Hydraulically piloted valves
Everything about hydraulically piloted valves for industry
The technology behind hydraulically piloted valves explained
Hydraulically piloted valves use a small pilot flow to operate a much larger main valve, so limited control energy can move a large closing element. Once hydraulically piloted valves is correctly specified it disappears from the fault list, and that is exactly the intention. Anyone looking into hydraulically piloted valves quickly runs into a choice that goes beyond picking a catalogue number. Vacuum service reverses the requirement, because atmosphere pushes inwards and the seal has to hold from outside to inside. In hot oil and thermal oil service packing creep and coking on leakage are the issues, which calls for a packing system that retains preload. Hydrogen also brings embrittlement into play, which rules out certain steel grades and hardness levels. In practice we find that most failures around hydraulically piloted valves come not from the material but from a wrong assumption during selection. With hydraulically piloted valves it pays to include phase changes in the medium, because those sharply increase the load on the seal. That principle explains why hydraulically piloted valves behaves differently from a standard execution under heavier duty. Hydraulic systems work with high pressure and small volumes, so leakage quickly leads to pressure loss and contamination. Hydrogen has a very small molecule, so a seal that is adequate for nitrogen may still leak on hydrogen. We find that questions about hydraulically piloted valves almost always come back to the same three points: medium, temperature and required tightness.
Hydraulically piloted valves and the decisive technical choices
The pilot circuit determines the response of the whole assembly, which makes pilot reliability critical. With hydraulically piloted valves the seat is the component that determines performance, and the body is rarely the limiting factor. Operating conditions govern the service life of hydraulically piloted valves far more strongly than the nominal figures on a datasheet. Because oil is virtually incompressible, the movement is stiff and holds position well under varying load. The medium governs a valve more than any other factor, because it fixes material selection, sealing and safety requirements. Cryogenic service starts roughly below minus one hundred degrees, and there the properties of almost every material change. Oxygen is not flammable in itself but accelerates any combustion, which is why an oxygen valve must be degreased and assembled clean. Cleanliness of the pilot oil is decisive, since the small passages inside a pilot block foul easily. A wrongly chosen seal on an aggressive medium is almost always the cause of premature leakage, not the body. Cryogenic valves belong on a low temperature test, because a test at ambient says little about behaviour at minus one hundred and sixty degrees. The balance between required tightness and available operating force is a recurring tension on hydraulically piloted valves. For hydraulically piloted valves this means that construction and operating conditions cannot be judged separately.
Hydraulically piloted valves in chemicals, power and process industry
They are used on large line valves, emergency shutdown systems, offshore installations and heavy machinery. Chemicals and petrochemicals bring the widest variety of media and therefore the most bespoke questions. In pharmaceutical and food production the drivers are cleanliness, flushability and demonstrable material traceability. In plants where hydraulically piloted valves is applied, the emphasis is on reliability rather than lowest purchase price. We supply hydraulically piloted valves both for new build and for replacement within existing installations. The application range of hydraulically piloted valves runs from simple utility duty to heavy process plant, with a corresponding difference in execution. On project supply we record per position which execution of hydraulically piloted valves was delivered, including materials and tests. In technical gases the subject is oxygen, nitrogen, argon, hydrogen and mixtures, each with its own cleanliness and safety requirements. 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. Our customers work in chemicals, petrochemicals, pharmaceuticals, power generation, offshore and in hydrogen and ammonia projects. In an existing plant hydraulically piloted valves is often part of a wider question about availability and maintenance. Our customers use hydraulically piloted valves in positions where a failure has immediate consequences for production.
Specifying hydraulically piloted valves correctly
Standardising across several positions makes hydraulically piloted valves simpler in maintenance and in spare parts management. We record the medium specification in the quotation, so it stays clear later on what basis the valve was selected. Degreased execution, nitrogen purging and sealed bagging are not extras on oxygen and high purity duty but part of the delivery. Phase matters too, because a medium that flashes inside the valve behaves completely differently from one that stays liquid. We never recommend a heavier execution of hydraulically piloted valves than needed, because over specification only raises price and lead time. The right choice around hydraulically piloted valves starts with a full set of process data rather than with a request for a price. Where hydraulically piloted valves forms part of a safety function we record the fail position and required stroking time explicitly. For hydraulically piloted valves total cost of ownership weighs more than purchase price, certainly when replacement has to happen during a shutdown. Cleaning procedures for oxygen service are recorded in the documentation, including the agents used and the packing method. On a new medium we always advise a compatibility check up front rather than an assumption based on a comparable plant. If you have an existing tag plate or serial number, send it along, because that lets us work directly from the original configuration. On hydraulically piloted valves we also state what an execution cannot do, because that prevents more problems than a list of advantages. For hydraulically piloted valves we ask as standard for DN, pressure class, medium, temperature and required actuation.
Hydraulically piloted valves supplied with technical advice
Dutch Valve Vision stays available after delivery of hydraulically piloted valves for technical questions and for parts. 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. We think along on the spare parts strategy for hydraulically piloted valves, so critical positions stay covered. On hydraulically piloted valves we come back with a proposal that explains why we recommend a particular execution. For hydraulically piloted valves you can come to Dutch Valve Vision for the selection, the delivery and the support afterwards. 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 keep spare parts and overhaul kits mapped per project, so that a breakdown does not start with a search from scratch. We record which execution of hydraulically piloted valves was delivered, so a follow up delivery or spare part matches exactly later on. We work on hydraulically piloted valves under a KIWA ISO 9001 certified quality system, which safeguards traceability. Documentation on hydraulically piloted valves has to be the kind a buyer or inspector accepts without discussion. We handle an enquiry for hydraulically piloted valves on its technical merits rather than as a price request that only produces a number. 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.
Frequently asked questions about hydraulically piloted valves
What exactly does hydraulically piloted valves mean?
Hydrogen also brings embrittlement into play, which rules out certain steel grades and hardness levels. Hydrogen has a very small molecule, so a seal that is adequate for nitrogen may still leak on hydrogen. Hydraulically piloted valves use a small pilot flow to operate a much larger main valve, so limited control energy can move a large closing element. Hydraulic systems work with high pressure and small volumes, so leakage quickly leads to pressure loss and contamination. For hydraulically piloted valves a good specification up front is cheaper than a correction afterwards. The answer to this question on hydraulically piloted valves changes as soon as the medium or the temperature changes. In practice hydraulically piloted valves is rarely a standard question once medium and temperature move away from average. 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 executions of hydraulically piloted valves are available?
A wrongly chosen seal on an aggressive medium is almost always the cause of premature leakage, not the body. Cryogenic valves belong on a low temperature test, because a test at ambient says little about behaviour at minus one hundred and sixty degrees. Cleaning procedures for oxygen service are recorded in the documentation, including the agents used and the packing method. Cryogenic service starts roughly below minus one hundred degrees, and there the properties of almost every material change. The answer on hydraulically piloted valves depends strongly on operating conditions, which is why we always ask for those first. We always explain why we arrive at a particular recommendation on hydraulically piloted valves, so you can follow the reasoning yourself. How hydraulically piloted valves behaves under varying load says more about the quality of the selection than behaviour under steady load. Our market is project driven and international, and we deliver worldwide to installers, EPC contractors and end users.
Which materials are used for hydraulically piloted valves?
Oxygen is not flammable in itself but accelerates any combustion, which is why an oxygen valve must be degreased and assembled clean. Cleanliness of the pilot oil is decisive, since the small passages inside a pilot block foul easily. The pilot circuit determines the response of the whole assembly, which makes pilot reliability critical. On a new medium we always advise a compatibility check up front rather than an assumption based on a comparable plant. If you are unsure about this on hydraulically piloted valves, we are glad to put the question alongside the actual process data. That makes hydraulically piloted valves a subject where discussion up front pays for itself in operation. We regularly see that a small change in the execution of hydraulically piloted valves makes a large difference to maintenance frequency. 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 should I watch technically on hydraulically piloted valves?
What should I watch technically on hydraulically piloted valves?
Which applications call for hydraulically piloted valves?
In technical gases the subject is oxygen, nitrogen, argon, hydrogen and mixtures, each with its own cleanliness and safety requirements. They are used on large line valves, emergency shutdown systems, offshore installations and heavy machinery. Chemicals and petrochemicals bring the widest variety of media and therefore the most bespoke questions. In pharmaceutical and food production the drivers are cleanliness, flushability and demonstrable material traceability. In most projects hydraulically piloted valves turns out to be less standard than it first appears. Our experience with hydraulically piloted valves comes from projects in chemicals, power generation, technical gases and offshore. We see demand for hydraulically piloted valves rising in hydrogen and ammonia projects, where tightness requirements are high. Our customers work in chemicals, petrochemicals, pharmaceuticals, power generation, offshore and in hydrogen and ammonia projects.
What determines the price and lead time of hydraulically piloted valves?
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 repeat orders we record the configuration, so a follow up delivery is identical to the first and installation holds no surprises. If you have an existing tag plate or serial number, send it along, because that lets us work directly from the original configuration. We keep spare parts and overhaul kits mapped per project, so that a breakdown does not start with a search from scratch. On hydraulically piloted valves we prefer a well founded answer to a fast one that turns out to be wrong later. On hydraulically piloted valves we include start up and shutdown, because that is where the heaviest loading occurs. For repeat orders of hydraulically piloted valves we record the configuration, so a follow up delivery is identical to the first. 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 hydraulically piloted valves?
Documentation such as material certificates, test reports and declarations is supplied as standard, matched to what the project requires. 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. 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. On repeat orders we record the configuration, so a follow up delivery is identical to the first and installation holds no surprises. The answer on hydraulically piloted valves depends strongly on operating conditions, which is why we always ask for those first. This is one of the points on hydraulically piloted valves where suppliers differ most clearly from one another. Material certificates and test reports are supplied with hydraulically piloted valves, matched to what the project requires. 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.
How do I request a quotation for hydraulically piloted valves?
For an accurate quotation we need the nominal diameter, the pressure class, the medium, the operating temperature and the required actuation. A P&ID, a datasheet or even a photograph of the existing installation often helps us faster than a long description. Please also state the connection standard, the required leakage class and any project requirements such as NACE, PED or ATEX. We come back with a proposal that explains why we recommend a particular execution, including the alternatives we considered. Our experience with hydraulically piloted valves comes from projects in chemicals, power generation, technical gases and offshore. For hydraulically piloted valves a good specification up front is cheaper than a correction afterwards. Our specialists are happy to discuss hydraulically piloted 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.