Issues regarding the installation of metal expansion joints

The tie rod in a stainless steel compensator (usually referring to a bellows compensator) is an important component, and its main functions are as follows: 1. Limiting the range of displacement to prevent excessive deformation – The compensator uses the elastic deformation of the bellows to absorb thermal expansion and contraction or mechanical displacements in the pipeline, but the tie rod helps to keep such displacements within the design limits, thereby preventing damage to the bellows due to excessive stretching, compression, or twisting. - For example, when the pipeline expands due to heat, the tie rod allows the compensator to move axially or laterally to a certain extent, but not beyond the safety limits, thereby preventing the bellows from expanding excessively and breaking. 2. Maintain alignment of the pipeline axes to avoid eccentric loads – Struts help ensure that the pipelines at both ends of the compensator are on the same axis, preventing eccentric stresses caused by uneven displacement and avoiding additional bending moments on the pipelines or compensator, thus extending their service life. 3. Transmitting axial forces and balancing internal pressure thrust – In pressurized pipelines, the medium pressure inside the bellows generates an axial thrust (internal pressure thrust). The tie rod can transfer this force to the pipeline’s fixing brackets or equipment, thereby reducing the load on the compensator itself and preventing it from failing due to excessive pressure. - Especially in high-pressure pipeline systems, the force-balancing function of tie rods is crucial. 4. Fixing supports during installation and transportation – During installation: Tie rods can be used to temporarily fix the position of the compensator, facilitating pipeline alignment and welding; after installation, the tie rod bolts should be adjusted according to the design requirements (either loosened or kept under a certain degree of pre-tension). - Transportation and storage: It prevents the bellows from deforming due to vibration or impact during transportation, serving as a protective measure. 5. Protect the bellows from mechanical damage – The tie rod, acting as a structural support component of the compensator, helps to reduce the direct impact of external mechanical forces such as vibration and shock on the bellows; this effectively enhances the reliability of the compensator, especially under complex operating conditions such as high-frequency vibration and multi-directional displacement. Precautions: - The adjustment of the pull rod must be carried out in strict accordance with the design requirements; either over-tightening or under-tightening will affect the performance of the compensator. - The pull rods made of stainless steel have corrosion-resistant properties, making them suitable for use in corrosive environments. However, it is necessary to regularly check the tightness of the bolts on these pull rods as well as any signs of corrosion, to ensure the safe operation of the system. Through these mechanisms, the tie rod and bellows work together to enable the compensator to effectively absorb pipe displacement while maintaining structural stability, thus ensuring the safe and reliable operation of the piping system.

The type to be selected can be determined in accordance with GB/T 35979-2018, in consultation with the manufacturer, and it is necessary to distinguish whether the component is a \"pull rod\" or a \"transportation fixing device\"”

Regarding the issue of the tie rods in stainless steel expansion joints, it is recommended to seek a professional assessment from an independent third-party authority, or consult the manufacturer regarding the specific usage and safety standards. At the same time, relevant industry standards and specifications should be reviewed to ensure that the installation meets the appropriate safety requirements. Ultimately, the decision to remove or retain the tie rod should be made with ensuring system stability and security as a prerequisite. .

The bellows of stainless steel expansion joints have a very thin wall thickness, and they are not capable of withstanding the internal pressure forces. These forces are then transmitted to the pipes and equipment, causing them to move and deform.

The larger the pipe diameter, the greater the internal pressure thrust

First, determine the type of expansion joint; for those that need to withstand internal pressure forces, the tie rods of such expansion joints cannot be removed.