Technical Features: Series 58 & 59
|STANDARD FEATURES||TYPE 59||TYPE 58||COMMENTS|
|Size range||1 1/2” FB up to 6” RB||6" FB up to 60"|
|Pressure||ANSI 150 thru 2500||ANSI 150 thru 2500|
|Fully welded body design||YES||YES|
|Self relieving seats||YES||NO||58 option (no extra cost)|
|Double Piston Effect seats||NO||YES||59 option *|
|Primary metal to metal seal,
secondary protection with o-ring
|Plastic polymer insert on seat sealing||YES||YES||58 option*|
|Lubricated seat||NO||YES||59 option*|
|Double block and bleed||YES||YES||Open/closed position|
|Metal to metal seats||YES*||YES*|
|Trunnion mounted ball||YES||YES|
|Full or Reduced bore||YES||YES|
|Stem anti-blow out proof design||YES||YES|
|N.D.T verification on body weld joints (ultrasonic examination)||YES||YES||According to ASME VIII Div. 1|
|N.D.T verification on welding ends (dye penetrant)||YES||YES||According to ASME VIII Div. 1|
|Minimum thickness ASME B16.34||YES||YES|
|RF or RTJ flanges to ASME B16.5||YES||YES||Other flange design*|
|BW (butt-weld) ends to ASME B16.25||YES||YES||Other code for BW design*|
|Bore and end-to-end dimensions to API 6D||YES||YES||Dimensions other than API 6D*|
|Manufacture in accordance with API spec. 6D/ ASME B 16.34||YES||YES|
|Materials certification to EN10204 type 3.1.B for pressure containing parts, ball, stem and seats||YES||YES||Type 3.1.C materials certification level*|
|Fire safe design to API 6FA (BS 6755 Pt.2)||YES||YES||Other fire safe code (e.g. API 607)*|
|Operation by lever, gear w/ handwheel or actuator||YES||YES|
|Ease of maintenance||The body construction precludes the internal disassembly at site. The complete replacement
on the upper stem seal can be achieved with the valve installed without pressure.
|* available with extra cost|
Trunnion mounted ball valve
When the ball is in fully closed position, two trunnions absorb the side thrust generated by line pressures, preventing excess friction between ball and seats. With this system, even at full rated working pressure, operating torque stays low. Therefore a generous sizing of trunnions is essential to the life and operability of the valve. The spherical surface is machined and ground to close tolerance. To reduce torque and minimize wear, the ball is then electroless nickel plated and polished to mirror finish. For special applications the ball may be hardfaced with T.C.C. (Tungsten carbide coating) to improve resistance to wear and prevent scratching caused by hard particles.
Emergency stem and seat sealant injection
In case of emergency, when sealing materials (seat sealing and stem o-ring) are damaged or decomposed by fire or other accidental causes, a sealant injection into fittings on both stem and seat prevents leakage until the primary seal is restored. For Type 59 ball valves the seat sealant injection is an optional feature available with an extra cost. However, the material between ball and seat is a thermoplastic seal, thus no further injection is necessary. Self lubricated, low friction materials are used for stem bearings, stem seals and body seats. Low friction materials, e.g. nylon, are used for seat inserts. Stem bearings and self-lubricating seals give predictable operating torque for the life of the valve.
The stem is made separately from the ball. It is blow-out proof, properly obtained with an integral collar in the bottom of the stem.
Sealing system consists of three sealing points: two static o-rings seal the stem, plus a third graphite seal is retained by the adaptor flange. This ultimate seal can be replaced when the valve is in line and in the closed position.
“59” Sealing Principle
The sealing between the seat and the ball is performed by a plastic polymer insert. The choice of this soft sealing is dependent on the service conditions. The initial seal, at low differential pressure, is obtained by the spring loaded floating seats (spring energized) which achieve independent sealing. Increasing the line pressure behind the upstream seat ring helps the seat spring load to force the upstream seat tightly against the ball.
“58” Sealing Principle
The sealing between the seat and the ball is performed by a primary metal to metal seal, and a secondary O-ring seal for both the seats. The choice of the secondary seal “soft sealing” is dependent on the service conditions. The initial seal, at low differential pressure, is obtained by the spring loaded floating seats (spring energized) which achieve independent sealing. Increasing the line pressure behind the upstream seat ring helps the seat spring load to force the upstream seat tightly against the ball.
Fire Safe design and test
Fire safe is a standard design on Valvitalia ball valves. Two o-rings and gland gasket prevent leakpaths from the valve stem area. If fire deteriorate the o-rings, the gland gasket, the stem firesafe packing prevents fluid or gas leakage. Valvitalia soft seat ball valve fire safe test (shown in the image) was witnessed and certified according to API6FA – BS 6755 PT.2
ANTI STatic device
This device is a standard feature on VALVITALIA ball valves. A coil spring thrusts a small sphere, providing grounded continuity between stem and other metallic components of valve (ball and body) in order to avoid sparks during stem rotation when opening and closing the valve and preventing problems in case of use with flammable fluids and gas.
body vent and drain
The drain and vent plug on the valve body enables verification of the seat ring's integrity. A bleed valve may replace the drain plug.
Double Block ANd Bleed
VALVITALIA valve design features two seating surfaces between which the cavity can be vented through a bleed connection thus confirming the tight sealing of the valve, in both the closed position and open position, when pressure is applied to either side or both sides of the valve.
Double piston effect (59-OPTION, 58-STANDARD)
With the DPE seat configuration when there is a leakage in the upstream seat, the pressure entering into the body cavity pushes the downstream seat against the ball and the valve seals. This effect is a sealing principle involved in utilising line pressure to effect a seal across the floating seat. A relief valve is recommended to be installed to protect the body cavity from excess pressure.
Self relieving seat (59-STANDARD, 58-OPTION)
In a self relieving condition, excessive internal body pressure is automatically relieved in both upstream and downstream directions by forcing the seats away from the closure element.