MOC.1.B. – Composite Cylinder Acoustic Emission Requalification

The Transportation of Dangerous Goods Directorate (TDG), as part of the Safety and Security Group at Transport Canada (TC) serves as the major source of regulatory development, information, and guidance on dangerous goods transport for the public, industry, and government employees. The transportation of compressed gases in Canada is regulated under the Transportation Dangerous Goods Act, 1992 and its Regulations (TDG Regulations).

Composite compressed gas cylinders are constructed by winding glass or carbon fibre filaments over a metal liner to form a composite overwrap. One example of use for these cylinders is in emergency response. First responders use composite cylinders containing compressed air in hazardous situations that require a self-contained breathing apparatus (SCBA). These cylinders require periodic visual inspections and hydrostatic testing throughout their service life to validate their structural integrity and safety.

TDG – Scientific Research performed research in FY 2019/20 under project MOC.1.A. to assess the mechanical integrity of TC‑3CCM composite cylinders at the end of their 15 year service life. The study also evaluated three test methods for cylinder requalification: hydrostatic testing, modal acoustic emission (MAE) testing, and acoustic emission (AE) testing. AE testing was performed as per draft ISO/CD 23876 standard, and the number of false positives and false negatives obtained (when results were compared to burst testing) were found to vary greatly based on the evaluation criteria used.

The ISO/CD 23876 standard is expected to be submitted for review by the ISO committee, and as a member of this committee, TDG-Regulatory Framework and International Engagement (RFIE) branch will be asked to provide comments on the draft. RFIE have asked for a re-evaluation of the AE data, by a new contractor, in order to assess whether there is variability in interpretation of results.