Triple offset butterfly valve
Triple offset butterfly valve: what matters in practice
The working principle of triple offset butterfly valve
A triple offset butterfly valve has three offsets, two geometric and one in the form of an inclined cone axis, so the disc only touches the seat in the last few degrees of closing. Anyone looking into triple offset butterfly valve quickly runs into a choice that goes beyond picking a catalogue number. With triple offset butterfly valve the difference between a good and a mediocre solution often sits in details that do not show on a drawing. 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 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. Because sealing is achieved by torque rather than by deformation of an elastomer, tightness is maintained over thousands of cycles. Operating conditions govern the service life of triple offset butterfly valve far more strongly than the nominal figures on a datasheet. We regularly see that a small change in the execution of triple offset butterfly valve makes a large difference to maintenance frequency. How triple offset butterfly valve behaves under varying load says more about the quality of the selection than behaviour under steady load. 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. Both the seat and the sealing edge are metal, so temperature, steam, vapour and aggressive media cause no degradation of the seal. We approach triple offset butterfly valve from the question of what the plant has to do, not from the question of what happens to be in stock.
Executions and materials for triple offset butterfly valve
The conical seat geometry turns the closing movement into a wedging action, which is why sealing is achieved by torque. In practice we find that most failures around triple offset butterfly valve come not from the material but from a wrong assumption during selection. The balance between required tightness and available operating force is a recurring tension on triple offset butterfly valve. Because there is no rubbing contact during travel, wear is dramatically lower than on a concentric design. 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 quadruple offset construction adds a fourth offset, which distributes the load far more evenly around the full circumference of the seat. Most triple offset valves have a preferred flow direction, and performance in the reverse direction is usually lower. The disc can be reworked when worn, so the service life of the body is often many times that of the sealing components. Installation orientation is less critical on bidirectional designs, which prevents mistakes during field assembly. With triple offset butterfly valve it pays to include phase changes in the medium, because those sharply increase the load on the seal. With triple offset butterfly valve the seat is the component that determines performance, and the body is rarely the limiting factor.
Typical applications for triple offset butterfly valve
They are used on steam, hot gas, hydrocarbons and any duty where a soft seat would not survive the temperature. In chemical and petrochemical plants these valves are used where both tightness and emission requirements carry serious weight. In technical gases and hydrogen applications the metal seal is decisive, because small molecule size and emission limits reinforce each other. In an existing plant triple offset butterfly valve is often part of a wider question about availability and maintenance. We supply triple offset butterfly valve both for new build and for replacement within existing installations. For triple offset butterfly valve the sector determines which documentation and tests belong with the delivery. We see demand for triple offset butterfly valve rising in hydrogen and ammonia projects, where tightness requirements are high. Offshore, weight saving counts, and at larger diameters a butterfly valve saves considerably compared with a ball valve. 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 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. Demand for triple offset butterfly valve reaches us mainly from projects where the standard range falls short. On project supply we record per position which execution of triple offset butterfly valve was delivered, including materials and tests.
Choosing the right triple offset butterfly valve
The right choice around triple offset butterfly valve starts with a full set of process data rather than with a request for a price. The choice between triple and quadruple offset depends on whether the valve has to seal in two directions and how high the differential pressure runs. 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. Operating torque is higher than on a concentric design, and that has to be reflected in the choice of actuator. On triple offset butterfly valve we check that the actuator is sized on torque at maximum differential pressure and not on an average value. Where there is doubt about triple offset butterfly valve we quote two executions side by side, with the trade offs stated explicitly. For triple offset butterfly valve total cost of ownership weighs more than purchase price, certainly when replacement has to happen during a shutdown. Maintenance is limited to packing and bearings, and because the seat is metal there is no liner to replace. In vacuum service a metal seated offset valve outperforms an elastomer seat, because there is no liner that can be drawn inwards. For an accurate quotation we need the nominal diameter, the pressure class, the medium, the operating temperature and the required actuation. If a simpler type will do the job, we say so on triple offset butterfly valve, even when that means a smaller order. We never recommend a heavier execution of triple offset butterfly valve than needed, because over specification only raises price and lead time.
Requesting triple offset butterfly valve from Dutch Valve Vision
On triple offset butterfly valve we come back with a proposal that explains why we recommend a particular execution. Our customers work in chemicals, petrochemicals, pharmaceuticals, power generation, offshore and in hydrogen and ammonia projects. Dutch Valve Vision stays available after delivery of triple offset butterfly valve for technical questions and for parts. We think along on the spare parts strategy for triple offset butterfly valve, so critical positions stay covered. 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. A tag plate with project data belongs with triple offset butterfly valve as standard where the project requires it. We record which execution of triple offset butterfly valve was delivered, so a follow up delivery or spare part matches exactly later on. Documentation on triple offset butterfly valve has to be the kind a buyer or inspector accepts without discussion. Our specialists are happy to discuss triple offset butterfly valve on the basis of your P&ID, your datasheet or simply a photograph of the situation. Even when the specification for triple offset 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.
Frequently asked questions about triple offset butterfly valve
What exactly does triple offset butterfly valve mean?
Because sealing is achieved by torque rather than by deformation of an elastomer, tightness is maintained over thousands of cycles. Both the seat and the sealing edge are metal, so temperature, steam, vapour and aggressive media cause no degradation of the seal. 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. 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 answer to this question on triple offset butterfly valve changes as soon as the medium or the temperature changes. The answer on triple offset butterfly valve depends strongly on operating conditions, which is why we always ask for those first. We find that questions about triple offset butterfly valve almost always come back to the same three points: medium, temperature and required tightness. We think along from the basic specification through to the tag plate, and supply documentation that a buyer or inspector accepts without discussion.
Which executions of triple offset butterfly valve are available?
That offset removes the rubbing movement across the seat, which is the main cause of wear in concentric butterfly valves. Maintenance is limited to packing and bearings, and because the seat is metal there is no liner to replace. 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. Most triple offset valves have a preferred flow direction, and performance in the reverse direction is usually lower. If you are unsure about this on triple offset butterfly valve, we are glad to put the question alongside the actual process data. That makes triple offset butterfly valve a subject where discussion up front pays for itself in operation. A correct execution of triple offset butterfly valve accounts for real operating conditions and not only for design values. 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 materials are used for triple offset butterfly valve?
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 vacuum service a metal seated offset valve outperforms an elastomer seat, because there is no liner that can be drawn inwards. 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. We see this come back regularly in enquiries about triple offset butterfly valve, and the answer is rarely a single sentence. In most projects triple offset butterfly valve turns out to be less standard than it first appears. On triple offset butterfly valve we always check the full operating envelope, including start up and shutdown. 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.
What should I watch technically on triple offset butterfly valve?
What should I watch technically on triple offset butterfly valve?
Which applications call for triple offset butterfly valve?
They are used on steam, hot gas, hydrocarbons and any duty where a soft seat would not survive the temperature. 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. This is one of the points on triple offset butterfly valve where suppliers differ most clearly from one another. On triple offset butterfly valve we include start up and shutdown, because that is where the heaviest loading occurs. During turnarounds triple offset butterfly valve is regularly on the critical path, and then predictability matters more than the lowest price. Our market is project driven and international, and we deliver worldwide to installers, EPC contractors and end users.
What determines the price and lead time of triple offset butterfly valve?
Please also state the connection standard, the required leakage class and any project requirements such as NACE, PED or ATEX. 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. For an accurate quotation we need the nominal diameter, the pressure class, the medium, the operating temperature and the required actuation. Our experience with triple offset butterfly valve comes from projects in chemicals, power generation, technical gases and offshore. For triple offset butterfly valve a good specification up front is cheaper than a correction afterwards. For repeat orders of triple offset butterfly valve we record the configuration, so a follow up delivery is identical to the first. 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.
What about maintenance and spare parts on triple offset 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. On repeat orders we record the configuration, so a follow up delivery is identical to the first and installation holds no surprises. Documentation such as material certificates, test reports and declarations is supplied as standard, matched to what the project requires. On triple offset butterfly valve we include start up and shutdown, because that is where the heaviest loading occurs. That makes triple offset butterfly valve a subject where discussion up front pays for itself in operation. Tests around triple offset butterfly valve are carried out by us or on our instruction according to the requirements in the specification. Alongside QUADAX and PRUSS we represent Pibiviesse, Schroeder, Striko, Malbranque, Daume, FluoroSeal and Guichon, so we can select the right brand for each project.
How do I request a quotation for triple offset butterfly valve?
We come back with a proposal that explains why we recommend a particular execution, including the alternatives we considered. 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. Documentation such as material certificates, test reports and declarations is supplied as standard, matched to what the project requires. On triple offset butterfly valve we include start up and shutdown, because that is where the heaviest loading occurs. We always explain why we arrive at a particular recommendation on triple offset butterfly valve, so you can follow the reasoning yourself. For triple offset butterfly valve you can come to Dutch Valve Vision for the selection, the delivery and the support afterwards. Bring us your question at sales@dutchvalvevision.com or +31 (0)70-2210560, even when the specification is not finalised yet.