The pipe flange standards used for important pipeline connections at home and abroad are mainly two systems, namely the European system (represented by the DIN standard) and the American system (represented by the American ASME B16.5 and B16.47 standards). The pipe flange standards of the same system and countries can basically be used with each other (connection size and sealing surface size). Two different systems cannot be used with each other.
Fasteners for pipelines: including hexagon head bolts, stud bolts, hex nuts for sale, and washers.
Select the standard fasteners in the current national standards, and select the materials for the specified special purpose.
The thread pitch of the pipe fasteners thread for flange connection should not be greater than 3mm, and the tube fasteners with a diameter of M30 or more can use fine thread.
The fastener material used for flange connection shall comply with the current national flange standards and be compatible with flange gaskets.
Under severe cyclic stress conditions, the bolts or stud bolts used for flange connection are made of alloy steel.
Carbon steel pipe fasteners should meet the operating temperature specified in the current national standards.
The yield strength does not exceed 235MPa, and low-strength metal pipe fasteners are only suitable for flange connections with PN≤2.0MPa non-metallic gaskets, and should not be used in severe cycle occasions. The working temperature range of low-strength pipe fasteners is -20℃～200℃.
Flange fasteners should be able to ensure that the gasket reaches the initial sealing condition and maintain the sealing performance of the gasket throughout the operation.
Hexagon head bolts should be used for PN≤2.0MPa or full-threaded bolts or equal-length stud bolts under high-temperature conditions.
It should meet the requirements of "Fasteners for Pipe Flanges" (SH 3404) or related standards.
When deformation-hardened austenitic stainless steel pipe fasteners are used for non-soft gasket flange connections, the bearing capacity of the fasteners should be checked to see if they can meet the connection requirements, and the operating temperature should not exceed 500 °C.
Selection of bolts and nuts for flange connection Bolts are divided into single-headed bolts and double-headed bolts according to their shapes. Single head bolts for flanges usually use hexagon head bolts. Both ends of the stud bolt are threaded and have a cylindrical shape. When the tensioning force is large, the single-headed bolt is easy to break at the connection between the screw rod and the screw head, so it cannot be used on medium and high pressure flanges. Stud bolts can not only be used on medium and high pressure flanges, but also easy to tighten from both sides