Clamp-type pipe joint

A clamp-type pipe joint for sealingly interconnecting pipes end-to-end in mutual longitudinal alignment, the pipes including hubs at ends thereof, the pipe joint comprising:

• a seal ring receivable between confronting end surfaces of the pipes to be joined;
• a clamp disposable about the hubs for urging the confronting end surfaces together in response to an applied clamping force;
• and
• the seal ring including a support structure and a first insulating layer disposed on a surface portion of the support structure which is brought into abutted contact with the confronting end surfaces when hubs are clamped, contact engagement of the first insulating layer with the hubs establishing a pressure-resistant seal therebetween, said first layer comprising a non-conductive ceramic layer impregnated with an insulating resin.

A clamp-type pipe joint for sealingly interconnecting pipes end-to-end in mutual longitudinal alignment, the pipes including hubs at ends thereof, the pipe joint comprising:

• a seal ring receivable between confronting end surfaces of the pipes to be joined;
• a clamp disposable about the hubs for urging the confronting end surfaces together in response to an applied clamping force;
• and
• the seal ring including a support structure and a first insulating layer disposed on a surface portion of the support structure which is brought into abutted contact with the confronting end surfaces when hubs are clamped, contact engagement of the first insulating layer with the hubs establishing a pressure-resistant seal therebetween, said first insulating layer comprising an insulating resin;
• said insulating resin presenting the following characteristics:
• a volume resistivity of not less than 10.sup.14 .OMEGA.-cm;
• compressive strength of not less than 800 kg/cm.sup.2 ;
• shear strength (ASTM D-732) of not less than 800 kg/cm.sup.2 ;
• and
• heat distortion temperature (ASTM D-648) of not lower than 100.degree. C. (at 18.5 kg/cm.sup.2).

A clamp-type pipe joint for sealingly interconnecting pipes end-to-end in mutual longitudinal alignment, the pipes including hubs at ends thereof, the pipe joint comprising:

• a seal ring receivable between confronting end surfaces of the pipes to be joined;
• a clamp disposable about the hubs for urging the confronting end surfaces together in response to an applied clamping force;
• the seal ring including a support structure and a first insulating layer disposed on a surface portion of the support structure which is brought into abutted contact with the confronting end surfaces when hubs are clamped, contact engagement of the first insulating layer with the hubs establishing a pressure-resistant seal therebetween;
• a second insulating layer disposed between the hubs and a surface of the clamp opposed thereto;
• and
• said second insulating layer including one of a coated layer of resin on said clamp and an element comprised of alternating laminated structure of metal and insulating resin receivable between the clamp and the hubs.