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Parallel slide gate valves are used at the power generating stations. The advantages over gate valves is lower friction, cannot be damaged for overtightening, and better sealing due to the flexubility built in the design. The manufacuring does not require matching gate to the body. I have used...

We find Velan Valves are the best. Their ball valves are low torque, and fire safe.

onuigbo: Just curious about your statement "We deliver steam as if your life depends on it". I hope you are not referring to your self and your boss.!!! Anyway, your steam pressure and temperature is the same. I am assuming that you are collecting the condensate. If so, then the following may...

Unclesyd, thanks for your comments; you have a wealth of knowledge and experience which is invaluable, especially to newer engineers. It is also nice of you to share it. Thanks again very much.

Unclesyd What is your opinion about hydrostatic testing in general. I have found that a material or fitting may be damaged visually to an unacceptable level and still pass the hydrostatic test at 1.5 times, if necessary. A weld of relatively poor quality will also pass similarly. NDT testing...

Ralph2: Unclecyd is correct. Go with a pup piece and end cap rated for class 1500. Alternative is to weld a WN flange to the tee and then bolt blind flanges to the welded flanges. You must use class 1500 gasket and cover the flange separation faces with a shield so that if the gasket leaks, no...

I cannot confirm it at the moment but I believe that stubs are permitted but you must derate the pressure rating by 50%. The maximun size of stub permitted is 0.5* main pipe nominal diameter. Like i said I cannot confirm this but this is our guide-line. The weld must be full penetration for stub...

You can calculate the thickness from the PressureVessel Codes. If you do not have one, I would suggest you get someone to do that. I presume your cast tee is cast steel, and the metal thickness will be well in excess of 1". Welding something to it, pressure testing it and them removing it to...

To add to your suggestion, consider heat transfer and cooling as a two way street. The inside of the tubes must be clean as well as the outside. we clean the inside of tubes as well as outside. Our fins are strong enough for chemical cleaning the outside. The inside is HP water blasted. Regards.

For testing oxygen piping which has been radiographed, nitrogen 9or inert gas) is the best medium. The nitrogen must be DRY and OIL FREE. the pressure test should be carried out in several small increments. We would normally snoop for leakage at all welds and gasket joints. When the final test...

Second UPDATE ON OUR 4-COMPRESSORS. We have increased the speed of our two turbine compressors to 3350 RPM. Now we export the excess copreesed air capacity to adjacent mill. Our BOSC runs fine on just 3 compressors. We have no problems with low pressure alarms on our Instrument Air systems and...

As mentioned by GregLocock, you need the Holzer method. In this you must include the motor inertia, shaft stiffness to the coupling, coupling inertia, the pump shaft stiffness, the impeller wet inertia. The latter will approximate to inertia of the impeller and the entrained water. Having...

AN UPDATE ON OUR 4-AIR COMPRESSORS. We checked the compressors for deficiencies and corrected them. This was mainly oil cooler fouling on the water side, thermostatic valves replaced, pneumatics cleaned and adjusted etc. We then increased the speeds of the two steamers to 3170 rpm in steps. We...

There are certain processes which require canned or sealess pumps for the very reason that a mechanical seal may fail and cause fires. I would not try to justify a mechanical seal. Where temeprature rise is a consideration, we have used a bypass route with a thermostatically controlled process...

zdas04 Thankyou for your valuable comments. We are planning to do exactly what you stated. We have a four compressor operation at our hot strip mill, and we use the stepper control. In our case all four machines run from a pressure switch & we can select the lead compressor. The rest follow the...

Thanyou Zdas04 for your question. It has helped me very much.

pmover & zdas04: It appears I am pretty good at confusing people. I have done a fair amount of research and am a bit wiser. We are working very closely with our maintenance people as this has been a longterm problem. To explain a bit more clearly: 1. The suction side of the valve has a...

mesqrueda an electric motor is a contant speed device. It maintains the contant speed even though the torque may fluctuate. an air motor can approximate to a constant torque device. it maintains the torque contant but varies the speed. I would use an electric motor of the appropriate class for...

pmover I hope you did not misunderstand me. The compressor reps say that since it is a positive displacement screw compressor, the output should be proportional to speed. To do this, the suction must also be positive(mass) suction. I donot believe one can get positive(mass) suction. This is what...

I have been on vacation for two weeks. Hence the delay in responding. My apologies. I also apologise (pmover & 4842) for the vague nature of my question. These are air compressors, flooded screw type. All compressors are the same type and size (but I am going to reconfirm this by their S/Nos.)...