A riser clamp (20) comprising a first jaw portion (211) and a second jaw portion (212) that can be opened and closed relative to each other. The jaw portions (211/212) each comprise a thermoplastic body (301/302) that can be, for example, injection molded pieces of polyethylene (e.g., HDPE). The jaw portions (211/212) can be connected by a hinge (39) that is integrally formed therewith. The clamp (20) can also include cradles (701/702) and caps (711/712) for holding auxiliary lines.