Bellows connection for water and gas: characteristics and advantages

A bellows water connection is a special device, which is a corrugated hose made of stainless steel. This product is very practical, however, it is inferior in flexibility to conventional rubber hoses with a metal braid. To choose the right bellows model, you need to familiarize yourself with its features and technical characteristics.

The bellows connection for water or gas is a flexible part that remains strong and sealed even under repeated deformations associated with pressure and temperature

What is it and where is it used?

Flexible bellows water line, made of stainless steel and has a corrugated structure. Such devices are used in cases where the installation of conventional pipes is difficult or impossible.

Let's look at the cases in which a bellows liner is installed:

connecting various plumbing equipment to the water supply network;
gas supply from the gas pipeline to stoves, boilers, etc.;
for organizing connections when installing various climate control equipment (for example, air conditioners);
as well as bellows models of connections are widely used for connecting sprinklers (sprinklers), which are part of automatic fire extinguishing systems;

Note! It is worth noting that the operational area of a bellows-type flexible water line expands if it is used in combination with various fixation fittings.

Such combined designs are used in enterprises and are part of equipment that supplies a variety of products:

air and other gases;
petroleum products;
aggressive chemicals.

In plumbing, such liners are used to connect faucets and other devices to the water supply.

Today, in addition to bellows eyeliners, there are other types of these devices. The range of such hoses is incredibly wide, which allows you to expand the operational scope of the connections. When choosing eyeliner, you should first of all pay attention to the material of the product, as this is considered a decisive factor.

Features of selection and installation

The durability of a stainless steel water line depends on compliance with the rules for its installation and on the correct choice of the hose itself. To manufacture it requires expensive equipment and high-quality material, so it cannot be cheap. To avoid problems with leaks and not flood your neighbors below, you should be careful when choosing bellows products.

Choose hoses only from trusted brands. Based on user reviews, the rating of reliable manufacturers includes Witzenmann GmbH (Hydraflex brand, Germany), Parigi and IDROSAPIENS Srl (Italy), Kofulso (South Korea), G-Beka (Turkey), AKVAPROF (Russia).
All parts of the hose in contact with water must be made of stainless steel and welded using the roller welding method. At this stage, unscrupulous manufacturers often save money by making parts from low-quality materials. You can check it using a simple magnet that does not stick to stainless steel. If it is attracted, then the pipe or sleeve is made of ordinary steel, which means that over time this element will rust and leak.
To connect to mixers, bellows hoses must have special small-diameter tubes with external threads. So when choosing a hose for such a connection, you need to tell the seller what exactly needs to be connected.

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Manufacturers who value their reputation offer not one, but two fittings of different lengths in the delivery set of the finished mixer. This can serve as an additional sign of product quality.

Before purchasing, you need to inspect the water pipes installed in the apartment. To prevent the mating parts from being subjected to electrochemical corrosion, the nuts and fittings on which they are screwed must be made of the same material. Only brass and copper parts can be connected to each other without any risk.

It is recommended to choose the length of the hoses with a reserve, since the bellows pipes cannot be stretched too much: this will significantly reduce their operating time.

A high-quality product must have a warranty period of at least a year and be supplied complete with a technical passport.

Types of flexible eyeliners

Let's consider the main types of flexible hoses based on the material of manufacture:

rubber hoses equipped with a special stainless steel braid. In some cases, aluminum or nylon is used as a braid, and sometimes the rubber hose has no braid at all;
hoses made of cross-linked polyethylene. This material is characterized by high flexibility;
corrugated stainless steel tube (bellows connection).

It should be noted that each of the above models has its own pros and cons. Rubber hoses equipped with aluminum braid are used to connect water or gas and have a service life of up to 3 years. The pressure that such devices can withstand does not exceed 0.5 MPa, and the temperature resistance is no more than 80 °C. The main disadvantage of this model is its weak resistance to the destructive effects of corrosion.

In terms of performance characteristics, a rubber hose reinforced with stainless steel is more reliable than the first option. The pressure that such a hose can withstand is 1 MPa, and the maximum temperature of the working environment reaches 95 °C. The service life of such models is about 10 years.

Rubber flexible hose, equipped with a nylon braid, is very popular in the modern market. The service life of such models braided from polymer threads can reach 15 years. The pressure that such models can withstand is 2 MPa, and the maximum permissible temperature of the working environment is -110 °C.

The most durable and reliable liner is made of stainless steel.

The product is made of durable cross-linked polyethylene, equipped with a metal braid, and is considered quite reliable. Such models are characterized by high resistance to corrosion and aggressive chemicals. However, polyethylene liners have temperature restrictions.

Bellows models of eyeliners are made of stainless steel and have a corrugated surface. Such products far surpass all previous types in their technical characteristics.

Technical characteristics of the main types of flexible water connections: which is better

In retail outlets you can see a large selection of flexible hoses for water supply from different manufacturers, which differ not only in price, model or functionality, but also in the quality of the materials used, which affect the service life of the product.

Bellows liner can withstand pressure of 20 atmospheres or more

Important! When choosing flexible hoses, it is necessary to take into account the quality of the materials used for their manufacture. The seller must present documents confirming the compliance of the flexible water supply with GOST standards, as well as certificates certifying the quality of the products.

A reliable flexible hose should be made of aluminum or stainless steel. The price is affected not only by the material, but also by the presence of additional options. Thus, some manufacturers offer hoses equipped with anti-vibration lines, which have a large cross-sectional diameter. This reduces the noise level when supplying water to a household appliance. To understand which flexible water line is the best, you should familiarize yourself with the technical characteristics of each type.

Rubber hoses. The main advantages of these models are considered to be low cost and the ability to operate under high pressure. Hoses consist of a frame made of strong threads or metal spirals. Rubber is used to cover either the outside or the inside. Main characteristics:

The maximum pressure level for which rubber reinforced hoses are designed is no more than 10 bar.
The temperature of the liquid that will be supplied through the hose must be within the range from -50 to +120 °C.

The bellows hose does not collapse when exposed to negative temperatures

Briefly about PVC hoses and reinforced hoses: main parameters

Hoses made of polyvinyl chloride (so-called PVC) are highly flexible. Additional rigidity is given to PVC sleeves by a reinforcing spiral placed inside the product. Main advantages:

light weight;
resistance to chemicals;
smooth internal and ribbed external surfaces for ease of installation;
are not afraid of direct sunlight;
The operating pressure for which the hoses are designed is 15 bar.

The main disadvantage of installing PVC hoses is the small temperature range at which it is permissible to use the device - from -20 to +60 ° C, which does not allow the use of this type of flexible hose for hot water.

PVC hoses made from polyvinyl chloride are very flexible and light in weight

Reinforced hose, which is a soft braided hose, is made of aluminum, stainless or galvanized steel. The most popular domestic manufacturer producing flexible water hoses is Elka, which offers products in a nut-to-nut design with a cross-sectional diameter of 1/2 inch.

Sometimes nylon is used instead of metal braid, but usually these hoses are not used in domestic environments. Technical parameters of various options for reinforced flexible hoses are presented in the table:

Type of reinforced liner	Parameter
Type of reinforced liner	Service life, years	Maximum permissible pressure, bar	Maximum temperature at which operation is possible, ˚С
Galvanized steel and aluminum	No more than three	5	+80
Stainless steel	To 10	10	+95
Nylon	15 and more	Up to 20	+110 and above

Design and features of bellows water connections

The bellows model is made from different grades of stainless steel (for example, AISI 304). The production process of this device itself can take place using various technologies. Depending on the manufacturing technology, two main types of bellows hoses can be distinguished:

welded;
seamless.

Regardless of the technology used, bellows products have almost the same technical characteristics. The wall thickness of these devices is usually 0.3 mm. In addition, all of them are equipped with special structural elements - union nuts.

Nuts for bellows connections are made mainly from the same material as the connections themselves. However, in some cases these elements may be represented by brass or bronze. To increase their service life, brass and bronze nuts are coated with a protective layer of nickel or chromium. It is also worth noting that to obtain the most reliable nut-hose connection, the end of the liner, consisting of approximately 2-3 rings, is folded.

Hose nuts are made of the same material or coated with a protective layer of chrome or nickel

Helpful information! Bellows water hoses cannot be installed without a special element - a locking ring. This part ensures that the seam and the special sealing gasket align evenly to the pipe or corresponding fitting during installation.

In addition, in order to connect the bellows hose to the fitting equipment, special adapters are used. Adapters are made of steel or brass and, among other things, ensure the connection of this device with pipes, the cross-sectional indicators of which differ from the diameter of the liner itself.

Main manufacturers of flexible stainless steel water line

The modern market provides a large selection of flexible bellows water connections. You can choose both European and domestic products. At the same time, products from Russian factories are more suitable for connecting to classic pipe options in apartments. Thus, the flexible water supply line “Giant Aquaprof” produces hoses with an increased internal or external diameter, which, in comparison with standard options, have a higher throughput. Gigant hoses are characterized by resistance to stress, and their surface is not subject to mechanical stress. High reliability is additionally ensured by the presence of thickened walls.

Related article:

Bellows gas connection: the safest way to connect gas equipment
Features of application, advantages and disadvantages. Other types of flexible hoses for connecting gas equipment. Safety precautions.

All hoses are made of high-alloy stainless steel, and the brass union nuts are reinforced by applying a layer of nickel. The flexible line meets the requirements of GOST 12.2.063.81 and GOST 15763-2005. The main cross-sectional dimensions of the flexible water line “Giant” are 1/2, 3/4, 1. Prices for these products are presented in the table below:

Section size, inch	Length, cm	Price, rubles
1	60	475-720
	80	540-800
	100	780-1100
3/4	60	230-280
	100	240-320
	150	300-420
1/2	40	230
	60	250
	80	270
	100	320
	150	410

Many plumbers, when carrying out repair or installation work, prefer to use hoses from European manufacturers, among which the leaders are Italy and Germany. Let's look at the most popular Italian companies that produce bellows.

Indrosapien. Thanks to the high quality of finished products and a large assortment, the manufacturer is popular with customers. All of the company's products have been certified in Russia and are recommended for installation in domestic conditions. AISI 303 stainless steel is used for the manufacture of products. The flexible water connection nut-fitting is made with an external thread. Fittings are made of nickel-plated brass. They are secured by industrial welding.

Gigant bellows liners are characterized by resistance to loads, and its surface is not susceptible to mechanical stress

Emiflex. Another Italian company that produces bellows. Flexible water supply hoses, available in a wide range of sizes, feature an attractive chrome-plated outer casing and durable stainless steel fittings. The most popular connection option for a flexible water line is a nut-nut or nut-fitting. The only disadvantage of Italian hoses is their high cost.

This is interesting! Flexible hoses for faucets from an Italian manufacturer are mainly sold in sets of 2 pieces.

Below is a table showing the sizes of Italian hoses and their prices:

Section diameter, inch	Length, cm	Manufacturer, price in rubles
Section diameter, inch	Length, cm	Indrosapien	Emiflex
1/2	0,4	725	980
	0,5	850	1120
	0,8	970	1270
	1	1130	1620
3/4	1	1050	1300
3/4	1,5	1370	1760

Operating parameters of bellows connections

Stainless steel is a very reliable and durable material. It is resistant to corrosive influences and aggressive chemical compounds, and is also resistant to temperature fluctuations. Let's take a closer look at the characteristics of corrugated stainless steel bellows liners:

the service life of bellows models can reach 20 years (and in some cases more);
temperature indicators that bellows models can withstand vary from −40 to +200 °C;
the operating pressure of such products varies depending on the cross-section of the hose and the thickness of its walls, however, in most cases, stainless steel bellows models can withstand from 1.5 MPa to 3 MPa.

In addition, it is worth noting that the most reliable part that is included in the bellows flexible liner is a special sealing gasket. The sealing gasket is made of the following materials:

paronitis;
fluorine-containing polymer;
copper.

Bellows hoses are also available for connecting gas appliances; such hoses have a yellow coating

The sealing element, as a rule, experiences the same pressure as the bellows itself. Based on this, experts recommend using sealing gaskets with a thickness of at least 2.5 mm.

The excellent performance characteristics of stainless steel make the bellows water hose a universal accessory. These products are approved for use for:

cold and hot water supply communications;
heating communications;
gas pipelines.

How to choose the right flexible water line for 1/2 and other diameters

The liner should be selected so that the fittings, whether nuts or fittings, form a reliable connection with the connected devices without the use of additional adapters. To do this, you should purchase products from manufacturers that offer standard sizes of flexible hoses for water supply - 1/2, 3/4 or 1. If you buy a 3/8 size supply, you can only connect such a hose using an adapter.

The bellows connection must correspond to the water temperature and pressure

If you plan to connect to hot water or a heating system, you need to additionally check the technical characteristics of the products and make sure that they correspond to the temperature of the supplied water and are designed for high pressure in the system. All this information is contained in the hose data sheet. You can find out what water temperature the product can withstand using the markings:

blue – hose for cold water only;
red – the product is designed to supply hot water;
red and blue - a universal hose that can be used to connect cold and hot water.

Depending on the conditions of use of the bellows, different materials from which the braid is made are selected. If you plan to use the hose in an environment where aggressive chemicals are present and high humidity is constantly observed, it is better not to purchase options made of ordinary metal.

Information about the bellows liner is contained in the passport that comes with it

You also need to be careful when choosing the size of the flexible water line. Despite the fact that the bellows is designed for double magnification, experts recommend buying a product with a small margin of length. If the sleeve is constantly under tension, this will not have the best effect on its service life. Other important points to pay attention to when purchasing:

Flexibility. If the product bends well, it will be easier to install. Hoses that are flexible are of higher quality.
Material used for the manufacture of fittings. Preference should be given to connectors made of non-ferrous metals or stainless steel, and the thickness of the metal plays an important role: thin aluminum will fail faster. To prevent electrochemical corrosion, threaded connections and union nuts must be made of the same alloys.
Weight of the finished product. The hose, which is light in weight, was most likely made of silumin, a cheap aluminum alloy. Silumin products rot within a few years.
Manufacturer. You should buy products only from companies that have been certified in Russia and received permission to sell.
Smell. A hose intended for drinking water should not have any foreign chemical odors.
Section diameter. If you install a flexible water line 3/4 rather than 1/2, the water noise will be less due to the large outlet hole.

If the hose is under tension, its service life is significantly reduced.

Important! When purchasing a certified product, you need to check the availability of a technical passport, which indicates the grade of steel used in production, the date of manufacture and expiration date, as well as basic information about the manufacturer. If the seller cannot provide a document, it is better not to purchase the product.

Before buying a hose, you need to conduct a careful visual inspection of the product for defects and check the quality of the corrugation. It is important that the fittings are securely welded to the hose, and that there are no signs of corrosion or mechanical damage on the surface. Gaskets and seals must also be inspected to ensure they do not look old or cracked.

Advantages of using stainless steel bellows connections

Let's consider the main advantages of using flexible corrugated stainless steel bellows connections:

resistance to oxygen diffusion;
Stainless steel is a fire-resistant material;
Stainless steel is an environmentally friendly material and does not emit any harmful substances that can cause any harm to human health;
high wear resistance.

Important! It is worth noting that during installation, if the bellows hose is bent, it does not change the shape of its working section (it does not become pinched). This is very important, since in this case the same pressure indicators are maintained along the entire length of the hose.

In addition, the use of such hoses in production is an ideal option, since they can be used to transport aggressive working media and petroleum products. Since these devices are wear-resistant, they can be used for transporting bulk substances.

The bellows liner is not very flexible, but it holds its shape without additional fasteners.

But such products also have some disadvantages. For example, stainless steel bellows models are inferior to rubber hoses in terms of flexibility. Because of this, installation of bellows connections is not always convenient, especially in limited space. However, this property is also an advantage, since the device is able to retain and maintain its shape without auxiliary structures.

Installation recommendations

When installing the liner, you should adhere to some rules:

It is necessary to ensure free access to the mounting points not only during installation, but also for further maintenance and repair.
Before installation, it is necessary to carefully inspect the hoses and fasteners again. Defects may appear during transportation or storage, even if high-quality products were purchased from the store.
The nuts should be tightened tightly, but without excessive force. It is not recommended to use gas wrenches for this: they can seriously damage the connecting elements.
During installation, do not allow the hose to twist or stretch.

The minimum bending radius of bellows hoses is indicated in the technical data sheet; usually it should not be less than the outer diameter of the hose multiplied by 6.
After completing the installation and supplying water to the system, you should observe the connections for about half an hour and, if necessary, tighten the threaded connections.

For a long service life of the hose without leaks, it is recommended to carry out a preventive inspection every six months and promptly replace worn out elements. The video below will tell you about some of the features of bellows flexible liner.

Tips for choosing eyeliner

When choosing the required sizes of bellows liner for water, you should be guided by the following rules:

before purchasing this product, you need to find out the water temperature and pressure indicators in your system, which will allow you to buy a product that meets the necessary parameters;
The diameter of the product is determined by the water consumption of a particular plumbing equipment. The optimal cross-section for connecting a toilet to a water pipe is 8 mm, for a sink - 10 mm, and for a bath - 15 mm;
The length of the bellows liner is determined on a case-by-case basis. It is not recommended to install such a device in conditions where space is too limited. In addition, the hose should not be too tight.
The fittings of the product must not have any defects or deformations.

If necessary, you can always consult with a specialist who will help you choose the necessary device for a particular case and explain to you all the nuances of using and installing such an eyeliner.

Disadvantages of bellows hoses

If we talk about the minuses, there are only two of them:

Bellows hoses are subject to strong vibrations, causing noise and humming, which increases if several valves are opened at the same time. This can easily be avoided by using a larger diameter product.
Relatively high cost. So, a hose 500 mm long and 3/4 inch cross-section will cost from 500 rubles.

Bellows products cannot be cheap; most often, a low price is associated with low quality workmanship. It is clear that if you purchase components of dubious quality, you cannot hope for long-term operation without leaks.