Material Substitutions

[a7992]

I am a Metallurgist right out of college and am frequently asked to give a recommendation for material substitutions. Generally, I'm not 100% positive and was wondering if there is a guideline on substituting materials or if the ASTM specs include materials they could be substituted with? Any help or guidelines would be great!!

How do most refinery/chemical processing plants deal with issues like these?

 

[metengr]

a7992;
Material substitutions in general can be very tricky because for one approach you can substitute with near equivalent materials or even upgrade materials as part of a substitution. However, for components that are designed and built to codes or standards one has to be aware that you do not substitute with materials that are not code approved. There are tables around the internet where you may have listed as an example, EN material designation with an ASTM listing side-by-side.

To be on the safe side, you should evaluate as a minimum three categories for a proper material substitution. These categories are chemical composition, mechanical properties and environment (or intended service use). You need to evaluate all three of these categories before deciding on a material substitution.

 

[CoryPad]

There are some good resources to help with this work. ASM's Worldwide Equivalents and the German book Stahlschl[ü]ssel are recommended.

 

[a7992]

Thanks for the help! I was looking at those three categories which is good.

Thanks Cory for the book recommendation. I walked by that book in our library many times without thinking it might have been important.

 

[dbooker630]

As a new Metallurgist do not hesitate to call on a more experienced person. This forum is definitely a good start. At your facility you will be expected to know everything about materials but the worst thing you can do is make the wrong call. If there is someone you respect as a mentor (professor?) I would contact that person as well.

 

[a7992]

Thanks for the advice. When I first took this position I was under the impression that I would be working with a more experienced metallurgist but he has since left the position. It has been quite the learning curve and I do work with other engineers on these decisions. I have also utilized outside vendors quite a bit but eventually I'd like to learn to be more independent.

I must say though that people do ask me a lot more questions about materials than I ever thought they would...it might be a curse being a metallurgist (jk). Even my in-laws will ask random questions at holidays..."Why is this made out of that?" etc.

Thanks everyone for the help!

 

[dbooker630]

Us metallurgists may be cursed AT but never are we cursed! I don't even have to say 'it depends' for that. I feel like I have the best job in my shop.

 

[rustbuster]

Experienced Inspectors are also a great resource. You would do well in asking for their input which will gain you respect and valuable allies.

 

[MSUKeith]

Another suggestion: work backwords from the requirements and environment then consider which aspects of the currently specified material are absolute must haves and which can be comprimised some. Sometimes you'll find the list of true requirements is relatively short.

Also - don't forget the material substutition effects on manufacturability.

'I have only come here seeking knowledge,
Things they would not teach me of in college' Sting

 

[CdotS]

If you are working in the oil and gas industry (upstream/downstream), NACE has several books including MR0175 (check the number). It has an equivalent ISO standards book for materials selection also.