Trim material selection

[KMur]

Dear All,
Crude details are as follows:
Pressure = 55 psig, H2s mole fraction = 0.0011 and partial pressure of H2S = 0.07667 psia, NACE Sour = YES and

Formation water analysis:
Chloride content = 161500 mg/l and pH=5.7

Please suggest me how to select valve trim material based on NACE MR 0175?

 

[SJones]

You haven't said what the valve body material is. First of all, you have to decide which type of material is to be used for the trim: carbon steel that could be subject to metal loss corrosion, or a corrosion resistant alloy that could be subject to SCC. Carbon steel will need to follow the requirements of ISO 15156 Part 2, and the corrosion resistant alloy will need to comply with Part 3. If you go down the path of Part 3, you will need to decide whether you require a straight material qualification, or whether you can tolerate a laboratory qualification test programme. You will also need to decide whether you believe that there is a difference between, for example, the restrictions placed on a material for "any equipment or components" versus any relaxed requirements for, say "valve components."

As a starter, with that chloride concentration, you will not be able to select 316 internals for a temperature (you have to decide whether that will be design temperature, or maximum operating temperature if different) above 60 degrees C without a) a laboratory qualification test programme, or b) instruction from the end user that they have satisfactory experience for such material in the same application in the same environment at the same temperature.

Simples

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

[KMur]

Thank you SJones.
Valve body material is CS. We are selecting the material based on ISO 15156 part 3.Finally, Inconel 625 is selected as trim material.

thanks