Valve gate

An unprotected rising stem that is corroded or painted can make the valve difficult to operate. Stem protectors and keeping the stem packed in grease help alleviate this problem. 

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Gate design Gate valves Gatorizing Gatorizing process Gatsch... 

Fig. 2. (a) Gate valve (b) plug valve and (c) globe valve. 

The modulus of elasticity (MOE) is related to the strength and can be used as a nondestmctive quaUty control test on high cost special refractory shapes such as sHde gate valves employed in the pouring of steel (qv). The sHde gate type must be selected to ensure chemical compatibiUty and it must be used in a way to reduce thermal shock. The performance of a properly selected and used sHde gate is direcdy related to its strength and therefore predicted by its MOE. 

Gate valve Globe valve Check valve Angle valve... 

A simple example of an area meter is a gate valve of the rising-stem type provided with static-pressure taps before and after the gate and a means for measuring the stem position. In most common types of area meters, the variation of the opening is automatically brought about by the motion of a weighted piston or float supported by the fluid. Two different cyhnder- and piston-type area meters are described in the ASME Research Committee on Fluid Meters Report, op. cit., pp. 82-83. 

Gate valves are used to minimize pressure drop in the open position and to stop the flow of fluid rather than to regulate it. The problem, when the valve is closed, of pressure buildup in the bonnet from cold liquids expanding or chemical action between fluid and bonnet should be solved oy a relief valve or by notching the upstream seat ring. 

Pressure drop through globe valves is much greater than that for gate valves. In Y-type globe valves, the stem and seat are at about 45° to the pipe instead of 90°. This reduces pressure drop but impairs ahgnment of seat and disk. 

Gate valves with rising spindles are friendlier than valves with nonrising spindles, as it is easy to see whether they are open or shut. Ball valves are friendly if the handles cannot be replaced in the wrong position. 

Particularly reasonably priced explosion isolation of systems involves the use of a relief pipe with which the flow direction can be diverted by 180°. It prevents flame jet ignition with precompression in constructionally protected equipment. If suction is present, explosion propagation can occur. To prevent this, the use of an additional extin-gui ing barrier or a rapid-action gate valve is necessary. If a diverter is installed where positive pressure feed is given, then the diverter is, in general, safe against an explosion propagation. 

Convert globe valves into gate valves if possible. 

This system piping uses fittings with bolted Ilanges, see Figure 8-5. The 6 inch elbows have a eonstant (K value) of 0.280. The 4 inch elbows have a K value of 0.310. The 6 inch gate valves have a K value of 0.09. The 4 inch gate valves have a K value of 0.15. The 4 inch globe valve... 

There are 5 valves in all. There are two 6 ineh gate valves in the siietion pipe. There is a 4 ineh gate valve, a 4 inch globe valve, and a 4 ineh cheek valve in the discharge pipe. The formula is ... 

A pipe size incrcascr can be used in the discharge piping. This will reduce the fluid velocity and friction losses. An isolation valve with a low loss characteristic such as a gate valve should he placed after the increaser and check valve. 

A refinery operation produces about 500,000 barrels of crude per year. There are approximately 1500 gate valves used in the operation. Develop an estimate of the potential hydrocarbon emissions resulting from valve leakage. What is this worth in terms of lost revenues to the facility You can find some information on typical valve leakage rates from searching on w w w. google. com. 

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