As of January 15, 2015, Transport Canada has added Closure Instruction notification to the requirements of small containers for the transport of dangerous goods, Classes 3, 4, 5, 6.1, 8 and 9. Therefore, this now applies to the manufacturers of non-bulk steel drums.
TP14850 is the standard that is currently referenced in the TDG Regulations for small containers. It has been adopted in TDGR last summer with a transitional period of 6 months. You may download a free copy at: http://www.tc.gc.ca/eng/tdg/publications-standards-TP14850-1093.htm
Specifically, clause 4.4 of TP14850 requires that a container manufacturer or distributor provides a procedure for assembling and closing the container as tested. The test reads as follows:
4.4 Container information
4.4.1 The container manufacturer and distributor must provide the following information in relation to each container design:
a. a list of components that includes enough information so that the user can assemble and close the container in the same fashion as it was tested;
b. a procedure for assembling and closing the container as tested;
c. the maximum capacity of any inner packaging, as applicable; and
d. the tare weight, maximum gross mass and maximum capacity of the container.
Note: For containers designed with a handle for lifting, the container information should include instructions on the proper use of the handle, including whether it is intended for lifting the container empty or full.
4.4.2 The container manufacturer and distributor must provide the container information to a container purchaser at each initial purchase of the corresponding container.
4.4.3 The container manufacturer and distributor must provide the container information to a container user upon request.
Manufacturers and shippers in the US are also required to give Closure Instructions with their packaging.