Power plant valves
Everything about power plant valves for industry
The working principle of power plant valves
Power plant valves cover the steam, feedwater, condensate, flue gas and bypass circuits around boilers and turbines. Once power plant valves is correctly specified it disappears from the fault list, and that is exactly the intention. We approach power plant valves from the question of what the plant has to do, not from the question of what happens to be in stock. Steam is a demanding medium because pressure and temperature rise together and the medium can change phase within the same line. An emergency stop valve shuts off supply in a hazardous situation, and closing time there is a safety parameter rather than a comfort requirement. On a boiler, blowdown valves control the salt content of the boiler water, with continuous blowdown for fine control and periodic blowdown for sludge at the bottom. What weighs heaviest on power plant valves in practice is the combination of temperature and differential pressure, not either one alone. With power plant valves it pays to include phase changes in the medium, because those sharply increase the load on the seal. With power plant valves the seat is the component that determines performance, and the body is rarely the limiting factor. A desuperheater injects water into the steam flow to bring temperature back to just above saturation, where atomisation quality determines the result. A turbine bypass routes steam around the turbine during start up and on a trip, and that valve has to handle a large duty within seconds. There are assumptions circulating about power plant valves that do not hold up under closer examination.
Material, seat and construction on power plant valves
Availability drives everything here, because an unplanned stop costs far more than the valve itself ever did. Operating conditions govern the service life of power plant valves far more strongly than the nominal figures on a datasheet. A correct execution of power plant valves accounts for real operating conditions and not only for design values. Pressure and temperature rise together in these circuits, which pushes selection towards alloy steel bodies and hardened trim. A pressure reducing station brings steam pressure back to the level the consumers require and holds that pressure stable under varying demand. Condensate carried along in a steam line causes erosion and water hammer, and both attack a valve faster than the steam itself. In superheated steam the temperature sits above saturation, and soft seats and ordinary packings are then no longer usable. Thermal cycling from start up and shutdown fatigues seats and packings faster than steady operation does. On commissioning we record set pressure, closing time and test results, so the plant can be shown to run within specification. Insulation around a steam valve should leave the actuator clear, because overheating of the actuator is a common cause of failure. We regularly see that a small change in the execution of power plant valves makes a large difference to maintenance frequency. That principle explains why power plant valves behaves differently from a standard execution under heavier duty.
Power plant valves in demanding installations
They sit in boiler houses, combined heat and power plants, waste to energy plants and increasingly in hydrogen fired installations. In process industry steam is used for heating, stripping and sterilisation, and each of those duties sets its own requirements. In power generation these valves sit on the critical paths around boiler and turbine, where downtime costs money immediately. We supply power plant valves both for new build and for replacement within existing installations. In an existing plant power plant valves is often part of a wider question about availability and maintenance. On replacement we always check the existing installation dimensions for power plant valves, so the pipework can stay untouched. During turnarounds power plant valves is regularly on the critical path, and then predictability matters more than the lowest price. Boiler houses, combined heat and power plants and district heating together form the largest application area for these valves. Our customers work in chemicals, petrochemicals, pharmaceuticals, power generation, offshore and in hydrogen and ammonia projects. We think along from the basic specification through to the tag plate, and supply documentation that a buyer or inspector accepts without discussion. Demand for power plant valves reaches us mainly from projects where the standard range falls short. On project supply we record per position which execution of power plant valves was delivered, including materials and tests.
Choosing the right power plant valves
If a simpler type will do the job, we say so on power plant valves, even when that means a smaller order. At large pressure ratios we use multistage or perforated trim to keep noise and erosion within acceptable limits. On steam applications we always ask for pressure and temperature upstream and downstream, because pressure drop defines the trim construction. Material selection for steam moves towards alloy steel with hardened trim, because erosion and thermal cycling weigh heaviest. The cleaning and flushing procedure counts too on power plant valves, because it can be more aggressive than the process itself. For power plant valves total cost of ownership weighs more than purchase price, certainly when replacement has to happen during a shutdown. We never recommend a heavier execution of power plant valves than needed, because over specification only raises price and lead time. Where power plant valves forms part of a safety function we record the fail position and required stroking time explicitly. On steam we always advise a condensate drain upstream of the valve, because it is the cheapest life extension available. PRUSS is strongly represented in this segment with valves for steam, boiler, turbine and gas turbine duty. If you have an existing tag plate or serial number, send it along, because that lets us work directly from the original configuration. The right choice around power plant valves starts with a full set of process data rather than with a request for a price. On power plant valves we also state what an execution cannot do, because that prevents more problems than a list of advantages.
Your enquiry for power plant valves at Dutch Valve Vision
For repeat orders of power plant valves we record the configuration, so a follow up delivery is identical to the first. Our market is project driven and international, and we deliver worldwide to installers, EPC contractors and end users. We supply power plant valves as a loose product or as a fully assembled unit with actuator and accessories. On power plant valves we come back with a proposal that explains why we recommend a particular execution. Dutch Valve Vision stays available after delivery of power plant valves for technical questions and for parts. For shutdowns and turnarounds we look at accelerated routes, and in those cases we are honest up front about what is and is not achievable. On power plant valves we make sure the chosen execution demonstrably meets the stated standards rather than merely looking plausible on paper. Documentation on power plant valves has to be the kind a buyer or inspector accepts without discussion. Material certificates and test reports are supplied with power plant valves, matched to what the project requires. We handle an enquiry for power plant valves on its technical merits rather than as a price request that only produces a number. Our specialists are happy to discuss power plant valves on the basis of your P&ID, your datasheet or simply a photograph of the situation. We are based at Vlotlaan 641, 2681 TZ Monster in the Netherlands and can be reached on +31 (0)70-2210560 and at sales@dutchvalvevision.com.
Frequently asked questions about power plant valves
What exactly does power plant valves mean?
On a boiler, blowdown valves control the salt content of the boiler water, with continuous blowdown for fine control and periodic blowdown for sludge at the bottom. A turbine bypass routes steam around the turbine during start up and on a trip, and that valve has to handle a large duty within seconds. In superheated steam the temperature sits above saturation, and soft seats and ordinary packings are then no longer usable. Steam is a demanding medium because pressure and temperature rise together and the medium can change phase within the same line. That makes power plant valves a subject where discussion up front pays for itself in operation. We see this come back regularly in enquiries about power plant valves, and the answer is rarely a single sentence. With power plant valves the difference between a good and a mediocre solution often sits in details that do not show on a drawing. Dutch Valve Vision supplies special valves for special applications from its base in Monster, the Netherlands, with QUADAX and PRUSS as the core brands in the programme.
Which executions of power plant valves are available?
On steam we always advise a condensate drain upstream of the valve, because it is the cheapest life extension available. A pressure reducing station brings steam pressure back to the level the consumers require and holds that pressure stable under varying demand. PRUSS is strongly represented in this segment with valves for steam, boiler, turbine and gas turbine duty. Pressure and temperature rise together in these circuits, which pushes selection towards alloy steel bodies and hardened trim. This is one of the points on power plant valves where suppliers differ most clearly from one another. For power plant valves a good specification up front is cheaper than a correction afterwards. In practice we find that most failures around power plant valves come not from the material but from a wrong assumption during selection. We work as a technical supplier rather than a catalogue reseller, which means we carry out the selection ourselves on the basis of medium, pressure, temperature and code requirements.
Which materials are used for power plant valves?
On commissioning we record set pressure, closing time and test results, so the plant can be shown to run within specification. Thermal cycling from start up and shutdown fatigues seats and packings faster than steady operation does. An emergency stop valve shuts off supply in a hazardous situation, and closing time there is a safety parameter rather than a comfort requirement. A desuperheater injects water into the steam flow to bring temperature back to just above saturation, where atomisation quality determines the result. In most projects power plant valves turns out to be less standard than it first appears. On power plant valves we prefer a well founded answer to a fast one that turns out to be wrong later. The balance between required tightness and available operating force is a recurring tension on power plant valves. Our market is project driven and international, and we deliver worldwide to installers, EPC contractors and end users.
What should I watch technically on power plant valves?
What should I watch technically on power plant valves?
Which applications call for power plant valves?
In process industry steam is used for heating, stripping and sterilisation, and each of those duties sets its own requirements. They sit in boiler houses, combined heat and power plants, waste to energy plants and increasingly in hydrogen fired installations. In power generation these valves sit on the critical paths around boiler and turbine, where downtime costs money immediately. Boiler houses, combined heat and power plants and district heating together form the largest application area for these valves. On power plant valves we include start up and shutdown, because that is where the heaviest loading occurs. If you are unsure about this on power plant valves, we are glad to put the question alongside the actual process data. The application range of power plant valves runs from simple utility duty to heavy process plant, with a corresponding difference in execution. Alongside QUADAX and PRUSS we represent Pibiviesse, Schroeder, Striko, Malbranque, Daume, FluoroSeal and Guichon, so we can select the right brand for each project.
What determines the price and lead time of power plant valves?
Please also state the connection standard, the required leakage class and any project requirements such as NACE, PED or ATEX. We quote a realistic lead time rather than an optimistic one, because a missed delivery date costs more than an extra week in the planning. Lead times depend on the execution, because a standard size from a running series behaves very differently from a valve in an exotic alloy with NACE certification. On repeat orders we record the configuration, so a follow up delivery is identical to the first and installation holds no surprises. We always explain why we arrive at a particular recommendation on power plant valves, so you can follow the reasoning yourself. The answer on power plant valves depends strongly on operating conditions, which is why we always ask for those first. Even when the specification for power plant valves is not yet finalised, you can bring the question to us. Send us your DN, pressure class, medium and temperature at sales@dutchvalvevision.com, or call +31 (0)70-2210560 to speak to a specialist.
What about maintenance and spare parts on power plant valves?
Documentation such as material certificates, test reports and declarations is supplied as standard, matched to what the project requires. For shutdowns and turnarounds we look at accelerated routes, and in those cases we are honest up front about what is and is not achievable. We keep spare parts and overhaul kits mapped per project, so that a breakdown does not start with a search from scratch. Lead times depend on the execution, because a standard size from a running series behaves very differently from a valve in an exotic alloy with NACE certification. On power plant valves we include start up and shutdown, because that is where the heaviest loading occurs. In most projects power plant valves turns out to be less standard than it first appears. We keep the configuration data for power plant valves on file, which saves a great deal of searching if a fault occurs later. We think along from the basic specification through to the tag plate, and supply documentation that a buyer or inspector accepts without discussion.
How do I request a quotation for power plant valves?
We come back with a proposal that explains why we recommend a particular execution, including the alternatives we considered. For an accurate quotation we need the nominal diameter, the pressure class, the medium, the operating temperature and the required actuation. If you have an existing tag plate or serial number, send it along, because that lets us work directly from the original configuration. A P&ID, a datasheet or even a photograph of the existing installation often helps us faster than a long description. Our experience with power plant valves comes from projects in chemicals, power generation, technical gases and offshore. That makes power plant valves a subject where discussion up front pays for itself in operation. For power plant valves you can come to Dutch Valve Vision for the selection, the delivery and the support afterwards. Requests can be submitted by phone on +31 (0)70-2210560, by e-mail at sales@dutchvalvevision.com or through the contact form on our website.