I. Project Overview

The Songpu Bridge, spanning the Songhuajiang River in Harbin, is a single-tower, double-cable-stayed steel bridge located in the high-altitude region of northeastern China (see Figure 1). The main span of the steel beam measures 268 meters, with side spans of 208 meters each, making the total length of the bridge 476 meters. The bridge deck has a full width of 39.3 meters and weighs approximately 7,000 tons. The steel structure consists of a main longitudinal beam, secondary beams, small longitudinal beams, and two side beams. The main longitudinal beam features a box-shaped section, with the outer belly plate welded to an anchor box. Except for the box-shaped sections at the auxiliary pier, all other beams are working sections. The small longitudinal beams and pick-up beams are constructed using an I-shaped cross-section. Shear studs are welded onto the main stringers, beams, and small stringers. The primary method of connecting steel beams is bolting. However, certain sections such as LZ0–LB0, LB14–LB19 are fully welded on-site. Additionally, some beams like HL3 and HL10 are also connected through welding with the main longitudinal beams.

The bridge tower houses 36 pairs of steel anchor beams, which are designed as shown in Figure 2. Each pair of these beams is 4.5 meters long and weighs between 6.98 to 8.86 tons, contributing to a total weight of about 270 tons. The main structural components of the bridge are made from Q345qE and Q370qE steel plates, with thicknesses ranging from 10 to 50 mm.

II. Challenges in Welding

During the steel structure manufacturing process of the Songpu Bridge, several welding challenges were encountered:

(1) The bridge features a unique and complex design. The main longitudinal beam uses a large-box section combined with a cable-stayed anchor box, both of which are entirely fabricated through welding. The welding space within the anchor box and steel anchor beam is limited, and most of the welds require full penetration, making them difficult to perform.

(2) The primary materials used are Q345qE and Q370qE steel plates, which demand a welded joint with low-temperature impact absorption energy of at least 34 J at -40°C. This requires a very high level of joint toughness, adding complexity to the welding process.

(3) Due to the large dimensions of the main steel box girder and its components—such as the large longitudinal steel plates, anchor boxes, and steel anchor beams (up to 50 mm thick)—the welding process results in significant deformation, requiring precise control and advanced techniques.

(4) The main longitudinal beams, beams, and the cable tower are primarily connected by bolting at the construction site, which demands high installation accuracy. The control of box welding deformation is particularly strict. Sections such as LZ0–LB0 and LB14–LB19 are fully welded on-site, presenting additional technical difficulties due to their size and complexity.

Rotary Rings

Rotary Rings are a type of rotating seal widely used in various rotating equipment, such as rotary joints, rotary couplings, rotary connectors, etc. Its main function is to prevent liquid or gas leakage and maintain the normal operation of the equipment. In different applications, the material, structure, sealing method, size, etc. of Rotary Rings vary to adapt to different working conditions.


1. Material classification

The materials of Rotary Rings are mainly divided into two categories: metallic and non-metallic.


1. Metal materials

Metal materials mainly include stainless steel, steel, copper, aluminum, etc., which have characteristics of high strength, corrosion resistance, wear resistance, and are suitable for rotary seals in harsh environments such as high temperature, high pressure, and high-speed.


2. Non metallic materials

Non metallic materials mainly include ceramics, silicon carbide, graphite, etc., which have characteristics such as high hardness, high wear resistance, and low friction coefficient. They are suitable for rotary seals under conditions such as low temperature, low pressure, and high speed.


2. Structural classification
The structure of Rotary Rings is mainly divided into three types: unidirectional rotation, bidirectional rotation, and rotational stationary.
1. Unidirectional rotating structure

The Rotary Rings with a unidirectional rotation structure can only rotate in one direction and are suitable for devices with only unidirectional rotation.


2. Bidirectional rotation structure

The Rotary Rings with a bidirectional rotation structure can rotate in two directions, suitable for devices that require bidirectional rotation.


3. Rotating stationary structure

The Rotary Rings with a rotating stationary structure are composed of a rotating ring and a stationary ring. The rotating ring contacts the stationary ring during rotation to achieve sealing, suitable for equipment that requires a rotating stationary seal.


3. Classification of sealing methods

The sealing methods of Rotary Rings are mainly divided into mechanical sealing and liquid sealing.


1. Mechanical seal

Mechanical sealing is achieved through the contact surface between the rotating ring and the stationary ring, which has the characteristics of high reliability, long service life, and simple maintenance. It is suitable for rotary sealing in harsh environments such as high speed, high temperature, and high pressure.


2. Liquid sealing

Liquid sealing is achieved by injecting liquid between the rotating ring and the stationary ring, which has the characteristics of good sealing performance, low friction coefficient, and preventing dry friction. It is suitable for rotary sealing under low speed, low temperature, low pressure, and other conditions.


4. Size classification

The size of Rotary Rings is mainly determined by the equipment requirements, including inner diameter, outer diameter, thickness, shaft diameter, etc.


Rotary Rings, as an important type of rotary seal, are widely used, with different materials, structures, sealing methods, dimensions, etc. to adapt to different working conditions. When selecting Rotary Rings, it is necessary to make the selection based on specific equipment requirements to ensure the normal operation of the equipment.

Rotary Seals,Rotary Lip Seal,Rotating Shaft Seal,V Seals

DG Zhongxingshun Sealing Products Factory , https://www.zxs-seal.com

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