Q1.  Does the HMR allow a variable specification plate to be placed on a newly constructed cargo tank that was originally rated for the maximum allowable working pressure (MAWP) and constructed to meet both the DOT 407 and 412 design specifications (e.g., DOT 407/412)? I have enclosed an example of a DOT 407/412 variable specification plate my company might use.

A1.  The answer is yes. Newly constructed cargo tanks that meet two design specifications must have a certificate signed by the responsible official of the manufacturer and a Registered Inspector certifying that the cargo tank, its certificate of construction, and specification plates meet both specification requirements prior to marking (see § 178.345-15(c)(2)).

Q2.  When a cargo tank is originally manufactured to meet two design specification requirements, do the HMR require that the cargo tank must be marked with the "variable specification" plate prescribed in § 178.345-14(e), and must comply with the certificate of compliance (COC) requirements in § 178.345-15(c)(2)?

A2.  The HMR require the manufacturer of a specification cargo tank to mark the cargo tank with a nameplate and specification plate that comply with § 178.345-15(b) for specification or American Society of Mechanical Engineers cargo tanks, and § 178.345-15(c) for variable specification cargo tanks. Further, the HMR require the manufacturer provide a COC for each cargo tank's design type listed in § 178.345-15(b) that the cargo tank is constructed to meet (see §§ 178.345-14(a) and 178.345-15(c)(2)).