Expansion joints fabrication

Offline injection mass flow. First, it is obvious that users are interested in low quantities of effluent water to be disposed off. It is also claimed that offline water effluent transported up to the exhaust during offline washing may wet and soak into the expansion joint fabric (or also in recuperator compensator). Thereupon... 

Apart from the above three types there are custom built rubber products such as expansion joints, flexible cell covers and large size rubber foils for the caustic soda industry, and many inflatables, fabric reinforced products and thick moulded sheets for specialty applications in certain process plants. These are all hand formed in aluminium or cast iron moulds or forms by laying up process and then cured in autoclave. Here the flow of the un-vulcanized rubber during cure is not very important as the shape is already formed rather the green strength and the stiffness of rubber stock with a low scorch time are the important requisites. A rubber expansion joint made by a hand layup method and cured in autoclave is shown in the following figure 14.1. 

Figure 14.1 A hand fabricated rubber expansion joint for the fertilizer industry pipelines.

All of these materials-brick, mortars and membranes-will be fully discussed in later chapters along with (1) Castables, grouts, and polymer concretes (2) Monolithics (troweled, sprayed and gunned linings) and (3) Expansion joint compounds, plus rigid plastic fabrications such as polyethylene, polypropylene and PVC. These components made from a whole host of materials are effectively used in a wide variety of industrial applications requiring superior chemical and thermal resistance. 

When bonding compounded rubber to fabric, for the manufacture of fabric reinforced expansion joints in the chemical plant piping systems, mechanical anchoring between cotton/Nylon/fibre and compounded rubber should be sufficient to ensure good adhesion. Synthetic fibres require treatment with chemical coatings to secure maximum adhesion and bond [8, 9]. 

This chapter deals with the actual fabrication of linings for vessels, piping, valves, hose, expansion joints, and internals. It also deals with the shop and field assembly of these components. 

All expansion bends, whether fabricated or not, require more installation space than either corrugated or slip-type expansion joints. This is often an important consideration in crowded refinery or petrochemical plant areas but can usually be overlooked on tank farms and other locations where a large amount of space is available. 

The first cost of a fabricated expansion bend may exceed the first cost of a bellows or slip-type expansion joint. A built-up expansion bend usually costs less than a fabricated bend or either type of expansion joint, unless a great deal of labor is required to build the bend. 

Standard Transiie pressure pipe for water and process use is furnished with a sulfur-base cemented cast-iron flanged hub. Fittings are fabricated of steel and lined with transits, produced in equivalent flanged ells, tees, crosses, laterals, packed expansion joints, and reducers used with steel pipe. 

This discussion has focused on the basic developments leading to successful commercialization of the Fluidized Solids Technique however, many areas were important to success of the project and were pursued vigorously at the same time. Some of these are listed in Table 3. For example, the availability of special equipment had to be assured, including cyclones, slide valves and expansion joints. Also, metals and refractories had to be tested and methods of fabrication developed. A large supply of catalyst was needed. Fortunately, the natural clay type catalyst used initially was readily available, having been used for clay treating of lubricating oils, etc. It was soon found that a synthetic silica-alumina catalyst was much better, with the result that a whole new industry was started to supply it. Twenty years later the silica alumina catalyst was displaced by the more active zeolites. 

Definition Elastomer with chem. and solv. resist., exc. thermal props. Uses High-performance fluoroelastomer for molded goods (shaft seals), calendered goods (flue duct expansion Joints), sol n. coatings (fabric, tanks or chem. containers), coated or calendered rubber-to-fabric applies. rubber for food-contact articles for repeated use Regulatory FDA 21CFR 177.2600... 

Differential thermal expansion between various components of calandrias, especially shell-and-tube types, has an important effect on the mechanical design of the equipment. Some types of tubular exchangers incorporate into the basic design and fabrication means to provide for thermal expansion. Other types, specifically fixed tubesheet units, must often be provided with expansion joints in the shell to meet specified differential thermal expansion between the tubes and shell. Another critical area affected by thermal expansion in fixed tubesheet units is the shell-to-tubesheet juncture. Gasketed joints may also be affected by thermal expansion therefore both the flange design and the gasket selection in... 

The major difference between rubber joints and metal bellows is in the way they absorb pressure loads. Circumferential loads (hoop stress) due to pressure are carried by the folds themselves in a metal bellows. In a rubber expansion joint, the convolution is incapable of resisting pressure by itself, but is supported by the adjacent tube with its internal fabric or fabric reinforcement or by the adjacent flanges. Expansion joints have integrally molded flanges, which are drilled to match standard pipe flanges. AU expansion joints require metallic retainer rings behind the flanges as back up. 

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]. 

Fabric expansion joints are designed to accommodate the thermal movements and vibration of turbines and adjacent ductwork without imposing any loads on the... 

Advantages of fabric expansion joints over metallic Joints... 

Proximity of buildings. Fabric expansion joints are designed to withstand the full gas temperature but for them to achieve this there must be a relatively cool ambient temperature of less than 100°C. The design of the fabric element is such that the gas temperature is lowered through the different layers of the joint to an acceptable level at the point where the gas barrier is located within the joint. Frequently joints are located within the acoustic enclosure where the ambient temperature can be higher than expected, which can result in an abnormal temperature rise throu the joint and premature failure. 

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