Separating Seam Welding

In the original design of the Atucha-1 charmel, the main shroud tube enclosing the fuel assembly was made of Zircaloy 4 and comprised a seam-welded tube (108.2-mm inside diameter and 1.6- or 1.72-mm in wall thickness). A thin (0.1-mm wall thickness) Zircaloy tube, dimpled to maintain separation, surrounded the shroud tube between it and the seam-welded Zircaloy 4 insulation tube (0.4-mm wall thickness). These were attached to austenitic stainless steel end fittings. The bottom end fitting sat in the bottom plenum lattice port allowing a small gap for the circulation of heavy water into the moderator space. The upper end was fastened to the upper plenum. 

Filter layers, frost penetration, and cap-liner connections are other factors to consider in designing the closure system for a hazardous waste landfill. Before using geotextiles for filter layers in closures, one should conduct pressure tests and clogging tests on the material. Freeze-thaw cycles probably have little effect on membranes, but their impact on clay is still not known. Because of this lack of knowledge, membrane and clay layers should be placed below the frost penetration layer. Finally, a cap membrane should not be welded to the primary FML. Differential settlement in the cap can put tension on the cap membrane. In such a situation, the seam could separate and increase the potential for integration of the surface water collection system into the LDS. 

Many vertical low-pressure storage tanks containing flammable or combustible liquids are designed with a weak weld seam on the wall-to-roof connection. This loss prevention feature allows the roof to separate and peel back if an internal fire, an internal explosion, or just a pneumatic overpressure situation occurs within the tank. If the roof relieves or is blown off, the liquid is still contained within the walls if these tanks are properly designed and fabricated. These conical roof tanks are often built to the American Petroleum Institute (API) Standard 650 Welded Steel Storage Tanks. ... 

The body blank is formed into a cylinder over a mandrel and the hooks are engaged and rolled closed to form the side seam, which is then soldered or welded. A recent development consists of making a cylinder long enough for three bodies, which is parted across previously made score lines into three separate can bodies. Speeds of up to 900 bodies per minute can be achieved, compared with around 500 for the conventional method. 

Three-piece (body and two lids) cans are now welded instead of soldered. The welding seam is coated separately with epoxy-phenolic resins or PVC organosols that are cured at 260 C for 10 20 s. The PVC organosols result in higher dry film thicknesses, whereas the epoxy phenolic welding seam coatings have better chemical resistance. 

T vo basic methods of RPV fabrication have been used. The first method used rolled and welded plates to form separate shell courses. Thus, an RPV fabricated in this manner has both longitudinal (axial) and circumferential (girth) weld seams. In some of the older (pre-1972) PWR RPVs, these longitudinal seams are of particular concern for RPV integrity due to high levels of Cu in the welds. All BWR and most of the PWR RPVs used this rolled and welded plate construction. 

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