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Interpretation Response #20-0038

Below is the interpretation response detail and a list of regulations sections applicable to this response.

Interpretation Response Details

Response Publish Date:

Company Name: Arthur L. Fleener

Individual Name: Fleener Consulting LLC

Location State: ID Country: US

View the Interpretation Document

Response text:

August 28, 2020

Arthur L. Fleener
Fleener Consulting LLC
3741 Mathews Road
Ames, IA  50014

Reference No. 20-0038

Dear Mr. Fleener:

This letter is in response to your April 29, 2020, email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to MC 331 cargo tanks. Specifically, you seek clarification regarding external visual inspections of MC 331 cargo tanks that have been treated on the lower 1/3 of the cargo tank with a product commonly known as "rock guard." You note that, similar to paint, "rock guard" is sprayed directly onto the unpainted cargo tank to provide a tough and scratch resistant surface that protects the cargo tank from rust and corrosion.

We have paraphrased and answered your questions as follows:

Q1. You ask whether an MC 331 cargo tank that has been treated with "rock guard" would require a yearly internal visual inspection as part of the external visual inspection.

A1. Section 180.407(d)(1) states, "If external visual inspection is precluded because any part of the cargo tank wall is externally lined, coated, or designed to prevent an external visual inspection, those areas of the cargo tank must be internally inspected." Therefore, if any portion of a cargo tank is covered with an external lining (e.g., a vinyl wrap) and/or coated (e.g., with paint or rock guard) in such a manner that prevents the proper external visual inspection as described in § 180.407(d)(1), then an internal visual inspection of those areas affected by the paint and/or coating would be required in conjunction with the external visual inspection for the remaining areas of the cargo tank wall.

Q2. If the answer to Q1 is yes, you ask how an MC 331 cargo tank treated with "rock guard" is different than a regular painted cargo tank.

A2. As stated in A1, if a cargo tank wall is externally lined, coated, or designed to prevent an external visual inspection, those areas of the cargo tank must be internally inspected.  As a result, for the purposes of performing the external visual inspection as described in § 180.407(d), both paint and “rock guard” are regarded as coatings and prompt an internal inspection on cargo tanks when they prevent an external inspection.

Q3. You ask whether a cargo tank that has been treated with "rock guard" and that is required to have a yearly internal visual inspection as part of the external visual inspection would still require the internal visual inspection if the “rock guard” was not applied to the welded joints.

A3. Please see A1 and A2.

I hope this information is helpful.  Please contact us if we can be of further assistance.

Sincerely,


T. Glenn Foster
Chief, Regulatory Review and Reinvention Branch
Standards and Rulemaking Division

180.407(d), 180.407(d)(1)

Regulation Sections

Section Subject
180.407 Requirements for test and inspection of specification cargo tanks