Selecting the proper material of construction (MOC) is a crucial decision for equipment selection. A mistake here can have catastrophic implications not just in terms of money spent but also in terms of the safety implications for a project. In this blog post we thought it was a good idea to outline some common tips and sugesstions to avoid pitfalls during the MOC selection process. Of course, MOC selection is unique to every project, and we strongly encourage you to contact your vendor, or our excellent team of application experts at Amar before your next project! Send an email to [email protected]
Stainless Steel (either the 314 or 316 grades) if often the default choice of MOC for most pilot plant projects. It is fairly resistant to a large range of common chemicals but it is always good to consult a MOC selection chart before you order. This is true for most projects in specialty chemicals, foods and API / Pharma industry. However, petrochemicals and refining industries still use Carbon steel for many projects at scale and hence driving the decision about what MOC to use for pilot plants for such applications
When designing pilot plants it is often critical to maintain geometric and kinematic similarity to the final [production equipment. It is useful if the MOC also remains identical to spot problems such as pitting or weld corrosion at the pilot plant stage of the project. This can save millions of dollars later by modifying the production equipment based on the data accumulated at the pilot plant stage. Resist the temptation to switch MOC between the pilot and production scales.
Often specialty chemical projects can use reagents for which reliable corrosion data is not available in literature. In such cases it is imperative that test “Coupons” be used to study the corrosion characteristics of various MOCs that are under consideration. There are standard protocols for performing this test and sometimes a vendor or a third party testing lab can be a good choice to perform this. Make sure the conditions used in the actual process are used for coupon testing and use accelerated testing if necessary to simulate the effect of longer time exposures.
Remember that often Impurities can have the deciding role on corrosion rates. Never ignore impurities. A past project we executed had a <1% impurity that was highly corrosive and led to unanticipated corrosion problems 3 to 6 months into the experimental trials.
Water content or residual water can be very tricky to deal with. Many MOCs can be compatible with a dry chemical (e.g. H2SO4) but rapidly corrode in the presence of water or moisture.
Again, MOC selection is a very complex topic and often the Achillis heal of process development projects. Make sure you talk to our in house experts at [email protected] for more guidance on this topic for your next project! Also stay tuned for a follow up blog post on this topic for more tips and suggestions!