Reciprocating Pump Packing Failure
Reciprocating Pump Packing Failure
(OP)
I am looking for some ideas as to why the packing is failing and how long packing on this type of pump in this application should last?
The pump is a Wheatley horizontal quintuplex plunger originally installed in 1983 and replaced in 2004. The original manufactures packing has a 25 day mean time between failures. The Slade brand packing being used since 2002 has a 32 day mtbf. Slade packing consist of braided reinforced graphite. There is no lubrication with this type of packing. The cross section of a ring is square. It has Kevlar fiber corners and 1/8” Teflon spacers for rigidity. When the packing begins to fail we will see an approximately ½” high cone shaped pile of packing material under the packing nut. The plungers will have minimal to no scoring when repacked. They are replaced along with the throat bushings every other failure.
The pump is used to provide seal injection for boiler circulating water pumps. So it runs continuously. Here are the specifications: Speed- 440RPM; Plunger- tungsten carbide, 1.25” bore X 3.5” stroke; Suction- 150deg F, 327psi, dampener charged to 150psi; Discharge- 2900psi, dampener charged to 500psi; Pumped Media- condensate with a chemistry of 3-4ppm silica, 0.1micromhos, 9.1PH, 1.0ppb sodium, 1-2ppb dissolved oxygen.
The manufacture has suggested a spring loaded self adjusting packing that has Kevlar incorporated in the rings. The cross section of a ring is V shaped. This is supposed to be a large improvement over what was originally installed. I do not know why we went to the Slade packing in 2002 over some other choice, other than it is used here successfully on other problem applications for pumps and valves.
The pump is a Wheatley horizontal quintuplex plunger originally installed in 1983 and replaced in 2004. The original manufactures packing has a 25 day mean time between failures. The Slade brand packing being used since 2002 has a 32 day mtbf. Slade packing consist of braided reinforced graphite. There is no lubrication with this type of packing. The cross section of a ring is square. It has Kevlar fiber corners and 1/8” Teflon spacers for rigidity. When the packing begins to fail we will see an approximately ½” high cone shaped pile of packing material under the packing nut. The plungers will have minimal to no scoring when repacked. They are replaced along with the throat bushings every other failure.
The pump is used to provide seal injection for boiler circulating water pumps. So it runs continuously. Here are the specifications: Speed- 440RPM; Plunger- tungsten carbide, 1.25” bore X 3.5” stroke; Suction- 150deg F, 327psi, dampener charged to 150psi; Discharge- 2900psi, dampener charged to 500psi; Pumped Media- condensate with a chemistry of 3-4ppm silica, 0.1micromhos, 9.1PH, 1.0ppb sodium, 1-2ppb dissolved oxygen.
The manufacture has suggested a spring loaded self adjusting packing that has Kevlar incorporated in the rings. The cross section of a ring is V shaped. This is supposed to be a large improvement over what was originally installed. I do not know why we went to the Slade packing in 2002 over some other choice, other than it is used here successfully on other problem applications for pumps and valves.





RE: Reciprocating Pump Packing Failure
I'd also make sure you are installing the Slade packing with the actual packing ring, not the Teflon spacer, is against that follower ring.
That said, I would be concerned that solid Teflon spacer rings are probably not appropriate for your application. The relatively high temperatures and pressures would likely cause that Teflon to soften and flow. Carbon filled Teflon spacer rings, Bronze, or even PEEK (overkill) would probably be a better choice.
I think it's reasonable to expect 3-4 months of service life from your packing. You will hear stories of years of service, but your non-lubricated, high pressure, hot water application is pretty tough to achieve those extreme lifes. Be careful about Kevlar. While durable as heck, it is often a lot harder on plungers than many of the other materials. Often, you get longer life on your packing only to trade for shorter life on your plungers, which tend to cost even more to replace.
V style packing can also work well in this application, but I don't know that it will work any better than a good set of braided packing. If you are out of luck with Weathley, then suggest you consult a reputable packing vendor for design assistance such as Utex Industries or CDI Seals, both out of the Houston area.
RE: Reciprocating Pump Packing Failure
Hope this helps
RE: Reciprocating Pump Packing Failure
This is the only useful information I’ve been able to find on the subject of packing. Maybe you can educate me a little more. We use a 3 cylinder pump to pressurize our fluid to 12,000 psi. Our packing only lasts about 200 hours. The particulars are as follows:
The fluid is water with 5% solids, 200 cp viscosity, 130 degF, 8.5 PH
On each cylinder we have a 1.25 inch ceramic plunger and the packing from the pressure side to the atmospheric side consists of
1 - loading spring,
1 - metal ring,
5 - Teflon braided packing rings with Teflon separators between rings,
1 - final Teflon separator and
the brass packing nut.
A couple of questions….
1) Why 5 rings? As I understand packing, 5 rings is the minimum but what determines this number?
2) My failures come in two varieties. The first type looks like pieces of packing coming out between the packing nut and the shaft; the second type of failure looks like a bulge on the outer diameter of the last (atmospheric) separator ring.
A little education would be most appreciated.
RE: Reciprocating Pump Packing Failure
RE: Reciprocating Pump Packing Failure