Shipping vessel with Nitrogen Purge 2

[gregdavison]

thread794-326793

Can you ship a vessel domestically or internationally with a 15PSIG Nitrogen Purge? Shipping company is telling me this is classified as a hazardous shipment which will cost more to ship.

 

[MJCronin]

Shipping company is blowing smoke up your butt...

Vessels have been shipped with dry nitrogen purge for decades... I have specified several, but at a pressure of 5 psig.....

Bear in mind, large vessels take a bit of time (days) to dry and purge. Most vessel customers are in a big rush to get their purchase...

Do not rely on what your shippers say, they do not have the ability to classify shipments as hazardous tell them to provide written chapter and verse of the regulations that would make this classified as a hazardous shipment.

MJCronin
Sr. Process Engineer

 

[SnTMan]

gregdavison, it used to be common practice to provide a "strap on" bottle to maintain the purge. This practice is now considered hazardous and rarely done, although the purge itself is not usually troublesome. Of course the vessel must be placarded for the nitrogen content. No Entry, etc.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[zeusfaber]

If you're proposing to fly this vessel, the move will be governed by the IATA Dangerous Air Cargo Regulations.

Regulation 3.2.2.4.1 provides an exemption for gases in Division 2.2 (this includes nitrogen) which are transported at a pressure of less than 200 kPa (2 bar) and are not liquefied or refrigerated liquefied gases. Gases covered by this exemption may be flown as ordinary cargo, hold baggage or cabin baggage.

If you're going to rely on this exemption or its equivalent in ADR or IMDG, it pays to label the item very clearly, complete with a specific reference to the exemption.

A.

 

[r6155]

No nitrogen inside. A thermofusion polyethylene film is placed on the entire outer surface.

Regards

 

[EdStainless]

I saw one shipped recently with the purge bottle inside it, that way it can't get damaged in transit.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[LittleInch]

Do you mean that the vessel is filled and SEALED with a pressure of 15 psig or that there is some sort of continuous bleed going on here? The word PURGE may be confusing people - it's confused me as a purge implies some sort of continuous flow.

If you said instead that the vessel was sealed and was filled with 10psig nitrogen then you might get a better understanding from everyone.

Maybe lower the pressure to 10 psig then you avoid the 15 psig limit which exists in certain peoples mind.

Or ship it with a huge bag of dessicant inside instead?



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[r6155]

My client regularly ships stainless steel pressure vessels in ocean shipping. Without desiccant and without nitrogen. Only thermofusion polyethylene film on the entire outer surface.

Regards

 

[MJCronin]

Yes, r6155,

I am sure that you and many others ship stainless steel vessels without desiccant or nitrogen blanket.

What about carbon steel vessels ?

MJCronin
Sr. Process Engineer

 

[r6155]

MJCronin.
1) Same as S.Steel, or
2) External: final painting selected to resist marine transport, all nozzles sealed with thermofusion film of polyethylene
Inside: dry

I disagree with thread794-299421

For special pressure vessel I suggest transport in cargo ship hold

Regards

 

[EdStainless]

Size dictates if cargo goes above deck or below.
And shipping above deck is much worse for Cl exposure.
I have seen every variety of packing.
Simply sealed and jacketed (heat shrink) with desiccant and VPI (if steel) inside.
Purged and lightly pressurized and sealed.
Purges and having continuous makeup gas available.
I have seen SS equipment painted for transit and then have the paint stripped upon arrival.
Personally I believe that using custom made fiber reinforced heat shrink wrap, nitrogen purge until dry, and the use of desiccant (and VPI for steel) is about the best.
The issue with just sealing is that the vessel will heat and cool every day, more so if on deck. It will sucking moist air as it cools in the evening, then at night there will be condensation. And it repeats every day for 6-8 weeks.
I have seen sealed boxed arrive with 2" of high purity water in the bottom of them.
Physics works that way.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[r6155]

Any system will fail with irresponsible manufacturers.
What went wrong?

Regards

 

[DriveMeNuts]

Nitrogen purge followed by shrink wrapping the nozzle end to keep the nitrogen in is crazy and dangerous.
The nozzles should have a thin plate blind flange or a welded cover followed by nitrogen purge and then sealed with a valve, then there is no need for a top-up cylinder.
The welded cover is then cut off at site.
Dry clean air is the safest option although it is more expensive.

 

[gregdavison]

Sorry for confusion. We dry the vessel with hot air in our factory. We then cover all connections with gaskets and metal blind flanges. We have a input valve at one end and an outlet valve at the other. We flow dry Nitrogen through the vessel for a period of time. We close the outlet valve and fill the vessel to 15 PSIG, close the inlet valve and remove the fill line. No external bottles are shipped with the vessel to maintain the pressure or purge flow. We just fill and close off and ship. I really do not think this is hazardous shipment but shipping company is probably not reading specifications correctly

 

[SnTMan]

gregdavison, that process is widely used in my former class of work (S & T HX). I never heard that anybody regarded it as hazardous, except for the confined space / non-breathable atmosphere aspect. But that has nothing to do with shipping.

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[r6155]

If the drying and sealing is done well, nothing is needed inside. No nitrogen or desiccant-

Regards

 

[Compositepro]

If you get a leak, the volume of N2 will expand to twice the size of the vessel. The size of this vessel has not been stated. If there is any chance of a leak creating asphyxiating conditions where a person can be present, then there is a clear danger that must be controlled for. Shipping with dry ice also requires dangerous goods forms to be filled out. The regulation of hazards during shipment has gotten very stringent over the last decade, and is just getting tighter. The hazard of 15 psig N2 is significantly greater than 3 psig N2. It also makes a big difference if the driver is (or can be) in the same compartment as the vessel. Why would anyone think to use 15 psig unless they think some leakage is likely?

 

[r6155]

I forgot mention. My client sent atmospheric storage tank of S.Steel. No air or nitrogen can be storage. Only thermofusion of polyethylene film on entire external surface.

Regards

 

[CuMo]

We usually ship our Nitrogen purged vessels at 0.5 BAR G in the UK.
And we usually have a pressure gauge fitted to one of the blinds to indicate the pressure inside the vessel.
Also several warning signs that the vessel is purged are also recommended.

At 0.5 BAR G the vessel is then not classed as a hazard in accordance with the Pressure equipment directive PED 2014/68/EU.

 

[DriveMeNuts]

15 PSI pressure is a lot. That means you are transporting a pressurised pressure vessel. Perhaps that is where your transport company is concerned, rather than the gas used. 3 PSI is adequate and standard.

So in reply to your original question, I would say that you can't ship a 15 PSI Nitrogen purged vessel without extensive paperwork and additional precautions.

I would say that you can ship a 3 PSI Nitrogen purged vessel without any issues.