Interpretation letters
How agencies have applied their regulations to specific questions.
- Sharps Containers in Wheeled Racks — PHMSA, Oct 15, 2026
- Transport of ASME Storage Containers Intended for Permanent Installation — PHMSA, Oct 14, 2026
- Authorized Materials for Specification 4BW Welded Steel Cylinders — PHMSA, Oct 13, 2026
- MC-338 Pressure Test Retest Date — PHMSA, Oct 13, 2026
- Limited Quantity Compressed Gases & Air Transport — PHMSA, Oct 6, 2026
- Portable Tank Limits and Heel Restrictions — PHMSA, Oct 6, 2026
- Marine Pollutants Continuing in Domestic Ground Transportation — PHMSA, Oct 6, 2026
- Return Shipments of Engine Assemblies — PHMSA, Sep 30, 2026
- Pressure Relief Devices and Components — PHMSA, Sep 24, 2026
- Nurse Tank Registration Requirements — PHMSA, Sep 24, 2026
- Radiation Survey Methods for Inaccessible Areas on Transport Vehicles — PHMSA, Sep 17, 2026
- LOI Applicability to Entities Outside of the Requesting Party — PHMSA, Sep 3, 2026
- Training & Tank Car Maintenance — PHMSA, Aug 28, 2026
- Software-Specific Hazmat Training — PHMSA, Aug 19, 2026
- Requirements to Prepare and Maintain a Dangerous Cargo Manifest — PHMSA, Aug 18, 2026
- Motor Carrier and Driver Responsibilities Under Section 177.817 — PHMSA, Aug 17, 2026
- Precedence of Hazards and Corrosive Label — PHMSA, Aug 13, 2026
- UN3536 Bulk Packaging Definition and Registration — PHMSA, Jul 29, 2026
- Requalification of Cylinders Used in Fire Suppression Systems — PHMSA, Jul 28, 2026
- Cylinder Requalification Recordkeeping Requirements — PHMSA, Jul 27, 2026