Tube & Tube Sheet materials for HIC (severe wet sour) service 2

[Xeros]

Hi.

there is a shell & tube heat exchanger that shell side fluid is in severe wet sour service (HIC serrvice).

Tube & Tube Sheet material are carbon steel.

What kind of requirement for carbon steel was applied?

According to NACE PUB 8x194, there is no requirement for carbon steel tubing (for tube) & forging (for tube sheet).
Or gernral requirement shall be applied as per NACE MR0175.
Or just Killed Carbon Steel is no problem.

I'm very confused...

I would appreciate it if you explain the reason, additionally.

thanks for reading.

Regards,

 

[0707]

Steel chemistry and manufacturing methods also affect susceptibility and can be tailored to produce the HIC resistant steels outlined in NACE Publication 8X194.

HIC is often found in so-called “dirty” steels with high levels of inclusions or other internal
discontinuities from the steel-making process.

HIC-resistant steels can be used to minimize the susceptibility to blistering and HIC damage. Detailed materials and fabrication guidance can be found in NACE Publication 8X194.

Blistering and HIC damage develop without applied or residual stress so that PWHT will not prevent them from occurring.

General requirement per NACE MR0175 are for Sulfide Stress Cracking Resistant Metallic Materials.

Regards

Luis marques

 

[Xeros]

Thanks 0707.

However, there is no HIC resist requirement for tubing & forging materials in NACE 8x194 (category 2). only for plate.

I can't understand this reason.

AND

What kind of HIC resistant requirements were applied for tubing and forging materials in HIC condition?

Regards,

 

[TomEun]

In addition to a sound answer of 0707,

First of all, NACE Publ.8X194 (1994) is not a code or standard but a good corrosion data survey report. There is a general definition of HIC resistant carbon steel, but no limitation/definition of qualified HIC resistant carbon steel in NACE standards and publications. It means that the definition and requirements for HIC resistant carbon steel should be developed and defined by end users. So it is greatly advised to study your client’s specifications.

According to the report, NACE Publ.8X194, severe wet sour service (Category 2), the HIC test (per NACE TM0284 & 0177) and severe chemical requirements (i.e. S<0.002%, P<0.010%) are generally applied to plate only while basic chemical control (i.e. CE<0.43, Cb+V<0.03%, Cb<0.02%, V<0.02%) and killed steel requirements are applied to all type carbon steels (except thin-wall tubes).

The most severe requirements for HIC environment are applied to plate carbon steel because the stepwise cracking (metal inside) or blistering (on the surface) due to HIC mechanism is generally initiated at the nonmetallic precipitation (especially flattened inclusion, MnS during rolling process of mill manufacturing).

Please find your client’s specification. I believe at least the HIC test and severe chemical control (i.e. S<0.002%, P<0.010%) are not required for forging and tube materials.

Hope this helps,

Thomas Eun

 

[EdStainless]

One practical reason why you do not see these requirements on forgings and thin walled tubes is that when those product forms are manufactured the inclusions are broken into small pieces. These smaller more distributed inclusions are of little risk for HIC.

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