Interpretation Response #15-0230 ([The Chlorine Institute] [Ms. Robyn Kinsley])
Below is the interpretation response detail and a list of regulations sections applicable to this response.
Interpretation Response Details
Response Publish Date:
Company Name: The Chlorine Institute
Individual Name: Ms. Robyn Kinsley
Location State: VA Country: US
View the Interpretation Document
Response text:
July 25, 2016
Ms. Robyn Kinsley
Senior Director, Transportation
The Chlorine Institute
1300 Wilson Blvd., Suite 525
Arlington, VA 22209
Reference No. 15-0230
Dear Ms. Kinsley:
This is in response to your December 3, 2015 email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) relating to a tell-tale indicator on a combination pressure relief device (PRD) for a rail tank car. Specifically, you ask this office to reconsider the guidance provided in our April 16, 2015 (Ref. No. 14-0229) letter of interpretation issued to your organization because it is inconsistent with industry application and guidance for emergency responders.
In the previous letter of interpretation, this office advised that a tell-tale indicator having a threaded outlet must be closed with an approved screw plug. You state that PRDs with this particular design are installed in a way that the port on the tell-tale valve faces outward, perpendicular to the relief valve. In an incident where there is a release from the PRD which cannot be mitigated, the Chlorine Institute’s recommendations are to cap the PRD with a CI Emergency Kit-C hood (C-kit hood). You state that implementation of the guidance in 14-0229 is problematic because the C-kit hood will not fit over the PRD when the tell-tale plug is installed. You note that the tell-tale valve does not serve the same purpose as the primary operating valve and is not exposed to the product in the tanks and as such, the industry understanding has been that tell-tale indicators are not required to have plugs installed. Because of this understanding, when the C-kit was designed, the tell-tale plug being installed was not a consideration.
Based on the request for reconsideration, we reviewed the letter of interpretation 14-0229, and the relevant requirements in the HMR. The tell-tale valves on the Midland 1400 series pressure relief valves were originally designed for a sample line. A configuration without the screw plug is not an approved design. In order to comply with the guidance in 14-0229 and accommodate a C-kit hood, the tell-tale valve may be rotated so that the screw plug is no longer outside its footprint. As a result, if the tell-tale valve is rotated, it must have a qualification of the threaded connection.
I trust this information is helpful. If you have further questions, please do not hesitate to contact this office.
Sincerely,
Duane A. Pfund
International Standards Coordinator
Standards and Rulemaking Division