Read about START-PROF pipe stress analysis software
Example project file: JacketedPipe.ctp
Jacketed piping requires special stress analysis.
Jacketed piping is commonly used:
The classic design solution is shown in figure below. Jacketed piping is a double-walled pipe. The special devices are used to control the distance between two pipes - spacers, guide plates, partition/end plate and spiders. Spacers support the core pipe from jacket pipe and to ensure uniform gap between core and jacket pipes. Partition plate and end plate placed where the flow of steam is interrupted.
Typical design scheme for warming viscous liquids
1 – outer pipe (jacket), 2 – inner pipe (core), 3 – flange pair, 4 - bypass pipe
Jacketed piping can be modeled as parallel inner and outer pipes connected with special elements -jumpers. The axial lines of these 2 pipelines are parallel with a small eccentricity 1-2 mm.
Jacketed piping model
1- outer pipe (jacket), 2 – inner pipe (core), 3 – jumper, 4 – anchor
All supports are placed on the outer piping. The outer piping product weight should be reduced by the volume of inner pipe. Pressure in outer piping should be real. The insulation weight should be added only for outer pipe. The wind loads should be applied only on outer pipe.
The pressure in inner piping should be specified as difference between outer and inner pipe real pressure. Insulation weight should be zero, the product weight should be real. Inner pipe is supported by spiders that could be modeled in START-PROF as special jumpers.
Jacketed piping design
a – flange pair; b – support between core and jacked (spider); c - spider design.
1- outer pipe (jacket), 2 – inner pipe (core), 3 – flange pair, 4 – spiders
Jumper is a rigid element with a nonstandard expansion joint in the middle, that allow the sliding between core and jacket along the pipe axis. The flexibility of expansion joint is very big λ = 100000 mm/kgf.
Two kinds of jumpers
a – jumper for spider modeling; b – jumper for flange modeling;
1- outer pipe (jacket), 2 – inner pipe (core), 3 - nonstandard expansion joint
The length should be very short (for example 2 mm) to reduce the eccentricity influence
Wall thickness should be equal to half of tie diameter
Pressure should be zero
Test pressure should be very small (1e-5 kgf/cm2)
Operating temperature should be equal to installation temperature
Weight should be very small (1e-5 kgf/cm)
Insulation and fluid weight should be zero
Length should be very small (2mm) to decrease the eccentricity influence of pipe axis
The flange pair jumper is modeled the same but without nonstandard expansion joint.