Valve materials specifications

[johnthebest]

Hello everyone
I wanna your opinion about deviations made by the vendors regarding our project specification:

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1. SPECIFIED REQUIREMENT
Seat Material -RPTFE
1*. COMMENTS / DEVIATIONS OFFERED BY SUPPLIER
"vendor valves has offered Devlon seat for class 600 "
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2. SPECIFIED REQUIREMENT
TRIM material - SS 316
2*. COMMENTS / DEVIATIONS OFFERED BY SUPPLIER
F51 Ball Material for Class 900 where SS316 is specified.
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3. SPECIFIED REQUIREMENT
Carbon Steel
3*. COMMENTS / DEVIATIONS OFFERED BY SUPPLIER
we have offerd CBB actautor for 1" 300# valve to meet Valve MAST and the actuator power cyclinder is in carbon steel & housing in Ductile iron material
---------------------------------------------------------
4. SPECIFIED REQUIREMENT
SS 316
4*. COMMENTS / DEVIATIONS OFFERED BY SUPPLIER
ASTM A564 Type 630 (17-4 Ph)
---------------------------------------------------------
5. SPECIFIED REQUIREMENT
SS 316
5*. COMMENTS / DEVIATIONS OFFERED BY SUPPLIER
ASTM A182 F51/ASTM A995 Gr4A
---------------------------------------------------------
6. SPECIFIED REQUIREMENT
seat material :RPTFE
6*. COMMENTS / DEVIATIONS OFFERED BY SUPPLIER
Vendor has offered DEVLON instead of RPTFE

So basically, vendor has made deviation to the material and I wanna your opnion about it. thx in advance.

 

[arunmrao]

How about engaging a consultant?

"Even,if you are a minority of one, truth is the truth."

Mahatma Gandhi.

 

[mrfailure]

I cannot comment on Items 1 and 6. The other proposed substitutions tell me you need a different vendor. Basically, all of these substitutions are asking you to change the material type, not just the grade within the type. Items 2 and 5 duplex SS for specified austenitic SS, Item 4 substitutes precipitation hardened ferritic steel for austenitic steel, and Item 3 substitutes ductile iron for carbon steel in the housing. It is never a good idea to use alternate types of steels for design specified. Even if properties look better, there are often hidden problems caused by differences in other properties (differences in thermal expansion first comes to mind).

 

[jmec87]

It is never a good idea to use alternate types of steels for design specified. Even if properties look better, there are often hidden problems caused by differences in other properties (differences in thermal expansion first comes to mind).

If the end user is specifying materials based on a previous project or the standard offering from a different manufacturer, then it could be a very good idea for the valve manufacturer to use an alternate material to that specified in the quote request. Generally, the valve manufacturer would/should have a much better understanding of the valve design and possible problems due to differences in thermal expansion than the user.

It looks like the valve vendor is offering their one of their standard trim options, which likely has a lower cost and shorter delivery time than customized material options. The purchaser/user should evaluate the suitability of the proposed materials for the service conditions. Depending on the service conditions, many or all of these substitutions could be acceptable.

 

[mk3223]

First reaction is simply reject this vendor.

The question are what's the basis of the deviations from this vendor, and do you have the bid from other vendor.

 

[IRstuff]

It's pretty clear that either your specifications are completely arbitrary and/or useless or your supplier doesn't want the job.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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