Flat bottoms

One production line of a paper mill consists according the size and the quality of the produced paper sometimes from more than 50 steam drums to dry and flatten the produced paper. These drums (cylinders with flat bottoms, see figure 1) will be used with a steam pressure up to 500 kPa (5 bar) and additionally with a rotation speed up 1200 m.min the material is mainly grey cast iron (with lamellar graphite). The diameters can reach up to 2.2 m and the cylindrical lengths up to 10 m. For the specific flattening drums the cyhndrical diameters can be up to 5 m and more. 

The calibration in UTDefect is perfomed by a side-drilled hole or a flat-bottomed hole. The flat-bottomed hole is approximated by an open circular crack with the probe s beam axis going normally through its centre. This approximation should be sufficiently accurate as long as the crack diameter is larger than about a wavelength. 

Fig. 2 Conventional flat-bottom hole calibration standard for corrosion detection.

When using the gradient method described above, conventional flat-bottom hole standards can not be used. Tbe probe will see only the edges of the holes and they all have the same gradient, i.e. vertical steepness, and will give the same signal responses. 

This paper deals with the control of weld depth penetration for cylinders in gold-nickel alloy and tantalum. After introducing the experimental set-up and the samples description, the study and the optimization of the testing are presented for single-sided measurements either in a pulse-echo configuration or when the pump and the probe laser beams are shifted (influence of a thermal phenomenon), and for different kind of laser impact (a line or a circular spot). First, the ultrasonic system is used to detect and to size a flat bottom hole in an aluminium plate. Indeed, when the width of the hole is reduced, its shape is nearly similar to the one of a slot. Then, the optimization is accomplished for... 

B-scan view of a flat bottom hole in an aluminium plate of thickness 2 mm. 

Figure I Simulation of a transducer calibration test, a) Calibration configuration T45° transducer and 6 flat bottom holes at various depths b) Predicted field by Champ-Sons c) Simulated Bscan d) Echodynamic curve.

Side drilled holes are widely used as reference reflectors, especially when angle beam probes are used (e.g. for weld testing). However, the distance law of side drilled holes is different to that of a flat bottomed hole. In the literature [2] a conversion formula is given which allows to convert the diameter of a side drilled hole into the diameter of a flat bottomed hole and vice versa, valid in the far field only, and for diameters greater than 1.5 times the wave length. In practical application this formula can be used down to approximately one nearfield length, without making big mistakes. Fig. 2 shows curves recorded from real flat bottomed holes, and the uncorrected and corrected DGS curves. 

BE = Backwall echo, SDH = side drilled hole, FBH = Flat bottomed hole... 

Assemble the apparatus shown in Fig. 56. F is a 200 ml. flat-bottomed flask supported on a sand-bath and connected by a glass delivery-tube to the wash-bottle B, which is about two-thirds full of 10% aqueous sodium hydroxide solution. A second delivery-tube leads from B into a beehive stand (or between two earthenware tiles placed side by side) in a pneumatic trough T containing water. 

Prepare a mixture of 25 ml. of concentrated nitric acid and 80 ml. of water in a 750 ml. flat-bottomed flask for which a steam-distillation fitting is available for subsequent use. Warm a mixture of 20 g. of phenol and 15 ml. of water gently in a small conical flask until the phenol is molten on shaking the... 

Place 0 5 ml. of the pyridine in a 200 ml. round- or flat-bottomed flask and add 34 ml. (30 g.) of benzene. Fit the flask with a reflux water-condenser, and then place it in a cold water-bath. If the experiment is conducted in a fume-cupboard, the top of the condenser can be closed with a calcium chloride tube bent downwards (as in Fig. 61, p. 105 or in Fig. 23(A), p. 45, where the outlet-tube A will carry the calcium chloride tube) and the hydrogen bromide subsequently allowed to escape if, however, the experiment is performed in the open laboratory, fit to the top of the condenser (or to the outlet-tube A) a glass delivery-tube which leads through a piece of rubber tubing to an inverted glass funnel, the rim of which dips just below the surface of some water... 

Then, while the diazonium solution is standing in ice-water, dissolve 55 g. of powdered copper sulphate (CuS04,5Ha0) in 200 ml. of water contained in a 1500 ml. flat-bottomed flask, for which a steam-distillation fitting is available for subsequent use. Place a thermometer in the copper sulphate solution and warm the latter to 60-65 . Now cautiously add a solution of 60 g. of powdered potassium cyanide in too ml. of water to the copper... 

Flat-bottomed flask (the so-called Florence flask) with vial mouth. The sizes vary between 50 ml. and 40 litres. 

Flasks. Round-bottomed, flat-bottomed, conical (Erlenmeyer) and bolt-head flasks up to a capacity of 2-3 litres are generally fitted with a 524 socket f those from 5 to 100 ml. are available with a 514 or 519 (from 25 ml.) socket. Round- and flat-bottomed flasks exceeding 1 litre in capacity are supplied with 534 necks. Whilst all sizes of sockets can be obtained from the manufacturers, it is usually convenient to limit the socket sizes to a small number (say, 514, 519, 524 and 534), thus per mitting interchangeability with the minimum number of adapters. 

Place 25 g. of dry acetamide in a 350 ml. conical or flat-bottomed flask, and add 69 g. (23 ml.) of bromine (CAUTION ) a deep red liquid is produced. Cool the flask in ice water and add 10 per cent, sodium hydroxide solution (about 210 ml.) in small portions and with vigorous shaking until the solution acquires a pale yellow colour. At this stage the bromoacetamlde is present in the alkaline solution. If any solid should crystallise out, add a little water. 

Tribromoaniline. Assemble the apparatus depicted in Fig. 7F, 47, 1. The distilling flask B has a capacity of 100 ml. and the bolt-head flask A (which may be replaced by a flat-bottomed flask) is 1 litre. Into the flask place 10 g. of aniline, 100 ml. of water and 10 ml. of concentrated hydrochloric acid shake until the aniline has dissolved and dilute with 400 ml. of water. 

The next day comes and the hung-over chemist wakens to see a dark red solution stirring away. In some cases where the chemist had made an enormous batch of this stuff, there may be seen a small mass of crystalline precipitate at the bottom of the flask. This is no big deal and will go away in the next step. If the chemist had made this in a flat-bottomed flask (which she really should have for convenience) then the ice tray is removed, the flask returned to the stir plate, a distillation setup attached, and the acetone is vacuum distilled from the flask. After all the acetone has come over the chemist can proceed in two different ways. One way is to just keep on distilling the solution until all of the formic acid has been removed. The chemist knows that just about all the formic has been removed when there is about 300mL of thick black liquid remaining in the reaction flask and hardly any clear formic acid is dripping over into the collection flask. If one were to swirl the reaction flask, the liquid will appear syrupy and kind of coat the sides of the flask. This is more evident when the flask cools. A quick sniff of the flask may indicate that some formic is still in there, but it should be too minimal to be of any concern. 

Flasks. Flask containing B can be a bottle. A is a round bottom flask, it s better because in a bottle or a flat bottom flask, PdCl2, wich is not dissolved in methanol until it reacts, could be in the corner of flask without reacting. 

Steel. The steel container s most usual form is cylindrical with a concave (or flat) bottom and a convex top dome with a circular opening finished to receive a valve with a standard 2.54-cm opening. The three pieces (body, bottom, and top) are produced separately and joined by high speed manufacturing. The size of the container is described by its diameter and height to top seam, in that order. Hence a 202 x 509 container is 54.0 mm (2 /jg in.) in diameter by 141.3 mm (5 /jg in.) high. Tables of available sizes and overflow volumes and suggested fill levels can be readily obtained from manufacturers. 

In most ultrasonic tests, the significant echo signal often is the one having the maximum ampHtude. This ampHtude is affected by the selection of the beam angle, and the position and direction from which it interrogates the flaw. The depth of flaws is often deterrnined to considerable precision by the transit time of the pulses within the test material. The relative reflecting power of discontinuities is deterrnined by comparison of the test signal with echoes from artificial discontinuities such as flat-bottomed holes, side-drilled holes, and notches in reference test blocks. This technique provides some standardized tests for sound beam attenuation and ultrasonic equipment beam spread. 

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