A question regarding expansion joints

Reply to 1# yy1007: You have only seen the surface phenomenon. The expansion joint fixed to the screw is corrugated in shape, and it serves to adjust for thermal expansion and contraction. And the screw you mentioned serves to fix and prevent excessive expansion or contraction. Please refer to the following: Introduction Expansion joints* are also commonly known as telescopic joints or bellows compensators. They are compensation devices that make use of the effective elastic deformation of their bellows elements to absorb the dimensional changes in pipelines, conduits, or containers caused by factors such as thermal expansion and contraction; they belong to the category of compensation components. It can absorb axial, lateral, and angular displacements, and is used to absorb vibrations caused by thermal and mechanical displacements in pipes, equipment, and systems, as well as to reduce noise. 　　An expansion joint is a flexible structure installed on a vessel shell or pipeline to compensate for the additional stresses caused by temperature differences and mechanical vibrations. Due to its advantages such as being a freely expandable elastic compensating element with reliable operation, good performance, and a compact structure, it has been widely used in industries such as chemicals, metallurgy, and nuclear energy. There are various types of expansion joints used on containers; in terms of wave shape, U-shaped expansion joints are the most widely used, followed by Ω-shaped and C-shaped ones. As for structural compensation, the expansion joints used in pipelines include universal type, pressure-balancing type, hinge type, and universal joint type. Elbow-type expansion joint: A type of expansion joint in which the pipe is bent into a U-shaped shape or some other shape (Figure 1), and the elastic deformation capability of this shape is utilized for compensation. Its advantages are good strength, long service life, and the ability to be manufactured on-site; its disadvantages are large space consumption, high steel usage, and high frictional resistance. This expansion joint is widely used in various steam pipes and long pipelines. Bellows expansion joint A bellows expansion joint is a type of expansion joint made from a metal bellows. It can extend and contract along its axis, and it also allows for a small amount of bending. Figure 2 shows a common axial bellows expansion joint, which is used to compensate for axial length changes in pipelines. To prevent the compensation amount from exceeding the allowable limit, protective tie rods or rings are installed at both ends of the bellows, and guide supports are provided on the pipes connected to them. There are also corner-type and lateral-type expansion joints, which can be used to compensate for the angular and lateral deformation of pipes. The advantages of this type of expansion joint are space savings, material conservation, and ease of standardization and mass production; the disadvantage is its shorter lifespan. Bellows expansion joints are generally used in pipes with moderate temperatures and pressures and relatively short lengths. With the improvement of bellows manufacturing technology, the application scope of this type of expansion joint is expanding. Sleeve expansion joint A sleeve expansion joint consists of an inner sleeve and an outer sleeve that are capable of moving relative to each other in an axial direction. The space between the inner and outer casings is sealed using a stuffing box. Keep the tubes at both ends moving on the same axis while in use. Guiding brackets are installed at both ends of the expansion joint. Its advantage is low flow frictional resistance for fluids, along with a compact design ； The disadvantage is poor sealing performance and high thrust on the fixing bracket. Sleeve expansion joints are primarily used in water pipelines and low-pressure steam pipelines. Standards for expansion joints: Standard number: GB/T 12777-1999 (new standard: GB/T 12777-2008). Name of the standard: General technical requirements for metal bellows expansion joints. Date of implementation of the standard: March 1, 2000 (date of implementation of the new standard: February 1, 2009). Issuing authority: Bureau of Quality and Technical Supervision. Summary: This standard specifies the definition, classification, requirements, testing methods, inspection rules, marking, packaging, transportation, and storage of metal bellows expansion joints. This standard applies to the design, manufacture, and inspection of circular expansion joints installed in pipelines, whose flexible elements are integrally formed without reinforced U-shaped, reinforced U-shaped, and ∩-shaped bellows. The design, manufacturing, and inspection of expansion joints for pressure vessels can also be referred to. 　　The English term for bellows is bellows; the term for expansion joints is expansion joints, and the term for compensators is compensator. Special materials include: 1. Super austenitic specialty stainless steels: 254SMO, 904L, AL6XN. 2. Duplex stainless steels: 2205 duplex steel (S31803). 3. Nickel-based alloy steels: INCOLOY800/800H/800HT/840/825, INCONEL600/601/690/625/X-750, Hastelloy C-276/C-22/X, MONEL400/K500. 4. Pure nickel: N4, N6 (Ni200, Ni201). 5. Titanium sheets for stamping: GR1, GR2, TA1, TA2. 6. Austenitic stainless steels: SUS304, SUS304L, SUS316, SUS316L, SUS310S, SUS321, SUS316Ti

Reply to 2# 3968668: Thank you very much.

Wow, that’s tough. *studying* Studying… And there’s even a requirement regarding the length of the text

The expansion joint is subjected to stretching and twisting, and the bolts determine the limits for these stretches and twists.

The fixing bolts are used to secure the equipment during transportation and installation; they need to be loosened before the equipment is put into use