"Shelby" Tube Sample Shipping

[Grouser]

I was recalling how I had to ship samples from Wyoming to the company laboratory in Forida and thought it might be a worthwhile topic for discussion/opinion.

As I recall, samples are prepped in the field by removing any loose material from the top and a small amount from the tip to allow for sealing with wax to prevent moisture loss. Any space in the top of the tube is filled, or the vacant tube is cut off, and plastic caps are taped to the ends hopefully to secure the contents.

Nowdays I guess the tube(s) would be wrapped in bubble wrap and/or set in a box full of styrofoam "peanuts". My questions are: Do the tubes have to remain vertical with tips down? Does this packaging protect the samples from changes in air pressure if air freighted? Is additional cushioning needed for bus/truck transport? Any other techniques/considerations?

I look forward to your opinions.

 

[ashjun]

Hi,
Just my thoughts:
Yes, the tubes "normally" should be transported held vertical in the box. Although, the tubes that I used to receive from the site were "usually" and conveniently placed horizontal. The reason cited by the site supervisor was that the tubes were unstable (rattled, fell down) during transportation (CG high, blah, blah); the container was too big for the number of tubes that were transported)…..sometimes I wondered that why a smaller box was not used to transport the tubes.

Your other question; well, air transport has never been cited in codes. However, consider this, the samples were already unloaded from their insitu effective stress state (by removing from the ground) and are probably are at 1 atmospheres (gauge?) when sealed. In the aircraft, decrease in pressure within would probably cause additional all around decrease in the effective stress. And when the aircraft lands and you happily receive the package, they are again at 1 atmosphere. Effectively, they were just unloaded and reloaded back to the state before the take off. "Theory" states that there is no difference in the results of the two samples (akin to the soil sample moving on the unloading reloading line in the stress state…things like that stuff); however, your results may (and definitely) prove otherwise.

Alternatively, you may carry the tubes in the aircraft cabin; but be careful not to scare the air stewardess or she may think you are carrying dynamite sticks…they are jumpy anyway these days…///cannot blame them.

Regards

 

[Focht3]

Do the tubes have to remain vertical with tips down?

Nope.

Does this packaging protect the samples from changes in air pressure if air freighted?

Not really. But this isn't important for most soils -

Is additional cushioning needed for bus/truck transport?

It depends on how sensitive the clays are -

Any other techniques/considerations?

Please describe your soil samples.




Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora.

 

[Grouser]

ashjun

Thanks for your response. I guess the air freight question was a stretch because heavy soil samples are rarely shipped by air because of high shipping costs. I was asking because the acceptable amount of disturbance has never been explained to me so I didn't know if the return to regular air pressure constituted a "loading".

Focht3

Thank you for your interest. The topic was intended to be more of a procedural discussion rather than specific to particular samples. The samples I shipped were for permiability testing more than strength testing of decomposed shale for a gypsum "stack" retaing pond dam.

Thanks to you both and happy new year to all.

 

[BigH]

Focht3 gives the basic answers. Most texts including a good chapter in Winterkorn and Fang (I believe) do indicate that they should be shipped vertically. But, I doubt I ever did that - mainly we should load them in back of the van and drive off! We were, for the most part, dealing with relatively insensitive clays so it wasn't a big problem. Our firm had some very very good geotechs - pioneers and we always stored them horizontally (space) so, again, this adds to the fact that they don't always have to be done so.
Ashjun has a point about the airplane - I did this once (way before 9/11) because the single tube represented a critical sample and the investigation was many thousands of dollars (1970s) - so it was worth "babying" it.

 

[Focht3]

I've checked Shelby samples and NX cores as "excess baggage", and also shipped by Greyhound bus. The difference in cost was small since I was already a passenger on the plane. But that was in a pre-9/11/2001 world. I don't think I'd try it now without a lot of discussion with the TSA and airline in advance.

All of the samples I handled this way were very heavily overconsolidated clays or were rock of some type. I don't ship soft clay samples very far; I prefer to test them with a motorized miniature vane in the field before the sample is extruded. This helps to keep the effects of disturbance as low as practical -



Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora.

 

[DRC1]

See ASTM 4220. If describes proper procedure for transporting samples.

 

[BigH]

A General Note:

One point about ASTM - or other "standards" - it is their interpretation of "proper". "Proper" in ASTM differs from proper in BS or IS or DIN or CSA or USBR or . . . And, remember, standardd are written by a committee - I've heard of some standards that don't change because there are two diametrically opposed groups that are both intransigent. So it stays the same - whether it is best or not in inmaterial. Most standards are developed for purposes or reproducibility of results or to ensure that "all" do it the same. So it is, as I see it . . . (at least at this moment!!)

 

[bmike]

I have never had to ship samples by air, but this raises some interesting questions. Aside from the air pressure difference in the cargo hold (which others have commented on) it occurs to me that the cargo holds are generally not heated, and could be significantly cooler than in the cabin.

In winter, we used to insulate the tubes, particularly if they were going to be sitting around outside (or in an unheated truck) most of the day before going to the lab. Split pipe insulation like plumbers use was very convenient for this purpose, and conveniently comes in 2 and 3 inch diameters.

In my experience, the lab usually would put the tubes in a vise (horizontally) to saw them up (rather than extrude the samples). In this case, shipping it horizontally or vertically is not worth worrying about.

Has anyone come up with any solutions to prevent sample freezing, or considered if it is even worth worrying about?

We also found that putting petroleum jelly/vaseline in the paraffin wax would stop the seals from shrinking, or used beeswax. This was quicker than the cheesecloth/wax layering method.

There are expanding seals available, kind of like a flat packer, but we never used these. My guess is that these would be less sensitive to pressure changes, for air travel.