it makes of insulating slab, sealing parts, insulating coating and short pipe , sleeve pipe etc. Between the two short pipes have one butt joint, the butt joint with sealing and insulating parts which form the performance of insulation and double sealing structure. the sleeve pipe takes two kinds of welding , Groove welding and directly welding on guiding pipe, it makes insulating parts and short pipes fixed stably and be a "sealing capacity" to ensure the good insulating performance .meanwhile, it highly improves the pressure-bearing ability. Insulating joint is the upgrading products of insulated flange As the insulated flange have problem during the usage. insulating joint is the essential main pressured parts widely used in the Steel pipeline cathodic protection system.