Metal seated butterfly valve
Metal seated butterfly valve: technology, application and the right choice
The technology behind metal seated butterfly valve explained
A metal seated butterfly valve seals metal on metal, because both the seat ring and the sealing edge of the disc are metal instead of an elastomer or PTFE liner. We find that questions about metal seated butterfly valve almost always come back to the same three points: medium, temperature and required tightness. Anyone looking into metal seated butterfly valve quickly runs into a choice that goes beyond picking a catalogue number. Both the seat and the sealing edge are metal, so temperature, steam, vapour and aggressive media cause no degradation of the seal. Because sealing is achieved by torque rather than by deformation of an elastomer, tightness is maintained over thousands of cycles. The result of that fourth offset is that sealing performs equally well in both flow directions, which is not a given with triple offset valves. With metal seated butterfly valve the seat is the component that determines performance, and the body is rarely the limiting factor. The balance between required tightness and available operating force is a recurring tension on metal seated butterfly valve. On metal seated butterfly valve we always check the full operating envelope, including start up and shutdown. That offset removes the rubbing movement across the seat, which is the main cause of wear in concentric butterfly valves. A triple offset design combines two geometric offsets with an inclined cone axis, so contact between disc and seat only occurs in the last few degrees of travel. The subject of metal seated butterfly valve touches both the construction of the valve and the way the plant is operated.
Executions and materials for metal seated butterfly valve
Because there is no soft liner, a metal seated butterfly valve has no upper temperature limit imposed by the sealing element itself. In practice we find that most failures around metal seated butterfly valve come not from the material but from a wrong assumption during selection. We regularly see that a small change in the execution of metal seated butterfly valve makes a large difference to maintenance frequency. The seat ring is usually a laminated or solid metal ring that is loaded by torque in the final degrees of closing. Since a controlled contact face is formed in the closed position, no run in period is required and the valve performs to specification from the first stroke. In an offset butterfly valve the centre of the disc does not sit in the centre of the flow, so the disc lifts away from the seat immediately on opening. A quadruple offset construction adds a fourth offset, which distributes the load far more evenly around the full circumference of the seat. Metal seats accept a small, defined leakage rate, and specifying the required leakage class up front avoids disappointment later. In vacuum service a metal seated offset valve outperforms an elastomer seat, because there is no liner that can be drawn inwards. Maintenance is limited to packing and bearings, and because the seat is metal there is no liner to replace. For metal seated butterfly valve this means that construction and operating conditions cannot be judged separately. That principle explains why metal seated butterfly valve behaves differently from a standard execution under heavier duty.
Typical applications for metal seated butterfly valve
Typical duties are steam, hot gas, flue gas, technical gases and any process where a liner would degrade within months. Offshore, weight saving counts, and at larger diameters a butterfly valve saves considerably compared with a ball valve. In chemical and petrochemical plants these valves are used where both tightness and emission requirements carry serious weight. The application range of metal seated butterfly valve runs from simple utility duty to heavy process plant, with a corresponding difference in execution. In plants where metal seated butterfly valve is applied, the emphasis is on reliability rather than lowest purchase price. On replacement we always check the existing installation dimensions for metal seated butterfly valve, so the pipework can stay untouched. For metal seated butterfly valve the sector determines which documentation and tests belong with the delivery. In technical gases and hydrogen applications the metal seal is decisive, because small molecule size and emission limits reinforce each other. 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. During turnarounds metal seated butterfly valve is regularly on the critical path, and then predictability matters more than the lowest price. We supply metal seated butterfly valve both for new build and for replacement within existing installations.
Choosing the right metal seated butterfly valve
If a simpler type will do the job, we say so on metal seated butterfly valve, even when that means a smaller order. A concentric butterfly valve with an elastomer seat is cheaper, but runs into limits on temperature, on vacuum and on media that attack the liner. Where a ball valve or gate valve becomes a problem through mass and face to face length, an offset butterfly valve often delivers the same tightness at a fraction of the weight. In selection we look first at medium and temperature, then at differential pressure, and only after that at body style and actuation. The cleaning and flushing procedure counts too on metal seated butterfly valve, because it can be more aggressive than the process itself. The required leakage class often drives the choice around metal seated butterfly valve more strongly than the budget does. For metal seated butterfly valve we ask as standard for DN, pressure class, medium, temperature and required actuation. Installation orientation is less critical on bidirectional designs, which prevents mistakes during field assembly. The disc can be reworked when worn, so the service life of the body is often many times that of the sealing components. Please also state the connection standard, the required leakage class and any project requirements such as NACE, PED or ATEX. Standardising across several positions makes metal seated butterfly valve simpler in maintenance and in spare parts management. On metal seated butterfly valve we also state what an execution cannot do, because that prevents more problems than a list of advantages.
Ordering metal seated butterfly valve from Dutch Valve Vision
On metal seated butterfly valve we come back with a proposal that explains why we recommend a particular execution. 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. Our specialists are happy to discuss metal seated butterfly valve on the basis of your P&ID, your datasheet or simply a photograph of the situation. For metal seated butterfly valve 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. 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 metal seated butterfly valve we make sure the chosen execution demonstrably meets the stated standards rather than merely looking plausible on paper. Documentation on metal seated butterfly valve has to be the kind a buyer or inspector accepts without discussion. We record which execution of metal seated butterfly valve was delivered, so a follow up delivery or spare part matches exactly later on. Dutch Valve Vision stays available after delivery of metal seated butterfly valve for technical questions and for parts. For repeat orders of metal seated butterfly valve we record the configuration, so a follow up delivery is identical to the first. 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 metal seated butterfly valve
What exactly does metal seated butterfly valve mean?
In an offset butterfly valve the centre of the disc does not sit in the centre of the flow, so the disc lifts away from the seat immediately on opening. That offset removes the rubbing movement across the seat, which is the main cause of wear in concentric butterfly valves. Since a controlled contact face is formed in the closed position, no run in period is required and the valve performs to specification from the first stroke. A metal seated butterfly valve seals metal on metal, because both the seat ring and the sealing edge of the disc are metal instead of an elastomer or PTFE liner. Our experience with metal seated butterfly valve comes from projects in chemicals, power generation, technical gases and offshore. The answer on metal seated butterfly valve depends strongly on operating conditions, which is why we always ask for those first. There are assumptions circulating about metal seated butterfly valve that do not hold up under closer examination. 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 metal seated butterfly valve are available?
The seat ring is usually a laminated or solid metal ring that is loaded by torque in the final degrees of closing. A quadruple offset construction adds a fourth offset, which distributes the load far more evenly around the full circumference of the seat. Because there is no soft liner, a metal seated butterfly valve has no upper temperature limit imposed by the sealing element itself. The result of that fourth offset is that sealing performs equally well in both flow directions, which is not a given with triple offset valves. On metal seated butterfly valve we prefer a well founded answer to a fast one that turns out to be wrong later. If you are unsure about this on metal seated butterfly valve, we are glad to put the question alongside the actual process data. Operating conditions govern the service life of metal seated butterfly valve far more strongly than the nominal figures on a datasheet. Our market is project driven and international, and we deliver worldwide to installers, EPC contractors and end users.
Which materials are used for metal seated butterfly valve?
A triple offset design combines two geometric offsets with an inclined cone axis, so contact between disc and seat only occurs in the last few degrees of travel. Installation orientation is less critical on bidirectional designs, which prevents mistakes during field assembly. The disc can be reworked when worn, so the service life of the body is often many times that of the sealing components. Because sealing is achieved by torque rather than by deformation of an elastomer, tightness is maintained over thousands of cycles. In most projects metal seated butterfly valve turns out to be less standard than it first appears. This is one of the points on metal seated butterfly valve where suppliers differ most clearly from one another. With metal seated butterfly valve it pays to include phase changes in the medium, because those sharply increase the load on the seal. 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 metal seated butterfly valve?
What should I watch technically on metal seated butterfly valve?
Which applications call for metal seated butterfly valve?
In chemical and petrochemical plants these valves are used where both tightness and emission requirements carry serious weight. Offshore, weight saving counts, and at larger diameters a butterfly valve saves considerably compared with a ball valve. In technical gases and hydrogen applications the metal seal is decisive, because small molecule size and emission limits reinforce each other. In power generation they sit in steam, condensate and flue gas lines where temperature is far beyond the range of soft seats. For metal seated butterfly valve a good specification up front is cheaper than a correction afterwards. That makes metal seated butterfly valve a subject where discussion up front pays for itself in operation. We see demand for metal seated butterfly valve 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 metal seated butterfly valve?
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. 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. For an accurate quotation we need the nominal diameter, the pressure class, the medium, the operating temperature and the required actuation. On metal seated butterfly valve we include start up and shutdown, because that is where the heaviest loading occurs. The answer to this question on metal seated butterfly valve changes as soon as the medium or the temperature changes. We think along on the spare parts strategy for metal seated butterfly valve, so critical positions stay covered. Call +31 (0)70-2210560 or send your specification to sales@dutchvalvevision.com and we will pick it up.
What about maintenance and spare parts on metal seated butterfly valve?
Maintenance is limited to packing and bearings, and because the seat is metal there is no liner to replace. 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. In vacuum service a metal seated offset valve outperforms an elastomer seat, because there is no liner that can be drawn inwards. On repeat orders we record the configuration, so a follow up delivery is identical to the first and installation holds no surprises. If you are unsure about this on metal seated butterfly valve, we are glad to put the question alongside the actual process data. The answer to this question on metal seated butterfly valve changes as soon as the medium or the temperature changes. Material certificates and test reports are supplied with metal seated butterfly valve, 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 metal seated butterfly valve?
Please also state the connection standard, the required leakage class and any project requirements such as NACE, PED or ATEX. Documentation such as material certificates, test reports and declarations is supplied as standard, matched to what the project requires. If you have an existing tag plate or serial number, send it along, because that lets us work directly from the original configuration. We come back with a proposal that explains why we recommend a particular execution, including the alternatives we considered. We see this come back regularly in enquiries about metal seated butterfly valve, and the answer is rarely a single sentence. This is one of the points on metal seated butterfly valve where suppliers differ most clearly from one another. Even when the specification for metal seated butterfly valve is not yet finalised, you can bring the question to us. 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.