Implosions Are Also A Mess......

There have been several posts in Cryogenic News regarding cryogenic tanks rupturing as a result of over-pressuring. This is important due to the real danger posed by tanks and cylinders that are improperly modified or otherwise malfunctioning.

Implosion is also a very real concern and Wil Ferch (Owner/Principal at Nordstern Associates LLC) has graciously allowed me to reprint his recent article "Don't Let This Happen to You!!" below without endorsement.

Interestingly enough, as I was reading Wil's article I remembered that Dan Ariely (of Predictably Irrational fame) is also a director with The Center for Advanced Hindsight which you can visit at http://web.mit.edu/ariely/www/MIT/thecenter.shtml.

Ideally, employing the lessons shared by Wil and others can help you avoid status as a case study for Dan's group so here it is:

"Don't Let This Happen to You !!!

The industrial gas industry, (producers of liquid oxygen, nitrogen and argon...amongst other products of air), require large site-erected tanks to be built in order to store these liquids for later use. These tanks can range in size up to 2 million gallons or more, and cost millions of dollars. The stored product, like liquid oxygen, exists at about minus 300 degrees Fahrenheit.

In the process of bringing such a newly constructed tank into service, it must first be carefully "cooled-down" such that it can accept incoming cold liquid later. Here is a photo of a typical tank on a representative plant site---> http://gazettextra.com/photos/2008/oct/02/10382/

Nordstern Associates LLC - CASE STUDY # 7

A major global producer of industrial gases, recently "cooled-down" such a tank as part of their commissioning process, utilizing their own qualified personnel and historical procedures. This time, however, things went horribly wrong, and their 450,000 gallon tank went from being a multi-million dollar asset... to nearly scrap metal value, in a fraction of a second ! In the process of cooling down the tank, it vacuum collapsed ! To illustrate the violence, sudden-ness and uncontrolled nature of the collapse, here is a YouTube film clip showing a similar ( this time, on purpose ! ) tank collapse of a railway tanker.---> http://www.liveleak.com/view?i=72e_1208694365&p=1

Also, when such a flat-bottom tank vacuum collapses, it may implode the top and side walls, and also start to "lift" the center of the flat floor. See here of what such damage looks like in yet another example ( once the web page is opened...move down to title, " Plastic bag vs. Storage tank" for photos and text.)----> http://www.driedger.ca/dp-1/Dirty%20Pictures%201.html

After the damaged tank was repaired, Wil Ferch of Nordstern Associates LLC was enlisted to provide both a revised cool-down procedure, and on-site supervision of the new attempt to cool-down the tank. Result?--> a perfect cool-down with no damage ! Wil Ferch, principal at Nordstern Associates had over 20 years of experience cooling down these types of tanks with a 100% recorded success rate throughout his career !

So....don't let this happen to you !

The industrial gas business has lost much in the way of retained skill sets and nuance-driven knowledge with long-term staff changes. Enlist people who have the training and knowledge to do this correctly. Call upon Nordstern Associates, LLC.

Contact--> Wil Ferch, principal at Nordstern Associates, LLC and let us discuss this.... or other support needs. ( ferch.wil@gmail.com .... business tel : +1 716 983 4089, alt tel: +1 716 662 7173). "

A Six Word Cryogenic Success Story

Tried a GOrilla; Bought 15 more.

Cryogenic Liquid Bulk Drops- Part III- Good for the Customer?

Having determined that bulk cryogenic convenience drops are usually a good thing for the vendor the question is “Are they good for the customer?” And, of course, comes the Millennium Answer: “It Depends.” So- what are the customer costs and benefits of convenience drops?

First- the potential negatives:

N-a) These drops are often commonly referred to as “dumps” where clients have a negative view. The biggest concern is that the liquid left in the transport is “hot” and will raise the temperature of the bulk tank receiving the product. In some cases a company is concerned that the transport has traveled from say Phoenix to Tucson to Albuquerque and back and now has 500 gallons they need to get rid of. When filling the delivery guy might blow down some of the pressure on the receiver of there might be a good deal of venting which could translate as wasted molecules. Or- the liquid did, in fact, heat the tank up a little it might cause product to boil off faster and there would be a net loss of product.

N-b) Most bulk agreements also include a “per delivery” fee and it is undesirable to be billed a delivery fee for partial drops.

N-c) There can occasionally also be logistics issues arising from getting a partial delivery on Tuesday when the regular delivery is Thursday resulting in less than a full drop on Thursday.

All these things can result higher total cost of goods.

And the potential positives:

P-a) A well placed client working closely enough with their supplier could see some significant cost savings if they are lucky enough to be strategic. This is especially true if the supplier is trying to expand into new territory and the client has a large enough tank to receive most of the excess product the transport might ever have. This could result in both good upfront pricing from the supplier and some waivers for delivery or other fees that significant reduce the total cost of liquid oxygen, nitrogen or argon.

P-b) A strong enough relationship (and big enough cryogenic bulk tank) could also almost eliminate the need for scheduling deliveries triggered by getting down to re-order levels.

P-c) And then there is the whole aspect of operating closely enough that “the right hand washes the left” where doing each other favors benefits both the supplier and client.
Jim Sherrow was one of my most influential members and he’d regularly point out that it is critical not to let the Aggravation Factor exceed the Incremental Dollar. Mostly he meant this as career counseling, but it also applies to relationships of convenience.

Are Bulk Cryogenic Spot Drops a Good Thing?- Part II – Supplier Perspective

In the last episode it was determined that it is costly for cryogenic bulk transports to return home with any of the liquid they departed with. One way to make it home empty is to drop off any liquid remaining after scheduled deliveries at some other customer tank that has some room available. Ideally for the supplier, this would convert the left over liquid from a cost to income. It was asked, “Is this a good thing?” First, we’ll look at the supplier side with the question, “Did the revenue generated offset the cost of an 800 gallon delivery considering that Company X typically hates to deliver under 1500 gallons at a time?”

Here, again, comes The Millennium Answer. The Millennium Answer came into vogue shortly after some high placed U.S. politico said something to the effect of “It depends on your definition of the word ‘is.’” Ever since then it seems everything is contingent. i.e. “It depends.” In this case- It depends on the cost of getting to a drop location and making the fill compared to the revenue that might be generated. Pretty simple, eh? But, not necessarily as simple as it appears on the surface and especially when asking about dropping off 800 gallons where 1500 is preferred.

The dependant aspect of whether 800 gallons is a good drop or not relates to whether it is the (first/only) drop or whether it is the last drop. 800 gallons as a first or only drop is not necessarily a profitable proposition for a bulk supplier. Costs associated with running a 4000 or 6000 gallon transport out on a unscheduled single drop delivery might just exceed any revenue that could be made. This is especially true with lower priced products like liquid nitrogen.
On the other hand, delivering 800 gallons (or even significantly less) as a convenience drop at the end of a route is markedly different. In this case, the costs associated with getting the transport loaded and out into the market place have already been incurred and the liquid is out there. Now, there is just the incremental cost of getting to another location and offloading versus the revenue that could be generated from the drop. Playing to the profit side of this equation are the opportunity costs of not doing the delivery:

- Liquid that would just vent off if left in the transport or be partially lost transferring back in and out of plant storage;
- Slightly higher fuel costs with the load,
- The need to return to the convenience drop site sooner by not having made the drop and not having enough liquid to completely fill the tank when the delivery is made.

All things considered-convenience drops are usually good for the bulk cryogenic liquid supplier as long is the drop is within relatively close proximity of the last scheduled stop or the return route home.
But then……. Are convenience drops good for the customer?

Cryogenic Vessels are Moisture Magnets

It happens almost every day that someone accidentally cracks open a vacuum evacuation valve on a cryogenic bulk tank or springs a leak in a vacuum probe tube and WHOOSH! The vessel just lost all or a lot of its vacuum.

Referring back to one of the #1 Laws of Science—“Nature Abhors a Vacuum.” Given any opportunity at all, a vacuum space will find molecules and pull them in to recover atmospheric molecule levels. And, we’ve discussed this before.

Untouched, though, is the element of just what kind of molecules get sucked in when a vacuum goes south. The millennium answer: It Depends. What it depends on is the kind of molecules that are available to suck in. In humid environments, a lot of those molecules are going to be moisture (H2O). The problem with moisture is that it is a bear to get out of a vacuum insulated vessel’s annular space once it gets in. This is particularly true if the vessel has perlite instead of super-insulation in the annulus.

Q: Once molecules get into an annular space, how do you restore the vacuum?

A: The only way to restore really strong vacuum in the annulus of a cryogenic vessel is with a really good vacuum pump.

Q: And what is the central dilemma?

A: The stronger the vacuum the less energy there is in the vacuum space. Since energy equals heat that means that the moisture in the annular space will freeze out making it almost impossible to withdraw all the molecules.

We’ll discuss this, the effects and cures some more next post………

"Fixed"- What's in a word?

It is said that a key to gaining knowledge is learning the right words. Working with cryogenic tanks has proven a challenge mostly due to the English language and the use of multiple words for a single item as well as the use of a single word for many items.

For example, a client might call asking for “a Safety.” Seems easy, right?

So, you sent them a “Safety.” Did you send them a relief, a burst disk, a rupture disk, a head safety, or a vacuum rupture disk? Was it an in-line device or open to atmosphere? What pressure was it set at and how did you know the right pressure? Did you simply look at the pressure of the device being replaced and put on the same thing?

I ask because a client called one day and somewhat urgently wanted to know if we could replace one of the safeties on their truck mounted liquid oxygen delivery vessel right away. Their safety was apparently “broken” and the vessel wasn’t holding pressure so they couldn’t do their medical oxygen deliveries. It was close to closing time and they were several hours away so we gave them an after-hours number to call when they got to the shop so we could meet them. Paraphrasing Jimmy Buffet, the phone never rang so we knew it was them.

Several days later the wayward van arrived with the driver all calm and composed. When asked how they survived without the safety being repaired the driver responded:

“Oh, we’ve been OK. It turns out that one of the guys in the shop has a lot of cryogenics experience and he ‘fixed’ it.” This gave rise to that little sick feeling that the wrong words can generate. Predictably, the “experienced” guy in the shop had removed a blown burst disk safety and installed plug in its place to “fix” it.

See the post dated 1/19/09 if you’d like a better idea of what this “fix” might have meant to the driver. http://cryonews.blogspot.com/2009/01/improperly-decommissioned-liquid.html

Vacuum Rupture Disk- Blown B

A client called upset that they’d just received 20 liquid cylinders back from rehab and now had 18 in the yard “bad.” They wanted immediate attention and got it. Two things were obvious on arrival. The first was that there were no DOT-4L repair “K” tags on the vessels indicating right away that we’d never seen the vessels in question. Number two, and most upsetting to the client, was the very apparent indication that someone had intentionally punctured the rupture disk on 18 of the 20 liquid cylinders. This was obvious as the protective disk covers were missing and the disks were blown “in” instead of “out.”

The purpose of vacuum rupture disks for cryogenic tanks and liquid cylinders is to prevent rupturing of the outer vessel which has no pressure rating. Vacuum rupture disks are very thin, concave and surrounded by knife edges which are lined up just over the surface. A very low pressure build up in the annular space of an oxygen, nitrogen, argon or carbon dioxide cryogenic tank will cause the disk to protrude against the cutting edges and rupture allowing free flow of the gas to atmosphere. So- any CSI investigator who sees the disk blown out can readily tell that a vessel with a disk blown “out” probably has some type of inner leak.

A disk that is blown “in” indicates a leak occurred in the disk and the vacuum in the annulus sucked atmosphere from outside pulling the disk in. There are slip-on plastic protective covers installed over most disks to prevent damage that would cause a leak. Many manufacturers and service companies also install a warning between the cover and disk noting that removal or tampering will void any warranty of the vessel. This cover helps protect the disk from welding or cutting sparks and corrosion that could cause a vacuum space leak in the cryogenic tank.

When there is a good vacuum on a tank then rupturing the disk will cause a great whoosh of flow into the annulus. It is an all too common occurrence for vandals to remove the covers and puncture the disks. Whether their intent is malicious or just for entertainment the result is the same. The liquid cylinder now has no vacuum and will have to be sent in for a rather expensive repair.

Next, we’ll talk about responsibility and how cryogenic liquid suppliers can save hundreds of dollars by training their drivers to be alert to damage and consistent in documenting it on site.

Vacuum Rupture Disk- Blown A

Which cryogenic liquid cylinder in this photo still has a vacuum?

Actually, the only thing we can tell from this photo is that the bottom two do not have any vacuum since their vacuum rupture disks are both blown. The top liquid cylinder might or might not, but this can only be determined through testing.

Vacuum rupture disks are installed on cryogenic liquid cylinders and tanks to protect the outer vessel from rupturing. The inner vessel of a cryogenic tank or liquid cylinder is typically designed as a pressure vessel. Both resetting relief devices and one time rupture disks (head safeties) are usually installed to prevent the inner vessel from over-pressuring and exploding. The outer vessel is only a protective skin and carries no pressure rating. A leak from the inner vessel into the annulus causes pressure to build against the outer vessel. Vacuum rupture disks or vacuum lift plates are installed on outer vessels to allow them the vent almost immediately in the event pressure begins to form in the annulus.

The next things we’d like to know are what might be determined from “how” the disk blew and “who” might should bear the cost of repair.

Medical Oxygen Wakeup Costs Reduction B

The second method for reducing the costs associated with filling medical oxygen delivery vessels seems obvious to the level of ridiculous: Install a bulk liquid oxygen tank at the delivery company’s home facility. Often missed are the not-so-obvious challenges and innovative methods employed by some companies.

Typically, homecare oxygen companies considering installation of a bulk cryogenic tank need demand to be high enough to entice a delivery company to come fill their storage vessel and there needs to be a location at their site for semi-permanent installation of a tank. Also, their use level high needs to be high enough to avoid excessive product waste from boil-off evaporation. A company that owns their own facility with surrounding open space and has a use rate of over 1000 gallons a week usually has no problem meeting these conditions and probably already has a bulk tank.

A more interesting twist has been employed by some companies with less demand and/or the inability to get approval for installation of a bulk tank. Several have chosen to purchase a portable bulk tank and operate much like the old book-mobile or roving library. These companies are buying mid-sized (500-850 gallon) portable liquid delivery vessels and truck or trailer mounting them. They are then taking their liquid oxygen vessel to their main site or a satellite facility and parking it so that their delivery drivers can fill more quickly and conveniently without waiting in line at the main liquid supplier. It is also possible for them to tie this liquid source into a small fill system to charge gas cylinders. Some are getting their portable vessel filled in the field by liquid suppliers who bring the liquid to them. Others are still driving to the main supplier for liquid oxygen, but they are greatly reducing waste by having only one truck go to the supplier instead of several. Time is also saved since they are able to schedule their pickups at lower demand times and avoid long lines.

At last night’s SMEI (Sales & Marketing Executives International) Houston chapter inaugural meeting one participant commented that there are a dozen different ways to DO things right. The emphasis remains on the “do” verb.