashes out of it into a special tank. At the same time, it can freeze at the surface of the earth, from which not only the condensate drain stops, but the tube in which this will occur, up to a break, can also suffer.

Underground condensate collector
To avoid freezing in the winter, in the underground condensate collectors of high and medium pressure, there is another riser filled with gas, installed parallel to the discharge pipe. It is connected to the main one at the surface of the earth and creates back pressure in it, not releasing the liquid into the cold.

In addition, such condensate storage devices are usually equipped with additional equipment. It could be pressure gauge to control the pressure inside the tank, fluid level sensorwhich will show how much condensate has already been collected, fill indicatorinstructing to service the unit and drain the collected fluid.

Not uncommon in such installations - automatic fluid removal device. On the condensate trap installed in front of the compressor, the fill indicator automatically disables it.

Recommendations for choosing condensate traps

Depending on the parameters of your gas pipeline, a huge range of condensate collectors for the gas pipeline is presented on the market.Some manufacturers are ready to produce a unit of any modification according to your personal order, which exactly meets all the requirements if there is no suitable model in the presented product line.

Gas systems are diverse in form, pressure, operating conditions, filling, operating conditions - there are many options for combining these parameters. And therefore, there are no less options for condensate collectors for gas pipelines.

An incorrectly selected unit will not cope with the tasks assigned to it or it will be unreasonably large and expensive, therefore we recommend that the final choice be entrusted to specialists. And in order to navigate a little in this variety, we will understand their main differences and the principles of selection for these parameters.

Criterion # 1 - condensate collector shape

The condensate collection tank itself can be located horizontally, like a tube or a small tank, or vertically, resembling a pot. It is possible to determine how the selected condensate collector should be located, not only in shape, but also in the location of the nozzles for connection: they are always directed horizontally.

Large condensate collector
The shape of the condensate collector does not always depend on the design pressure: there are vertical pipes for main pipes and mini-tanks for low pressure

Vertical condensate traps are most often used on gas tanks, they are connected to the tank and to the vertical pipe supplying gas to the house, while the condensate collecting pot is located vertically parallel to the pipe.

Horizontal models are usually hung or mounted on supports under a horizontal pipe parallel to it. They are often high pressure and large volumes.

Criterion # 2 - pressure in the gas pipeline

It is important to purchase a condensate trap designed for the same pressure as the entire gas pipeline. There are 3 options: for low, middle and high pressure.

Condensate collector with pipe
Sometimes condensate traps are produced already connected to the length of the gas pipe - this minimizes the amount of welding work in the field

They differ not only in the size and diameter of the nozzles for connection, but also in the internal device, the method of installation and maintenance. Therefore, a pressure mismatch can make installation and operation not only inefficient, but also dangerous.

Criterion # 3 - other equipment parameters

In addition to the mentioned form and pressure, they differ in such parameters:

  • Volume - from a couple of hundred milliliters to several cubic meters, depending on the tendency of the gas pipeline to form condensate, the composition of the gas mixture, climatic conditions, the volume of gas transported and the location of the condensate collector.
  • MaterialThe condensate receiver is made of, usually stainless steel. Without additional processing, it can withstand the aggressive environment of moisture and liquid butane for a long time. However, often condensate collectors, especially of large volumes, are made of ordinary steel. For additional protection, it is treated not only outside, like the entire gas pipeline, but also inside - for example, with an epoxy compound.
  • At the place of installation condensate collectors are underground and aboveground. On the second, the marking "Gas", "Flammable" is mandatory.
  • Outdoor waterproofing should be the same as on the gas pipeline. Most often, these are polyethylene adhesive tapes, but there may be bitumen mastic or bitumen-polymer coating. For above-ground equipment, protection with waterproof paint, necessarily yellow, is sufficient.
  • Branch pipes for connection to the gas pipeline differ in diameter, and can also be designed for a weld or one-piece connection of steel with plastic.
  • Optional equipment. In addition to the inlet and outlet pipes, there is always a tube for draining or pumping the collected condensate.There may also be connectors for a pressure gauge, liquid level sensor, tank fill indicator, for pressure equalization.

Private consumers, as a rule, purchase a condensate collector for private gas holders, when arranging an autonomous gas supply to the estate.

Gas holder for home
Gas holders for a private house come in different volumes, gas quality and operating conditions also differ - this affects the choice of the condensate collector

For such purposes, small devices with a vertical, glass-like capacity, and a long tube for pumping out condensate are usually used. They are installed more often underground, directly at the entrance of the gas tank, and usually do not have additional equipment.

High pressure condensate traps are mounted on gas pipelines, at gas distribution points and to large industrial consumers. They have a large volume and shape of the tank, almost always equipped with additional sensors and signaling devices.

Condensate collector installation procedure

The method and procedure for connecting the encoder depends on the place of its installation.

The main places for the collection and removal of condensate from gas are as follows:

  1. At the exit of the gas tank in autonomous gas supply systems.
  2. In low sections of the gas pipe or at the junction of pipes with an opposite slope.
  3. At the beginning ("head") of the gas pipeline - at a refinery, after a gas distribution station or storage tank.
  4. Before compressor, in order to avoid failures in its work, as well as in front of factories and other industrial consumers.
  5. At the gas outlet from the compressor - here the condensate is collected if the compressor was stopped, or oil was pumped out of the tanks, filling them with gas.

The development of a location plan for the coke collectors is a task for the chief engineer of the company transporting and distributing gas to consumers.

It determines not only the installation locations of such units and the distance between them, but also the type, size and other characteristics. After installation, the location of the equipment must be accurately signaled by special plates indicating the direction and distance to it.

Condensate collector plate
The installed underground condensate collector should be located at a distance from water bodies, wells, trees and buildings, its location is indicated by signs

When choosing a location for the condensate collector, the convenience of further maintenance is also taken into account. Not only free access to the condensate drain pipe should remain, but also the ability to dig it out if necessary for maintenance, repair or replacement. The device itself is located no less than 2 m from the nearest wall, and its connection to the pipe is no closer than 1 m from the wall. It is also forbidden to install such devices above the freezing point of the soil.

Private consumers may be faced with the need to install a condensate collector only on a gas tank - we’ll dwell on this issue in more detail. The gas holder is installed on distance from home, according to the requirements of the standards - at least 10 m, but because the pipe to the basement is usually laid horizontally underground.

In such a scheme, this pipe is divided into 2 parts with an opposite slope, and a condensate collector is installed at their junction, at the lowest point. A small foundation is poured under it, and the unit itself is put on its legs, to minimize corrosion. The inlet and outlet of the device are welded to a gas pipe, and the condensate pumping tube is extended to the surface of the earth, plugged with a stopper and covered with a carpet.

Condensate collector installation
The condensate collector can only be connected with one-piece joints, welding, and threaded and flanged are not allowed. This ensures safe operation and reduces the risk of leaks.

If gas is discharged to the surface of the earth vertically, directly from the gas tank, that place for condensate collection is the very beginning of the pipe.In this case, one pipe is welded to the pipe, and the second either to it, a little lower, or to the tank itself. The condensate drain pipe is discharged parallel to the gas riser.

Nuances of equipment maintenance

According to the schedule developed by the engineer of the gas supplying enterprise, purge condensate collectors and checking their technical condition. These works are considered hazardous because the condensate contains not only water, but also flammable liquid butane, which often makes up most of the liquid. Therefore, two specialists carry out maintenance, only during the day, not during a thunderstorm.

It is also forbidden to drain condensate directly into a tanker truck - only into stationary metal tanks with a fence or into a foundation pit. If there is an oil pipeline nearby, you can drain the condensate into it.

To empty the low pressure condensate collector, you will need a pump, a motor pump or a vacuum tank. The plug is removed from the end of the tube, the pump hose is connected to it, the tap is opened and the pump is started. Pumping is continued until the liquid stops flowing from the pump, and then it is turned off, the valve is closed, the hose is disconnected and the plug is returned to its place.

Condensate pumping circuit
A small volume condensate collector can also be handled by a hand pump, and from some models for overhead installation, liquid is drained by gravity

Condensate collectors of medium and high pressure in the pump, as a rule, do not need. They have 2 risers: with condensate and gas, each has a tap, and usually only the one on the gas is open.

To release the tank from the liquid, both valves are turned: the gas valve is closed, and the condensation valve is opened. The fluid exits under pressure from the gas line. To save time and labor, this process can be automated through instrumentation and automation.

If condensate is not removed on time, a water hammer or plug can not only interfere with the gas supply, but also damage the pipe.

In addition to removing collected condensate, gas pipeline bypassers check the availability and accuracy of plates indicating their location, as well as the serviceability of the unit itself and the associated valves. If necessary, repairs are carried out immediately or an act is drawn up, according to which a special team subsequently leaves.

How to do without gas condensate traps?

The condensate collector installed on the gas pipeline is a guarantee of safety and safety of equipment.

But there are alternatives. As a rule, they are aimed at preventing the formation of condensate. Among such means - evaporatorsreturning vaporous butane to the gas holder, thermal insulation and heating of the pipeline, laying it deeper than the freezing point, the use of pipes of larger diameter.

Gas holder below freezing point
Heating the gas pipeline will prevent the formation of the most dangerous part of the condensate - the liquid phase of butane, but its arrangement and operation are not cheap

However, their use is not always possible and effective; moreover, it is usually more expensive than installing a condensate collector.

Conclusions and useful video on the topic

To better imagine the principle of operation of the condensate collector, we suggest watching the following video:

A visual aid on what gas condensate is in the following story:

We figured out why gas condensate traps are needed, what they are and how they work and what criteria to look for when choosing the right tank. We also talked about how and where they are installed and maintained by the condensate collectors and what alternative solutions are there.

Have you already encountered this equipment? With which and for what reason? Share your experience and other information on the topic - the feedback form is located below this publication.

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