The seat material of general purpose ball valve employs generally non-metal material, such as PTFE. Limited by the seat material, the general purpose ball valve can not be used in case of high temperature application, and application medium with solid articles, and ash dregs neither. So, the application scope of general purpose ball valve is restricted partially. Taking this into consideration, NAINAI company has developed successfully after years of hard study full range of metal to metal sealed ball valve, including floating ball valve and trunnion ball valve, which have found extensive applications in such industries as petroleum, chemistry, power, metallurgy, and light industry. The metal to metal seated ball valve made by NAINAI has been patented by the state (patent No. ZL 99 2 03651.8).
Standards and specification
> Design & manufacture: API 6D,API 608,ASME B16.34,ANSI/AWWA C507,MSS SP-72,BS 5351,BS 6364,BFCI 70-2,ISO 5211,NACE MR0175 .
> Connection ends: ASME B16.5,ASME B16.47,API 605,MSS SP-44,ISO 7005-1,JIS B2238,BS 12627,ASME B16.25,ASME B16.11,BS 12760 .
> Face to face dimension: ASME B16.10,ISO 5752,BS 558,BS 12982
> Testing & inspection: API 598,API 6D,API 607,API 6FA,BS 6755,BS 12569,MSS SP-82,MSS SP-61
> Normal pressure or rating: Class 150~ Class 2500,JIS 10K ~ 20K,PN 10 ~ PN 420
> Normal diameter or bore: NPS1/2~NPS10,DN15~DN250
> Applicable temperature: -196 degrees celsius~540 degrees celsius
> Operation type: Manual, worm gear, pneumatic, electric
Design features of metal to metal sealed ball valve
Except for such features as wrong operation prevention, stem blow-out proof, mounting pad provited, the metal to metal sealed ball valves made by NAINAI posses the following unique features.
1,Advanced hardening technology employed for ball and seat
Metal to metal sealed design has been employed perfectly for the ball and seat, which has also adopted the advanced hardening technologies, such as ultro-sonic spray coating, nickel base spray welding, surface specially hardening, stellite spray welding, ceramic material with high strength and hardness, and so on. Surface hardness of the ball and seat may generally reach more than HRC60, Maximun is up to HRC74, and application temperature of the material may be up to 540degrees celsius, Maximun is 980degrees celsius. Combining strength of the material gets to more than 10000 PSI. Besides, the surface materials posses also very good resistance properties of friction and impact. Metal to metal sealed ball valves made by NAINAI are suitable for use in most criticle working conditions.
2,Valve stuck under high temperature prevented
In the case of high temperature working condition, the valve seat and ball would easily get stuck due to heat expansion, and the valve could not be open. Metal to metal sealed ball valves made by NAINAI employ the patented design of bevelling spring loading, which would absorb the heat expansion of parts caused by the bevelling spring. So, it is ensured that the valve would not get stuck and be open and close easily in the case of high temperature condition.
3,Excellent tightness function
A unique technique has been employed for the ball grinding, which makes the ball surface reach extreme round and smooth by rotating the ball and grinding apparatus at different directions in space. The tightness function of the valve meets completely and exceeds the standard requirement.
4,An entire fire safe structure
The metal to metal sealed structure has been adopted for the valve sealing surface design. Packing is so designed with graphite, and gasket is so designed with stainless steel, plus graphite that the valve can assure reliable tightness even if under fire condition.
5,Natural anti-atatic structure
Metal to metal sealed ball valve with its body seat, ball, other metal parts , and so forth, closely contact with each other, having naturally formed a static electricity passage. In this respect, there is no need to provide special anti-static device.
6,Double-block and bleed function
NAINAI's metal to metal sealed trunnion ball valve is in general of the front ball sealing structure. Actually, two seats of the metal to metal sealed trunnion ball valve can both cut off separately the medium at inlet and outlet to realize double-block function. When the valve is closed, the body cavity and both the bore ends can be blocked with each other even if both ends of the valve are under pressure at the same time, whereas the medium left in the body cavity may relieve through the relief valve.
NAINAI's metal to metal sealed floating ball valve is of behind ball sealing structure, employing in general single direction tightness. The flow direction is indicated on the valve body. If specially required by customers, NAINAI's patent of bi-direction sealing design may be selected.
Metal sealed floating ball valve
Products range of metal to metal sealed floating ball valve as follows.
Note: For the manual ball valve, Five-pointed star symbol indicates that Lever is suggested , Triangular symbols indicates that worm gear is suggested.
Typical drawing and parts composition
Parts and material list
Note: The chart above only lists out some common composition of steel ball valve parts. We may provide other different parts material composition according to the customer's request or the actual valve working condition.
Main sizes and weights
Refer to that of floating ball valve for main dimensions and weights of metal to metal sealed floating ball valve. The flange dimensions and face to face dimensions are the same as that of floating ball valve.