Expansion Joints—General

There are many expansion joint materials. The general practice is to leave the mortar out of the joint. Then partially fill with a vinyl sponge rod as a back-up. 

It should be noted that, if interlocking expansion joints are to be used, it is generally advisable to go to an 8" lining. The reasons for this will be discussed under that heading. 

They generally feature a much longer span of uninterrupted tube length. The use of expansion joints has been kept to a minimum because of the difficulties of gaining access to them within a tall chimney structure. This tends to aggravate conditions wherein the coefficient of thermal expansion of the coating is even slightly different from that of the steel substrate. 

Strength, Calculation and Testing of Bonded Joints For thermal expansion it generally applies ... 

For bridges in marine or semimarine environments, the entire structure is subject to corrosion. In the case of bridges in nonmarine environments, the corrosive areas are generally limited to expansion joints, drainage, traffic splash, and tidal areas. If these areas can be isolated and maintained by a better protection system, large expenses can be avoided in the maintenance of the bridges. Improved inspection procedures and standards will also be a positive contribution. 

The quantity of joint sealant to be poured into the joint depends on the depth and width of the gap or groove to be filled. As a rule of thumb, for expansion joints, a depth-to-width ratio of 1 1 to 1 1.5 is used, and generally, the depth should always be lower than or equal to the width. To limit the amount and depth of sealant applied to the joint, a sealant backer material (compressible caulking material) conforming to ASTM D 5249 (2010) or other standards is used. 

As for the expansion joints, it is stated that the use of expansion joints is generally minimized on a project due to cost, complexity and performance problems . 

Polyurethanes Expansion joint and general sealing markets. 

Loading criteria of a general nature, such as superficial loading on flooring and the basis for calculation of frictional reactions at standard expansion joints. 

In general, weld repair of any cracked metallic bellow is not recommended, as it is not possible to restore the original bellow functionality after repair. That will further jeopardize its operational integrity. Therefore it is always considered safe to replace the entire expansion joint bellow assembly from the reliability point of view. Procuring a new bellow joint for replacement normally takes a minimum of 10 to 14 weeks subject to the supplier / manufacturer constraints. Shutting down SRU totally and flaring Acid gas for extended periods imtil the replacement of bellow is not permitted as it is anti-environmental. 

Cover the cover of the rubber expansion joint is made out of a rubber which resists weathering attack and mechanical damage, if any, caused during handling and installation. In general. 

When minimum movement capability is required, the arch is sometimes filled with soft rubber using a suitable adhesive. The maximum amount of movement (axial extension and compression, lateral deflection and angular rotation) that an expansion joint is capable of absorbing is called the rated movement. This rating depends on various factors, such as the size of the expansion joints, the thickness of the tube, arch or convolution, and the type and properties of rubber compound and fabric used in construction. Rated movements are established by manufacturers of expansion joints theoretically, or are based on actual load deflection curves of each size of joint. Rubber expansion joints are generally subjected to hydraulic and vacuum tests at 1.5 times the operating pressure. No internationally accepted standard technical specification for rubber expansion bellows is available, since they are mostly custom built to specific operational requirements. The Expansion Joint Manufacturers Association in New York has laid down standards for rubber expansion joints, which are called EJMA standards [2]. 

According to Konopicky (1957), the expansion joints should, as a rule of thumb, be designed to absorb half the thermal expansion that develops up to the service temperature of the refractory lining. Approximate values to be adopted are 0.5% for fireclay and silicon carbide brick, and 1.2% for magnesite-chrome and dolomite brick. The expansion joints are filled with cardboard, which burns away when the kiln is heated, leaving the joints clear. In general, it is more favourable to provide a larger number of narrower expansion joints than a smaller number of wider ones. 

Heat exchangers in the United States are normally designed according to the Standards of Tubular Exchanger Manufacturers Association (TEMA) and the ASME Code, VIE. In general, TEMA requirements are a supplement to the ASME requirements, for they tend to include areas not discussed in the ASME. Most of the TEMA design equations relate to tubesheet design when affected by differential pressure and temperature, expansion joints, bustles, and so on. 

Expansion joints bellows may be described in terms of gauge of metal, being that they are usually very thin. This term is not unconunon in welding and general plant repair work. For the reader s reference. Table 5.1 lists wire and sheet metal gauges. The Birmingham wire gauge (B.W.G.) is very common for tubes. 

Expansion joint suppliers have individual designs that they have developed and tested over many years. These designs may vary from one supplier to another but generally there are three basic configurations of expansion joints as seen in Figs. E-45A, E-45B, and E-45C ... 

Generally expansion joint flexible elements have a buildup of ... 

Generally at gas temperatures of 400 to 500°C conventional expansion joints operate successfully without the need for any special precautions. For temperatures above these the overall design configuration shotdd be reviewed by finite-element analysis to establish the temperature of the backing bars. 

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