NELSON curve API 941

[HOUARI YAHIAOUI]

HELLO EXPERTS;
My question is : How to use the NELSON curve API 941 to confirm if the material shoosen is the right material? may my question is a basic question so sorry.
as an exemple :
A drum containing a fluid withe 93 mol% of H2, operating at 55°C at operating pressure equal to 129.2 Barg, the datasheet indecate that CS+3mm is the material of construction. is the CS suitable for the combination of this operating conditions??

 

[XL83NL]

Nelson curves found in API RP 941 are used to determine if a specific carbon steel alloy group is susceptible hydrogen attack, such as hydrogen embrittlement, at elevated temperature and pressure.
This is mainly determined by the temperature and partial hydrogen pressure, but other factors play a role as well, such as PWHT. You have not specified the specific carbon steel alloy youúre using. The 3mm CA doesnt affect the susceptibility, as hydrogen permeates through the steel, regardless of your 'margins'. Your temperature of 55 °C is however sufficiently to waive out the susceptibility of HTHA.

Do you have a copy of API RP 941? Review the foreword of API RP 941 to get a first start.

 

[HOUARI YAHIAOUI]

thank you for your response, yes I verified the combination of temperature and pressure partial of hydrogen withe API RP 941 :
I foud that according to nelson curves the HTHA risk begin at temperatures above 140°C and this suficient to say that the equipements is away wuth these conditions to be attaked with HTHA.
thank you a lot mister have a great day.