PVC for Cyanide Piping 1

[bulkhandling]

I posted this under Polymer Processing but maybe this is the right forum.

A PVC pipe for sodium cyanide transportation needs to be replaced due to aged material. Does anyone know if any code or regulation is related to the piping material for cyanide solution? I need to decide if I have to use a CS pipe (our standard pipe spec) or use a new PVC pipe( same as original and a little bit lower labor cost).

 

[MJCronin]

bulk,

You may want to get a piping engineer and review ASME B31.3 the "Process Piping" code. On particular category of piping designed for hazardous service is called category "M". Under this particular design category, certain type of piping constructions are banned or endorsed. (The seal welding of threaded fittings, for example, is required)

You may also want to review the HAZOP analysis that was done for this system. The HAZOP is a psedo-legal document that is frequently refered to in any legal or regulatory review.

You do have a HAZOP for this plant and for this particular system........don't you....???

regards

-MJC

 

[MJCronin]

ooops..

I also suggest that you repost this qustions under the ASME code issues forum...

-MJC

 

[moltenmetal]

The owner should be considering whether or not this is Category M piping, but it probably isn't. This isn't hydrogen cyanide gas, it's sodium cyanide solution.

 

[EGT01]

Bulkhandling,

I would have trouble accepting a deviation from your standard carbon steel pipe spec to use PVC pipe just because it was less expensive. Maybe your company allowed PVC in the past but sounds like they have decided that PVC is no longer acceptable.

It is not unusual for pipe specs to change over the years and my experience is that piping systems containing old pipe specs may stay in service until time for them to be replaced then the current spec will be used for the replacement unless there is sufficient justification to use otherwise. Certainly your company shouldn't criticize you for following company specs.

I've not worked with cyanide before but have experience with other lethal service chemicals. You have not identified your sodium cyanide solution but if it is a 30% solution, the information in this MSDS makes it sound like something that is due much consideration....

http://www.coogee.com.au/MSDS/MSDS_SodiumCyanideSolution.pdf

Looking under the Safe Handling section of the above MSDS, it indicates that containers should be adequately protected from physical damage which would seem to be a more difficult task for PVC pipe.

If you are not familiar with ASME B31.3 Process Piping Code, then you should review it, especially if you are looking to revise your pipe spec.

You used the word "transportation", so if you are transporting outside your company boundaries you may need to comply with any local department of transportation requirements.

Also, here is another organization that may could help you...

http://www.cyanidecode.org/index.php

Finally, if you are a user of sodium cyanide, contact your supplier. I'm sure they will be more than willing to assist you in recommending safe storage and handling systems.