How to select the metal hose and compensator for subway stations

Metro stations are an important part of subway project. The water supply,drainage and fire protection construction of subway stations are trivial and intersect with other majors. Subway station water supply and drainage and fire protection have the general characteristics of public civil buildings, and also have the characteristics of subway project.

Subway station water supply and drainage

Metal hose and compensator

The main structure of the subway is more complex than that of general public buildings,which with a large station span, many deformation joints and many pumps. There are higher requirements for seismic and corrosion resistance of pipeline installation. Metal hoses and compensators should be installed according to the actual situation on site and related technical requirements. When the end of the design is noted, special attention should be paid to the selection of metal hoses and compensators.

Selection elements:

  1). Nominal diameter and joint type; 2). Working pressure; 3). Conveying medium; 4). Working environment; 5). Length.

1. Metal hose

Metal hose is a flexible pipeline element. When the pipeline passes through the deformation joint, a metal hose should be installed to compensate the displacement of the pipeline in various directions due to the settlement of the foundation and absorb vibration energy.

Metal hoses are mainly installed at deformation joints in subway stations. Deformation joints are mainly distributed at the entrance of the station, and the air duct is close to the damper wall.

1.1 Principles of metal hose installation

 Different lengths of metal hoses are selected according to the actual site. Generally, the nominal diameter of the hose is the same as the nominal diameter of the pipe. The length of the hose is determined according to the displacement caused by the settlement of the deformation joint and the installation deviation.

1.2 Precautions for installing stainless steel metal hose

When storing and transporting metal hoses, handle them gently to avoid injury to the metal mesh;

When installing metal hoses at the construction site, care must be taken to prevent welding slag from splashing the metal hoses;

When installing metal hoses, a certain degree of freedom should be ensured to prevent the metal hoses from receiving tensile stress. For easy installation, you can add a tie rod before installing.

2. Compensator

The compensator is a non-standard product. The compensation amount and installation position must meet the requirements of the design and product technical documents, and it should be pre-stretched or pre-compressed according to the design calculation compensation amount. This station uses axial type internal pressure corrugated compensator (TNY), which is mainly produced for compensating axial displacement.The products of some manufacturers can also compensate the ability of lateral displacement, axial and lateral combined displacement and angular displacement.

 The tie rod on the bellows expansion joint is mainly used for rigid support during transportation or as a product for pre-deformation adjustment. Whether the tie rod is removed should be determined according to the role of the manufacturer's tie rod. The temporary fixing rod should be removed after the pressure test is completed. If it is a load bearing member and the guide tie rod cannot be removed.

2.1 Precautions for Compensator Installation

1). In order to make the bellows in a good working state, the deformation of the compensator including axial, lateral, and torsional cannot be used to adjust the installation error of the pipe system during installation.

2), All moving components of the compensator must not be stuck by external components or restrict the normal movement of its moving parts.

3). During the operation of the pipeline equipped with the compensator, the opening and closing of the valve should be carried out gradually to prevent the pressure in the pipeline from changing sharply and causing damage to the bracket or compensator.

4). The bracket must meet the design requirements. It is prohibited to test the pressure in the pipeline before the bracket is installed strictly, so as not to damage the compensator.

5). If the pipeline needs to be insulated, it should be insulated on the outer protective sleeve of the compensator, and no chlorine-containing insulation material should be used.

6). The corrugated pipe is formed of thin-walled stainless steel plate. Therefore, they must be taken during transportation and storage to avoid damage the compensators due to knocks, scratches, arc strikes, welding splashes, and other reasons.

2.2 Compensator bracket setting principle

1). A guide frame should be set near the compensator. The distance between the front guide bracket and the compensator should be less than or equal to 4 times the nominal diameter. The distance between the second guide bracket and the front guide bracket should be less than or equal to 14 times the nominal diameter to avoid pipe bending and radial offset damage the compensator.

2). Only one compensator can be arranged between two fixed su