API-571 Exam - Topic 1 Question 111 Discussion

Actual exam question for API's API-571 exam

Question #: 111
Topic #: 1

A carbon steel bundle from the overhead condenser in the crude unit operates at 300 F and is in hydrochloric acid service. It showed severe pitting type corrosion when pulled for inspection. What type of material would be best suited for this service?

A5Cr-0.5Mo

B316 stainless steel

C9Cr-1Mo

DTitanium

Show Suggested Answer

Suggested Answer: D

by Carlene at Jun 14, 2025, 02:17 PM

Limited Time Offer

25%

Off

Get Premium API-571 Questions as Interactive Web-Based Practice Test or PDF

Contribute your Thoughts:

Submit Cancel

Nobuko

3 months ago

Not sure if 316 is enough for severe pitting, though.

upvoted 0 times

...

Hortencia

3 months ago

Definitely agree with 316 stainless steel for hydrochloric acid service.

upvoted 0 times

...

Kent

4 months ago

I think 9Cr-1Mo could handle the heat better.

upvoted 0 times

...

Tabetha

4 months ago

Titanium? Really? That seems overkill for this situation.

upvoted 0 times

...

Dorsey

4 months ago

316 stainless steel is known for its corrosion resistance in acidic environments.

upvoted 0 times

...

India

4 months ago

I recall that 5Cr-0.5Mo is often used for high-temperature applications, but I’m not sure how it performs in hydrochloric acid. I think stainless steel is safer.

upvoted 0 times

...

Leontine

5 months ago

I feel like we had a similar question in practice about materials in acidic service. I think 9Cr-1Mo was mentioned as a potential candidate, but I’m not confident.

upvoted 0 times

...

Nu

5 months ago

I'm not entirely sure, but I think titanium could handle the corrosion better than the others. It’s more resistant, right?

upvoted 0 times

...

Hollis

5 months ago

I remember we discussed that carbon steel isn't great in acidic environments, especially hydrochloric acid. I think 316 stainless steel might be a good option here.

upvoted 0 times

...

Ilda

5 months ago

I'm a bit unsure about the 5Cr-0.5Mo and 9Cr-1Mo options. I'll need to research their corrosion resistance in hydrochloric acid service to make a confident decision.

upvoted 0 times

...

Pearly

5 months ago

Titanium could be a good choice here, but it might be overkill and more expensive than necessary. I'll have to weigh the pros and cons.

upvoted 0 times

...

Yvonne

5 months ago

Okay, I know pitting corrosion is a major issue in acidic environments. I'm leaning towards 316 stainless steel since it has good corrosion resistance.

upvoted 0 times

...

Leeann

6 months ago

Hmm, this seems like a tricky one. I'll need to think carefully about the corrosion resistance properties of each material option.

upvoted 0 times

...

Eric

8 months ago

Hold on, did someone say 'overhead condenser'? I bet the engineers were just daydreaming about their next vacation when they designed this thing. Better bring a snorkel for that acid shower!

upvoted 0 times

...

Elenora

8 months ago

Hmm, I'm not sure 5Cr-0.5Mo would be robust enough for this service. Seems like it might be a bit too lightweight for the job. Time to beef up the alloy content!

upvoted 0 times

Berry

7 months ago

User 2

upvoted 0 times

...

Burma

7 months ago

User 1

upvoted 0 times

...

Hailey

7 months ago

User 2: Yeah, I agree. It's important to have a material that can withstand the harsh conditions.

upvoted 0 times

...

Twila

8 months ago

User 1: I think 9Cr-1Mo would be a better choice for this service.

upvoted 0 times

...

Belen

8 months ago

I'm going with 316 stainless steel. It's a classic choice for corrosive services and should hold up well to the pitting issues. Just hope the cost doesn't blow the budget!

upvoted 0 times

Danilo

7 months ago

User 2: Agreed, it's a reliable option for corrosive environments.

upvoted 0 times

...

Santos

8 months ago

User 1: I think 316 stainless steel is a good choice for this.

upvoted 0 times

...

Carey

8 months ago

Titanium is a great option here. It's highly resistant to pitting and crevice corrosion, even in aggressive acid environments. Plus, it's lightweight and easy to fabricate.

upvoted 0 times

Mona

8 months ago

A: It's also lightweight and easy to work with, which is a bonus.

upvoted 0 times

...

Alise

8 months ago

B: Yeah, titanium is known for its resistance to corrosion in acid environments.

upvoted 0 times

...

Ceola

8 months ago

A: I think titanium would be the best choice for this service.

upvoted 0 times

...

Pete

9 months ago

Why do you think 9Cr-1Mo is better?

upvoted 0 times

...

Theodora

9 months ago

I think 9Cr-1Mo would be the best choice for this application. The high chromium content provides good corrosion resistance in hydrochloric acid, and the molybdenum addition further enhances the corrosion protection.

upvoted 0 times