Pipes Should Use Thread Flange Connection Requirements

When use the thread flange connection, hot-dip galvanized steel pipe fittings should use "forged cast iron pipe fittings" GB3287 ~ 3289, hot-dip galvanized seamless pipe fittings should be used "forged steel pipe fittings" GB / T14626; Thread connection should be consistent with the current national standard "55o tapered pipe thread" GB7306 the relevant provisions, seal tape can be used as a screw seal, the seal tape should be applied on the male thread; In the flange connection, flange sealing surface form and pressure level should be consistent with the fire water supply system technical requirements; Flange type According to the connection form should adopt flat weld flange, butt welding flange and thread flange, flange selection must meet the "steel pipe flange" GB9112 ~ 9131, "steel welded seamless pipe" GB / T12459, "Flange with PTFE coated gaskets" GB / T13404 standard.

Hot-dip galvanized steel pipe flange connection should be used when the choice of thread flange. System piping with inner wall is not anti-corrosion pipe, can be welded connection. Pipeline welding should be consistent with "field equipment, industrial pipeline welding construction and acceptance of norms" GB5036; 

When pipeline use welding, it should be consistent with the existing national standard "field equipment industrial pipeline welding construction and acceptance of norms", "industrial metal pipe construction and acceptance of norms" GB50253 the relevant provisions; Pipe diameter greater than DN50 shall not use threaded connection.