5 replies to this topic

[AnduiH]

Hi people...

I'm new here and I'm from Venezuela, so please excuse me if I can't explain myself very well when typing English.

My question is as follows:

I'm working on a project to dispatch - or load- trucks with sodium hypochlorite from a storage tank. The tank and its pump are about 300 mts distance away from the loading area, so my problem is that when I finish loading the truck I don't want sodium hypochlorite to remain in the main pipeline because it decomposes with any increase in temperature. Therefore, I am asking the Forum for suggestions or ideas on how to do a "flowback" or "blanketing" (return hypochlorite to tank - excuse my English) after I finish loading the truck. I have process air available, but I'm not quite sure about the calculations I need to do to have an optimum flowback. I would appreciate any help you can give me.

[maitreyee ghosh]

I'm not sure about my suggestion but I think a nitrogen line can be added for purging purpose. Also if the material decomposes at high temperature then won't an insullation serve the purpose?

[Art Montemayor]

AnduiH:

I consider sodium Hypochlorite solutions as potentially very hazardous – especially in those situations where human intervention is required, such as loading and unloading.

I don't know what strength of aqueous solution you are handling – 15% or higher – but regardless, I would recommend you design and employ an efficiently operated pigging system in your 300 meters of pipe between the storage tank and the truck loading facilities.

Go to:

http://www.pipepigs.com/

This is the surest and safest way to dispose of the solution from your loading line (or any other line) where you certainly do not want to have static, excess solution just waiting to decompose or corrode out your system.

Download all the information you can get from pipepigs and even get in direct contact with them to discuss your application. They can help you out in doing a preliminary and a Final design for installation. Share all your basic data and concerns with them and pay careful attention to the recommendations and suggestions that they have. They are experts in this type of system and can really help you put together a serious, efficient and SAFE loading system that saves you money, lives, and makes you a local hero in Venezuela.

I seriously recommend that you NOT EMPLOY any free, pressurized nitrogen "purging", or "blow-back" in your operations. You run a serious risk of doing damage to your storage facilities and/or causing a very serious accident. Additionally, no free nitrogen purge is going to displace all of the solution from the pipeline. That is impossible. What you will cause is a very violent and heavy solution spray entering your storage tank and causing a potential large pressure rise that could damage or rupture your tank. DO NOT TRY TO DO THIS.

The correct, safe, and proper way to clear your pipeline is to pig the line with low pressure nitrogen back to the storage tank. This ensures that ALL the solution is returned to storage and that you will have a minimum of human exposure or over-pressure dangers.

[AnduiH]

Thanks for the advice... i'll propose to pig the line then

But another question refering the same issue... it's about calculations.... i know i should know this but i think i forgot it....

What are the calculations i need to know the pressure needed in a gas to displace any given volume of liquid in a pipeline.... ? in how much time? stupid question but i had to ask :S... thanks in advance for any aswer....

[Art Montemayor]

AnduiH:

The advantage you have when you deal with an experienced and capable supplier is that they will do most - if not all - of any required calculations or specifications of what is required to apply their system. What you have to do to protect your interests and ensure you get the right stuff is to be VERY SPECIFIC in your basic data and project specifications to the supplier. Do not assume that you can just sit there and let the supplier do all the work. Your work load is to ensure that all the information that is required by the supplier is given to him/her AND in an accurate, timely, and efficient manner. Be specific and detailed in explaining and outlining your needs and requirements. Insist on specific and detailed answers to your questions and concerns. The more correct and accurate information the supplier has, the better the chance that you will obtain an excellent application.

Take the attitude that in this case, the supplier is the EXPERT on the application. You are the learner - but you control practically all of the necessary basic data and information that the supplier needs to do a good, safe job. Make sure that the supplier has ALL that is needed by him/her.

[Qalander (Chem)]

AnduiH:

The advantage you have when you deal with an experienced and capable supplier is that they will do most - if not all - of any required calculations or specifications of what is required to apply their system. What you have to do to protect your interests and ensure you get the right stuff is to be VERY SPECIFIC in your basic data and project specifications to the supplier. Do not assume that you can just sit there and let the supplier do all the work. Your work load is to ensure that all the information that is required by the supplier is given to him/her AND in an accurate, timely, and efficient manner. Be specific and detailed in explaining and outlining your needs and requirements. Insist on specific and detailed answers to your questions and concerns. The more correct and accurate information the supplier has, the better the chance that you will obtain an excellent application.

Take the attitude that in this case, the supplier is the EXPERT on the application. You are the learner - but you control practically all of the necessary basic data and information that the supplier needs to do a good, safe job. Make sure that the supplier has ALL that is needed by him/her.

AnduiH, I must strongly endorse the views and Expert advice our beloved 'Art'.I will just share somewhat "raw experiences" as compared with Art's.
The suggested foam pigs are propelled/pushed and driven by compressed air as used in certain edible oil, molasses,lube oil and some other chemicals services and find their great utility where turning radius of pipelines/pipe-fitting do not permit use of standard pigs to separate products/internally clean the pipelines.
Certain observations although not with such highly corrosive liquids service.
All the bleeders/vents /drains are sources of trapped pressurised air& liquid and human contact of any sort must be duly safegurded with proper PPE's(Personal Protective Equipments) e.g.Chemical resistant Large Hand gloves, body protection, Eye Protection and breathing protection (as per exposure concerns)
Another observation was the use of some flexible sheet top coverings for foam pigs with appropriate material e.g leather or pvc etc. safeguarding the foam pig from in-contact liquids effects.
Hope this helps!
Best regards
Qalander