Upgrade of column bearing / wear plates

Question

Upgrade of column bearing / wear plates

GetAtMeWolf (Mechanical)

(OP)

11 Jul 23 14:06

A storage tank we're currently working on has an arrangement per the attached image

.

They're a very picky client and pretty much require any recommendations to be written into the code. My concern is that there is zero way to inspect underneath this column bearing pad. Additionally, any lateral movement of the column will tear the clips and cause a potential crack / leak in the floor. The client does not want to lift the columns and put in a wear pad as would be required under current code. The tank was built in 1977, and those historical 650 codes have nothing requiring this.

My question is if API-653, Section 9.11.2.2 which states that "new bearing plates for fixed roof support columns shall be installed" covers a requirement for the wear plates in this situation?

Thanks!

IFRs (Petroleum) · Answer 1 · 2023-07-11 16:22:45

Current API 650 shows three ways to support a column, see figure 5.26 - the one at the top of the figure is what yours could be without adding any wear plates. Just weld the plate to the floor, cut the column weld off and install clips. At this point I'd suggest cutting two large slots maybe 4" x 4" in the bottom of the column to make it easier to clean out and gas free the column.

GetAtMeWolf (Mechanical) · Answer 2 · 2023-07-11 16:31:28

I've proposed this solution to them. The question for me here is if the section 9.11.2.2 requires this upgrade or not? Are there any code clarification questions published for this?

IFRs (Petroleum) · Answer 3 · 2023-07-11 17:35:38

You mention using 9.11.2.2 - 9.11.2 covers replacement of bottom plates. If they have replaced the bottom plates then 9.11.2.2 requires new bearing plates. 9.11.3.1 says that bearing plates should be instaled per 9.11.1 which is somewhat of an odd reference for bearing plates. However, you can always go back to 9.1.1 which says that "the basis for repairs and alterations shall be an API 650 equivalence." You might also point to 9.11.2.4 "Installation of a new tank bottom, after removal of the existing tank bottom, shall meet all requirements of API 650."

In general, if API 653 does not offer guidance, I go to API 650 latest edition for details.

They are not really "required" to do anything unless there is a regulation or law requiring them to adhere to a specific or the latest edition of industry standards (which are updated regularly based on good engineering judgement and owner experiene).

Your job as an inspetor is to let them know when something does not meet current standards. I'd just include in the documentation that the column bearing plate does not meet curent API 650 and let them decide how their appetite for risk goes along with their actions or lack of action.

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Upgrade of column bearing / wear plates