How to calculate stress on a pipe wall

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Discussion Overview

The discussion revolves around calculating the stress exerted by a compressed PVC hose on a fitting, specifically addressing the mechanics of a compression fitting used in a flexible PVC ribbed hose application. Participants explore the factors contributing to the cracking of the fitting and seek to understand the relevant material properties and calculations involved.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant describes the configuration of the PVC fitting and the dimensions of the hose, seeking to calculate the stress on the fitting due to compression.
  • Another participant requests a diagram to clarify the fitting's configuration and dimensions.
  • A later post suggests that if there are discrepancies between the initial description and the drawing, the drawing dimensions should be used.
  • One participant questions whether the failure of the fitting occurs after a period of service and prompts investigation into environmental factors that could affect the material's strength.
  • Another participant clarifies that the fittings are not in service and are not exposed to foreign elements.
  • A suggestion is made to obtain the compressive modulus of the flexible PVC hose material from the supplier or manufacturer to aid in calculations.

Areas of Agreement / Disagreement

Participants express differing views on the factors contributing to the fitting's failure, with some focusing on the mechanical calculations and others on environmental influences. The discussion remains unresolved regarding the exact cause of the cracking and the appropriate calculations to apply.

Contextual Notes

Participants have not reached a consensus on the necessary parameters for calculating stress, and there are unresolved questions about the material properties and potential external influences on the fitting's integrity.

Who May Find This Useful

Individuals interested in mechanical engineering, materials science, or those dealing with plumbing and fitting applications in flexible materials may find this discussion relevant.

Galvax85
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I have a PVC fitting that keeps cracking. The fitting consists of 2 parts. One piece is placed over the end of a flexible PVC ribbed hose, and the other is inserted inside the hose. The 2 parts act as a compression fitting to attach to the end of the hose. The hose typically has an outside diameter of 1.85". When the internal part is screwed into the hose, it expands the hose's outer diameter to 1.9". The inner diameter of the external part is 1.8". How do I calculate the stress exerted by the compressed hose material on the external part of my fitting?
 
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Galvax85 said:
I have a PVC fitting that keeps cracking. The fitting consists of 2 parts. One piece is placed over the end of a flexible PVC ribbed hose, and the other is inserted inside the hose. The 2 parts act as a compression fitting to attach to the end of the hose. The hose typically has an outside diameter of 1.85". When the internal part is screwed into the hose, it expands the hose's outer diameter to 1.9". The inner diameter of the external part is 1.8". How do I calculate the stress exerted by the compressed hose material on the external part of my fitting?
Can you provide a diagram?
 
Is this failure something that occurs after a period of time in service? If so, have you investigated all of the potential environmental and service elements that might cause loss of strength and/or embrittlement of the outer ring.
 
No, they are not in service. No, they are not exposed to foreign elements.
 
Can you find out from the supplier/manufacturer the compressive modulus of the flexible pvc hose material?
 

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