Cast Steel or Iron Gate Valves?
Cast Steel or Iron Gate Valves?
(OP)
Which gate valve is better for 125 psig steam, cast steel or iron? Why?
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Cast Steel or Iron Gate Valves?
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RE: Cast Steel or Iron Gate Valves?
RE: Cast Steel or Iron Gate Valves?
Check out www.kirsner.org for some shots of failed 125 cast iron components - usually involving fatalities.
I've worked with steam for 30 years, and I absolutely LOATHE 125 cast iron valves & fittings - even where permitted by code.
RE: Cast Steel or Iron Gate Valves?
RE: Cast Steel or Iron Gate Valves?
Here's a link to a web site that has several articles on cast iron versus steel:
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Patricia Lougheed
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RE: Cast Steel or Iron Gate Valves?
Paul Ostand
www.ostand.com
RE: Cast Steel or Iron Gate Valves?
So, if you drop a cast iron valve it may crack but not a steel.
My customers prefer also steel in steam service because of the chance of water hammer. Large banging in the pipes could crack the flange of cast iron and not steel.
In refineries and chemical plants they often do not allow cast iron, but for another reason. If there is a fire, the cast iron tensile strength breaks down at a lower temperature than that of steel.
Ductile Iron is more malleable than cast iron, has many of the same properties of steel at a reduced cost. It is a great material!
RE: Cast Steel or Iron Gate Valves?
RE: Cast Steel or Iron Gate Valves?
RE: Cast Steel or Iron Gate Valves?
RE: Cast Steel or Iron Gate Valves?
RE: Cast Steel or Iron Gate Valves?
Gate valves do not throttle well like globes. However, gates do offer large Cv's for the size and if used for shut-off only and maintained full open for flowing they may be appropriate. However, do look at the design to assure the gate is out of the flow stream and talk to the manufacturer.
Further, regardless what you select the valve should be for steam service in addition to having the T & P capabilities.
Paul Ostand
www.ostand.com
RE: Cast Steel or Iron Gate Valves?
However, while I don’t think the particular all ductile iron valves pictured should be used for steam applications you may nevertheless be interested in the general material-related features and special testing of some gate valves contained in the four minutes or so video "Ductile versus Gray Presentation" near the bottom of the page http://www.acipco.com/afc/videos.cfm under the heading “Product Presentation Files”. This video provides some more information/clues as to how/why gray cast iron valves might be more easily overloaded or broken in handling, installation, and or service events than the much stronger/tougher ductile material, and probably also why some manufacturers and users have opted instead for ductile iron constructions.
RE: Cast Steel or Iron Gate Valves?
That is a nice video.
BronYrAur:
One more bit of information. Jordan Valve makes a sliding gate valve specifically for steam service. It is available in DI, Steel and other materials. You might look at it for your application.
(I don't work there but I did at one time.)
Paul Ostand
www.ostand.com
RE: Cast Steel or Iron Gate Valves?