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Tubes with internal ribs

Properties of tubes with internal ribs

Seamless tubes with internal ribs (internal riffling) are made by cold drawing. They are used as boiler tubes or heat exchangers tubes.

Steel grades according to EN 10216: P235GH, 16Mo3

Compared with tubes that have a smooth internal surface, tubes with ribs offer the customer many advantages:

    • improved level of heat transfer even with a higher share of steam;
    • very good level of heat transfer, retained also at lower medium flow;
    • lower temperature of tube walls = lower risk of tube’s distortion;
    • internal riffling prevents from sedimentation of solid particles present in the medium = lower risk of corrosion process = increased lifetime of a tube;
    • improved heat transfer by a suitable optimization of the riffle geometry.
Parameter Range [mm] Range [inch]
Outside diameter D 18-72 .750-3.000
Tube wall thickness T 1-6,5 .047-.250
Number of ribs 6-8
Rib height h 0,3-1,0 .016-.047
Rib width at the top f 3-8 .125-.313
Rib side angle ß 30°
Rib radius r 0,1-0,15 .004-.006
Rib pitch angle a 25°-35°
Rib pitch length (360°) w zależności od średnicy zewnętrznej
Distance of rib centers in the longitudinal direction do uzgodnienia
Rib width at the top do uzgodnienia
Width of the distance between ribs at the top do uzgodnienia
Inside tube circumference do uzgodnienia
Transversal tube diameter do uzgodnienia
Tube length do uzgodnienia

Dimensions of tubes with internal ribs