fugitive émission and hydcrocarbon fluid 3

[MECA 02]

Hi,

Please, I need your help. I am currently working on a valve datasheet for both manual and control valves. These valves are installed on an unloading platform connected to a pipeline used for unloading hydrocarbon fluids (Jet fuel, gasoil, gasoline).

It might be a broad question, but is it necessary to specify fugitive emissions test "API 624/ API641" for this type of fluid?

If yes, why is it required?
If not, why not?

thanks

 

[Danlap]

Hello,

If the company bound to clean gas act or Brussels Accord or similar (on other parts of the World), then Yes, it should be specified. Control valve would be a tricky one though


Please connect below dots to support the narration:

• Leakage path from valve can be from: gland packing (graphite and/or PTFE); body to bonnet gasket (graphite/Kamprofile/etc.) and body to body gasket
• Product, eventhough in piping is liquid state, once leak can contribute to:
  • Emission to the atmosphere…please see so many literatures of how much oil and gas contribute to greenhouse effect and how much of that portion is due to flange and valves
  • Health and Environmental Hazard…almost all companies have defined substances used/produced in the premises into hazardous categories (shall leak) from very toxic, toxic acute, severe, etc. I believe your Jet fuel and gasoil is part of this category. Thus some sections of the refinery/platform might subject for environmental emission audit periodically. Some even before starting up, fugitive emission certificates will be checked.
• Boundaries (lets assess it from temperature only for this case)
  • ISO 15848-2 à fugitive emission testing at room temperature
  • API 624 à testing at 260 degC
  • Valve datasheet à design temperature e.g. -20degC to 400 degC?? based on piping design temperature (and not product)??
• How to achieve good emissions
  • Good quality graphite
  • Sufficient torque
  • On gland packing: good surface finish and straight spindle, good quality graphite gland packing, sufficient torque, etc.
  • Etc.

Challenges:

• Packing (gland and gasket) : Graphite (93-99%) + bonding agent such as PTFE, Zinc, etc. that start to permeable around 200deg. Then older version of gasket is prone for thermal relaxation (remember that you want to operate up to e.g. 400 degC)
• Control valve mainly use PTFE gland for smooth operation. PTFE (marketing brochure) can be up to 250 degC, which may not entirely true as it is often at lower temperatures already show signs of leakage.

It is very possible for good manufacturers to achieve fugitive emissions class B and even A up to 400 degC. There is high possibility that control valve with PTFE gasket will put a disclaimer up to which temperature their gasket still work optimal.
I might miss some numbers above, but hope you got the picture.

Regards,
D

 

[MECA 02]

Thank you for your explanation. I have another question, please.

For a ball valve, can API 624 be applied, or is it strictly applicable only to gate valves? In that case, would API 641 be the applicable standard?

 

[Danlap]

Yes/Yes

API 624 title is 'Type Testing for Rising Stem Valves Equipped with Graphite Packing for Fugitive Emissions' whilst API 641 title 'Type Testing of Quarter-turn valves for Fugitive Emissions'.
It's quite self explanatory. Gate is rising stem and ball is quarter turn.

Rising stem valve's gland packing usually worn out faster thus API 624 mandate only 300 cycles mock up testing, whilst API 641 is up to 600 cycles (open and close the valve at testing facility). Ball valve gland packing friction factor considerably lesser than rising stem.