Shut-off valves: the working principle in practice
Shut-off valves have one task, which is to isolate a section of pipework fully and reliably, and every design choice follows from that single duty. In practice shut-off valves is rarely a standard question once medium and temperature move away from average. The term shut-off valves is used broadly in the market, which is why it helps to define precisely what it means in your case. A check valve allows flow in one direction only and works without actuation, purely on the basis of the flow itself. Every valve type has its own working principle, and that principle determines where the type is strong and where it falls short. A throttling or control valve is intended to vary flow area rather than to shut off completely, and that difference drives the trim construction. With shut-off valves the seat is the component that determines performance, and the body is rarely the limiting factor. Operating conditions govern the service life of shut-off valves far more strongly than the nominal figures on a datasheet. A correct execution of shut-off valves accounts for real operating conditions and not only for design values. A butterfly valve closes with a rotating disc in the line, giving the most compact and lightest solution at larger diameters. A gate valve closes with a plate moving across the flow, giving an almost unrestricted bore but requiring a long stroke and considerable height. The subject of shut-off valves touches both the construction of the valve and the way the plant is operated.
Specifications and executions of shut-off valves
An isolation valve is not a control valve, and using one for throttling erodes the seat within a short time. What weighs heaviest on shut-off valves in practice is the combination of temperature and differential pressure, not either one alone. How shut-off valves behaves under varying load says more about the quality of the selection than behaviour under steady load. The required leakage class is the defining specification, because that is what isolation actually means in practice. A ball valve closes with a bored ball turning through a quarter turn, which allows fast switching with a full bore. Directional valves are not about shutting off but about routing flow to one of several outlets. A balancing valve makes it possible to limit and measure flow in a branch, so that a system can be brought into balance. Where isolation serves a safety function, tightness stops being a performance figure and becomes a safety requirement. When standardising across a plant we advise deliberately limiting the number of different types. We regularly replace gate valves with metal seated butterfly valves, gaining on weight, space and operating torque. We regularly see that a small change in the execution of shut-off valves makes a large difference to maintenance frequency. For shut-off valves this means that construction and operating conditions cannot be judged separately.
Shut-off valves in demanding installations
They are used for plant isolation, maintenance isolation, tank connections and emergency shutdown duty. In process industry all types sit alongside each other in the same plant, each where that type is strongest. In chemicals the choice is driven mainly by medium compatibility and by the required tightness. In an existing plant shut-off valves is often part of a wider question about availability and maintenance. The application range of shut-off valves runs from simple utility duty to heavy process plant, with a corresponding difference in execution. On replacement we always check the existing installation dimensions for shut-off valves, so the pipework can stay untouched. In plants where shut-off valves is applied, the emphasis is on reliability rather than lowest purchase price. In utilities and water treatment butterfly and gate valves dominate through their price at large diameters. Alongside QUADAX and PRUSS we represent Pibiviesse, Schroeder, Striko, Malbranque, Daume, FluoroSeal and Guichon, so we can select the right brand for each project. Our market is project driven and international, and we deliver worldwide to installers, EPC contractors and end users. Our customers use shut-off valves in positions where a failure has immediate consequences for production. For shut-off valves the sector determines which documentation and tests belong with the delivery.
How to select shut-off valves without mistakes
Standardising across several positions makes shut-off valves simpler in maintenance and in spare parts management. We choose the type on the basis of the duty, because an isolation valve and a control valve are two different products. On fouled or fibrous media we look at the shape of the flow path, because build up and blockage are the real failure mechanisms. Where there is doubt we quote two types side by side, with advantages and disadvantages stated explicitly. On shut-off valves we also state what an execution cannot do, because that prevents more problems than a list of advantages. The required leakage class often drives the choice around shut-off valves more strongly than the budget does. The cleaning and flushing procedure counts too on shut-off valves, because it can be more aggressive than the process itself. In our advice we also state what a type cannot do, because that prevents more problems than a list of advantages. Dutch Valve Vision deliberately does not supply every type, but focuses on the specials where the standard market drops out. If you have an existing tag plate or serial number, send it along, because that lets us work directly from the original configuration. On shut-off valves we check that the actuator is sized on torque at maximum differential pressure and not on an average value. The right choice around shut-off valves starts with a full set of process data rather than with a request for a price.
Ordering shut-off valves from Dutch Valve Vision
We handle an enquiry for shut-off valves on its technical merits rather than as a price request that only produces a number. What defines us is that we would rather spend an extra half hour on the specification than ship the wrong valve that comes back two months later. Our specialists are happy to discuss shut-off valves on the basis of your P&ID, your datasheet or simply a photograph of the situation. We think along on the spare parts strategy for shut-off valves, so critical positions stay covered. For repeat orders of shut-off valves we record the configuration, so a follow up delivery is identical to the first. 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 quote a realistic lead time rather than an optimistic one, because a missed delivery date costs more than an extra week in the planning. We work on shut-off valves under a KIWA ISO 9001 certified quality system, which safeguards traceability. We record which execution of shut-off valves was delivered, so a follow up delivery or spare part matches exactly later on. Tests around shut-off valves are carried out by us or on our instruction according to the requirements in the specification. Even when the specification for shut-off valves is not yet finalised, you can bring the question to us. Bring us your question at sales@dutchvalvevision.com or +31 (0)70-2210560, even when the specification is not finalised yet.
Frequently asked questions about shut-off valves
What exactly does shut-off valves mean?
Every valve type has its own working principle, and that principle determines where the type is strong and where it falls short. A check valve allows flow in one direction only and works without actuation, purely on the basis of the flow itself. Directional valves are not about shutting off but about routing flow to one of several outlets. A butterfly valve closes with a rotating disc in the line, giving the most compact and lightest solution at larger diameters. We see this come back regularly in enquiries about shut-off valves, and the answer is rarely a single sentence. In most projects shut-off valves turns out to be less standard than it first appears. We approach shut-off valves from the question of what the plant has to do, not from the question of what happens to be in stock. What defines us is that we would rather spend an extra half hour on the specification than ship the wrong valve that comes back two months later.
Which executions of shut-off valves are available?
Where isolation serves a safety function, tightness stops being a performance figure and becomes a safety requirement. A ball valve closes with a bored ball turning through a quarter turn, which allows fast switching with a full bore. We regularly replace gate valves with metal seated butterfly valves, gaining on weight, space and operating torque. Dutch Valve Vision deliberately does not supply every type, but focuses on the specials where the standard market drops out. We always explain why we arrive at a particular recommendation on shut-off valves, so you can follow the reasoning yourself. That makes shut-off valves a subject where discussion up front pays for itself in operation. With shut-off valves it pays to include phase changes in the medium, because those sharply increase the load on the seal. 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 materials are used for shut-off valves?
A throttling or control valve is intended to vary flow area rather than to shut off completely, and that difference drives the trim construction. A gate valve closes with a plate moving across the flow, giving an almost unrestricted bore but requiring a long stroke and considerable height. A balancing valve makes it possible to limit and measure flow in a branch, so that a system can be brought into balance. In our advice we also state what a type cannot do, because that prevents more problems than a list of advantages. On shut-off valves we include start up and shutdown, because that is where the heaviest loading occurs. On shut-off valves we prefer a well founded answer to a fast one that turns out to be wrong later. In practice we find that most failures around shut-off 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.
What should I watch technically on shut-off valves?
What should I watch technically on shut-off valves?
Which applications call for shut-off valves?
In process industry all types sit alongside each other in the same plant, each where that type is strongest. In chemicals the choice is driven mainly by medium compatibility and by the required tightness. In utilities and water treatment butterfly and gate valves dominate through their price at large diameters. They are used for plant isolation, maintenance isolation, tank connections and emergency shutdown duty. Our experience with shut-off valves comes from projects in chemicals, power generation, technical gases and offshore. The answer to this question on shut-off valves changes as soon as the medium or the temperature changes. Demand for shut-off valves reaches us mainly from projects where the standard range falls short. Dutch Valve Vision operates under a KIWA ISO 9001 certified quality system, which in the RFQ stage of chemical and offshore projects is usually a hard requirement.
What determines the price and lead time of shut-off valves?
For an accurate quotation we need the nominal diameter, the pressure class, the medium, the operating temperature and the required actuation. 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. We come back with a proposal that explains why we recommend a particular execution, including the alternatives we considered. We keep spare parts and overhaul kits mapped per project, so that a breakdown does not start with a search from scratch. If you are unsure about this on shut-off valves, we are glad to put the question alongside the actual process data. The answer on shut-off valves depends strongly on operating conditions, which is why we always ask for those first. Dutch Valve Vision stays available after delivery of shut-off valves for technical questions and for parts. You can reach us on +31 (0)70-2210560 and at sales@dutchvalvevision.com, and our office hours are Monday to Friday from 09:00 to 17:00.
What about maintenance and spare parts on shut-off valves?
Documentation such as material certificates, test reports and declarations is supplied as standard, matched to what the project requires. On repeat orders we record the configuration, so a follow up delivery is identical to the first and installation holds no surprises. 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. 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 always explain why we arrive at a particular recommendation on shut-off valves, so you can follow the reasoning yourself. That makes shut-off valves a subject where discussion up front pays for itself in operation. We keep the configuration data for shut-off valves on file, which saves a great deal of searching if a fault occurs later. Our customers work in chemicals, petrochemicals, pharmaceuticals, power generation, offshore and in hydrogen and ammonia projects.
How do I request a quotation for shut-off valves?
If you have an existing tag plate or serial number, send it along, because that lets us work directly from the original configuration. Please also state the connection standard, the required leakage class and any project requirements such as NACE, PED or ATEX. A P&ID, a datasheet or even a photograph of the existing installation often helps us faster than a long description. We come back with a proposal that explains why we recommend a particular execution, including the alternatives we considered. On shut-off valves we prefer a well founded answer to a fast one that turns out to be wrong later. We always explain why we arrive at a particular recommendation on shut-off valves, so you can follow the reasoning yourself. For shut-off valves you can come to Dutch Valve Vision for the selection, the delivery and the support afterwards. 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.