Valves Stock

Valves for pressures below 5,000 psi are designed according to ASA standards and are generally available from stock. Valves for higher pressures may be purchased from companies which design and produce special valves. 

The work was carried out in a Stock high-vacuum apparatus (see Part 1, p. 66) because of the sensitivity of these compounds to air, moisture, and stopcock grease. The apparatus was constructed according to Wiberg and Siitterlin s directions however, each trap was also connected to the large diameter pump manifold via a Stock valve so that an optimum vacuum could be maintained by the pump during the transport of material. 

The first target of quality control in MD is to keep the main quality parameters of the produced paper within the limits defined for the current production. As an example, basis weight control is achieved by continuously adjusting the stock valve, which feeds the blended stock to the machine. 

MD controls are slow but complex control loops. Only two to three measurements are available per minute. Using interpolation techniques or Kalman filters, control steps can be performed every 5 to 10 s. MD controls are complex because of the considerably large transport dead time between actuators (i.e. stock valve) and measurement (i.e. scanner at the reel), which is typically larger than 1 min. 

Cylinder oil is a viscous oil used for lubricating the cylinders and valves of steam engines (see Lubrication and lubricants). It is prepared from cylinder stock. The product from cylinder stock, when filtered and processed, is bright stock. 

Stainless steel centrifiigal pumps may be used to transfer dimer acid stocks. Pipe, valves, and fittings may be of 304 stainless steel if the Hquid temperature is maintained below 107°C. The recommended temperature ranges for transfer (pumpiag) of dimer acids and related stocks are as follows. 

The valve was made of brass and was of a type stocked for use on domestic water systems. It was not the correct pressure rating for LFG. 

Try 1/ -inch (i.d. = 1.61), since 114-inch (i.d. = 1.38) is not stocked in every plant. If it is an acceptable plant pipe size, then it should be considered and checked, as it would probably be as good pressure drop-wise as the 114-inch. The support of 114-inch pipe may require shorter support spans than the 114-inch. Most plants prefer a minimum of 114-inch valves on pressure vessels, tanks, etc. The valves at the vessels should be 114 inch even though the pipe might be VA inch The control valve system of gate and globe valves could very well be lA inch. For this example, use 114-inch pipe, Schedule 40 ... 

The feed stock, usually topped or reduced crude oil, is heated in pipe coils (Figure 1) from about 900° to 950° F. The oil is then fed to one of two or more vertical, insulated coke drums. The coke drums are connected by valves so that they can be switched onstream for filling, then switched off-stream for coke removal. The temperature in the drum will ordinarily be 775° to 850° F. and the pressure 4 to 60 pounds per square inch gage. Hot, coke-still vapors from the coke drum pass to a fractionator where gas and gasoline, intermediate gas oil, and heavy gas oil are separated. More or less of the heavy gas oil is recycled. The ratio of recycled heavy gas oil to fresh feed is usually less than 1 but may go up to about 1.6 (5,15,28, 40). 

Sour gas applications Here, NACE recommendations (see Section 4.4) should be followed. Most wrought grades are acceptable to NACE. Therefore, in general, duplex valves with bar stock nozzles and discs will meet NACE requirements. Some limited cast grades will generally comply also ... 

A database such as this is also important where valve interchangeability is required in order to determine a minimum stockholding for maintenance purposes. Valves of similar body and trim materials can possibly be utilized in many different locations and services, thus removing the need for one-to-one valve stocking. This system will also mean that valves can easily be sourced from non-essential systems in order to maintain essential system viability. 

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