HIC Resistant Steel 2

[Inspector2003]

I am in the process of replacing a carbon steel pressure vessel at our refinery which is suffering from hydrogen blistering due to wet H2S service. No cracking has been identified in the vessel other than the blistering. For the new vessel I intend to use carbon steel and stress relieve all welds. Does anyone have any comments regarding the use of HIC resistant steel? I have heard that though it reduces the problem with HIC, it does have other problems. Any comments would be appreciated.

 

[priyasachin]

Priyasachin

Dear friend,

Use very low sulpher bearing steel. Such steels are produced for serving in ' Sour Service'. The specified sulphur content is in the order of 0.003% max. Such steels are very resistant to H2S blistering and HIC too.

MRCN

 

[stanweld]

HIC resistant steels have been used for over 20 years in construction of vessels and pipe. They can be and are welded with all of the normal vessel welding processes - SAW, SMAW, GTAW, FCAW.

 

[TomEun]

Hopefully it is recommended to make a company standard about the application in sour service. Most of the companies have severity categories and definition (HIC resistant steel or HIC tested steel) of sour services according to partial pressure, normal operating pressure, thickness, H2S wet%, pH, %CN-,etc.

The following requirements are based on the most critical condition.

1. Vacuum Degassing Treatment
2. Fully killed fine grain practice (greater than ASTM No.7 for vessels)
3. Normalizing
4. Tempering temperature for Q-T or N-T steels; min 650C
5. Max Y.S for piping: 8000psi (SA-516-55 or 60 preferred)
6. Metallic inclusion shape controll required. TMCP steel rolled at 1300 to 1650F is not recommended.
7. S<=0.002%, P<=0.010%, Ceq ; max 0.22% for t<=1/2&quot;, max 0.24% for 1/2&quot;<t<=2&quot;, max 0.26% for t>2&quot;
8. Ca treatment
8. Tempering temperature for Q-T or N-T steels; min 650C
9. UT for steel: SA-578 Level S1-100% scanning
10. To apply the plate type pipe and vessel necessarily.
11. HIC Test
(1)Test time: 96 hours
(2)Test Procedure-NACE TM0284/ pH;at Design condition or 3 (TM0177)
(3) Acceptable Criteria;
CLR<5.0%
CTR<1.5%
CSR<0.5%
12. PWHT ; Required
13. Hardness <=200 BHN on weldments and HAZ
14. RT : Full
15. MT : Required with WFMT on weldments and HAZ

Thanks,

Thomas
thomaseun@shaw.ca