4" ball vavle (for steel pipe network) blocked

[CostasV]

We recently found that a buried ball valve (welded on a steel pipe network) can not be manouvered, even with very high torque. It is blocked in open position. The pipe pressure is about 48 bar.
Hopefully the valve is not in critical position. We can just forget about it, because there are others in front and after the mentioned valve.
Fortunately, the ball valve has grease fittings, so we plan to put some thin grease as a first step.

Any ideas for the second (if the first one does not help)?


Thank you in advance
Costas

 

[GasDistEng]

Costas-

What brand name is the valve. What is the size?

TB

 

[CostasV]

4 in., Ball valve, #600, L=2450 mm

Supplier: Petrovalves
Serial No. : KO206

Costas

 

[CostasV]

Correction : Petrolvalves SRL (Italy) (not Petrovalves)

Costas

 

[CostasV]

Well, we put grease in the valve. Applying a torque of about 300 to 400 Nm (there is no gearing), we opened and closed the valve for about 15 times, while before the greasing we could not even "crack" the valve.

Any comment/idea will be apreciated.

Costas