Danlap
Mechanical
- Sep 17, 2013
- 309
Dear fellow valves practitioners,
Would really appreciate some insights over likelihood or possibilities for internal pressure to “push” the stem outside (blowout) for two scenarios
a.Common check valve with external hinge pin, however the pin is protruding inside the other side of the body. Is it possible once the nut’s thread and or packing fails, aside from the leaking, the spindle will be blown-out spontaneously?
Understand that most incident related to pin blow out were related to check valve with counterweight design where shaft segregated into two section (per hinge of the disc). Where one side of the pin (blue circle below) is pressurized thus whenever the pin separated from the disc, there is a possibility that it might be blown-out.
sketch courtesy of
But is it really the case for below standard check valve (without blow out preventer / shoulder type inside)?
b. For relatively old (wedge, slab, through-conduit, double expanding) gate valves without spindle locking mechanism. Once in fully close position, and during the absence of its gearbox / actuator due to repair, is it possible for the spindle (along with the wedge) to be lifted up?
Isn’t that once it is “wedged” inside the cavity, shall the flow passing through the seat it is very unlikely for the “small” passing flow rate to lift this thing e.g. 8” or bigger gate valve.
I am inquiring experiences from others since this uncertainties may result my site to tack-weld the spindle nut of all check valve, and always lock the spindle of gate valve by any means when we are about to replace the gearbox.
Thank you in advance for the input.
Kind regards,
MR
All valves will last for years, except the ones that were poorly manufactured; are still wrongly operated and or were wrongly selected
Would really appreciate some insights over likelihood or possibilities for internal pressure to “push” the stem outside (blowout) for two scenarios
a.Common check valve with external hinge pin, however the pin is protruding inside the other side of the body. Is it possible once the nut’s thread and or packing fails, aside from the leaking, the spindle will be blown-out spontaneously?
Understand that most incident related to pin blow out were related to check valve with counterweight design where shaft segregated into two section (per hinge of the disc). Where one side of the pin (blue circle below) is pressurized thus whenever the pin separated from the disc, there is a possibility that it might be blown-out.
sketch courtesy of
But is it really the case for below standard check valve (without blow out preventer / shoulder type inside)?
b. For relatively old (wedge, slab, through-conduit, double expanding) gate valves without spindle locking mechanism. Once in fully close position, and during the absence of its gearbox / actuator due to repair, is it possible for the spindle (along with the wedge) to be lifted up?
Isn’t that once it is “wedged” inside the cavity, shall the flow passing through the seat it is very unlikely for the “small” passing flow rate to lift this thing e.g. 8” or bigger gate valve.
I am inquiring experiences from others since this uncertainties may result my site to tack-weld the spindle nut of all check valve, and always lock the spindle of gate valve by any means when we are about to replace the gearbox.
Thank you in advance for the input.
Kind regards,
MR
All valves will last for years, except the ones that were poorly manufactured; are still wrongly operated and or were wrongly selected
