The attention and standard of marine flange

　　In industrial pipelines, the use of flange connections is very wide. Level and form of flange, according to the medium conditions, such as temperature, corrosion, and ultimately determine the sealing surface and leak proof pad selection. Flanges for ships and ships.

　　1, the production method can be divided into the method of making, pressing, forging, casting, etc..

　　2, to classified material of carbon steel, cast steel, alloy steel, stainless steel, copper, plastic, Aluminum Alloy, argon Ge Lek, PPC etc..

　　3, makes the standard can be divided into standard, standard, water, electricity American Standard, German standard, Japanese standard, Russian standard, etc..

　　Marine flange needs to pay attention to the following points:

　　1, bolt preload:

　　A, appropriate to improve the preload, can increase the sealing capacity of gaskets.

　　B, the pre tightening force evenly on the pad can be taken to reduce the bolt diameter and increase the number of bolts.

　　C, pre tightening force can not be too large, can not be too small.

　　2, compression surface type

　　A, marine flange trapezoidal groove pressing surface: at the bottom of the groove can not afford to seal is groove inside and outside cone and gasket contact trapezoidal form a seal, and elliptic or octagonal cross section of the metal gasket with.

　　B, bump type: consists of a concave surface and a convex combination. Put in the concave washer. Advantages: easy to medium, can prevent gasket extrusion.

　　C, tongue and groove type: a tenon groove sealing surface composition, the utility model has the advantages of neutral good, the seal pretightening pressure small, gasket is not easy extrusion is not affected by the medium erosion for flammable and explosive sealing requirements high. The disadvantage is the replacement is difficult, easy to damage the tenon.

　　D, plane type compression surface: the surface of the compression surface is a plane or a plane with a groove. Advantages: simple structure, easy processing. Disadvantages: large contact area, the need for a large preload ratio, bolt bearing large, so the flange and other parts of the requirements of high, bulky, easy to squeeze out of the gasket, sealing performance is poor. The use of P pressure less than 2.5Mpa, not the use of toxic, flammable and explosive medium.

　　E, conical face: usually used for high-pressure seal, the disadvantage is the need for the size accuracy and surface roughness requirements. Must be matched with lens gasket, commonly used in high-pressure pipeline.