Riddick Engineering Corporation — Hazardous Materials Safety Interpretation

Page 1J.S. Department of Transportation 400 Seventh St., S.W. Washington, D.C. 20590 JUN 13 2003 Mr. Chris J. Teas, PE Riddick Engineering Corporation Consultants Ref. No.: 03-0093 2300 Cottondale Drive Suite 200 Little Rock, Arkansas 72202 Dear Mr. Teas: This responds to your letter regarding requirements for an internal self-closing stop valve on a DOT 407 cargo tank under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). Specifically, you asked whether a "swing check valve" as shown in the enclosed diagram would be acceptable to meet the "internal self-closing stop valve" provisions in §178.345-11(b). Each specification DOT 407 cargo tank must conform to the general design and construction requirements in §178.345 in addition to the specific provisions contained in §178.347. Each cargo tank (e.g., DOT 407) loading/unloading outlet must be equipped with an internal self-closing stop valve ot with an external self-closing stop valve located as close as practicable to the cargo tank wall. An internal self-closing stop valve is a self-closing stop valve designed so that the self-stored energy source is located inside the cargo tank oi cargo tank sump, or within the welded flange, and the valve seat is located within the cargo tank or within one inch of the external face of the welded flange or sump of the cargo tank. The regulations do not prohibit a design of the type, such as the "swing check valve," shown in the enclosed diagram if it meets all of the requirements for an "internal self-closing stop valve," specified in §178.345-11(b). You did not provide sufficient information in your letter or a detailed drawing of the components of the "swing check valve" for us to determine if it complies with the requirements in §178.345-11(b). If we can be of further assistance, please contact us. Sincerely, Delmer F. Billlings Chief, Standards Division Office of Hazardous Materials Standards 030093 176.347#

Page 2a: Edward Mazzullo From: Chris J. Teas 3/28/2003 14:07:09 (Page 2 of 2) RIDDICK ENGINEERING CORPORATION 4600 WEST MARKHAM Consultants LITTLE ROCK, ARKANSAS 72205 Engrum FAX 501-374-3700 501-000-7300 3178.347-11 (b) Cargo Tank EDGAR K. RIDDICK UR, PE 1923-1997 FOUNDER March 28, 2003 03-0093. Mr. Edward Mazzulto Director, Office of HAZMAT Standards USDOT/RSPA (DHM-10) CHRIS J: TEAS, PE VICE PRESIDENT 400 7* Street Southwest Washington DC, 20590-0001 Re: Formal interpretation request Part 178.347-11 (b) Tank outlets. Code Needing Interpretation: Title 49, SUBTITLE B, CHAPTER 1, SUBCHAPTER C, Cargo Tank Description: Cargo tank to be designed and manufactured is as follows: 2. 1500 gallon, stainless steel DOT 407 vacuum cargo tank vehicle. 3. Used to clean up various hazardous spills. 5. Besides this interpretation, all other regulation requirements are in direct compliance. Customer: US Government. Questions: 1. This section states, "Each cargo tank loading/unloading outlet must be equipped with in internal self-closing stop-valve...". By definition from section §178.345-1 (c) professional opinion that a swing check valve (as shown below) will meet the intent of is type valve must be shut by self stored energy within the tank. Therefore, it is m -SWING CHECK VALVE VACUUM SHEAR SECTION -BALL VALVE -DUST CAP Sincerely, Chris J. Teas, PE, DOT CT10023 Mechanical Electrical Industrial Structural Powor & Procoss Energy Analysis & Computer Modeling Industrial Studies & Masterplanning ENGINEERS SCIENTIFIC CONSULTANTS Co-generation#