Welding screens

The lug screen is basically a wire wrap screen located on vertical bars on a perforated pipe, facilitating free entry of fluid over the entire exposed surface of the screen, to increase its efficiency. This principle is further extended in the lug plus version, where the bars are welded to the wedge-wire screen, and the whole is shrink-fitted to the perforated pipe. The slip-on screen is of similar construction, but is a slip on fit. In the weld screen the wedge-wires are welded to vertical rods. The Protecto-Screen mcorpoiates a perforated protective shell guard over the wedge-wire screen. 

Simulations of that kind result in a wide variety of A-scans and wavefront snapshots. The first screening of this material reveals, that the simulations in which the transducer is coupling partly to the V-butt weld and partly to the steel exhibit quite a number of pulses in the A-scans because the coupling at the interface of the weld results — due to the anisotropic behavior of the weld — in a complicated splitting of the transmitted wavefront. The different parts of the splitted wavefront are reflected and diffracted by the backwall, the interface, and — if present — by the notch and, therefore, many small signals are received by the transducer, which can only be separated and interpreted with great difficultie.s. 

The 3D inspection system has a number of measuring and report utilities that enables the user to easily find, analyse and report possible indications in the test object. As an example, a moveable 2D projection view plane can be moved along e.g, the welding geometry dynamically updating the content of the 2D projection view window. Indications can be measured using any referenee co-ordinate system and the results and screen dumps can automatically be dumped in report files suited for later import into a word processing application. 

In general, the higher the residual or applied metal stress, the more severe the corrosion at a given acidic pH. This explains why many heat exchanger tube ends are often attacked so severely (Fig. 7.1). Tube ends that have been rolled or welded often contain high residual stress. Further, crevices are sometimes present in which acidic species may concentrate (see Chap. 2, Crevice Corrosion ). Screens, rolled sheet metal, and other highly worked metals (not stress relieved) are also prone to attack. 

Normally the filter strueture consists of a stack of plates attached to a hollow shaft which are mounted inside a pressure vessel with eaeh plate eovered with a suitable filter medium. The slurry is fed under pressure into the vessel and the eake, which is retained by the filter medium, forms on the top of eaeh plate whilst the filtrate passes through the hollow shaft further to the proeess. Filter sizes may vary but generally the maximum is 60 m area and designed for a 6 bar operating pressure. Each circular plate in the staek is eonstructed with radial ribs that are welded to the bottom and support a horizontal eoarse mesh screen whieh is eovered with a fmer woven metal screen or filter cloth to retain the cake. The bottom of the plate slopes towards the hollow eentral shaft whieh lets the filtrate flow freely through circumferential holes and further down the shaft to the filtrate outlet. The elearanee between the plates is maintained by speeial spacers... 

Some are attached to headgear and equipped with a chin-guard to prevent upward splashing of acids/alkalis The transparent screen is commonly made of polycarbonate Heavier special versions are available e.g. for welding... 

A steel liner reinforced with a steel I-beam baffle was installed in the LEAP tank for secondary containment of the experiment. The primary liner was a 0.64-cm thick welded seam high-density polyethylene (HDPE) liner installed within an outer steel liner. Baffles in the steel liner were backfilled with pea gravel and contained eight fully screened 5-cm-inner-diameter (ID) wells. These wells could be used for leak detection as well as mitigation by inducing a hydraulic gradient into the tank. The finished interior dimensions of the tank were 8.5-m wide, 8.5-m long, and 3-m deep. 

Kolb et al. [52] applied small externally heated sandwich-type reactors for catalyst screening for propane steam reforming. Two plates of 2 mm thickness were attached to each other and bonded by laser welding. The reactors where 41 mm long and 10 mm wide carrying 14 channels each, which were 25 mm long, 500 pm wide and 250 pm deep on each plate, thus resulting in a total channel cross-section of 500 pm x 500 pm when mounted. 

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