How to specify valve trim?

[sks4338]

There are many valve trims in API STD 600.
When do you specify #1(13Cr)?
And when do you specify #8(13Cr/HF)?

I mean what is the selection criteria of valve trim?
Is it related to service fluid or temperatrue, pressure?

 

[carthago]

Table 13 of this API 600 gives the trim types/numbers.

This gives I believe the material generic name and hardness of the trim.

1/- I think the process engineer, by defining the product + its composition and its physical properties, thus by indicating if it is Sour or Not , if it is NACE or not, caustic, or not ,etc..

This will enable your valve supplier to make a better quotation and indicate the right trim.

2/- If you have an existing piping spec. defining pipe materials & thickness. pressure/ temperature rating, and VALVES than the trim is implictly given.

3/- You can find info about valves and trims, for instance in the Fischer (now Emerson) control valve handbook (chapter 3):

http://www.documentation.emersonprocess.com/groups/public/documents/book/cvh99.pdf

 

[Ashereng]

carthago,

You are correct. Valve trim is matched to the requiremeents, and factors include:
1) process fluid properties, including sour, acid/base, corrosion, salinity (chlorides), hydrogen, etc. usually use more exotic materials other thank 316SS (eg. monel, hastelloy, etc)
2) temperature (matched to temp range of mat'l)
3) erosion, cavitation, flashing, big pressure drops (eg. steam let down) usually uses hardened materials,
4) noise uses special trim designs (eg. Whisper Trim)

In some instances, it is not just the trim that needs to be considered, but the valve type also (straight globe, angled body, lincoln log, stacked disc, etc)

Oh, my industry is oil and gas. I would think that trim selection probably varies across the different industries.