Average life and warranty life of the sealing materials identified when testing valves with water according to GOST 2874-82
When operating valves for working mediums other than water, the reliability parameters are determined by the specific mediums, depending on its parameters.
The warranty period is 12 months from the date of putting into operation, but not more than 18 months from the date of sale under condition of observance by the consumer of rules of transportation, installation and operation.
Conservation period - 3 years.
Average service life of body parts is not less than 30 years.
Average life removable parts and components – at least 5 years.
Sealing diagram in butterfly valves with triple offset
This figure shows the design of valves with triple offset: the disk axis of rotation and the seat axis in the valve create offset "a"; the disk axis of rotation is offset from the pipeline axis - this is offset "b"; the third offset "c" is formed due to the conical shape of the sealing surface. This design reduces friction in the points of contact between the disk and the seat, which increases reliability and durability of these valves, reduces the torque to control the valve.
Metal-on-metal seat - stack seat of graphite and stainless steel rings
Metal-on-metal seat is all-metal
By default, valves series PA900 have one-sided tightness, i.e. the direction of the working medium must be unidirectional, in accordance with the arrow on the body. It is not allowed to use such valves to block the flow of the working medium in the opposite direction, this can lead to valve breakage. Although in exceptional cases, after agreement with the manufacturer, it is possible to use these valves for the return flow of the working medium with a pressure less than the nominal pressure. Upon request, it is possible to manufacture bidirectional valves series PA900 for any flow direction of the working medium.
This is achieved by using stronger parts of the valve design, such as the stem, bearings, gearbox, etc. Valves series PA900 with double-sided tightness have a seat designation = 8.
For example, PA928.500.16-02F is a "rotary disk flanged valve with triple offset (body – steel WCB, disk – steel WCB, seat – stainless steel + graphite, direction of working medium - bidirectional) with gearbox".