Valve steels

Ventil-kiiken, m. valve plug. -SI, n. valve oil. -schlauch, m. valve tubing, -sitz, m. valve seat. -Stahl, m. valve steel, -stopfen, n. stopper with a valve, valve stopper, -zelle,/. (Elec.) valve cell. 

An interesting case of ash attack is encountered with valves in engines powered by high octane fuels containing lead compounds. These compounds are deposited from the gases as mixtures of lead oxide, sulphate and bromide, and can cause serious scale-fluxing effects with high-alloy valve steels. 

Bilots ky A.V., Yurkova A.I.Strengthening of Valve Steel by Friction Nitriding, Technologiya i Organizatziya Proizvodstva, 1988, No. 2,40—41. 

Stainless), Valve Steels, and Iron-Base Superalloys ... 

Fig. 2.20 High temperature fatigue failure under axial loads of a valve stem of 21-2 valve steel [24]. Note the ratchet marks around the circumference that denote the presence of multiple initiation sites (indicated by arrows)...

High temperature fatigue failure under axial loads of a valve stem of 21-2 valve steel (21 % Cr, 2 % Ni, 8 % Mn, 0.5 % C, 0.3 N) in solution-treated and aged condition and faced with stellite 12 alloy (30 % Cr, 8 % V, 1.35 % C, rem Co), Fig. 2.20 [24]. Note the ratchet marks around the circumference that denote the presence of multiple initiation sites (indicated by arrows). The wavy shape of beach marks is indicative of oflF-axis load that has introduced a bending component. 

The manifold is typically a tubular steel structure (similar to a template) which is host to a series of remotely operated valves and chokes. It is common for subsea tree control systems to be mounted on the manifold and not on the individual trees. A complex manifold will generally have its own set of dedicated subsea control modules (for controlling manifold valves and monitoring flowline sensors). 

Figure Bl.27.7. Schematic diagram of isothennal displacement calorimeter A, glass calorimeter cell B, sealed heater C, stainless steel stirrer D, thennistor E, inlet tube F, valve G, window shutters Ft, silver rod ...

A mechanical device embodying a bellows-sealed needle valve with a lever reduction movement for fine control is shown in Fig. II, 23, 5. The needle is of stainless steel. This fine control valve assembly is useful for pressures ranging from 20 to 100 mm. of mercury when used in conjunction with a good water pump. 

In figure 4 is shown how a separatory funnel and a pressure equalized addition funnel are made. The funnel part is just a PP funnel from the grocery store and what it is attached to is a stainless steel ball valve. See how the addition funnel is made by using a rubber stopper and an extra extension of tubing to the top of the funnel Well, that s how one can make a sealed addition funnel out of the ordinary glass separatory funnel that one gets with a distillation kit or from wherever. 

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. 

The mounting cup (ferrule for botde valves) mechanically joins the valve to the container. The mounting cup may be made from a variety of materials, but is typically tin-plated steel coated on the underside. It contains the gasket which provides the seal. Soft gasketing material is appHed wet and bonded in place or, more frequently in larger cans, cut mbber, polyethylene, or polypropylene gaskets are used. 

The spring ensures a soHd closing action and is usually wound from stainless steel wire. The dip tube conducts the product from the container to the valve. It is usually extmded from polyethylene or polypropylene and has an inside diameter of over 2.54 mm, although it can be provided in capillary sizes having diameters down to 0.25 mm. These small tubes are used to reduce flow rate and may function in place of the Hquid metering orifice in the valve housing. 

Bromine ttifluoride is commercially available at a minimum purity of 98% (108). Free Br2 is maintained at less than 2%. Other minor impurities are HF and BrF. Free Br2 content estimates are based on color, with material containing less than 0.5% Br2 having a straw color, and ca 2% Br2 an amber-red color. Fluoride content can be obtained by controlled hydrolysis of a sample and standard analysis for fluorine content. Bromine ttifluoride is too high boiling and reactive for gas chromatographic analysis. It is shipped as a Hquid in steel cylinders in quantities of 91 kg or less. The cylinders are fitted with either a valve or plug to faciUtate insertion of a dip tube. Bromine ttifluoride is classified as an oxidizer and poison by DOT. 

Aqueous hydrogen fluoride of greater than 60% maybe handled in steel up to 38°C, provided velocities are kept low (<0.3 m/s) and iron pickup in the process stream is acceptable. Otherwise, mbber or polytetrafluoroethylene (PTFE) linings are used. For all appHcations, PTFE or PTEE-lined materials are suitable up to the maximum use temperature of 200°C. PTEE is also the material of choice for gasketing. AHoy 20 or Monel is typically used for valve and pump appHcations. Materials unacceptable for use in HE include cast iron, type 400 stainless steel, hardened steels, titanium, glass, and siHcate ceramics. 

Molybdenum hexafluoride is classified as a corrosive and poison gas. It is stored and shipped in steel, stainless steel, or Monel cylinders approved by DOT. Electronic and semiconductor industries prefer the cylinders equipped with valves which have Compressed Gas Association (CGA) 330 outlets. 

Sodium fluoride is normally manufactured by the reaction of hydrofluoric acid and soda ash (sodium carbonate), or caustic soda (sodium hydroxide). Control of pH is essential and proper agitation necessary to obtain the desired crystal size. The crystals are centrifuged, dried, sized, and packaged. Reactors are usually constmcted of carbon brick and lead-lined steel, with process lines of stainless, plastic or plastic-lined steel diaphragm, plug cock, or butterfly valves are preferred. 

Handling Temperatures. Optimum temperature for pumping is in 37—48°C range. Piping should be stainless steel, aluminum, or galvanized iron. Valves and pumps should be bronze, cast-iron with bronze trim, or stainless steel. A pump of 3.15-L/s (50-gal/min) capacity unloads a tank car of warm glycerol in ca 4 h. 

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