When we worked for Powerchem I remember SGB had some special clamps made that went around circular sections of steel supports, the jaws were coated in rubber to stop them slipping,they had double attachments and swivel attachments and I seem to remember ones with a foot long section of I section girder attached. I never used them but can remember a big crate of them stacked in the yard at Stoke and thinking "heavy but usefull" a similar sort of thing Podger, these things were about 500mm in diameter so quite big, rig supports do you think ?Was building a job off pipe work today and a light bulb moment !!! What a useful piece of kit a jordan clamp with a gravlock type fixing woulld be or is there somthing similar all ready out there ?