Inspecting Insulated Liquid Asphalt Cement Tanks

[cwigg66]

I am faced with the task of inspecting both horizontal and vertical AC tanks. The tanks are heavily insulated with approx. 4" insulation with aluminum backing on all sides. Has any ever faced this kind of task before, and if so, how did you conduct an inspection of such a tank?

Do the tanks even need to be inspected at all, given the viscous nature of the contents? Not at all sure how to approach this, so any input you have would be greatly appreciated. It is important to note that the tanks are being inspected as part of the federal SPCC rule, corporate auditing, and state regulatory requirements.

Chris

 

[chicopee]

In MASS, any atmospheric storage tank over 10,000 gallons in capacity containing products other than water need annual inspections per State Fire Marshal. Check out your State law.
Are these tanks consideed pressure vessels because if they are than they would have to be inspected per your local jurisdiction on fired and unfired pressure vessels?
Who is requiring the inspection? Owner, Insurance Company, potential property buyers?

 

[cwigg66]

We do not have that regulation here (Oklahoma), although SPCC regs require inspections at an industry standard interval, which in API varies dependent on several factors.

The tanks are atmospheric tanks I believe, with internal heating coils. I coudl very well be wrong about the atmospheric part. Maybe someone coudl chime in with some knowledge of the asphalt business?

The inspections are required by the Oklahoma Corporation Commission, which is a very strange entity only in OK. Something akin to the EPD here or DEP in other states. Also, the company's internal auditing protocol requires inspections as well. Not to mention federall SPCC regulations. Thanks for the input.

Chris

 

[chicopee]

No, I suspect those tanks would not be pressure vessels and would probably be similar to portable tanks found on tack and asphalt trucks. Such tanks incorporate hatchways which can be open during the heating process for the purpose of checking content level or for top loading.

If you conduct a external inspection, you can report on the condition of piping, support system, sign of leakage thru the insulation but obviously you could not say much about the metal surfaces of the tanks pointing out in your report the limitation.

If such tanks are safely prepared for an internal inspection then you can report on metal thichness, condition of seams, extent of pitting and corrosion, baffle condition and wear of surfaces around openings.

 

[MJCronin]

Cwigg...


I'll give you some of my limited knowledge of asphalt tank storage..

Commercial grade asphalt is typically stored in aboveground, vertical axis, flat bottomed tanks. (but most any shaped tank is suitable)Storage temperatures range from ~140F to ~180F. The tanks are insulated and ususally kept full if possible.

Corrosion is typically found in the interior roof area and sometimes on the exterior tank bottom (galvanic corrosion with the soil)


Interesting links on asphalt tank corrosion and safety:

http://www.pca.state.mn.us/publications/t-a2-08.pdf

http://www.nacestore.com/nace/content/pubsonline/free/9907mpab.pdf

http://www.steeltank.com/library/pubs/news-012004.pdf

http://www.systems.endress.com/news/assets/Systemlinkmar_2003.pdf

Have you considered contacting a state agency or are trying to develop internal company inspection guidelines ???

My opinion/ramblings only

MJC