Fire Test Certificate for a replacement gasket 1

[PeterIgg]

Hi,
I have a client who is requesting a 'Fire Safe Certificate' (API 6FA) for a gasket supplied as a spare part. I have explained that as a gasket cannot be tested in isolation, only as part of an assembly, that I am unable to supply such a certificate. However my customer is adamant and states that other suppliers have done so.
1. Am I wrong?
2. If not, has anyone else had a similar request and found a solution, other than to offer a statement saying that the gasket is identical to that which was supplied in the original valve?

My concern is that (a) gaskets can fit in a variety of different valves and (b) if, by coincidence (however unlikely), the gasket fits a non fire-safe valve it does not make that valve fire safe.

Cheers.

 

[themad1]

I hade exactly the same concern with mechanical rotary seals.

You are right: the gasket does not make the valve fire safe. It depends on the design of the valve and also on the material used for the gaskets.

The scope of API 6FA is "..to establish the requirements for testing and evaluating the pressure-containign performance of API6A and 6D valves when exposed to fire."
So a gasket only can't be cerfied API 6A

You can make a declaration stating that the gasket is the same tipe of material and dimensions used for the fire safe certification of that valve.

 

[Danlap]

Hi,

Fire safe certificate applies to particular valve(s) as a whole which prototype has been tested accordingly. May also apply at some extend for some sizes and class below and or above of its tested prototype.
Gasket, soft parts and even metals (Piping, valve body, etc.) which are commonly used in the industry are burnable.
Whats different are its flammability, burning rate and exemption pressure.

Exempt material (which requires a very high pressure, and other unlikely conditions to be burn) too name a few are Monel, Bronze, Copper, etc.

Gasket: Raw (pure) material which flammability (may) have been tested in accordance with ASTM G124 may have different burning rate with its end product (read: not so pure anymore) which have been in contact with 'oily' dice / machinery, etc. ; lubricant.
What is the allowable contaminant level? You can refer to ASTM G93 para 10.1.2.2.
PS: Cost for testing a sample for ASMT G124 approx. 8K US dollar.

Short answer to your question: Gasket (as a single entity) cannot have fire (proof) test certificate

Long answer (to satisfy your customer + additional effort + additional cost):
a. The valve design itself should be fire tested
b. Detail Gasket specification which were used during the fire testing (type, composition, batch number, etc.)
c. Evidence that indeed the current gasket used is as per design / batch number and in accordance with ASTM G93 (impurities) or manufactured in in a clean way (dedicated clean molding machinery which is certified by BAM (Europe), ASME, etc.)
d. LOC of point above
The gasket manufacturer will be very reluctant to show point c.

Unless this is for nuclear, oxygen, or other easily self ignite medium, I would say challenge back the end user whether it is required to do so. Probably they have their own experience/opinion.

PS:
[li]A pure gasket (let say 99% pure graphite which is relatively dry) will requires delicate tightening, a precise dimension of mating surface (stem, housing,etc.) and controlled process condition. Susceptible for higher leakage rate (Fugitive Emission wise). Whereas a 'not so pure' graphite (w/ lubricant and so) is less stringent on above parameters, have lower leakage rate (initially), however have higher risk on easily ignite medium. So it is a trade of[/li]
[li]Normally PTFE/Teflon only gasket used on a spindle / body join and or balanced arm-Check valve will not satisfy the Fire Safe testing (it will be burned straight away)[/li]

Hope to provide some insights.

Regards,
MR



Greenfield and Brownfield have one thing in common; Valve(s) is deemed to "run to fail" earlier shall compared to other equipments

 

[PeterIgg]

Many thanks for taking the time and effort to assist. Your answers are far more detailed than my question, and give me more points to ponder. Excellent stuff.

Now all that remains is to convince the customer.......