6 replies to this topic

[04_che_uet]

Guys

 

We have acid (98% sulfuric acid) and caustic (Sodium hydro oxide 45%) stage tanks at our site.

 

Due to continuous operation it is not possible for us to empty out these vessels and carry out inspections to ensure mechanical integraty of these vessels.

 

Both of these vessels are horizontal and cylindrical. Caustic storage vessel is internally lined with 

 

Can anybody please suggest a way or inspection technique to ensure mechanical integrity of these vessels.  

 

 

Regards 

[breizh]

Hi ,

you may be able to start with external inspection then thickness measurement . One day you have to stop your operation to inspect the tanks , the quality of the liner, Nozzles, etc  , preventive maintenance is key for any operation.

 

Breizh

[04_che_uet]

Hi ,

you may be able to start with external inspection then thickness measurement . One day you have to stop your operation to inspect the tanks , the quality of the liner, Nozzles, etc  , preventive maintenance is key for any operation.

 

Breizh

Sir,

We have these vessels in service for past 6 years we have an outage planned by the end of Y2018. 

 

Till now we have not faced any issue with these vessels but we want to make sure that we are not taking any safety risk.

 

My question is , is there any testing method to measure wall thickness of these vessels if there is sludge present in the vessels?

 

We currently use Ultrasonic devices to measure thickness but i believe these devices will not give accurate enogh reading at the bottom where acid/caustic sludge will be present.

Edited by 04_che_uet, 04 May 2017 - 11:03 AM.

[breizh]

Hi ,

To me you need regular visual inspection !

my view .

Breizh

[Napo]

Hi,

You can review the NACE SP-0294, Standard Practice, Design, Fabrication, and Inspection of Storage Tank Systems for Concentrated Fresh and Process Sulfuric Acid and Oleum at Ambient Temperatures.

Napo.

[Art Montemayor]

I totally agree with Breizh's experienced advice.  This type of operation deserves nothing less than a detailed, safe visual AND instrument documented inspection - ON A ROUTINE BASIS.   These factors and plans should be established by and through a production department safety meeting - including both operators and engineers - that agrees on the appropriate hazards identification and the inherent risks to be taken when visual inspection with vessel entry are not employed to establish the true, verifiable physical state of the vessels in question.

 

When it comes to trusting the predicted corrosiveness of sulfuric acid and caustic soda, I would not operate more than a year with such vessels without a thorough visual inspection and gauging - all to be kept in the engineering files and monitored yearly as to corrosion rate and documented physical state of the respective vessels.  These are chemicals that allow your operators no level of safety once they develop a rupture or leak.  Unexpected or accidental spillage from these chemicals can be a deadly and tragic occurrence.  If you fail to take ALL the available safe steps to safeguard your operators, any exposure to these chemicals cannot be shrugged off as an "accident".  I would consider that shoddy and careless plant engineering and a direct cause to any tragic results.

 

I would not rely on general codes or recommended inspections by others - who have no responsibility for any consequences.  I would establish my own safety concerns and standards to secure a safe and reliable system with these chemicals.  I would also ensure that all members of the production team and force are participants and shareholders in ensuring that the established safety procedures and precautions are religiously followed.  In the final analysis in the event of a tragic occurrence it is the engineering and managerial staff that are (and should be) held responsible for the event.  NACE, ASME, nor anyone else will respond or assume responsibility.

[Napo]

Sirs,

A last recommendation:

https://www.cheresou...s/?fromsearch=1

Napo.