The techniques employed when bending pipes and tubes using pipe benders are fairly simple.It is a simple job to bend pipes an tubes using pipe benders.Although, there is a learning curve to every job, it can be reduced to a great extent by picking up pointers from experienced technicians.
The following guidance is provided for bending:
a) Hot bending of piping should be performed in accordance with written procedures. Hot bending of austenitic stainless steels should be followed by a full solution anneal in accordance with written procedures.
b) No bending should be performed at metal temperatures less than 40°F.
c) Cold bending may be performed using hydraulic or mechanical bending machines. Bending machines should be qualified by test for pipe minimum wall and ovality.
d) Mandrel and die used in bending stainless steel piping should be free of zinc.
e) Pipe longitudinal welds should not be located within 30 degrees of the plane of bend measured axially from the pipe centerline.
f) Necking as determined by reduction of the outside circumference should not exceed 4%.
g) Creased or corrugated bends are not permitted.
h) After bending, the finished surface should be free of cracks and substantially free from buckling, by visual inspection. Depth of wrinkles on the inside of the bend as determined from crest to trough should not exceed 1.5% of the nominal pipe size.
i) Flattening or ovality of a bend, the difference between maximum and minimum diameters at any cross section, should not exceed 8% of nominal outside diameter for internal pressure and 3% for external pressure.
j) Wall thinning in piping shall not exceed:
2) Tube bending differs from pipe bending in that it is usually performed in the field with a manually operated bender.
d) Mandrel and die used in bending stainless steel piping should be free of zinc.
e) Pipe longitudinal welds should not be located within 30 degrees of the plane of bend measured axially from the pipe centerline.
f) Necking as determined by reduction of the outside circumference should not exceed 4%.
g) Creased or corrugated bends are not permitted.
h) After bending, the finished surface should be free of cracks and substantially free from buckling, by visual inspection. Depth of wrinkles on the inside of the bend as determined from crest to trough should not exceed 1.5% of the nominal pipe size.
i) Flattening or ovality of a bend, the difference between maximum and minimum diameters at any cross section, should not exceed 8% of nominal outside diameter for internal pressure and 3% for external pressure.
j) Wall thinning in piping shall not exceed:
- 10% - Bend radius of 5 pipe diameters and larger
- 21% - Bend radius of 3 pipe diameters.
- 12% - Bend radius of 5 pipe diameters
- 22% - Bend radius of 3 pipe diameters
- 37% - Bend radius of 1.5 pipe diameters
2) Tube bending differs from pipe bending in that it is usually performed in the field with a manually operated bender.
The following guidance is provided to ensure good results on each bend.
a) Measure and mark exactly, then insert tube in bender.
b) Always attempt to bend in the same direction. If backbending, be sure to compensate for tubing stretch or pickup.
c) Clamp tubing securely in bender.
d) Check to make certain that the length mark is tangent to the desired angle on the radius block or in line with the desired degree on the link member.
e) Bend accurately to the desired angle plus springback allowance.
f) Remove tube and check bend angle and measurement length.
a) Measure and mark exactly, then insert tube in bender.
b) Always attempt to bend in the same direction. If backbending, be sure to compensate for tubing stretch or pickup.
c) Clamp tubing securely in bender.
d) Check to make certain that the length mark is tangent to the desired angle on the radius block or in line with the desired degree on the link member.
e) Bend accurately to the desired angle plus springback allowance.
f) Remove tube and check bend angle and measurement length.
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