Pipeline designers and constructors have a range of options available to achieve the correct pipeline position. In some sort of logical order; the pipeline string can be “roped” into place, installed with cold-field bends, hot bends or even fittings.
Cold-field bends can be formed from individual coated pipe joints for the pipeline utilising specialised field bending machines. Generally, the smallest radius obtainable by cold-field bending in practice is about 1 ½° of angle deviation per diameter – this is equivalent to a bend radius of about 40D.
To ensure suitable results are achievable, trials are conducted to qualify the cold-field bending machines and operators against the range of pipe to be used to construct the pipeline.
The field bending activities shall be accordance to ASME B31.8 and end users’
requirements. The bend curvature shall have minimum radius 25 times of pipe
diameter (R25D).
Codes and Standards
- API 5L Specification for Line Pipe
- ASME B31.8, 2010 Gas Transmission and Distribution Piping System, The American society of Mechanical Engineers, New York, USA.
- NACE RP0274 High Voltage Electrical Inspection of Pipeline Coating Prior to Installation
