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We have a 4 stage vertical pump which suddenly has a lower output pressure and flow. The motor amps has also dropped by 10% or 20%. Marking the pressure and flow on the pump curve, it would appear that the pump curve has dropped by about 1/4. Is it possible that 1 impeller lost its key so...

If the actuator malfunctioned and continued to try to open the valve (pull up on the stem) past its fully open limit, there is a larger section of the stem below the stretched portion that hits the backseat. The stretched area is between where the stem is loaded (by the actuator) and the where...

desertfox - yes, where you see the step or change in the stem's cross section - that is where it is stretched. The stem was of constant cross-section along its length when it was new. It has not completely broken yet (no fracture surface). Very doubtful it is caused by corrosion because the...

This picture shows the damaged/apparently strecthed section of the stem, looking down into the stuffing box/packing area. This valve is currently backseated and locked open but when we get a chance to replace the stem we will test the material...

This picture shows a manual operator, but an electric actuator was installed when the failure occurred. http://files.engineering.com/getfile.aspx?folder=5185cfb3-7026-4812-9609-5a45cdc8912c&file=PC070689.JPG

We have a high pressure, high temp steam valve with a 2.5" stem, 416 SS material, with an electric actuator. We found the stem stretched like a tensile test specimen just before breaking. I do not think the actuator is large enough to exceed the stem's yield strength, even considering the...

Is the rate of pressure change in a piping system limited by the speed of sound? That is, if in a piping system the pump suddenly stops will the pressure at the end of the line be constant until a pressure wave travelling at the speed of sound reaches that point?

We have lubrication oil system that depends on continuous pressure to protect a pump and turbine system with jounal bearings. When power to one pump is lost a second pump turns on immediately but we have found that the system still trips on low bearing oil pressure. Are there any guidelines...

I would like to know what the coefficient of friction is for 90 - 92% alumina ceramic tile. I know that there are many variables that affect it but I do not need precise numbers. I just want to know how alumina ceramic compares to mild steel, stainless steel, and/or chrome carbide overlay. I...

I am looking for approximate relative wear lives of various wear resistant materials, such as ceramics, AR plate, Ni-Hards, chrome carbides, UHMW's, etc. I want to use the relative wear lives combined with the cost differences and ease of installation to choose the optimum wear liner material...

gwolf, Yes, I realize that a person would die - I just did not think I had to actually say it. The water would suck someone into the pipe. What I am looking for is whether or not the flow is enough to suck someone in. A lawyer or insurance agent will not be able to tell me that. I would...

Sorry for the confusion - is a person were to get caught in the flow it could carry them into a 70" diameter pipe that is at least 50 ft long. They could then bump their head and/or become trapped part-way through the pipe.

We have an unprotected dishcarge point from our power plant's cooling pond. It is possible that swimmers can come near it and we need to decide how to protect against someone becoming trapped in the flow of water. We are considering either a cage around the discharge or just floating barriers...

We have an unprotected dishcarge point from our power plant's cooling pond. It is possible that swimmers can come near it and we need to decide how to protect against someone becoming trapped in the flow of water. We are considering either a cage around the discharge or just floating barriers...

I have a drawing that specifies 1/8" thick C.I.R. for a flange gasket material. I suspect that it is actually natural rubber but what does C.I.R. stand for?

We need to torque bolts holding teeth in a conveyor drive sprocket, but there is not enough room to fit the head of the torque wrench on the nut (the bolt head is head by the tooth casting). I have heard of a method to estimate torque by counting the number of turns after finger tight. How...

We have Hawker Siddeley electric motors with a E213TC frame size. I know what 213TC means but what does the "E" refer to?

I am looking for the properties of Nicromol. I am guessing it is a nickel-chrome alloy, Nicromol is probably a brand name, and it is likely obsolete.

I need to know what cast flint is. It is a type of steel we once used for sprockets on large coal scraper conveyors, but have since replaced with a different material. I want to know its hardness, strength, etc to compare to what we are currently using.