small 98% sulfuric acid storage tank design 5

[Jtpaiz]

thread124-472938

Seeking design advice for vent and overflow details. Tank is HDPE ~6000 gallons and located indoors.

Not planning on a absorbent for vent as the volume will be in continual flux. Id like to vent to the roof of the building using precaution to prevent precipitation and foreign matter ingress. Do I need to be concerned with any other additional details for the vent at the roof? Corrosion to metal roof panels? U vent or mushroom design?

Tank overflow will be separate from the vent piping and down to concrete secondary containment. I would rater not "vent" to the interior of the facility via the overfill and I am not really interested in glycerin or other barrier. Is a PVC spring loaded (maybe titanium) check valve a viable solution? Should I not worry about "venting" through the overfill?

Thank you in advance for your guidance and experience.

JTPAIZ

 

[bimr]

I have worked on Sulfuric Acid unloading and Storage systems in the past ....

Some things to consider:

1) Your 6000g tank seems a little small, IMHO...... According to many H2SO4 guidelines, the tank capacity should be 1.5 times the standard tanker volume plus two weeks usage. This rule usually gets you to approximately a 7-8,000 gallon tank.

2) Concentrated Sulfuric acid storage tank design should be in accordance with NACE International (National Association of Corrosion Engineers) SP 0294-2006 standard. Pay particular attention to corrosion allowance, tank inlet pipe placement, tank overflow and tank tank venting. There are many specific tank and system recommendations in this Standard and they are the resultant of many years of experience

3) Consider safety shower placement and location when sizing the tank and unloading facilities. Federal and State Safety shower regulations have changed a lot in the past ten years (regarding water temperature, shower time and alarm indication) so be aware ...

4) Consider administrative procedures for tanker truck driver hook-up and delivery early in the project. how will delivery be handled ?

5) Place the Storage tank in it's own separate coated containment. If there is a transfer pump, locate it on a tall pedestal inside of containment

6) If acid usage will be modest, consider an elevated horizontal axis tank and no transfer pump

7) DO NOT use a FRP/CPVC/PVC/Plastic tank if the acid is to be air-offloaded from a tanker truck

An excellent detailed guideline can be found here:

https://info.veolianorthamerica.com/hubfs/offers/i...

Respect us ........ and keep us posted as your details become final

MJC

MJCronin
Sr. Process Engineer

Agree with MJCronin, you are making a huge design error if you use HDPE. Most HDPE tanks only have a service life of around 7 years. Don't talk to the plastic tank suppliers as they are just selling tanks. You will be responsible when the tank fails. Talk to the sulfuric acid manufacturers for guidance.

"Sulfuric acid storage and work areas should be adequately ventilated to reduce the possible hazard of exposure to fumes or accumulation of hydrogen gas."

See the attached guidance from General Chemical.

 

[MJCronin]

Thank you bimr ...

I agree with your statements and with the General Chemical Guideline.

I believe that the GC document is highly important because it is both positive and prescriptive. It is a statement of best practices based on company experience. (e.g. Use Alloy 20 valves !)

Sulfuric acid is the most common and most commercially traded mineral acid in the world ......

By the way, IMHO it would be great if the people of the American Chemical engineering Society got off their dead asses developed and published a universal Sulfuric Acid Handling Guideline.

It would be far better to have an official Sulfuric Acid guideline than to listen to the recollections of old ghosts and geezers that haunt the engineering forums

MJCronin
Sr. Process Engineer

 

[Jtpaiz]

Thank you MJ and bimr,

We are designing to a 5year service life for the (2) 6000 gallon tanks. The building will be sufficiently ventilated. I have been through the Dupont and NACE guidance documents but my original question remains, any further guidance on the overflow check valve or other?

 

[dik]

bimr... link is missing, can you re-post it? I assume the safety shower comes with an eyewash...

Sulfuric acid is the most common and most commercially traded mineral acid in the world ...

I understand that with various salts, it can be used to manufacture the 'other' acids... and that it has a high 'boiling' point to make this possible.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[bimr]

bimr... link is missing, can you re-post it? I assume the safety shower comes with an eyewash...

The quote is in the attachment.

 

[bimr]

You should not have an overflow for the sulfuric acid tank. When transferring sulfuric acid, the operator or unloader of sulfuric acid should be present at all times.

"Sulfuric acid should be stored in an atmospheric or non pressurized system. Under these
conditions, an elevated storage tank with gravity flow to process is the safest and from an operations
and maintenance standpoint will eventually provide the most economical and trouble free
installation."

"Sulfuric acid storage tanks should be designed for atmospheric pressure The material of
construction recommended is ASTM AS16 Grade 70 flange quality (copper bearing preferred) steel
and all welded construction in accordance with Part UW of the latest edition of the ASME Code for
Unfired Pressure Vessels but not code stamped. Other suitable alloys may be substituted. Plastic
tanks are NOT recommended as they are more subject to rupture than steel tanks."

Read the attachment Storage and Handling of Sulfuric Acid by General Chemical.

 

[EdStainless]

If you are working with H2SO4 you need to own a copy of the MTI Material Selector vol 1. This book is detailed an covers all aspects of acid handling. As with GC they strongly advise against storing acid in polymer tanks. I have seen HDPE used for short term (90 day) while the primary tank was being removed and replaced, and on day 91 they condemned the tank.

"Desiccating vents are incorporated when the average absolute humidity of the
ambient external atmosphere is consistently high, as in the Texas Gulf Coast and
other industrial marine locations. Arid climates (e.g., high plateaus and desert areas)
are not conducive to ingress of atmospheric moisture. In less well-defined geographical
locations an individual assessment must be made.
The ingress of atmospheric humidity is less important with higher acid concentrations.
In storing 70% acid in steel on the Texas Gulf Coast, expected corrosion rates
are of the order of 40 mpy (1 mm/y) uninsulated and without vent-gas drying, but
only about 10 mpy (0.25 mm/y) if insulated and provided with gas drying.25
It is prudent to provide vent-gas drying in any consistently humid geographical
location. It should be noted that some systems for vent-gas drying are not effective
for tanks with low usage rates. Other systems have proven ineffective even with high
usage. Vent-gas drying units are high-maintenance devices requiring frequent
inspection and service."

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P.E. Metallurgy, consulting work welcomed

 

[pierreick]

Hi,
Consider the document attached with Q&A .
Good luck
Pierre

 

[dik]

Thanks Bimr... it downloaded that time... got an error when I first tried it...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[dik]

What is the problem with HDPE? UV degradation or some other thing? Why are they prone to rupture? hardening? aging?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[EdStainless]

From MS-1

Concentrated Acid and Oleum
Although nonmetallic materials do not corrode electrochemically, they do suffer specific
types of degradation in concentrated sulfuric acid, including chemical stress corrosion
cracking (CSCC), also known as environmental stress corrosion cracking
(ESCC). The powerful oxidizing nature of hot strong acid limits many materials and
can desiccate other materials containing hydroxyl groups (e.g., cellulose in wood).
Plastics, elastomers, coatings, and carbon or graphite comprise the nonmetallics of an
organic nature, while inorganic materials consist of ceramic-type materials.

Thermoplastics
In the form of plastic-lined pipe or valves, plastics may be used in concentrated sulfuric
acid within certain limits. Solid plastics, plain or reinforced, can pose safety and
reliability problems. Even when solid plastics are exposed to chemically compatible
conditions, problems may arise from the high thermal expansion, notch sensitivity,
creep characteristics, and other inherent weaknesses. Some process chemical companies
simply forbid the use of solid plastics in strong sulfuric acid, regardless of chemical
resistance, because of concerns over safety, reliability, and insurance aspects of
their utilization. Also, bonded plastic linings, like elastomeric linings, are susceptible
to blistering if the acid contains dissolved sulfur dioxide. Plastics other than fluorocarbons
can be attacked by sulfur trioxide and oleum.

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

 

[Jtpaiz]

Pierre,

Thank you for the document, what is the source of the information?

JPaiz

 

[dik]

Thanks... I didn't know and thought it might be environmental or from the desicating properties of H2SO4...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[EdStainless]

You can find the 1st ed here

https://www.scribd.com/document/347751795/Materials-Selection-for-Sulfuric-Acids-Davis-MTI-MS-1-2005

As of now only members can get the revised second ed.

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

 

[pierreick]

Hi Jtpaiz,
The link I used to get the info :

https://docplayer.net/23980976-Equipment-related-faqs.html

Sorry I don't remember the source, may be Dow chemical or Dupont?

Pierre