Control valves

ENERGY

VALVITALIA reserves the right to change design, specification and materials without notice

2

NEE

DS

CONTROL CONTENTS Globe Control Valves LTG1 LTG2 LTG3 LTG4 LTG5 RV631

4 4 6 8 9 18

Tree-way Control Valves TRV1 TRV2

10 10

Rotary Control Valves DYNA-LOK K-LO CB-54 CB-55

12 14 16 16

Steam Conditioning Control Valves PRDV SAN nozzles

20 22

3

VALVITALIA reserves the right to change design, specification and materials without notice

ENERGY

NEE

LTG1 and LTG2 Control Valves Globe straight-way, single seat LTG1 and LTG2 series are very versatile control valves of general use for any applications under moderate p/T service conditions. LTG1 is the standard design with screwed seat ring while LTG2 is the corresponding quick-change version with the same flow coefficients and pressure differentials capability.

Due to their simple construction and to their large range of available materials these valves are suitable for a wide range of applications, such asr corrosive, dirty, sticking and slightly abrasive fluids. Angle-body LTA special design is also available with the same trims of LTG series.

Main advantages:

● ● ● ●

Excellent plug stability provided by heavy top guiding design Interchangeable low noise and anticavitation trim either for std or quick-change design Tight shut-off class V and VI also available Wide flow range capability is allowed by a great number of reduced capacity trims

LTG2 ANSI 300 Diaphgram Actuator

Technical characteristics: Body:

● ● ● ● ● ● ● ●

Bonnet:

● ● ● ● ●

Trim:

● ● ●

Packing:

●

Sizes: 3/4”, 1”, 1”1/2, 2”, 3”, 4”, 6” Ratings: up to ANSI 600 /PN100 Flanged, butt-welded, SW, and threaded Cast construction, also wrought or by bar for smaller dimensions Face-to-face dimensions as per IEC 60534 –3-1 materials: carbon, Cr-Mo and AISI 316 stainless steel Flow direction: – to open.

– to close for some flashing applications Materials: Carbon, Cr-Mo and Stainless Steels Bolted to body Extended for high and low temperatures Bellows seal Special design for cryogenic applications Same materials as body Top guided plug both in LTG1 and LTG2 constructions Linear, modified linear and Eq% flow characteristics Plug types: – contoured – flat disc for quick opening operation – skirted and drilled BRD design (linear characteristic) for special services – soft seat - only for contoured and flat disc

●

Adjustable by nuts and follower Seal rings: reinforced braided teflon or pure graphite split-rings Bellows seal

Rangeability:

●

Cvmax / Cvmin better than 50:1 for 1" port and over

Cage (LTG2 only):

●

Seat ring clamped into the body by the cage for quick-change feature Large windows of cage do not affect the inherent flow characteristic (including max Cv) of LTG1 corresponding trims

●

●

VALVITALIA reserves the right to change design, specification and materials without notice

4

DS

CONTROL

Seat Ring:

●

Threaded in LTG1 model and clamped-in in LTG2 model

Leakage Class (IEC 60534-4) :

●

Standard: class IV Optional: class V and VI

Actuators:

●

●

●

Pneumatic diaphragm or Piston type Electric and Electro-Hydraulic actuators

LTA design Globe types LTG1 and LTG2 are also available with angle body.

In this case they are designated as LTA1 and LTA2 Control Valves.

LTA series are special engineered designs. The advantages provided by LTA series are the following: 1 - Different dimensions for valve inlet and outlet are available 2 - Inlet and outlet ratings can also be different 3 - Centre-to-face dimensions consistent with IEC standard when the connections have the same dimensions 4 - Increased Cv values in comparison with LTG1 and LTG2 standard body style due to less pressure drop of angle path 5 - Trims, characteristics, material and actuators are the same of standard LTG series

LTG1 ANSI 600 Electric Actuator

LTA Control Valve Standard contoured plug

LTG1 Std contoured plug

BRD trim

Soft seated plug

LTG2 Std contoured plug

5

VALVITALIA reserves the right to change design, specification and materials without notice

ENERGY

NEE

LTG3 Cage Control Valves Globe straight-way LTG3 series is a very versatile control valve for the main applications.

Its high performance derives by using a balanced and cage-guided plug. LTG3 is particularly suitable for heavy duties and for any other application under most demanding service conditions. Due to their simple construction, to the large range of trim types and available materials, these valves are suitable for a wide range of applications, including also high temperature and corrosive fluids, severe low-noise requirements and sour service in accordance with NACE standard.

Main advantages:

● ● ● ● ● ● ● ●

High pressure drop capability with no practical limitations Improved plug stability due to large guiding areas Wide-range capability is allowed by a great number of reduced capacity trims Excellent noise attenuation with low-noise single-stage trim for gas and steam service Improved cavitation protection on liquid services Multistage trims also available for cavitation control.

Balanced plug construction reduces thrust and actuator sizes Piloted plug construction for tight shut-off up to class V in high temperature services

LTG3 20” ANSI 900

LTA design LTG3 are also available with angle body. In this case they are designated as LTA3 Control Valves.

LTA series are special engineered designs. The advantages provided by LTA design are the same of LTA1 series.

Technical characteristics: Body:

● ● ● ● ● ● ● ●

Bonnet:

● ● ●

Trim:

● ● ● ●

Cage:

● ● ● ●

Sizes: 2", 3", 4", 6", 8", 10", 12", 14", 16", 18", 20" Ratings: up to ANSI 150, 300, 600, 900, 1500, 2500 and equivalent PN Flanged, butt-welded, socket-welded and threaded Cast standard construction; wrought or bar for 2" and 3" sizes Face-to-face dimensions as per IEC 60534-3-2 - long series materials: carbon, Cr-Mo and AISI 316 stainless steel Flow direction: – to open - general feature – to close - for piloted plugs and some flashing services Materials: Carbon, Cr-Mo and Stainless Steels Standard or extended type either for high or low temperature applications Bolted to body Same materials as body Balanced and fully cage-guided plug Unbalanced design for small ports or low pressure drop applications Piloted design for tight shut-off associated to high fluid temperature Plug seal rings: PTFE, metal or metal and graphite Low-noise drilled cage single stage LN and special ELN type with additional acoustical benefit of 4 dB. MPS multistage trim special design for high pressure drops Multi-cage construction up to 6 stages. 7 stages and over are obtained from a solid disk stack Linear and equal% characteristics for standard trim design

VALVITALIA reserves the right to change design, specification and materials without notice

6

LTG3 balanced plug

DS

CONTROL

Seat Ring:

●

Quick-change and free-expanding type, precisely coupled to the cage to ensure a perfect plug alignment

Leakage Class:

●

Classes III, IV, IV S1 and V according to IEC 60534-4 Class VI is also available with soft-seat

Actuators:

●

Pneumatic diaphragm or Piston type Electric and Electro-Hydraulic actuators

●

Single stage Low noise cage

MPS trim balanced plug

LTG3 plug with soft insert

Low noise cage construction

Linear characterized LTG3 cages

MPS multistage trim

LTG3 - cage assembling

7

Double stage balanced plug

LTG3 - control valve under cryogenic test VALVITALIA reserves the right to change design, specification and materials without notice

ENERGY

NEE

LTG4 Series Control Valves Globe straight-way LTG4 Series Control Valves have the same body, bonnet and seat ring of LTG3 series. The main difference is the design of the plug which is balanced type and contoured shaped for the throttling function. The cage, provided with large windows, clamps the seat ring against the body and acts also as the integral guide of the plug.

The trim is of quick change type for an easy maintenance. These valves combine the benefits of plug balancing and quick-change feature of LTG3 series with the simple and versatile construction of contoured plug which allows a wide selection of materials, coatings and flow characteristics. Also dirty, abrasive and very corrosive fluids can be successfully handled without the inconvenient sometime occurring in conventional throttling cage valves. The limitations about low-noise and anticavitation characteristics are compensated by the free-passage shape of the plug with reduced risk of local erosionand clogging.

Technical characteristics: Body:

● ● ● ● ● ● ●

Bonnet:

● ● ●

Trim:

● ● ● ●

LTG4 10” ANSI 2500

Flanged, butt-welded Cast std construction; also wrought or bar construction for 2" and 3" sizes Face-to-face dimensions as per IEC 60534-3-1 long series Sizes: 2", 3", 4", 6", 8", 10", 12", ratings up to ANSI 150, 300, 600, 900, 1500, 2500 Materials: Carbon, Cr-Mo and Stainless Steels materials: carbon, Cr-Mo and AISI 316 stainless steel Flow direction: to open Bolted joint to body Extended type either for high and low temperature applications as a standard feature Same materials as body Balanced and fully guided plug Seal rings for leakage classes IV and better: metal, teflon, metal and graphite Linear and equi% up to 2” port included - modified linear for higher sizes Plug types: – contoured – flat disc for quick opening operation – soft seat – soft seat – cascade trim

Seat Ring:

●

Quick-change and free-expanding type, precisely coupled with the cage to ensure a perfect plug alignment

Leakage Class:

●

Classes III, IV, IV S1 and V according to IEC 60534-4 Class VI is also available with soft-seat plug

Actuators:

●

Piston or pneumatic diaphragm spring return Electric actuators on request

●

Cascade trim Represents one of the most valid systems to reduce erosion and cavitation and it finds wide applications in small size valves, whether other “multistep” solutions can not be used. The pressure drop is equally splitted through a lot of labyrinth paths specially machined inside the trim itself. Control valves equipped with “cascade trim” can operate under very high pressure drops with a longer working life compared to standard single stage trims. Two separate sealing surfaces can be provided: by this way the first seal, between seat and cage, acts as a sacrifice element.

VALVITALIA reserves the right to change design, specification and materials without notice

LTG4 - cascade trim

8

DS

CONTROL

LTG5 Series Control Valves LTG5 Series top guided control valves are specially designed for the control of particular fluids where dead zones inside the valve body are not tolerated due to risk of crystallization, local corrosion, scaling or seizure. These features pertain to top guided LTG1 series, but a different plug-to-stem solid construction is performed in LTG5 valve to avoid any residual areas where fluids can stagnate. Particular care is paid to the packing zone where stagnation of fluid could cause stem corrosion, wear and leaks. Cv and other sizing factors are the same of LTG1 series. Typical applications of these valves are: ● ● ●

Food industry and drinking water Pharmaceutical processes Urea, melamine and similar plants

Main features: 1 - No dead zones inside the body with reduced contamination and erosion 2 - Stem-to-plug solid design which: – avoids dead zones inside the bonnet including packing box chamber – avoids coupling stem–to–plug which can be affected by local corrosion and consequent loosening – provides an excellent alignment between stem and plug with benefit for the packing tightness – increases trim stiffness due to oversized stem diameters 3 - reduced distance from packing to body inside cavity keeps the packing temperature very close to that of internal fluid so to prevent solidification inside the packing

LTG5 high pressure lug body type for urea service

Technical characteristics: Body:

● ● ● ● ● ● ●

Bonnet:

● ● ●

Trim:

● ● ● ● ● ●

Flanged and butt-welded connections –also plug type is available Cast construction – also wrought or by bar for small dimensions Face-to-face dimensions as per IEC 60534-3-1 long series Sizes: 3/4”, 1”, 1”1/2, 2”, 3”, 4”, 6” Ratings up to ANSI 600 – ANSI 1500 for sizes up to 2” included Materials: carbon, Cr-Mo, AISI 316, AISI 316L, duplex, hastelloy for sizes up to 3” – other on request Flow direction: – to open – to close only for balanced plug Flanged to body Same materials as body seal rings: reinforced braided Teflon or pure graphite Top guided unbalanced plug – integral with stem Guide: an extra-long bush fitted into the bonnet Flow characteristic: linear and equi% up to 2” port included modified linear for higher sizes Type of plug: contoured or flat for quick opening operation Soft seat: teflon insert fitted into the plug seat ring: threaded in std design – also welded-in or integral for high corrosive services

Materials:

●

Inox, hastelloy, duplex, HVD1, other alloys and coatings on request and when necessary

Leakage Class:

●

Std IV – optional V or VI

Actuators:

●

Pneumatic diaphragm or piston types Electric and electro-hydraulic on request

●

9

VALVITALIA reserves the right to change design, specification and materials without notice

ENERGY

NEE

TRV1 and TRV2 3-way Control Valves TRV control valves series are especially designed for heat exchangers control where the flow rate of the heating fluid which enters the heat exchanger is changed by the temperature controller. As outlined in the sketches of Fig.1 and 2 both the two methods used for this process switch-off the flow rate into a by-pass line around the exchanger. In the layout of Fig.1 the valve is the diverting type TRV1 with one inlet and two outlets while in the arrangement of Fig 2 the valve is the mixing type TRV2 with two inlets from heat exchanger and by-pass. The use of the by-pass around the exchanger limits the changes of pressure in the main line with many benefits for the assisted final equipment (boilers, headers, etc.).

Fig.1 – DIVERTING TYPE 3-way control valve in heat exchanger application

Fig.2 – Mixing type 3-way control valve in heat exchanger application

TRV Design In both designs the fluid tends to open the plug to ensure the max stability to the valve operation. The selection between the two solutions is basedprincipally on fluid temperature and on the differential temperature T1-T2 across the exchanger. TRV1 diverting type is generally preferred for high ⌬T(120° and over) but when T1 exceeds 350°C (up to 450°C) mixing type TRV2 is preferred. Generally, mixing type is preferred as it is less expensive and due to easier maintenance.

Technical characteristics: Body:

● ● ● ● ● ●

Bonnet:

● ● ●

Trim:

● ●

Sizes: from 1" up to 12" Ratings: up to ANSI 150, 300, 600 900 and 1500 on request Flanged connections Cast standard construction; wrought or bar construction also available for small sizes Flow direction: see sketckes Materials: carbon, Cr-Mo and stainless steels Plain or extended type either for high or low temperature applications as a standard feature Bolted to body Same materials as body Intrinsically balanced in heat exhanger application Plug is available in two design: standard and low-noise TRV2 Control Valve 12” ANSI 600 (mixing type)

VALVITALIA reserves the right to change design, specification and materials without notice

10

DS

CONTROL

11

VALVITALIA reserves the right to change design, specification and materials without notice

ENERGY

NEE

DYNA-LOK rotary Control Valves DYNA-LOK rotary control valves are provided with a double eccentric disc and a very easy-to-be changed TFE based or metal seat ring. Thanks to DYNA-LOK disc off-set design, the torque tending to close the valve and, more in general the torque needed to control the disc rotation is sensitively reduced. In addition, the cam effect performed by second shaft eccentricity guarantees a seal ring longer life. These valves can offer a great flow control with an excellent shut-off withstanding also very high pressure drops, independently of the flow direction.

Technical characteristics: Body:

● ●

● ● ●

Disc:

● ● ● ● ● ●

Shaft:

● ● ● ● ●

Bearings:

●

●

Sizes:

wafer and lug body design: from DN 150 up to DN 2000 flanged body: from DN 250 up to DN 2000 Ratings: up to ANSI 300, PN 40 up to DN 600 included, ANSI 150, PN16 for greater sizes For water mains DYNA-LOK control valves can be supplied in accordance with AWWA std ratings and connections Cast or fabricated construction depending on body style, size and material selection Face-to-face dimensions as per EN 558, IEC 60534-3-1, ISO 5752 Materials: all carbon and stainless steel grades, duplex and copper alloys Double eccentric design when tightness in closed position is requested Full-bore swing-through construction with single off-set disc when no tightness is requested in closed position Solid or whrougt cast construction Bi-directional flow but inlet on flat disc side gives better performance Flow characteristic: increasing gain up to approx. 50° opening, linear from 45° to max travel Materials: same as the body Constructions: one or two pieces depending on sizes Connection to the disc: by pins protected by set screws External sealing: single stuffing box actuator side Packing materials: teflon or graphite seal rings Materials: stainless steels, 17-4-PH, XM19 Radial bearings: Teflon-based compounds embedded in SS bushing. Over-sized bearings (total length = 3,5 x ⌽) allow a smooth rotation and a long maintenance-free valve life Axial bearings: axial thrusts are held by a couple of anti-friction washers

High pressure DYNA-LOK control valve with PRA actuator

Seat Ring:

●

Two designs are available to fulfil different temperature conditions: – spring-energized Teflon ring for temperatures up to 200°C – SS ring for higher temperatures Both seal rings are locked inside the body by means of an easily removable spacer.

Leakage Class:

●

Teflon seal ring assembly is consistent with class V (IEC 60534-4) for sizes up to 20”. For higher dimensions IVS1 class or better depending on actuator For metal SS type IVS1 class is allowed for all sizes

●

Actuators:

● ● ● ●

VALVITALIA reserves the right to change design, specification and materials without notice

Valvitalia DRA pneumatic diaphragm actuator for valve sizes up to 16” Valvitalia PRA piston types actuators with low friction scotch-yoke mechanism for larger valve sizes Pneumatic rack and pinion both single and double acting for sizes up 24” included Electric, electro-hydraulic and hydraulic actuators for heavy duties control purpose

12

DS

CONTROL The requested torque to move the disc of a DYNA-LOK valve is mainly depending on the differential pressure across the disc and on the values of pressures inside the body. The ⌬p increases friction of seal ring and shaft bearings in closed position, while, in opened position, it creates a dynamic force due to a not balanced distribution of pressures acting on the disc. DYNA-LOK disc design limits very much this second well-known effect especially in the usual working travel range from 40° to 90°.

32” DYNA-LOK control valve - lug body construction

13

VALVITALIA reserves the right to change design, specification and materials without notice

ENERGY

NEE

K-LO high-performance Rotary Control Valves K-LO rotary control valves have been especially designed to meet the usual cavitation problems of processes when hot liquids and not negligible pressure drops facilitate the development of cavitation. These special valves are deriving from the double eccentric DYNA-LOK series by modifying the basic disc design with particular baffles, integral or welded-in on both the disc sides, which increase the recovery factor of valve as well as its cavitation index grows. These baffles are wing-shaped and machined with many rectangular windows providing a moderate pressure drop so to not greatly affect the Cv of the valve with the plain disc. The distribution of the windows takes into account the presence of the sealing ring fitted into the body, with particular care to the area close to the shaft axis. Due to particular disc baffled design, max valve openings greater than the usual 90° are allowed to achieve higher Cv values. As for DYNA-LOK valves, the off-set design reduces the torque tending to close the valve. In addition, the cam effect caused by second shaft eccentricity improves the seal ring life.

Technical characteristics: Body:

● ● ● ● ●

Disc:

● ● ● ● ● ● ● ●

Shaft:

● ● ● ● ●

Bearings:

●

●

Sizes: from DN 250 up to DN 2000 Ratings: up to ANSI 300, PN 40, up to DN 600 included, ANSI 150, PN16 for greater sizes.

Flanged design (cast or fabricated construction depending on the size and material selection) Face-to-face dimensions as per EN558, ISO 5752, basic series 13 Materials: all carbon and stainless steel grades, duplex and copper alloys Double eccentric design when tightness in closed position is requested Two disc designs are available: drilled wings for low noise services and multi-windows wings for anticavitating service Full-bore swing-through contruction with single off-set disc when no sealing device is requested in closed position Both sides flow directions. Best leakage performance is assured by flow on flat disc side Opening up to 100° High xFZ cavitation index values Flow characteristic: increasing gain up to approx. 50° opening, linear from 50° to max travel Materials: same as the body Constructions: one and two pieces depending on sizes Connection to the disc: by pins protected by screws External sealing: single stuffing box actuator side Packing materials: teflon or graphite seal rings Materials: stainless steels, 17-4-PH, XM19 Radial bearings: Teflon-based compounds embedded in SS bushing. The oversizing of these bearings (tot. length = 3,5 x ⌽) allows a smooth rotation and a long maintenance-free valve life allow a smooth rotation and a long maintenance-free valve life Axial bearings: axial thrusts are held by a couple of anti-friction washers

Seat Ring:

●

Two designs are available to fulfil different temperature conditions: – spring-energized Teflon ring for temperatures up to 200°C – SS ring for higher temperatures Both seal rings are locked inside the body by means of an easily removable spacer

Leakage Class:

●

Teflon seal ring assembly is consistent with class V (IEC 60534-4) for sizes up to 20”.

For higher dimensions IVS1 class or better depending on actuator For metal SS type IVS1 class is allowed for all sizes

Actuators:

●

●

● ● ●

Valvitalia DRA pneumatic diaphragm actuator for valve sizes up to 16” Valvitalia PRA piston types actuators with low friction scotch-yoke mechanism for higher valve sizes Pneumatic rack and pinion both single and double acting for sizes up 24” included Electric and hydraulic actuators available on request

VALVITALIA reserves the right to change design, specification and materials without notice

14

DS

CONTROL

Cavitation and noise control Multi windows wings These special trim executions are machined, depending on wings size, from a solid cast or forged block. The design of K-LO disc is very effective against potential cavitating conditions due to its high xFZ values, which are close to 0,4 at 70째 opening approximately for all the dimensions. This allows to avoid cavitation under critical conditions, such as, for example: p1 = 15 bar, p2 = 10 bar and max vapour pressure = 2,5 bar (water at 125째C). Flow coefficients are slightly affected by the anti-cavitation large windows of the wings, while allowed disc opening is limited to the region where recovery factor is higher.

Drilled wings Special drilled wings allow K-LO control valve to reduce noise. This peculiar trim pattern combines high efficiency in reducing noise with an excellent modulating performance.

Low-noise disc design

Anti-cavitation disc design

15

VALVITALIA reserves the right to change design, specification and materials without notice

ENERGY

NEE

CB54 – CB55 Ball Control Valves Control Ball Valves of CB series provide an excellent tightness, typical of on-off ball valves with a high rangeability. CB series valves match together the ability to transfer large flows with a precise regulating action at small flows. In this way it is possible to reach reangeability of 200:1 and with particular trims until 300:1. Furthermore the special trim design of CB series provides noise and cavitation abatement.

CB series are available in two configurations: 1. CB 54 has a downstream drilled disc especially engineered to reduce aerodynamic noise 2. CB 55 special multi-path / multi-stage trim allows an excellent flow control, and it is especially designed to reduce both noise and cavitation effects.

Technical characteristics: Body:

● ● ● ● ●

Ball:

● ● ● ●

●

Shaft:

● ● ● ●

Bearings:

●

●

Seat:

● ●

Actuators:

● ● ●

Side entry flanged and butt-welded design Size: from 2” to 42” Rating: from #150 to #2500 Face to face dimensions API 6D Materials: carbon and stainless steel, duplex, nickel alloys CB 55 series with integral trim up to 4” With removable trim for 6” and over Soft / metal to metal seat Flow direction: – unidirectional: CB 54 – bidirectional: CB 55 Materials: same as body

CB54 drilled disc view

Anti blow-out design Quick changing shaft packing Materials: stainless steel, A564 T630, A479 XM19 Packing: teflon or graphite ring Radial bearings: generous sizing of these bearings allows a smooth rotation and a maintenance-free long life Axial bearings: thrust due to internal pressure is held from an antifriction washer Spring energized, double-effect piston construction on request Soft / metal to metal seat Pneumatic low friction skotch-yoke PRA type DRA pneumatic diaphragm type Electric, hydraulic, electro-hydraulic CB54 gas plant installation

Leakage Class:

●

Classes IV, IV S1 and V according to IEC 60534-4, Class VI is also available with soft-seat

VALVITALIA reserves the right to change design, specification and materials without notice

16

DS

CONTROL

CB54

CB55 sectional view

CB55

17

VALVITALIA reserves the right to change design, specification and materials without notice

ENERGY

NEE

RV631 series Control Valves RV631 control valves have their main application in boiler feedwater process, They are expressly designed for processes that require low pressure drops when the flow rate is high and the need to avoid cavitation when flow rate is small.

The special design of its cage, splitted in 3 steps along the travel, allows the RV631 trim to meet these process requests. During the first travel section, in which high pressure drops might generate cavitation phenomena, the process is controlled by a properly designed multistep cage, which causes the fluid to pass through six pressure reduction stages: in this way any vaporization is avoided.

The last section has a final single stage cage with large flow passages which ensures the maximum flow rate with moderate pressure drop. Each section of the cage, welded together to form a solid rugged unit, is separated by lips that prevent the fluid passage between adiacent sections.

Technical characteristics: RV631 Control Valve

Body:

● ● ● ● ● ● ●

Bonnet:

● ● ● ● ●

Trim:

● ● ● ●

Cage:

●

●

Sizes: 3”, 4”, 6”, 8”, 10”, 12” Ratings: ANSI 150, 300, 600, 900, 1500 Flanged, BW, SW Cast standard construction Face-to-face dimensions as per IEC 60534-3-2 Flow direction: to open Materials: Carbon, Cr-Mo and stainless steels Bolted to body Same material as body Flow direction: to open Packing materials: teflon or graphite seal rings Materials: Carbon, Cr-Mo and stainless steels Balanced and fully cage-guided plug Unbalanced design for small ports or moderate pressure drop applications Plug seal rings: PTFE, metal or metal and graphite Flow characteristic: modified linear (see diagram) Variable resistance along the travel: 6-stages for low openings, 3-stages for intermediate travel and single-stage at full opening.

Different arrangements of stages distribution can be performed to fulfil special applications

Seat ring:

●

Quick-change and free-expanding type, precisely coupled with the cage to ensure a perfect plug alignment

Leakage Class:

●

Classes IV, IV S1 and V according to IEC 60534-4

Actuators:

●

Pneumatic diaphragm or piston type Electric and electro-hydraulic actuators

●

6-stage multistep cage detail VALVITALIA reserves the right to change design, specification and materials without notice

18

DS

CONTROL

RV631 3-step cage

Last cage section with single-stage and high specific CV Intermeditate section with 3-stage and increased specific CV 6-stage first anti-cavitation section

CV and XFZ vs travel

19

VALVITALIA reserves the right to change design, specification and materials without notice

ENERGY

NEE

PRDV steam conditioning Control Valves PRDV control valve is a very efficient and compact equipment for steam conditioning either in turbine by-pass lines discharging to condenser or in cogeration processes (see included layout). Conditioning includes pressure reduction and integrated desuperheating devices. Pressure reduction is obtained through three stages, except in LP applications where two stages are adequate to provide good performance and noise limitation. The first stage is the throttling section where flow rate is adjusted by the change of plug position inside a drilled cage. The second stage is a fixed resistance performed by a drilled basket, which creates a backpressure on the seat in order to reduce its velocity head and the generated noise. The third stage has a patented cone-shaped special designed drilled ring wich contributes to noise reduction and improves the mixing of steam with the downstream injected water. Shape and orientation of this ring optimize the steam impact against the external surface of sprayed water pattern, where the biggest water drops tend to reunite and to improve the atomizing efficiency of the equipment as a whole. Desuperheating section consists of a chamber installed downstream the third stage where some spring-assisted nozzles are mounted. Great care is taken to avoid any risk of thermal shocks, including a jacketing of internal surface of injection chamber which is recommended for high pressure sytems and whenever steam inlet temperature exceeds 500°C. PRDV Control Valve (patented design)

Technical characteristics: ●

●

Sizes: sizes depending on service conditions Ratings: inlet section up to ANSI 2500. Outlet section up to ANSI 900 included Construction: from bar stock or forgings. Inlet connnection and injection chamber are welded to main body section Pressure seal design for inlet ratings over ANSI 900 Materials: carbon steel or Cr-Mo steels, F91 (9%Cr) depending on service conditions

Plug:

●

Unbalanced or balanced with seal rings and pilot assisted depending on service conditions

Seat Ring:

●

Welded-in by a double lip-seal joint which grants against thermal distortions and allows an easy removal from the body

Leakage Class:

● ●

Unbalanced and pilot assisted plug: class V (as to IEC 60534-4) Balanced plug with seal ring: class IVS1

Actuators:

●

Double effect, spring-assisted Valvitalia LPA pneumatic piston actuators are commonly used Electric, electro-hydraulic and hydraulic actuators for heavy duties control application

Body and Bonnet:

● ● ●

●

Materials:

●

● ● ●

Trim: stellited or nitrided F6NM alloy steel and AISI 422 (1-4935) 17-4-PH is used for inlet temperature up to 375°C Stem: AISI 316 or XM19 depending on service conditions Packing: pure graphite seal rings Pressure seal ring: low hardness AISI 316 PRDV Control Valve section

VALVITALIA reserves the right to change design, specification and materials without notice

20

DS

CONTROL Sizing and noise prediction Standard well-known sizing equations (IEC 60534-2-1) are notapplicable to PRDV control valves as a whole due to the fixed area devices assembled downstream the throttling stage. For this reason, all the stages are separately sized according to IEC equations and the selection of the whole valve is performed for each specific application. The accuracy of the combination of calculated Cv is guaranteed by the Valvitalia’s deep knowledge and large experience on this matter. The total Cv of PRDV, including all downstream devices (fixed resistances), is not useful for selecting the valve.

In limit flow conditions, where flow rate does not depend on downstream pressure, the effective Cv value for predicting the flow rate is the same of first stage.

The sizing of 2nd and 3rd stage is based on the assumption that full pressure recovery occurs between the stages so to allow a complete fluid reheat after the restrictions.

However, unexpected errors on fixed resistances sizing do not affect the flow rate passing through the valve as long as limit conditions are held on first stage.

To predict noise generated by PRDV control valves the basic principles of IEC 605434-8-3 standard are taken into account.

Both cone shaping of 3rd stage and the optimized steam/water mixing do contribute to the reduction of acoustic power transmitted downstream (IEC rw factor).

The overall PRDV noise calculation is made by a proprietary VALVITALIA method based on the most advanced studies supported by on-line verifications.

Steam conditioning PRDV valves in a combined cycle process plant

21

PRDV preheating layout – circulation type VALVITALIA reserves the right to change design, specification and materials without notice

ENERGY

NEE

SAN series desuperheating nozzles SAN NOZZLES are variable area spring-assisted nozzles for desuperheating service.

The closed position of the plug (51) is assured by the action of a calibrated spring (53) loaded by a threaded nut (52) locked in position by a pin (54). When the water pressure inside the nozzle rises, the âŒŹp between steam and water increases till the water action on the plug exceeds the spring load and the plug starts opening.

The water starts to come out from the nozzle flowing through several holes that, due to their special design, whirl the flow before it gets in contact with the inside surface of the plug.

The plug perfectly atomizes the water performing a 90 degrees-shaped conical blade.

The special plug profile on the external surface which is in contact with steam flow improves plug stability in open position.

Spring load can be adjusted to obtain the desired opening pressure. 1,3 and 5 bar are our standard settings. Other set pressure values can be provided for special requirements.

Materials: SAN body materials are carbon steel or Cr-Mo steel according to operating temperature.

INCONEL X-750 has been selected for springs to ensure maximum stability at highest temperatures.

Injection chamber is normally manufactured with the same pipe material.

SAN 5 nozzle VALVITALIA reserves the right to change design, specification and materials without notice

SAN nozzle spray pattern

22

DS

CONTROL

SAN nozzle rear view

Spring settings for SAN nozzles

SAN series

SAN Desuperheater Mounting

Side-pipe mounting

Probe mounting

One or more SAN desuperheater can be fastened at the end on a tubular element flanged or welded to the pipe.

The spray is performed close to the pipeaxis by selecting the probe lenght.

A reference pin located on the desuperheater flange ensures the correct orientation of the nozzle inside the piping.

23

VALVITALIA reserves the right to change design, specification and materials without notice