Maximum Allowable Valve Input Torque (MAVIT) 2

[feng09]

Hello Valve Engineers,

can any body tell me what is maximum allowable valve input torque?
i would imagine it is nothing but the MAST but i am not sure, ISO 12490 explain MAST very well
is MAVIT mentioned in any valve/actuator standards ?

many thanks in advance

 

[valvit]

In my experience, it has been used as an equivalent to MAST.

MAVIT is more commonly used by actuator manufacturers (both Metso and Emerson use this term in their publications), whereas most valve manufacturers use the term MAST.

I am not aware of any API, ISO, EN or other standard that uses this term.

 

[gerhardl]

...see also thread408-321957

 

[feng09]

Thanks a lot valvit and gerhardle for quick response.

i Would imagine the MAST value is more related to torque carrying capacity of stem which is in actuator point of view

but if we think of butterfly valve then stem disc connection or stem groove for anti-bolow out ring could be the weakest section in drive train assembly isnt it?

based on this if i describe MAVIT (Maximum Allowable Valve Input Torque) as

''The maximum torque carrying capacity of a valve at weakest section in drive train assembly''

generally MAST is calculated for the top section of the stem which could be single key or double key section
and if we calculate the torque carrying capacity of the same stem at stem groove then it could be lower than the top section torque.

Any suggestion on this form your experience..?

many thanks in advance

 

[valvit]

In my experience, the MAST value is calculated based on the weakest link in the drive train...not just the valve stem. With this interpretation, it is the same as the MAVIT term you are describing.

 

[feng09]

thank you valvit..