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The difference between a full-bore ball valve and a class 300 butterfly, in terms of Cv is HUGE. A ball valve manufacturer you may wish to try is PBV of Houston, Tx. http://www.pbv-usa.com/ Mike Mike

Hahaha. Spears make a great valve. Any quality iron or steel butterfly valve comes with an epoxy-coated lever. Good choice. Mike

If the control room stays under 140F and you chilled water pressure is under 150psi, they'll be fine. Mike

A safe way to go would be to purchase ASME code 2:1 elliptical heads as opposed to welding plates. Brighton Heads (don't have the web address) can supply them. Mike

It sounds like you may be adding to your problems by replacing sections with stainless steel. Your initial problem was probably carbonic acid formation due to air in the system. Now you'll encounter galvanic corrosion as well. It may sound overly simplistic, but consider a heavier wall carbon...

The short-version answer is 'fully open'. For gate and globe valves you want to fully backseat the valve.

I'm not sure 'upgrade' is a good term. The pvc valves are twice as expensive as cast iron resilient seated butterflys. PVC butterfly valves are rated to 150psig@73F for sizes 12"NPS and less and 40F is within it's limitations. Class 125 (good for 200WOG) cast iron body butterfly valves...

pmover, For coal ash hoppers I'd recommend a metal-seated knife gate valve with grafoil packing. They do a good job slicing through, and sealing, againt ash. They're used with much success in the New England area. Yes, they'll wear out eventually, but the pricing and ease of installation...

http://www.velan.com/ Velan manufactures ball and gate valves and has an awesome engineering group.

If particulate is an issue, and you decide to use a ball valve, a metal-seated ball valve would be in order. Just a precaution with ball valves, if you were to close the valve and bring it to the surface at some point, the ball would trap the pressurized media. You may wish to consider a vented...

A knife gate valve is just what it implies. Knife gate valves were originally designed for the pulp and paper industry. Stringy pulp would impinge between the wedge and seat of a normal gate valve and prevent flow shut-off. The knife gate valve was designed with a sharp edge to cut through the...

Thanks abeltio. I'm going with thermostatic traps for that exact reason (12 degree subcool).

Yes it is, but it's 'free' (haha). The coils are 40 years old and have worked well up until 4 of the 24 coils froze and burst (yep, trap failures). Thanks TD2K.

I'm trying to calculate the condensate load of a steam coil (steam is taken from the cold reheat line off a boiler) used to warm inlet air to the boiler. Conditions are as follows: 65psig superheated steam @ 610F inlet pressure, heating 176,000 cfm air from 0F to 123F. Steam velocity is roughly...

Wow, my first question on here... I'm trying to calculate the condensate load of a steam coil (steam is taken from the cold reheat line off a boiler) used to warm inlet air to the boiler. Conditions are as follows: 65psig superheated steam @ 610F inlet pressure, heating 176,000 cfm air from 0F...

I'd advocate 75-100psi pressure if substantial backpressures are not an issue. The abilty to use as much latent heat as possible, without freezing, is desireable. If your traps are working properly, freezing won't be an issue at 75#.

Currently produced bellows-sealed globe valves are produced to API Class 800 at minimum. B16.11 covers socket weld dimensions. B16.34 is relative to pressure class. Bonney Forge, Edward Vogt, OMB, and a variety of other manufacturers produce Class 800 valves in A105 quite economically. Mike

Metal-seated ball valves are rated to ANSI Class VI leakage at best and have very high torque values. I normally use steam traps for main turbine drains. Plenty Products offers 2" traps in F22. Pressures to 10340 KPa at 570c are no problem. Capacities up to 30000 Kg/Hr at this criteria. Mike

Your valves are most likely trunion style ball valves with RTFE seat and seals. The original leakage rate for these valves is 'bubble tight' (zero leakage at full rated Dp). If the valves are trunion style, they are in-line repairable. The seats are designed using a molded polymer with 'memory'...

MJC's point is well taken, I neglected to state at ambient temp. Again, not knowing the specific stress value (using minimum) of the pipe and without developing a line spec, the calc above will get you close at ambient temp. I believe flanges are B16.5 Mike