Chlorine PRD with Tell-Tale Valves - Compliance Options and Repair Procedures

Oct 23, 2026

Uploaded by Connor

Bilateral compliance bulletin detailing requirements for chlorine tank car pressure relief devices (PRDs) using tell-tale valves with threaded outlets. Summarizes PHMSA’s final interpretation (14-0229) confirming screw plugs are required, plus Midland’s response to manufacture tell-tale purge valves without threaded outlets effective Feb 16, 2016. Defines scope for specific Midland Series A-14227, A-14377, and A-14378 valves and provides in-shop and in-field procedures, including leak testing of the threaded connection.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages2

Reading Time5 min

AccessFree to download

Compliance background

PHMSA final ruling and Midland response

Scope and applicable valve series

Compliance options

In-shop repair procedure

In-field or in-shop repair procedure using screw plug

Model purge valve reference

Date: September 23, 2016 From: Midland Manufacturing REASON FOR BULLETIN: On December 2, 2015, the Chlorine Institute, with support from member organizations, issued a request to PHMSA to re-consider the use of screw plugs on tell-tale valves used with chlorine tank car pressure relief devices (PRDs) . On July 25, 2016, PHMSA issued a final ruling in the letter of interpretation 14-0229 (re: HMR 49 CFR Parts 171-180) . The ruling confirms that tell-tale valve designs with threaded outlets used for chlorine tank car pressure relief devices must include screw plugs. MIDLAND RESPONSE: Effective February 16, 2016, Midland began manufacturing all chlorine tank car PRDs with tell-tale purge valves that do not include a threaded outlet. The Midland purge valve \#17-240-ML complies with the PHMSA ruling, and ensures that PRDs can be capped with Chlorine C-Kit \#24A hood and Midland ERK \#4 hood without manipulating the alignment of the tell-tale valve. SCOPE: The following options apply to Midland Series A-14227, A-14377 and A-14378 PRD valves used for chlorine tank cars. OPTIONS TO ENSURE COMPLIANCE FOR TANK CARS USING TELL-TALE VALVES WITH THREADED OUTLETS: In-Shop Repair Procedure Replace tell-tale valves with threaded outlets with Midland purge valve \#17-240-ML. Note: it is necessary to test the threaded connection between the purge valve and the PRD mounting flange. This process cannot be done in the field because the rupture disc must be removed from the PRD. See Midland Instruction and Operations Manual A-1402C, Procedure Without Rupture Disc Installed for instructions to test the threaded connection between the purge valve and the PRD mounting flange. [Visit](Visit www.MidlandMfg.com)[ ](Visit www.MidlandMfg.com)[www.MidlandMfg.com](Visit www.MidlandMfg.com) , select the REPAIR MANUALS button under QUICK LINKS for a copy. Model 17-240-ML Purge Valve OVER In-Field or In-Shop Repair Procedure Procedure to use tell-tale valves with threaded outlet and screw plug. 1. Install screw plug (Midland \#18-ML) . If the plug faces outward, away from the PRD it will extend into the footprint of the Chlorine Kit \#24A hood. This interference will not be acceptable for emergency hazmat valve capping procedures. The needle valve with screw plug must be rotated towards the PRD. Plug extends into the Chlorine C-Kit \#24A Hood Footprint 2. Rotate the valve so that the screw plug will not extend beyond the footprint of the PRD. It is important to rotate the needle valve to ensure that the screw plug cannot interfere with the potential capping of the PRD. 3. The rotated needle valve must be tested for leaks at the threaded connection. Remove the plug and pressure test the connection at 30-55 psi for 2 minutes. When it is confirmed that no leaks are present, replace the plug to complete the process. Per M-1002 CIII A[3.3.6.3](3.3.6.3), chains are not required to be used with tell-tale valves.

FAQs

What did PHMSA confirm regarding tell-tale valves on chlorine tank car PRDs?

PHMSA confirmed that tell-tale valve designs with threaded outlets must include screw plugs when used with chlorine tank car pressure relief devices.

What changed in Midland’s manufacturing process effective February 16, 2016?

Midland began manufacturing all chlorine tank car PRDs with tell-tale purge valves that do not include a threaded outlet.

How should the threaded connection be tested when using a tell-tale valve with a screw plug?

Remove the plug and pressure test the threaded connection at 30-55 psi for 2 minutes; if no leaks are confirmed, replace the plug to complete the process.

Oct 23, 2026

Uploaded by Connor