Features of HDPE, PE-RT, PP-H, PP-R, PVC-C, PVDF
The main features of HDPE piping and other plastic piping related to steel piping are:
- The allowable stress of plastic piping is dependent on service life and temperature. The equation is. The A, B, G, and J factors are stored in the Start-Prof material database
- In some cases, swelling elongation due to a chemical reaction with the product should be considered. The swelling strain should be specified in the pipe properties
- Linear expansion for plastic piping is much greater than for steel piping and caused by the Bourdon effect, thermal expansion, and swelling elongation
- Pressure elongation of plastic piping is significant (Bourdon effect), and thermal expansion is also great.
- Unlike steel piping, Young’s modulus (creep modulus) for plastic piping depends on service life. For higher service life – the lower creep modulus is used. The support loads, displacements, etc. are calculated at 100 minutes of creep modulus. The seismic analysis was performed using a 0.1-hour creep modulus.
- In operating conditions, the average creep modulus is used (average between installation and operating temperature)
- Allowable stress for plastic piping depends on the chemical resistance factor, laying condition factor, safety factor, and joint strength factor
- The wall thickness check is performed only for straight pipes and not performed for fittings
Modeling of HDPE pipe in Start-Prof
To model HDPE piping or other plastic piping choose GOST 32388 code:
Then create a pipe and choose the appropriate material from the database:
In an additional pipe, properties specify the chemical resistance factor (usually 1.0), Joint strength factor (0.4-1.0), and Laying conditions factor (0.8 for buried piping, 0.9 for underground piping in concrete channels, 1.0 for above-ground piping). The temperature range is multiplied by this factor. It considers the nonlinear distribution of temperature across the wall thickness. For plastic piping recommended value is 1.0 and for fiberglass piping 0.85 for fluid and 0.8 for gas if no other information is available.
The swelling strain is used for a chemical swelling elongation. It is the same as temperature elongation but caused by the chemical reaction between the pipe material and the product.
That’s all. All other job is the same as steel piping.
The Database contains all material properties. If there’s no material you need in the database, you can add its properties manually.
All load cases for analysis will be created automatically. After analysis, you get results according to the code.
Videos for HDPE Piping Stress Analysis in START-PROF
Part 1 of HDPE Piping Stress Analysis video:
Part 2 of HDPE Piping Stress Analysis Video: