Several connection methods for precision stainless steel pipes

Stainless steel pipes are mainly widely used in industrial pipelines for transportation in industries such as petroleum, chemical engineering, medicine, food, light industry, mechanical instruments, etc., as well as in mechanical structural components. There are many connection methods for precision stainless steel pipes, and today's article will introduce several common connection methods to you. 

1. Compression connection: Insert the stainless steel pipe into the pipe fitting's opening, secure it with a nut, and use the screw force to compress the sleeve at the pipe opening through the sealing ring, achieving a sealing effect, and completing the connection.

Features: From the perspective of connection alone, the pipe wall can be relatively thinner, saving materials, facilitating installation, allowing for disassembly, being convenient for maintenance, and having a large pulling force with tools.

Application scope: Below DN50, it can be installed openly.

Explanation: For compression connection, the pipe end of the stainless steel pipe needs to be flanged, or a convex groove can be formed on the pipe end using a groove tool, or a concave groove can be formed on the pipe end with a C-shaped thrust ring. The on-site workload is large, and the quality cannot be guaranteed. 

II. Compression Connection: At the U-shaped groove at the end of the compression fitting, there is a specially designed rubber sealing ring. During installation, insert the stainless steel pipe into the socket fitting until it reaches the positioning step. Use a dedicated compression tool to simultaneously press the U-shaped groove and the compression area on one side or both sides of the U-shaped groove. The rubber sealing ring undergoes compression and provides sealing function. The simultaneous contraction and deformation of the fitting and the pipe (forming a hexagonal shape in the cross-section) serves as a positioning and fixation function, effectively achieving the connection of the stainless steel pipe.

Features: Installation is simple and fast, with reliable sealing. However, it cannot be disassembled.

Application scope: Below DN100, it can be installed openly or buried underground.

Explanation: The work volume at the construction site for compression connection is small. Only cutting the pipe, removing burrs, inserting the pipe for positioning, and compression are required. No other processing is needed for the connected pipe material, avoiding quality defects caused by human factors. 

III. Rotatable Connection: This method involves inserting the stainless steel pipe into the pipe fitting's opening, tightening the cover-shaped nut with a special wrench, and sealing the pipe fitting with the sealing ring through the compression ring. Thus, the connection between the stainless steel pipe and the pipe fitting is completed.

Features: Easy installation, detachable, and suitable for harsh environments such as foundation subsidence.

Application scope: Below DN65, indoor exposed installation, underground buried piping, environments subject to earthquakes, subsidence, and passage of heavy vehicles.

Explanation: A slotting machine is required to roll a groove on the end of the stainless steel pipe to fix the C-type ring on site. 

4. Welding Connection: The ends of the stainless steel pipe are processed into bevels, and the fittings are welded in a circular pattern using manual or automatic welding.

Features: A traditional connection method with high welding strength, but requires on-site welding conditions.

Application scope: Can be used for both large and small pipe diameters, and can be installed openly or buried underground.

Explanation: The wall thickness of the stainless steel pipe needs to be relatively thick. The on-site welding requires high technical skills from the installation personnel. The solution treatment cannot be performed, and the welding quality cannot be fully guaranteed. 

V. Socket Welding Connection: This method involves inserting the stainless steel pipe into the socket-type pipe fitting. The pipe fitting and the stainless steel pipe are sealed together through circumferential argon arc welding, completing the connection.

Features: This is a traditional connection method with high strength and low leakage in the pipeline network.

Application scope: It can be used for both large and small pipe diameters, and can be installed either openly or underground.

Explanation: The welding is done on-site and cannot undergo solution treatment. The corrosion resistance at the weld seam decreases, basically similar to that of carbon steel, and intergranular corrosion and stress corrosion may occur, affecting the service life of the stainless steel pipeline system. 

6. Flanged Connection: This method involves performing circumferential argon arc welding between the flange and the stainless steel pipe. The flange is then secured using a clamp or bolts, allowing the sealing gasket to function as a seal, completing the connection.

Features: Traditional connection method, safe and reliable.

Application scope: DN125 to 200, for public buildings or large-scale buildings' pipelines.

Explanation: It is also possible to modify the traditional flange welding method, converting the flange into a slip-on flange. The end of the stainless steel pipe is bent or welded into a ring, the ring has a slot, and a rubber seal is placed in the slot. The sealing element is protected using a compression limit method. 

Vortex Thread Connection: The outer thread is welded to the pipe using ring-shaped argon arc welding. The inner thread pipe fittings are connected by vortex threads to achieve sealing, completing the connection of stainless steel pipes.

Features: Traditional connection method, simple, with high pulling force.

Application scope: DN65~100, for public buildings and large-scale buildings' pipelines, suitable for environments with foundation subsidence and other harsh conditions, more suitable for high-temperature and high-pressure projects.

Explanation: On-site welding is required. The outer thread may be inclined welded, and the welding quality cannot be guaranteed, which may lead to rework or sealing failure. There is also a problem of decreased corrosion resistance at the weld seam.