greassing ball valve 3

[godel123]

hi
is there a specific type of grease for the lubrication of ball valves?

thanks

 

[gerhardl]

See my comments to the posting 'valvesealants' below.

 

[PeterIgg]

I would add the caveat that, in general, ball valves DO NOT require greasing whilst in service. It is a common misconception that the fittings which lead to the seats and stem are called 'Lubrication' points. IN GENERAL they are NOT, they are 'Emergency Sealant Injection' points, the emphasis being on the word 'Emergency'. Indeed, especially with the stem fitting, the filling of these points with grease (or sealant) when not required can lead to the premature failing of the seals. If a product is forced into the sealant area it has to go somewhere and that 'somewhere' could well mean that it forces itself past a seal and a leak appears when prior to this there was none.

BEFORE undertaking any greasing of ball valves - contact the manufacturer for their recommendations. In general, for ball valves: if it is working OK, leave it alone.

 

[gerhardl]

I do absolutely agree PeterIgg, good point! Hope this also is (somewhat?) obvious from my answer!

 

[vpl]

I'll add the comment that, in the US nuclear world, greasing of valves -- especially prior to a planned surveillance test -- is frequently considered a violation of federal requirements.

Patricia Lougheed

******

Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.

 

[godel123]

i think when talking about greasing ball valve it's about the gearbox lubrication , as said PeterIgg about the valve fonction its self : "if it is working OK, leave it alone"

 

[gerhardl]

.. godel123, I do not believe we are talking about the gearbox. Even at that many gearboxes (mechanical gearboxes) are greased for life, pneumatic only lightly greased or non-greased, electrical usually not or exceptionally at given points at given intervals.

As for grease type if required: as given in the gearbox manual.

 

[godel123]

if the gearbox is used frequently, the need for greassing is more probale

 

[valvesarefun]

Peterlgg has a very valid point about the misconception that valves need to be greased. I would add that when you pump grease into a valve cavity it will fill the cavity and then extrude by the seats and into the valve bore. That grease is now an adhesive that is going to trap any trash as it comes down the line. Trash like sand, gravel, weld slag, etc will then be ground into the seat ring when the valve is operated, thereby damaging the seat ring. If a valve is stuck it is usually recommendable to try a valve flush before you ever consider using grease.

Best regards,

VRF