Control Ball Valve Type W

Transcription

1 Control Ball Valve Type W A MEMBER OF THE ARCA FLOW GROUP ARTES VALVE & SERVICE GmbH - Lessingstraße Berlin Tel.: +49(0) 30 / Fax: +49(0) 30 /

2 Your memos Your contact persons Sales department Name Telephone Fax Mobile Ingo Mathes +49(0) 30 / (0) 1 72 / ingo.mathes@artes-valve.de Henner Roßmann +49(0) 30 / (0) 1 72 / henner.rossmann@artes-valve.de Horst Hagedorn +49(0) 30 / (0) 1 72 / horst.hagedorn@artes-valve.de Engineering department Horst Jäkel +49(0) 30 / (0) 1 72 / horst.jaekel@artes-valve.de Pierre Schüler +49(0) 30 / (0) 1 72 / pierre.schueler@artes-valve.de Service department René Hagedorn +49(0) 30 / (0) 1 72 / rene.hagedorn@artes-valve.de Bernd Seiferth +49(0) 30 / (0) 1 72 / bernd.seiferth@artes-valve.de 2

3 Application of the ARTES type W control ball valve The control ball valve W is a control valve that has been specially designed for regulating pressures and quantities. The construction allows for secure shut-off of the medium in addition to the control function. The valve has been designed for use with liquid and gaseous media, for example water and steam. Advantage of the turning valve compared to nozzle and control valves Leak-proof passage Shut-off by ball seat ring system Leak-proof to the outside Gland packing: leak-proof, because no contamination can get drawn into the packing No vibration cracking No forces or torques act on the stem Cost advantage by drawn-in valves The flow rate is determined by the valve size and not by the nominal width of the pipeline connection. Controllability at lesser differential pressures Straight flow-through permits a permanent pressure loss 0.2 bar whilst guaranteeing constant control performance Easy adjustment of control characteristics Easy exchange of the control discs / possible even on-site Low stockkeeping at user 3

4 Description and design of the ARTES control ball valve The control ball valve comes in a two- or three-part split body design. The three-part design contains all functionally relevant components in the module. The housing connections are the connections of the module to the pipeline. The housing connections and the module are connected by means of bolts. The connection to the pipeline is determined by the customer and can be done by flange or be welded on. The adapter to the drive conforms to DIN / ISO 5211 and can therefore be combined with any type of drive. Electrical, pneumatic, hydraulic, or electro-hydraulic drives can be implemented. 2-part design 3-part design Connection F Toothed shaft, DIN 5480 WA Connection F Toothed shaft, DIN 5480 WA Flange connection, DN/PN Flange connection, DN/PN Flange connection, DN/PN Face-to-face dimension L Length of model Face-to-face dimension L 4

5 The following cutaway shows the design of the 3-part ARTES type W control ball valve Connection DIN ISO F10 Square profile DIN AP4C17k6 Length of model L M = 140 mm Face-to-face dimension The standard design works with a seat ring that blocks the media in the direction of flow at the inlet of the ball. If it should be possible to seal off the media flow in both directions, a second seat ring is necessary. This design then allows reliable sealing in both flow directions. 5

6 There are two different versions of the seat ring. These are: Soft seal Metallic seal The seal version is specified in the valve data sheet. The type of seal that should be used is prescribed by the implementation parameters. Primarily these are: A soft-seal valve should only be used for applications with differential pressures of up to 10 bar. When a soft seal is used, the medium may not contain any abrasive substances. If solids are transported, metallic-seal seat rings have to be used. The soft-seal control ball valve, RKH-W, works with carbon (hard-burnt coal) shrunk into the seat ring. The ball itself consists of a stainless material and is untreated. In the metallic version, RKH-WM, the ball and the seat ring(s) are coated with tungsten carbide. The tungsten carbide is applied by a high-speed flame spraying process. The wear resistance of the coating is so good that further processing can be done only by diamonds. During operation the tungsten carbide coating guarantees a long service life so that the leakproofness of the valve can be ensured for a long operational period. The construction of the control disc is determined by the operating conditions. Steel, stainless steel, plasma-nitrided, or tungsten carbide-coated models are possible. Employing one or two control discs is possible. Two control discs are used in order to minimise the wear, prevent cavitations, or to lower noise emissions. In the tender and the valve data sheet, this is denoted as 2-stage pressure reduction. 6

7 Mode of operation of the pressure and flow control A typical pressure control circuit is shown in the following illustration and is described in the subsequent text. The flow control is the same. The sensor is then a flow meter (differential pressure transmitters, ultrasonic meter, turbine flowmeter, etc.). Sampled-data system input Direction of flow Regulator Measuring transducer Sensor 7

8 The control function of a control ball valve is basically no different from the control function of conventional control valves. A pressure sensor records the ACTUAL pressure value and transmits it to the controller. If the SETPOINT and ACTUAL values deviate, the actuator of the control ball valve is actuated. Usually a 4-20 ma control signal is used. The valve is closed at 4 ma. The actuator sets the control ball valve to the required position, in accordance with the change in the control signal. By the turn of the ball the control contour in the control disc(s) is uncovered. The appropriate control characteristic is applied to control the flow quantity in accordance with the requirements of the valve's characteristic curve and the pressure in the pipeline increases or decreases. This process continues until the SETPOINT and ACTUAL pressure values match. The 90 turn by the ball over the control disc(s) opens the control diameter and thus realises the control function. 8

9 Characteristic curves The mode of operation of a control valve is based on specified opening of diameters depending on the control signal sent by the regulator. The control diameters are opened up depending on the lift of the valve according to the specified characteristic curve. The curves are standardised in the valid regulations, such as VDI/VDE. The control ball valve type W creates the standard defined characteristic curve or a specially designed one. By the turn of the ball the control contour machined into the control disc is uncovered in the ball borehole. The process is the same as the opening of the control diameter in the perforated cone of a lift valve. Linear characteristic curve Equal percentage characteristic curve Rotation angle (%) Rotation angle (%) The filling characteristic curve is a typical special characteristic curve. Up to a defined opening, control is by a perforated control disc. Beyond this opening angle an open diameter is machined into the control disc. 9

10 The advantage of this filling characteristic curve is the regulated throttling during filling of the downstream line units and the negligible pressure loss when the valve is fully open. The design makes it possible to easily adapt the flow rate and the control characteristics to changed operative parameters by replacing the control disc. This task can also be done on-site. For gaseous media or for cavitating operating conditions the control discs are always supplied as perforated control discs. This also minimises the wear and the noise. The following diagram shows a perforated control disc with control characteristics of equal percentage. Alignment: control contour! Control contour made to order! Production note plasma-nitrided, min. Layer depth Nht Werkstoff/Material As ordered Replacement for Replaced by Use Material no. Material Material no. - Table Cerification acc. DIN EN

11 Data sheet Control valve 1 Customer: ARTES no. 2 Plant: Item 3 Installation location: Quantity: 4 ID no. 5 Pipe line Input Output 6 Pipe line Ø Dxs mm 7 Pipe material 8 Flange ends Ø Dxs mm 9 Weld-on ends 10 Valve design Input Output 11 Nominal width DN 12 Nominal pressure PN 12 Pressure bara 13 Temperature C 14 Material 15 Operating conditions Load case Load case Load case Load case Load case 16 Medium: Flow rate m 3 /h 18 Temperature C 19 Pressure on bara 20 Pressure off bara 21 Noise level db(a) 22 Kv (valve flow coefficient) m 3 /h 23 Valve design Control ball valve WM Materials: Valve parameter: Housing: PG250GH or equal Ø Seat mm 28 Stem : Ø Stem mm 29 Seat ring: WCB Throttle stages: 30 Ball: WCB Kvs (flow rate value): m 3 /h 31 Control disc: WCB Characteristic curve: 32 Seals: Pure graphite delta p actuator bar 33 Packings: Pure graphite Face-to-face dimension: mm 34 Seal type: Metallic/tungsten carbide 35 Acceptance Pressure equipment directive 97/23/EC, CE marking 36 Compliance with requirements of: AD Leak rate: 0,05 % of Kvs 38 Installation instruction Actuator 41 Type: Comments Revision Date: 52 Created: H.Roßmann 53 Checked: I. Mathes 11

12 Spare/wear parts list Item Description Material 9 Seat ring / tungsten carbide coated / with EK Ball / tungsten carbide coated / (uncoated) 6 Control disc / / Bearing bush Seat ring seal Pure graphite 65 Disc Pure graphite 3 Stem / Threaded bolt / Nuts / Seal assembly Pure graphite 12