[Purpose of Lantern rings in environmental packing] 2

[gguliye]

Dear All,
I am new to valve engineering, and would like to ask the following question.
What is the purpose of lantern ring and packing box ring in the attached sealing picture?
Regards,

 

[SPDL310]

This is just a guess, but to me it seems like the packing box rig is a machined part installed in the stack up to provide a flat surface for the packing to rest on. This allows for the bore to be drilled using an angled drill bit.

As for the lantern ring:

http://lmgtfy.com/?q=purpose+of+lantern+rings+in+valves

 

[gguliye]

SPDL310,
I have done googling before posting the question. I dont really understand how lantern ring help lubrication of packing.
Sorry..

 

[SPDL310]

There should be a lubricant/grease injection fitting between the two packing sets. It is not shown in this section view. The hole illustrated near the arrow allows the lubricant to pass from the outer annulus to the inner annulus creating a pocket of lubricant around the stem. When the stem strokes it will bring the lubricant into the packing sets. This is a setup that will work much better with frequent operation and a continuous supply of fresh lubricant. I would guess that this is some sort of control valve in frequent modulating service. Historically speaking I believe this set up originated in reciprocating pumps.

 

[bcd]

As said correctly by SPDL310, the packing box ring provides a square, flat surface that is perpendicular to the bore for the packing to be pressed against. It has a tight fit against the packing bore and shaft so the packing does not extrude into any gaps at the OD and ID. If the packing pressed directly against the as machined bottom of the packing bore, it can create uneven loading by the angled surface, plus there is a larger gap between the body and stem for the packing to extrude into.

Lantern rings serve many different purposes. Grease injection is one, but is not very common as lubricant needs to be fully compatible with the media in the valve. Most common is for a leak-off port that is machined through the side of the valve body and into the area of the lantern ring. This port can be used to check if the lower set of packing is leaking or not.

Another common way this type of arrangement is used is to inject pressure. It is common to inject gas or liquid pressure into the port that is slightly higher than the process pressure inside the valve. This helps to ensure that whatever is inside the valve cannot leak externally.

 

[gerhardl]

..... and in addition the lantern ring will mechanically support and center the spindle aganst sidewise forces and movement, and also give less friction than if the whloe spindle length were packed...

 

[gguliye]

Very big thank to both of u

 

[Dinu Stan]

Hi

In General, Lantern Ring are widely used in applications where outside lubrication is necessary in order to keep packing lubricated, cool and flushed of abrasives and chemicals. it is used to increase the life of compression packing, resulting in less maintenance and downtime over the life of the equipment.

Mostly lantern ring is used in pump applications. but for valve application, it is used when we are using the environmental packing for splitting the two packing sets to provide the better performance and sealing, also lubricating the packing.

lantern ring will be in any form of material such as steel, PTFE etc. depends on application.

Thanks...

Dinu...

There are no secrets to success. It is the result of preparation, hard work, and learning from failure.

 

[Isha90]

Lantern ring can be used in Valves Stuffing bore for Vacuum application too.