Sanitary Clamps in Flammable Liquid Service 3

[BlackSmoke]

All, I am working on a biochemical process service where both flammable solvents and a sticky substance requiring frequent cleaning are used together. Sanitary clamps (<2" diameter) are desired to facilitate disassembly and cleaning, and I have been asked to confirm that they can be used in this service.

I have heard anecdotally that such clamps were used in ethanol plants, but otherwise in my experience they are rarely if ever used in petrochemical service. I can understand why I would not want large diameter sanitary clamps in these sorts of services, due to low pressure ratings and potential for material to collect on the clamp body while disassembling. My research has turned up no reason that these clamps could not be used in this type of service in a well ventilated environment, and vendor rep I spoke with preferred not to comment, and I'm waiting for a response from another supplier.

Is the group here aware of any code, standards, or other practical limitations that would prevent the use of sanitary clamps (Tri-clover, tri-clamp, BPE-pattern, etc.) in flammable liquid or vapor service?

 

[Compositepro]

I cannot see any reason for your concern. Sanitary piping is expensive, so it is only used where you need to break the piping for cleaning or rerouting or isolating vessels.

 

[Latexman]

Sanitary pipe and fittings has to pass a Code pressure test just like pipe joined by welding, flanging, screwing, etc. It would be wise to test it each time it is cleaned and re-assembled, especially in a flammable service.

Good luck,
Latexman

To a ChE, the glass is always full - 1/2 air and 1/2 water.

 

[moltenmetal]

Sanitary piping is NOT firesafe. Can you use it for flammable materials handling? Yes, but generally you want such systems to pass a modicum of basic fire safety which sanitary systems CANNOT PASS because they use gaskets which will melt out immediately once there's a fire.

 

[EdStainless]

A few cautions.
Not all flanges and clamps are compatible, there are slight differences.
The pressure capacity of these is fairly low, so check carefully.
There are gaskets with metal backing rings that provide some closure even when the gasket fails.
Pick your elastomers carefully.

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P.E. Metallurgy, Plymouth Tube

 

[BlackSmoke]

Thank you all for your responses, they were helpful to understand how others were practicing.

In particular, moltenmetal's comment regarding firesafe certification triggered us to look at the codes again. I concur that I have not been able to find fire-safe gaskets for the sanitary clamps. I agree that best practice dictates their use wherever possible, especially for larger capacity installations.

To close the loop for others searching for the answer on this topic, we were able to identify a section of NPFA 30 covering the use of Low Melting Point Materials (27.4.4) which we would argue that non-rated gaskets would fall under in the US. This paragraph allows for their use with certain provisions from a Code perspective in our jurisdiction. Obviously, it is still up to engineering judgement and formalized risk assessments to ensure that appropriate safeguards are in place to mitigate the risk of fire and leakage in each particular case.

 

[MJCronin]

What is your Code of Record for your flammable liquid piping system ??

This is not a "best practices" issue.... This is an issue of using the correct PIPING CODE !

Where is this plant being constructed and what are the local laws and statutes there ?

NFPA-30 relates to storage tanks and will not tell you about piping gaskets ..... But the ASME piping codes will

You do NOT have the option of buying a "bunch of stuff" and making up a piping system ...

In your search for rules and codes, did you find ASME B31.3 ?

There are specific rules contained that regulate flammable systems and acceptable flange types....

The fact that there are rumors about the buffoons constructing corn ethanol plants using sanitary flanges really means nothing ...

MJCronin
Sr. Process Engineer

 

[EdStainless]

Have you looked at the ASME BPE?
This is the hygienic service code and the only place that I of that these clamped systems are detailed.
There are elastomers that are meant to char in place at high temp to still provide some level of sealing.


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P.E. Metallurgy, Plymouth Tube

 

[BlackSmoke]

Re: EdStainless yes I am familiar with the requirements of the BPE standard. It implicitly mentions use in flammable service by stating that flammable materials should be protected with relief devices per the relevant codes (e.g. NFPA 30). I'm definitely interested in the details of a sanitary gasket that provides as much resistance as possible.

Re: MJCronin I agree that my first reaction was to say no to the sanitary clamps, but in this case I need to be convincing utilizing codes and standards to back my argument. The point about hygienic clamps being used in the ethanol plants was one of the justifications used and so I was hoping to understand if there was a special exception for ethanol or if they really are just being cowboys.

Yes, I have examined ASME B31.3 and this will be the code of record for the affected piping. This is under Wisconsin jurisdiction and we are not aware of any additional provisions of state code that would affect this. Based on flammability but limited toxicity, I determined this was a Normal Fluid Service under B31.3. However, I did not find an explicit statement requiring fire-safe certification of gaskets; I did find statements only that considerations must be made to the melting point of the materials, which is far weaker than I hoped. Perhaps I missed something or there is a corresponding API standard for piping that requires the firesafe certification under API 6FB?

What I did find was that the 2016 B31.3 code App. M seems to specifically suggest Normal, High Purity Fluid Service be subject to the requirements Chapter X, which specifically allows the use of sanitary clamps. So unless I find something else, my conclusion is still that the sanitary clamps are allowed per Code. I'm still reluctant to specify and will be investigating the available gaskets further to ensure that the most heat resistant gaskets available are put into this service.

Thank you both for the additional feedback, I appreciate your willingness to engage and challenge my assumptions.

 

[EdStainless]

I have seen someone try this. They were going to need to install numerous pressure relief devices along the line because it was so easy to exceed the pressure rating in an 'event'. It was going to be so complicated that they chose to simply weld the lines in.

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P.E. Metallurgy, Plymouth Tube