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It's not just the mining of coal that has come under increased efforts to improve worker safety. Recently, Jeffrey Specialty Equipment Corporation took a look at how previously installed Jeffrey Flex Tooth Coal Crushers could be made safer for operators by converting them to our EZ Access technology .

EZ Access technology offers significant safety and productivity improvements for operators and maintenance personnel. The EZ Access hydraulically operated door gives operators and maintenance personnel access to the machine from a safer location and lets them change hammers in a more ergonomic position.

The EZ Access design eliminates home-made apparatuses for opening and holding access doors in position. Plus the rotor can be removed without removing feed chutes and associated feed equipment, all of which take time and increase machine outages for maintenance. A rotor locking device keeps the rotor in position while it's being serviced.

Because the machine is easier to service, it will be serviced more frequently and on a regular basis, rather than when there is a problem. We also know that machines is serviced regularly are less likely to have a catastrophic failure.

This technology is only available on Jeffrey machines. We can equip new machines with EZ Access technology, or convert old machines . If you think of a machine as consisting of 3 major components--Upper Housing, Lower Housing and the Rotor—our EZ Access conversion replaces the housings and leaves the rotor in tact, and in the process we make the rotor more accessible.

Sometimes when our customers are looking for a replacement machine, they really only need a new housing. But they perceive they need the whole machine because of the way the housing looks. A retrofit can give them all the technical advances and safety features of a new machine, with a savings of 1/3 off the cost of new equipment. You can request a quote online to upgrade your old Jeffrey crusher. All we need is your serial number.

Douglas J. Sublett
Manager, Sales and Marketing
Phone: 864-476-7530
Fax: 864-476-7510
Web: www.jeffreycorp.com

When a silo fails it can be devastating, in more ways than one.  Loss of the vessel, contamination of the material it contains, loss of material, clean-up, replacement costs, AND possible injury or loss of life (the most important). 

Have you ever seen a silo fail, or that has failed (the aftermath)?  I recently surfed around the web and searched for images and documents that might tell me more about why silos fail and what can be done to make sure this doesn't happen.  I thought I'd post what I have found.

What I Did

After searching for images of silo failures and collapses I spent some time at the website of a company I feel is an expert in bulk solids storage, silo design and bulk solids flowability.  The company is Jenike & Johanson.  I discovered a wealth of information, some about silo failures and collapses, and I will review it with you here.

I reviewed "plastic-frictional theory" at the website for the Granular Volcano Group.  This was exciting (wink-wink).  But seriously, this highlighted a cause of silo failures specific to a certain class of material in specific industries.

I also uncovered a paper that discussed the failure of a grain storage facility in France.  This occured in 1997 and caused 11 deaths and 1 injury (twelve victims overall).  Let me start my summarization with this paper.

INERIS Report On Grain Elevator Silo Collapse

INERIS is a public research body employing 525 people with an annual budget of about 47 million Euro.  INERIS was founded in 1990, is an ISO-9001:2000 certified organization and has as its mission to "assess and prevent accidental and chronic risks to people and the environment originating from industrial activities, chemical substances and underground works".  A noble and worthwhile endeavor.

The report documents the sequence of events in the failure of this grain elevator.  The facility consisted of three rows of reinforced concrete silos, 44 in total.  The facility measured approximately 100m long, 20m wide and 40m high.  The capacity of the facility was 130,000 metric tonnes of grain.  The company owning the facility had 21 people to operate the facility, almost half were killed and injured during the catastrophe.  In fact, ten of the victims were found in the administrative/technical offices "at their workplace, apparently not having had the time to react to the incident".

The picture of the failed facility, figure 5 of the INERIS report, is quite graphic and indicates the failure of the entire center section of the facility with silo structures remaining to the right and left of the center.  The cause of the silo failure/collapse was an explosion, no big surprise for a grain elevator.  However, INERIS examined a tremendous amount of information and exhaustively studied the facility.  Their description of "The Explosion Sequence", section 3.2 on page 11 of the report is fairly detailed in how the explosion likely traveled and eventually resulted in the facility destruction and collapse.  They also conclude that "it is possible that the collapse of the structures was facilitated by structural weaknesses".  However, these possible structural weaknesses were not speculated upon.

The summary conclusion as to the cause of the explosion which resulted in the facility collapse is as follows:

"Following analysis of the various possibilities, and bearing in mind that no component parts of the centralised dust removal circuit were found, it appears plausible that the explosion arose either from mechanical impacts or friction in the fan of the centralised dust removal circuit, or from an incipient fire caused by self-heating in the dust chamber".

I found this report a facinating read and it reminds me of the dangers associated with the facilities handling powders and other bulk solids, especially grain elevators.  Careful design of the structure, proper equipment and maintenance are all critical to plant safety and silo integrity.

Why Silo Failures Happen - Jenike & Johanson Case Study

As a recognized industry expert in bulk solids storage and handling (Jenike, not me) I reviewed the information at the Jenike & Johanson website.  I uncovered a wealth of information on this subject, including newsletter stories, two white papers and a great case study that exemplifies the need for proper design, construction, inspection and use of silos containing powders and bulk solids.

The case study is an easy read and interesting.  This case study documents a silo failure that occurred in the southwestern USA in 1996.  The silo was a large 80ft diameter bolted steel vessel containing 9,000 tons of fly ash.  The only employee near the facility was very lucky as he recognized a warning sound just seconds before the silo collapsed and he hurried away, avoiding being buried under the 20 feet of flyash that covered the ground where he had previously been standing.

After studying the collapse it was concluded that several factors worked together to lead to the failure of the vessel.  These included a design issue and a manufacturing issue.  In addition, the infrequent discharge of the vessel may have precipitated the failure, when taken in conjunction with the other issues.  It is possible that had even just one of these issues not been present that the silo may not have failed. 

Click here for the case study.  It's number 2 on the list.  Also, I suggest you check out the papers titled "Load Development and Structural Considerations in Silo Design" and "Silo Failures: Case Histories and Lessons Learned".

I hope this trip down the "silo failure" lane has been interesting.  I do not work for either of the organizations mentioned, nor do I know anyone who does.  But their research and documentation helped me learn more about this problem, "silo failures - why do they happen".  I hope you enjoy the review.

Joe Lewis
Vice President - Marketing & Sales
jlewis@monitortech.com
Monitor Technologies LLC
www.monitortech.com
www.flexar.info

In "Networking on the Network" UCLA associate professor Phil Agre sets out a detailed plan (66,000 words) for PhD students to develop the professional networking skills needed to advance their careers.

His advice is on the mark for engineers and other knowledge workers as well. As befits an MIT PhD whose research interests range from information technology and institutional change to Internet culture, Agre recognized the potential of the Internet for professional networking way back in 1993, when he wrote the first version of this article.

In thinking about Agre's advice for PhDs, it seems clear that the burden to "publish or perish" has also been an advantage academics have over other professions in terms of (a) finding peers with similar professional interests, (b) building and gaining visibility in a mutually beneficial professional network, and (c) publicly sharing knowledge and expertise in print and public presentations.

If you think that it's only academics who need to develop this sort of personalized professional network, you're living in the wrong century. The growing power of online media – websites, blogs, podcasts and vlogs (video blogs) – is transforming every company into a media company, and every knowledge worker into an online reporter, editor and publisher (over internal intranets as well as the Internet).

Agre provides two tips for creating a customized professional network specific to your interests and abilities:

Articulate the commonalities you discover you have with others (which includes exploring differences). "The principle of articulating commonalities is the secret to getting along with people," Agre writes.

Find a "structural hole" in your profession that you can help fill. "A structural hole, intuitively speaking, is a bunch of people who don't know each other but ought to."

How can you find and build your own network using the Internet? "To begin with," Agre writes, "the most fundamental way of finding people online is to help them find you." The easiest way to do that is through a blog like this. If you're not blogging, or commenting on blogs, you're missing a really easy and powerful way for people of like interests to find you.

This should be a no-brainer for engineers who sell process equipment. But the potential benefits of blogging may be even greater for those who buy and use the equipment. Articulating your process needs and ideas online gives you the possibility of the sort of serendipitous results that come when you fill one of those "structural holes." Not to mention it gives you professional visibility in an age when invisibility can be a real drag on your career.

Don Dunnington