Index 1. Intention 2. Fields of Application 3. Definition of Terms 4. Dimensions 5. Angles 6. Corrugation Formation 7. Out-of-Roundness 8. Wall Thickness 9. Tolerances for Elbows Manufactured according to Special Bending Processes 10. Drawing Grooves 11. Surface Finish 12. Other Applicable Documents Page 1 of 5
1. Intention It has to be ensured that the elbows, bends and tube coils, which are not manufactured and tested according to a standard, customers instructions and / or other tolerance data, range within certain tolerance limits and correspond consequently to a uniform quality. 2. Fields of Application This company standard applies to all elbows, bends and tube coils to be manufactured by TUBE-TEC for which no specifications relating to the tolerances to be kept have been given in the drawing, order or production order. This company standard applies to all materials and to the bending processes: bending by mandrel, bending without mandrel, upsetting bending processes (with and without mandrel) as well as the bending according to the 3-roll-process. This company standard is also applicable for particular bending methods, which have not been mentioned before. Deviant requirements have to be pointed out separately by the customer when placing the order. 3. Definition of Terms QS VGB-R 501H VGB-R 110L = Quality assurance = TUBE-TEC company standard = VGB guideline R501H = VGB guideline R110L 4. Dimensions All dimensions are given in mm. - Elbows and bends nominal < 50 > 51 > 101 >251 > 501 > 1001 > 3001 size... 100... 250... 500... 1000... 3000 tolerance +/- 1 +/- 1,5 +/- 2 +/- 3 +/- 4 +/- 6 +/-8 Dimensions = mean bending radius ( Rm ) + leg prolongation (SVL) Page 2 of 5
- tube coils nominal < 30 > 31 > 316 > 1000 > 2001 > 4001 > 8001 size... 315... 1000... 2000... 4000... 8000 tolerance +/- 1 +/- 2 +/- 3 +/- 4 +/- 6 +/- 8 +/- 10 4.1 Tolerance in Radius for Elbows nominal size < 50 > 51 > 100 > 251 > 500...250...500 tolerance +/- 1,5 +/- 2 +/- 3 +/- 4 +/- 5 5. Angles The tolerances for angles on elbows and bends are as follows - depending on the degree of accuracy: degree of accuracy f: +/- 0,5 degree of accuracy m: +/- 1,0 degree of accuracy g: +/- 2,0 If no particulars are given, degree of accuracy m is applicable. 6. Corrugation Formation The forming of corrugations in the bending compression zone has to be strictly avoided. If a corrugation formation arises due to unfavorable ratio in radii / wall thickness, due to the material or other factors, the herein mentioned tolerance has to be kept after consultation with the responsible production manager respectively the QS department. Flat corrugations are acceptable if hm is not bigger than 3% of da1 and the corrugation interval amounts to > 15 x hm. hm = (da2 + da4) 2 - da3 hm = mean corrugation height da1 = nominal outer diameter da2 = height of the biggest corrugation (diameter) da3 = height of the valley between da2 and da4 (diameter) da4 = height of the corrugation abutting to da2 (diameter) Page 3 of 5
7. Out-of-Roundness The acceptable out-of-roundness amounts to: - If Rm < 4 x da OV zul = 20 however not to be more than 10%( after consultation with QC acceptable up to 12,5%) Rm / da - If Rm > 4 x da : maximum 5% (after consultation with QC 7,5% acceptable) The calculation for the measured out-of-roundness is as follows: OV = 200 x da max da min da max + da min ( in % ) OV OV zul da max da min Rm da = measured out-of-roundness = acceptable out-of-roundness = max. measured outer diameter = min. measured outer diameter = mean bending radius = nominal outer diameter 8. Wall Thickness Bending tension zone: smin = ((s - w) - s ) 10% 4 Rm da +2 W smin s d a = wall thickness reduction of the straight tube according to DIN respectively EN = minimum required wall thickness in the bending tension zone (outer zone of the bend) = nominal wall thickness = nominal outer diameter Bending compression zone: Refer to VGB R 501H / R 110L (if required, it has to be pointed out separately when placing the order) Page 4 of 5
9. Tolerances for Elbows Manufactured according to Special Bending Processes, for example, 3D Bending and 3-Roll-Bending-Process. 9.1 Tolerance in Radius Bending process 3-Roll-Bending- 3D-Bending Process, Process 3-Roll-Bending-Process Tube diameter < 101,6mm > 101,6mm Bend radius < 1500mm ± 10mm ± 30mm Bend radius 1500-2500mm ± 20mm ± 50mm Bend radius > 2500mm ± 30mm ± 80mm 9.2 Out-of-Roundness The acceptable out-of-roundness at 3D-Bending Process amounts to < 4,0% in the bending zone, < 1,0% at the end of the bend. The acceptable out-of-roundness at 3-Roll-Bending Process amounts to < 8,0% in the bending zone, < 2,0% at the end of the bend. 9.3 Wall Thickness Tolerance The wall thickness reduction amounts to 10 40 % of the input wall thickness depending on the respective bending radius. 9.4 Surface Due to processing, an interior and exterior surface showing slight drawing grooves in longitudinal and transverse direction is acceptable. Equally, spiral slots in the interior of the tube in range of the outside zone of the elbow are acceptable. Smooth transitions at the interior surface, which pass from unformed into deformed section, are acceptable. 10. Drawing Grooves More or less deep and visible drawing grooves left by the tools on the workpiece surface, e.g. by bending, rolling and sawing are acceptable. When bending according to particular bending processes so-called drawing grooves, which are acceptable - may arise on the outside and / or inside. Page 5 of 5
11. Surface Finish Elbows, bends and tube coils are standardly delivered without any surface treatment (e.g. pickling, passivating, and blasting). 12. Other Applicable Documents VGB-R 501H VGB-R 110L Page 6 of 5