Stuffing box question/can of worms

[captmorgan23]

I know there are probably extremes on both sides of this, but i respect all opinions as there seems to be an amazing wealth of knowledge here....so here goes.

I have been doing a lot of research ever since my initial post on my older boat. One of the suggestions was to replace the stuffing box with a *more modern dripless unit. I am now confused as it seems there are two camps on this, one being the camp that there are failure issues with the old flax way, but it also seems there are worse failure issues with the 'maintenance free' units....to quote "catastrophic failure", whereas the old school flax stuffing boxes seems to give you a margin of error before a gusher in the boat.


Opinions please.


TY


MP

 

[Marin]

I'm not aware of failure problems with the standard, flax-packed (or Gore packed) stuffing boxes. The packing material wears out over time but this does not result in a catastrophic failure but simply an increased water seepage that can't be adjusted away. The packing is then replaced and you go a bunch of more years until you have to do it again.

On the recommendation of the yard we use, we run regular flax in our packing glands and have gotten nine or so years out of them before they were repacked. And even then they weren't repacked because the flax was failing but because we had the shafts pulled for various reasons so we had the packing replaced at the same time.

 

[captmorgan23]

The catastrophic failure I am talking about is with the newer dripless shaft seals without the flax. I guess I am now even more confused as to what the ceramic seals and bellows are then. If someone wouldn't mind giving an example, maybe linkwise, as to what this is.....I GOOGLED ceramic seals and bellows and came up with nada.......I thought you guys were referring to the older style stuffing boxes and were suggesting I replace with this: http://www.shaftseal.com/product_categories/300000001

These shaft seals are maintenance free, but when they fail you fill your boat up with water hence the "catastrophic failure" quote.

MP

 

[Capn Chuck]

MP, Perhaps you are not getting any info on ceramic seals since the dripless systems use a carbon material for a seal. I would suggest you search for info on the dripless and you will find a few example of catastrophic failures but they are pretty much old information and the same reports repeated over and over. We just installed the PSS on our trawler and covered 800 miles with it so far. We love it and really like not having a stuffing box dripping and the constant need to adjust it on long cruises. Each owner needs to do what is within their comfort levels. We received reports of owners with the dripless systems 5, 10, and one 18 years on the boat with nothing more than normal maintenance. We discounted the advice of those that said don't do it, and had no experience with the units other than internet rehashes of a few cases. But we all know if it is on the internet it must be true, right? I have installed many of these units on other folks boats over many years and to date have heard absolutely no failures. We did add a high water alarm directly under the shaft log as a safety measure, but we are a bit anal on safety devices anyway and have more than one high water alarm. The choice is ultimately yours and remember that on a boat there are any number of possible catastrophic failure points. Chuck

 

[captmorgan23]

OK......I guess my real question has been getting clouded by my confusion......so here is what I need to know:

What are ceramic seals and bellows, and how do I know if I have them?




I thought they were referring to the wet cooled stuffing box with flax(which I have) and now it seems I need to be looking for something else and need to know what I'm looking for.


Thanks for the patience guys


MP

 

[RickB]

"What are ceramic seals and bellows, and how do I know if I have them?"

-- Edited by RickB on Wednesday 14th of October 2009 10:39:37 AM

 

[Codger2]

Excellent answer Rick! Very short, informative and answers the question....we need more of this!

 

[Marin]

So is carbon graphite considered a ceramic? I see nothing in the illustration Rick posted that says "Ceramic."

MP--- It sounds like you have basically the same setup as our boat--- a conventional, flax-packed stuffing box with adjustment nuts but with a water feed from the engine's raw water cooling system that is there to ensure proper cooling and lubrication of the cutless bearing in the shaft log.* SOme boats have a water feed, some don't, but the setup you are describing is the conventional system.* As opposed to the drippless system.* There is nothing wrong with the system you have--- a bazillion boats have it--- and the only practical reason to change to a dripless system is if you don't like the idea of a slow drip of water into your bilge as the boat is underway.

-- Edited by Marin on Wednesday 14th of October 2009 11:19:02 AM

 

[captmorgan23]

Thanks....answers the question perfectly......I now know where to look for the ceramic seals and I think Marins ? as to if carbon graphite is considered ceramic is a good one. As to the bellows....what material do I need to look for there.....is there something besides the rubber that would need replacing?
I am headed to my boat this weekend as I live in Bend OR and my boat is anchored in Mats Mats Bay in Port Ludlow,WA, so I will be able to inspect the shaft closer. I've loaded up my tools and am going to make a list of craaap that needs a'doin'.....so get ready for a bunch of naive questions in the next few days.

MP

 

[RickB]

Marin wrote:

So is carbon graphite considered a ceramic? I see nothing in the illustration Rick posted that says "Ceramic."

*Ask one of Boeing's brake gurus.

 

[Marin]

They're called carbon brakes here. I've never heard them referred to as ceramic brakes.

PS-- Okay, did some research on the web and carbon graphite and ceramic are two different things entirely.

-- Edited by Marin on Wednesday 14th of October 2009 12:31:38 PM

 

[Phil Fill]

We installed PYI dripless shaft seals 13 years ago.* Here is their phone number and address


ShaftSeal.com, ShaftSeal and PSS ShaftSeal are trademarks of PYI, INC

Home Office: ****Telephone: 425-355-3669 ****Toll Free: 800-523-7558 ****Fax: 425-355-3661 ***

Address: 12532 Beverly Park Rd, Lynnwood, WA 98087-1524 ****E-mail: Contact Us

 

[sunchaser]

I have sufficient space in my ER to do routine hourly checks when under way.*Two *of the checks are:

---- Visually inspect each PYI dripless system*for drips*
---- Use and IR gun to check temperature at PYI fittings, it should closely match the**** water temperature feeding the raw water pump

I'd do the same if it were a flax or Gore system

 

[RickB]

Marin wrote:

PS-- Okay, did some research on the web and carbon graphite and ceramic are two different things entirely.

Sort of an Europa vs**Sedan thing*I guess*but the following description sure sounds like a ceramic to me.


"SUBJECT : How the Carbon/ Graphite seal face is manufactured ...

Seal companies purchase carbon/ graphite molded faces from one of several carbon manufacturers. The seal companies pay for the necessary molds and then retain the exclusive use of them. A good seal face would be a mixture of carbon, graphite and nothing else. The carbon is purchased as a by-product of a manufacturing process while the graphite is mined with the main sources being in Canada and Madagascar. The cost of these elements is determined by two things:
<ul>[*]How finely is the product milled? A fine talc is desirable. [*]How pure is the product? [/list]
A good mixture would be 80% carbon and 20% graphite. Graphite is a good conductor of heat, a natural lubricant, and has a laminar grain structure similar to a deck of cards, allowing the individual grains to slide over one another. It is this laminar structure that allows the graphite to release from the carbon/ graphite face and deposit on the hard face in the same manner a graphite pencil will write on a sheet of paper.

To manufacture the finished product we place this mixture in an oversized mold using a hydrocarbon as the glue to hold the powder together. Years ago "pitch" from a tree, was used for the same purpose. The mixture is then compressed and placed in an oven at 2000° Fahrenheit (1000° C) for a period of thirty to sixty days. The hydrocarbon will convert to carbon at this temperature. The piece must be heated slowly or otherwise the carbon will combine with oxygen to form carbon monoxide, or carbon dioxide which will, in either case, ruin it."

http://www.mcnallyinstitute.com/04-html/4-7.html

Ceramic materials are inorganic, nonmetallic materials. Most ceramics are compounds between metallic and nonmetallic elements for which the interatomic bonds are either totally ionic or predominantly ionic but having some covalent character. The term ceramic comes from the Greek word keramikos, which means burnt stuff, indicating that desirable properties of these materials are normally achieved through a high-temperature heat treatment process called firing.

http://www.engr.sjsu.edu/wofmate/ceramics.htm



*

 

[Marin]

I can see how this conclusion can be reached given the use of heat in*both the carbon graphite and ceramic processes.* But in the various materials I've read about brakes, for example, they talk about carbon brakes and ceramic brakes as two different things.* An advantage cited for ceramic brakes is the lack of brake dust, where carbon brakes do not have this advantage.

The terms used here*when talking about the materials used on the planes do not include "ceramic."* They talk "composite" or "carbon fibre" or "carbon" or "graphite," etc.

FWIW here is a description of two of the heat-shield materials used on the Space Shuttle.* They seem to make a distinction between a carbon-based material and a ceramic.

Reinforced carbon-carbon (RCC), used in the nose cap and wing leading edges. Used where reentry temperature exceeds 1260 °C (2300 °F). High-temperature reusable surface insulation (HRSI) tiles, used on the orbiter underside. Made of coated LI-900 Silica ceramics. Used where reentry temperature is below 1260 °C.

 

[RickB]

"Sort of an Europa vs**Sedan thing*I guess*..."

 

[Codger2]

captmorgan23 wrote:"What are ceramic seals and bellows, and how do I know if I have them?"

That question has been answered ....it may have been the wrong question but answered it was.* Now I think his question is "what kind of a shaft seal do I have? Stuffing box or dripless shaft seal?

A digital photo of his shaft seal area would be nice to have!

*

 

[RickB]

Geez, it's almost time to fly in Steve D ...

(click on the photos for source and more information)

Does it look anything like this dripless seal?



or does it look like this stuffing box?



Or has this turned into some colossal joke?

One easy test is to step on it. If water pours out and gets your ankle wet it is a dripless.

If your foot slips off and you break your ankle it is a stuffing box.

If you can't even reach the darn thing it is probably a stuffing box with old, hard, and worn out packing.



-- Edited by RickB on Wednesday 14th of October 2009 03:29:19 PM

-- Edited by RickB on Wednesday 14th of October 2009 03:30:26 PM

 

[Codger2]

LOL* I love it!

 

[Phil Fill]

I suppose the dripless could have more of a catastrophic, if it was not maintained?* The two biggest causes would be the SS Rotor -#6 slipping on the shaft causing to be no pressure against the graphite flange, the O ring inside the SS rotor failed, or the bellow developing a hole/leaking?* The most common is probable the SS slipping on the shaft because the set screws backed off, and/or the O ring failing.**A quick solution is to calk the SS flange to the*shaft to help prevent it from slipping and if the O rings failed it would also prevent/slow a leak.*
*

*
As for the bellows developing a hole the most like cause would be rotting*which is the same concern**with hoses on the boat, which should be checked regularly and/or changed at least every 10 years. Also the space between shaft and the shaft log is usually not that great and/or a front cutlass bearing. **If the bellows did start to leak it would not a sudden burst but a slower leak giving some warning.* If the bellows did leak, I would warp plastic wrap and duct tape around until the boat could be pulled.*
*

*
I have a blue paper towls under the dripless so if there is a leak it will be noticeable, and double bilge pumps with alarms. *If maintained properly there is little chance of a catastrophic failure?* **********


-- Edited by Phil Fill on Thursday 15th of October 2009 10:21:38 AM

-- Edited by Phil Fill on Thursday 15th of October 2009 10:24:01 AM

 

[sunchaser]

I have in front of me a very large $$ order for agitators in a pressure vessel. I note that the seals are silicon carbide/antimony as well as* PD pumps for the seal water package. For decades this type of system, has been used in industry. PYI is just a simple offshoot. But like anything mechanical, good maintenance is required.

 

[captmorgan23]

Here is the stuffing box picture....look familiar to anybody?.......any comments?

 

[Marin]

That's a pretty conventional unit. I've seen these on a number of boats. The other style has two large nuts that completely surround the forward end of the packing gland. One nut is the adjustment for tightening or loosening the pressure on the packing material--- flax in the case of our boat--- and the other one is a jam or locking nut to keep the adjustment nut from working loose. I thought you said there was a water feed to the stuffing box but I don't see one in your photo.

 

[RickB]

Marin wrote:

*I thought you said there was a water feed to the stuffing box but I don't see one in your photo.

It looks like threre is a grease zerk about 11 o'clock.

Maybe*the water feed is further aft, behind the*forward end of the stern tube.*

 

[Marin]

The plug in the photo on the near side looks like the square-headed drain plugs that are on all our seacocks. On the seacocks they are to facilitate draining the water out of the valve in preparation for a winter layup. You can also use your finger to force grease into the valve bodies through the plug mounting holes.

There appears to be a shiny "thing" on the far side of the stuffing box that could be the top of a very clean zerk fitting.* I assume that's what you're talking about.



-- Edited by Marin on Saturday 17th of October 2009 02:43:41 PM

 

[RickB]

That looks like a zerk to me. The bright spot just above the zerk looks like a meniscus*of the bilge water between the hose and the housing made shiny*by the flash.

Or, if that zerk really is a square ended plug (which it does more and more) that might be where the cooling water was supposed to be injected when that unit was used i other applications. It appears to be located where a "lantern ring" might be found in a traditional stuffing box.*

-- Edited by RickB on Saturday 17th of October 2009 05:30:25 PM

 

[Phil Fill]

The picture shows the main reason for not having a conventional stuffing box as they leak and water/rust/corrosion in the bilge.* Where as a drippless, the bilge is completely dry.* I took one look at the Eagle bilge with the water when we bought her and said that simply has to go.* That is one of the first things I look at when checking the engine room on our boat or any boat.* Is the bilge dry?

I noticed the newer SS collar has 4 set screws were as the oler one we have has only one, so the collar slipping on the shaft has been taken care of, but I would still run a bead of calking in case the O rings leak.***

 

[FF]

"The picture shows the main reason for not having a conventional stuffing box as they leak and water/rust/corrosion in the bilge. "



This is mostly correct UNTIL the more modern Gore and other materials were marketed.

Now your 1905 antique stuffing box can be packed with modern material that runs with a dry bilge , even underway , lower shaft temperature than even tefflon, and far less chance of a scored shaft from flaking being captured by the antique packing.

"Where as a drippless, the bilge is completely dry."

However the danger of a failed rubber part or other mechanical mishap may allow MORE WATER to enter the boat than most Pairs of bilge pumps can handle.

As a firm believer in KISS , the thought that my boat might be on the bottom is worth the extra cost of a less than disasteriouus failure mode.

FF

 

[BaltimoreLurker]

FF wrote:
This is mostly correct UNTIL the more modern Gore and other materials were marketed.

Now your 1905 antique stuffing box can be packed with modern material that runs with a dry bilge , even underway , lower shaft temperature than even tefflon, and far less chance of a scored shaft from flaking being captured by the antique packing.

FWIW, I used the Gore packing material this season, and it certainly seems to work as advertised and as FF describes.* Once I got everything adjusted correctly I had no drips and, according to the IR gun, the shaft and packing gland never goes above 105 degrees. Which is probably little above ambient temp in the engine room on the Chesapeake in the summer when the air temps are in the 90s and the water temps in the mid/upper 70s.



*

 

[Marin]

I'm always curious when I read posts from people who say their packing glands never get above 105 or whatever degrees, or that they are hot but not real hot. This is obviously a normal situation for their boat. Our boat has conventional packing glands with flax packing. Once they are properly adjusted--- a very slow drip when running, maybe one every three or four minutes--- and no drips at all when stationary, they run dead cold to the touch. I haven't measured the temperature so I can't give a degree number, but by feel they are as cold as the seacocks feeding the engines. The single-engine GB we chartered before buying our own boat was the same way. So why the apparent large differences in the running temperatures of packing glands of the same basic type?