Smart Sealing

I found this graphic in a paper from Garlock in a paper presented at the 2004 Valve World conference. Basically this graph show that only 2 rings seals 70% of all the stuffing box pressure. From the old EPRI report it is slighted more to the top 5 rings instead of the top 2. But the main idea I think here is how important packing consolidation is on effecting this graph.
Now, to be fair, they are showing that it does take 5 rings to seal the entire pressure load.
I also have a hard time understanding how they "proved" this graph ~ perhaps it was just made up to support their new packing product.

I first heard this story a few years ago and was very interested because I am a bolting geek. Well this accident is no funny story - 10 people lost their life because of a bolting mistake. I highly recommend reading this story and seeing how important bolting is.

I was talking to a class recently and I was trying to drive home the thought of how much error can be in a torque value. With all the factors (thread condition, lubrication, stable coefficient of friction,etc) they all add up to more and more inaccuracies. But the world believes that a torque value is very accurate and scientific.
Well I tried to make the comparison of reading a torque wrench is like reading a faulty speedometer. The torque wrench will give you value just like a speedometer but it is not accurate to the "real" tension on the bolt.
If a police officer pulls you over you will still get a ticket if you have a bad readout.
I know, it needs some work..

A friend forwarded me this article about a 6 sigma program at Boeing to improve torque reliability. the program focused mostly on how quick torque wrenches go out of tolerance. They saw some wrenches over by 1.5 -2 times range.
They started a new program using a PDA to calibrate the wrench before each job by the maintenance staff.
Here is the link to the article..

This has been an issue that has been debated with me and my work friends for many years. At this link is a page written by legendary seal guy Bill McNally. Here I agree with most of his points but when he talked about mechanical seals he keeps talking in the "old" world. First I take issue with his comment about pump packing friction is like "driving with your emergency break on". With the old days of asbestos I might of believed it but with modern pump packing friction is marginally higher then seals. In tests that I conducted we saw less then 10% increase in total power consumption. Now in this article he says it is "6X". He is thinking that every ring is exerting an even load on the shaft creating friction. From the previous post, this is not true.
Teh second point I have to argue with him is that all packing needs a flush for dilution. I believe that many packed pumps have a flush when they do not need one. Many pumps could go without a flush with a change in packing and some embedded solid controls.

That is my 2 cents, please feel free to leave a comment if you feel differently.

The best solution for sealing emissions in valves is using a bellows. I have heard that for many years but never really see that many around. I know there is a major cost factor to using the technology and that there is wear and tear on the metal parts. But for a completely zero emissions product I would of thought this would of had a bigger acceptance.
Here is the link to a company in Texas that make them.

Found two really good safety related articles from the Hanford nuclear site. Over the years as laws got more defined about personal safety some of the best places to get information about industry issues is the safety departments.
As I was cruising the internet on valve packing issues stumbled on this site regarding "Lesson Learned at the Hanford site".
The first article is about a control valve breaking apart when put pack in service. Something to check for when working on old equipment.

The second article deals with valves that are subject to blowout. It goes over an accident at the plant and what safeguards the plant put in place to reduce incidents in the future.

Last night I went with the ISA to visit Pilgrim Nuclear power station control room simulator. The tour was conducted by the trainers at the facility and they have a real state of the art facility. The machine is an exact replica to the one in the plant down to the floor tiles. The have the massive computer that simulates everything that could possibly happen at the plant. They put new and old operators through the ringer with different scenarios ~ In our demo they turned off pumps and broke main feed water lines.
I was really surprised how much training the group does and certification. They also talked about the self regulation the industry did after TMI.
All and all, very cool.