F91 Valve

[Isha90]

In F91 Globe valve 316disc was used, customer complain Disc eroding, Working temperature 550°C Pressure 160bar, Steam,Can we say F316 wrong material selection & suggest F91/Inconel disc material.
In B16.34, A 182 Gr. F316, At temperatures above 538°C, use only when the carbon content is 0.04% or higher. Flanged end valve ratings terminate at 538°C. Please clarify

 

[metengr]

Clarify what? The Notes are specific. Above 538 deg C means temperatures above 538 deg C requires higher carbon content meaning 316 not 316L for creep strength.

 

[Isha90]

A182 Gr.F316L ,as per B16.34 Group 2.3 Material 450°C, A182 Gr.F316 ,as per B16.34 Group 2.2 Material 816°C, with 538°C note

 

[metengr]

The Note you refer to is for creep strength concerns and has nothing to do with erosion resistance. Sounds like the 316 SS disc material was a poor choice for erosion resistance in this application and not because of the Note cited.

 

[Isha90]

Flanged end valve ratings terminate at 538°C. Please clarify
What might be the causes for 316 eroding

 

[weldstan]

From an empirical standpoint, you are aware of the inadequacy of 316 in your operating parameters. You can always specify some other material. I believe that the majority of similar valves installed on our projects used a stellite type hard surfacing on the disks.

 

[MintJulep]

Flanged end valve ratings terminate at 538°C. Please clarify

It means you need to read this requirement.

5.2.2 Responsibility. When service conditions dictate
the implementation of special material requirements,
e.g., using a Group 2 material above 538°C (1000°F), it
is the user’s responsibility to so specify to the manufacturer
in order to ensure compliance with metallurgical
requirements listed in the end notes to Table 1 and the
notes in Table 2

 

[Isha90]

Thank you, Yes hard face was done on seating area, but still Disc A479 Ty316+St6 eroded, is it due to application in 550°Cplease

 

[metengr]

First, have you had a metallurgical analysis performed to conclude this is erosion or possibly something else is occurring rather than trying to place the blame on Notes in B16.34? If not, you need to have this done rather than guess or have someone tell you the problem.

Second point, this is a dissimilar material combination F91 ferritic in contact with an austenitic stainless steel in elevated temperature service which means from a design standpoint you have differences in the linear coefficient of expansion. This translates to thermal stresses at elevated temperature resulting in possible warpage and cracking. If anything, you should have used a Cr-Mo or Cr-Mo-V seat material with Stellite hardfacing for steam erosion resistance.

 

[Isha90]

Thank you.

 

[weldstan]

Agree with metengr. It would have been helpful, if you would have stated in your opening question that the disk was 316 with stellite hard surfacing and stated the hard surfacing method used. More info provided the better the answers!