Types, characteristics and installation of metal chimneys

Today, the construction industry has reoriented the production of chimney structures by 90%. Metal chimneys for heating systems are in great demand.

Types, characteristics and installation of metal chimneys

When designing a house, it is necessary to responsibly approach the arrangement of the structure for smoke removal and compliance with all building and fire regulations. Otherwise, metal steel chimneys will be ineffective and unsafe.

Technical characteristics of smoke structures

Before you carry out the installation work of chimney structures, you need to familiarize yourself with their features.

• Steel air outlets are in great demand. They are durable and reliably protected from external damage, resistant to corrosion. Great preference is given to stainless steel pipes with the addition of an alloying substance molybdenum, which protects the surface of the chimney from an acidic atmosphere.
• The system configuration is suitable for all types of heating systems.
• The connection of round sections of different diameters contributes to the rapid removal of combustion products. A small amount of soot accumulates on the inner walls of the structure. It is easy to assemble, maintain and transport.

When carrying out installation work, you need to pay attention not only to the diameter, but also to the chimney system, how many elements it consists of and what its height is.

Advantages:

• lightweight construction does not require a foundation;
• installation directly over a fireplace is possible;
• little space is required, at a chimney with Ø20 cm, the size of the outer walls will be equal to Ø 30-35 cm;
• resistant to precipitation and aggressive acids;
• withstands burning ash;
• can be installed in inhabited houses;
• operating temperature and required thrust are quickly reached.

Flaws:

• if a long pipe, mount the supporting structure;
• not always suitable for the design of the roof and the architecture of the house.

A properly selected chimney system does not affect the replacement of heating equipment.

Design features and requirements according to GOST

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According to building codes and aesthetic aspects, one smoke system is being built per medium-sized house. In the design of the house, the chimney is arranged so that all heating structures that emit combustion products are laid through the entire building and removed in one place. If the area in the house is more than the permissible norms, then several pipes are designed.

The calculations are made by the engineering staff, which develops the project documentation. An important factor is the diameter of the pipe, as the draft in the chimney depends on it. The calculation of the chimney is carried out according to exact formulas, therefore, very often pipes are produced by enterprises whose main focus is the design of tanks. It is assumed that it has a round cross section. This allows you to quickly remove the products of combustion into the external environment. Experts have proven that the height of the pipe should be ≥4 m. Since the draft of combustion products depends on its length.

Chimney pipe installation requirements

Primary requirements:

1. Design and installation work for the installation of chimney pipes is carried out in accordance with SNiP No. 2.04.50-91, adhering to safety rules. Installation work should be carried out only if there is an appropriate certificate for this scope of work.
2. The diameter of the chimney structure depends on the power of the furnace.
3. The height of the chimney must be ≥4 meters. It does not depend on the architecture of the building.
4. This is a strictly vertical design. The error from the vertical axis can be 30⁰.
5. Horizontal sections longer than 1 meter are not allowed. This worsens traction. The pipe in such a section should be raised by 5⁰.
6. To prevent condensate from flowing, locks must be mounted in the direction of condensate flow. The lower part of the upper chimney is inserted into the upper part of the lower pipe.
7. For its fastening, special screeds or self-tapping screws are provided.
8. Separate elements of the chimney are fastened with a heat-resistant sealant that can withstand t = 1000℃.
9. For reliability, the fastening step should be 1.5 m.
10. Inspection hatches are installed for inspection and cleaning of the chimney.
11. To avoid moisture from the street, special fungi are installed, and spark arrestors are installed to extinguish sparks.

To avoid fire, a non-combustible, thermally insulating material must be used between the roof and the structure.

The content of alloying additives in steel grades:

AISI	GOST	Si	Cr	FROM	Mn	Ni	Ti	Mo
430	12X17	0.8	16	0.12	0.8	—	—	—
439	08X17T	0.08	17	0.8	0.08	0.6	one	—
304	08X18H10	0.08	17	0.8	2	9	—	—
321	08X18H10T	0.08	17	0.8	2	9	one	—
316L	03Х16Н15М3	0.6	17	0.03	0.9	fourteen	—	2

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By adhering to all the requirements, you can ensure a comfortable and reliable stay in the house for 15-20 years.

Types of metal chimneys, their scope

Heating structures are installed together with chimneys, which:

• remove smoke from the room;
• prevent overheating and fire structures;
• create a natural draft, which removes combustion products from the flow chamber.

Note! For stoves, fireplaces, gas equipment, smoke exhaust structures are used.

What are metal chimneys:

• Single wall. They are installed as temporary taps for stoves in baths. They do not have thermal insulation material.
• Double layer. They have a second name «sandwich». The design consists of two pipes of different diameters, between which there is a heater.
• Coaxial. They consist of two pipes of different diameters. They don’t touch each other. For this, special jumpers are used.

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The construction industry produces a large number of different types of pipes:

• Steel corrugated. Used for chimneys, in which the fuel combustion elements have a low temperature. For example, for a gas column.
• Steel without alloying additives. With constant operation of heating structures, they are not advised to use because of their weak strength. However, if the pipe has sufficient thickness, it is installed if there is a backup boiler.
• Galvanized. The material is poorly affected by corrosion and aggressive acids. It burns out quickly. Installed for intermittent use when the flue gas is at a low temperature.
• Steel stainless. Material with alloying additives — molybdenum, chromium, nickel, titanium and others, has high strength. A chimney made of a steel metal pipe is designed for heating structures with a high temperature.
• Sandwich chimneys. A metal chimney pipe consists of elements wrapped in a heat insulator (basalt wool) and enclosed in galvanized steel or inexpensive stainless steel sheathing. The entire structure is securely connected into a socket, baguette or flange method.
• Seamless heat resistant. They are used in industrial or chemical plants. Such pipes are able to withstand temperatures over 1200℃ with acrid smoke. The brand of this steel is 20x23H18. For domestic chimneys, it is desirable that the steel contains an alloying addition of nickel. It will protect the structure from sulfur compounds.

A metal chimney pipe made of stainless steel is not cheap, but it has excellent qualities for operation.

Used steel grades, wall thickness

For stoves, fireplaces and other types of heating systems, different types of fuel are used — solid, liquid and gas. Exhaust gases are removed through steel chimneys, which come in different brands and have different wall thicknesses.

Stainless steel grade	AISI 321	AISI 304L	AISI 316L	AISI 304	AISI 309/ 310	AISI 316ti	AISI 430	AISI 439
Wall thickness (inner pipe), mm	0.6, 0.8, 1.0	0.8	thirty	0.8	0.8-1.0	100	1.0	0.8
Exhaust gas temperature, ℃	600-800	120-200	150-250	up to 300	up to 1000	450-600	up to 900	up to 850
Thermal insulation thickness, mm	50-100	30-50	30-50	30-50	100	100	30-50	40-50

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Characteristics of steel grades for chimneys:

AISI 304L	The material withstands temperature changes and other climatic influences. It has high anti-corrosion properties.
AISI 316L	Alloying additives improve acid resistance. Connect to diesel system.
AISI 304	Used for the manufacture of chimney pipes in a private house, which are connected to gas equipment.
AISI 309/310	Used for stoves, fireplaces that run on solid fuels
AISI 316 Ti, 321	Steel grades that are often used for the manufacture of chimney systems. They have high thermal and acid resistance. They are the best choice for diesel and gas systems.
AISI 430	The metal has a low carbon content. Used to make sandwich pipes. It has high strength and anti-corrosion properties.
AISI 439	This is a type of AISI 430 steel to which titanium has been added. The metal is corrosion resistant and durable. Sandwich pipes are made from it, which are used together with heating systems with low power (less than 3.5 kW)

In the metal modular design of the chimney, the chemical composition of the material is of great importance. From alloying additives, strength, anti-corrosion, hardness, ductility and the ability to withstand shock loads increase.

Types of structures (internal and external)

The design of the chimney depends on the design features of the house, on the heating equipment and on its installation location. The chimney is of two types: internal and external.

It is installed inside the room, and only a steel or lightweight metal chimney is brought upstairs. To install the system, you need to perform additional work:

• equip the chimney support;
• install protective cover and so on.

It is not necessary to insulate the internal chimney. More often the street part of the system is insulated. Compared to an external chimney, the installation of an internal chimney carries a certain risk for the inhabitants of the house. For example, fire or carbon monoxide poisoning. Therefore, the operating instructions for steel metal chimneys must be strictly observed!

This is an attached chimney structure, which is installed on the outside of the house.

The main elements of the pipe:

• connecting flue;
• load-bearing wall bracket;
• revision;
• main sections.

They are easy to install, safe and maintainable. They do not depend on the architectural type of the room.

How to calculate the required section and height of the pipe

To calculate the required parameters of the chimney, you must adhere to the following requirements:

• Cross section of a round pipe. If the stove or boiler runs on solid fuel, then the volume of the flow chamber affects the cross section of the chimney. In a ratio of 1:10, here 1 refers to the cross section of the flue pipe, and 10 is the size of the combustion chamber.
• The height of the pipe is over 5 meters. The distance is measured from the outlet pipe of the heating system to the top of the pipe — the head. It looks like an «umbrella cone», a «deflector cone», an insulated head that protects the chimney and decorates the roof.
• The height of the outer part of the chimney depends on where the pipe outlet will be located, relative to the ridge. If the chimney is located at a distance of 1.5 m from the ridge, then the height of the chimney must be at least 0.5 m. 0.3 m

Note! The difference in temperature inside the heating system and from the side of the street, as well as the height of the chimney, affects the draft of combustion products.

Drawing and diagrams

Before installing the chimney, you must first complete a typical design of the future pipe. It will display the estimates of consumables, their quantity and the cost of the work. Next, a diagram and drawing of the entire structure is performed.

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Building regulations

For the correct installation of the smoke system, there are SNiP — 2.04.05-91 and DBN V.2. 5-20-2001, which must be taken into account in order for the system to work correctly. The regulatory documents describe the procedure for performing installation work and the principle of application.

• SNiP 41-01-2003 — basic regulation on ventilation and heating systems;
• NPB 252-98 — systems that are designed for the processing of various types of fuel;
• GOST 9817-95 — technical requirements for heating equipment;
• VDPO — technical requirements for the rules for the repair of chimneys and stoves.

Chimneys must comply with SNiP, and the operating permit is confirmed by a special inspection certificate.

FROMrock service

In order for the system to last longer, the question arises: how can you wrap a metal chimney pipe? The pipe is insulated with hydro- and fire-resistant thermal insulation:

• foil insulator;
• thermal insulation;
• sandwich pipes.

According to experts, the service life is from 10 to 15 years.

Note! However, in reality, the service life of metal chimney structures is 5 years.

In order for the system to serve for a long time, it is necessary to carry out preventive work on time, such as cleaning and diagnostics. Failure to comply may result in a fire hazard or personal injury.

Installation procedure for metal chimneys

During installation work, you need to take care of fire safety: think about how to isolate the chimney pipe through the wall? For insulation use ceramic mix, refractory paper LYTX-2368, CIP-2368, SUPERWOOL 607 paper, refractory mastic SUPERWOOL 607 HT MASTIC, KAOWOOL MASTIK, MKR ceramic tubes and other thermal insulation materials.

Installation technology:

1. It is necessary to install the chimney system from the stove, rising up to the head. The beginning of the top tube is inserted into the top of the bottom tube.
2. At the junction of the chimney elements, an inspection window must be provided.
3. Joints, bends, joints, other components are connected with clamps, coated with a heat-resistant sealant rated at 1000℃.
4. On the vertical section of the pipe, the fastening distance must be ≥ 150 m, and on the horizontal ≥ 100 cm.
5. Chimney systems pass through the walls, ceiling and out onto the roof. The diameter of the hole must be significantly larger than the diameter of the chimney. The pipe with the hole must not come into contact. To do this, cut out a square metal plate. You will also need a stainless steel passage glass, on which the insulating material is fixed.
6. The installation of the head is completed. It protects the structure from external precipitation and debris.

If you install the pipe yourself, you can make a mistake in calculating the length of the chimney. In this case, you need to read the instructions attached to the equipment or consult with experienced stove-makers.

Recommendations and typical mistakes

If mistakes were made during the construction of the chimney, this can lead to costly rework, waste or fire.

The main five mistakes that can occur during installation work.

1. Do not invent with the configuration of the pipes. The shape of the chimney must be cylindrical.
2. The lengths of the horizontal sections are not respected. Their length must be ≤ 1 m.
3. Don’t skimp on materials. The pipe should be 0.5 m higher than the ridge. If the roof is flat, then the height of the pipe is ≥ 1 m.
4. Do not use materials that are not intended for pipes — asbestos, aluminum.
5. When installing an additional stove or fireplace, they should not be combined into one chimney system.

In order not to make mistakes, it would be useful to get acquainted with SNiP 41-01-2003 «Stove heating».

Chimney earth loop

The role of the chimney is not only to safely remove combustion products into the atmosphere, but also to protect a person from electric shock if lightning strikes him. To avoid this, you need to use RD 34.21.122-87 «Instructions for the installation of lightning protection of buildings and structures» and install grounding:

• It does not need to be erected if reinforcement is laid in the foundation of the chimney, and any metal parts attached to the reinforcing bars are present in the base of the base. In this case, the chimney already has a lightning rod.
• To protect the building from lightning, use a ground loop. The norm of the ground loop is specified in the PUE (rules for electrical installations) p. 1.7.101, p. 1.7.103. It must be calculated and built from steel bars, fittings or pipes that have a circular cross section. The ground contour has the form of an equilateral triangle with a side ≥ 2 m. At the top of each corner, a vertical support must be driven in to a depth of 2 m. The distance between them must be at least 1.5 m. When the elements are in the ground at the base of the pipe, they must be strengthened with nuts, bolts or welding. When making grounding, it is necessary to choose longer supports, the thickness of which is indicated in the rules for electrical installations — table 1.7.4.

Today, ready-made kits (ZU) for grounding a house are sold — screens made of armored cables, reinforcing or pipe structures.

Rules for the care and cleaning of a metal chimney

If the chimney is used all year round, then cleaning the inner surface is indispensable. The ventilation will work smoothly and there will be no emission of combustion products through the flow chamber.

Soot removal

It is performed twice a year. If coniferous wood is used for the firebox, then cleaning is recommended to be done once a quarter. Chimney systems are cleaned with chemicals and a special tool, which consists of a steel fishing line with a load. A ruff with a hard pile is fixed at its end. The diameter of the ruff is equal to the internal section of the chimney. It is lowered from above the pipe. He removes all the soot from the walls of the pipe.

With the help of chemicals, tar deposits are removed naturally. For this, the product is laid out on coals. When it burns, salt is released, which softens the soot, and it sinks into the furnace or flies out.

To prevent soot from settling on the inner walls of the pipe, it is necessary to periodically use aspen firewood or potato peelings for the firebox. Firewood burns well, and a large fire contributes to the combustion of soot. This method is used for structures if they are designed for temperatures above 1000℃.

Chimney repair

Chimney repair can be done in three stages:

1. Clean the smoke channel.
2. Perform diagnostics with special equipment.
3. Replace the problem item.

Dismantling in a private house of a metal chimney is carried out on a damaged area. The burnt or damaged part of the pipe is replaced with a new one. The demolition of the chimney of the boiler room is carried out in the following ways:

1. With the help of industrial mountaineering.
2. Directional explosion.
3. With the use of special equipment.
4. With the help of robotic manipulators.

Note! Burning potato peelings helps soften soot. But it is considered ineffective. It is used before mechanical cleaning.

The chimney system has a simple appearance, but performs a very important function. Without it, it is impossible to imagine the environment around us. Common modular systems provide a smooth interior surface and increase the service life.