The emphasis on support is primarily placed on the conduit. Liquid tight or seal tight Fittings have a criteria as follows:
Conduit is required to be supported adequately, and bending is restricted to 360 degrees total.
Please refer to the following for further details and complete information:
1. UL 360 – Safety standards for liquid tight flexible steel conduit
2. UL 514A and 514B – Safety standards for outlet boxes and fittings
3. W-F-406 – Federal specification: Fittings for cable, power, electrical and conduit, metal, flexible
4. NEMA FB-1 – Standards publication: Fittings, cast metal boxes and conduit bodies for conduit, electrical metallic tubing, and cableFederal
6. Federal standard H-28 (Threads)
2014 Code Language:
348.30(A) Securely Fastened. FMC shall be securely fastened in place by an approved means within 300 mm (12 in.) of each box, cabinet, conduit body, or other conduit termination and shall be supported and secured at intervals not to exceed 1.4 m (4 ½ ft).
Exception No. 4: Lengths not exceeding 1.8 m (6 ft) from the last point where the raceway is securely fastened for connections within an accessible ceiling to a luminaire(s) or other equipment. For the purposes of this exception, listed flexible metal conduit fittings shall be permitted as a means of support.
See the actual NEC text at NFPA.ORG for the complete code section