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PRCI PR-201-9320
- Design Guidelines for High-Strength Pipe Fittings
- Report / Survey by Pipeline Research Council International, 01/01/1994
- Publisher: PRCI
$375.00$749.00
L51704e
Stress Engineering Services, Inc.
This report presents guidelines based on the study of current practices in the design and manufacture of high-pressure pipe fittings (size tees, reducing tees, elbows, and caps) from 4 to 12 inches. Based on fitting measurements, finite-element models for linear analysis were developed and the results were compared to existing standards. The models were verified with two experimental burst tests. Tensile strength proved to be the most significant factor for burst pressure and fatigue. For fittings of unknown origin, the tensile strength can be estimated with non-destructive material hardness tests. Yield strength showed no effect on burst pressure or fatigue due to cyclical pressure loading.
Need: Through a unique set of circumstances, a member company determined that hundreds of their pipeline in-ground fittings were at risk for failure due to poor engineering design and testing. Within two weeks, PRCI made a mid-year funding allocation and had a contract signed to review the issue.
Result: Initial work revealed that many of today's fitting manufacturers do not have engineering design capability. The intensity and flexibility coefficients used to scale up bigger and higher pressure fittings were based on work done, mostly on four-inch Schedule 40 pipes with standard wall thicknesses, in the 1940's and 1950's. Dimensional information was obtained on a number of as-built fittings. Finite element analysis (FEA) was used to calculate stress concentration factors. Two burst tests were performed that validated the FEA model. Purchase specifications were recommended. Guidelines for fitting design and selection, material testing and requirements for material strengths were provided.
Benefit: The immediate benefit of this work was that the member company that initiated the project was able to determine that his system fittings were not at risk and did not have to be replaced. In the long term, members can now be comfortable in the purchase of pipe fittings using the information available from this project.
Stress Engineering Services, Inc.
This report presents guidelines based on the study of current practices in the design and manufacture of high-pressure pipe fittings (size tees, reducing tees, elbows, and caps) from 4 to 12 inches. Based on fitting measurements, finite-element models for linear analysis were developed and the results were compared to existing standards. The models were verified with two experimental burst tests. Tensile strength proved to be the most significant factor for burst pressure and fatigue. For fittings of unknown origin, the tensile strength can be estimated with non-destructive material hardness tests. Yield strength showed no effect on burst pressure or fatigue due to cyclical pressure loading.
Need: Through a unique set of circumstances, a member company determined that hundreds of their pipeline in-ground fittings were at risk for failure due to poor engineering design and testing. Within two weeks, PRCI made a mid-year funding allocation and had a contract signed to review the issue.
Result: Initial work revealed that many of today's fitting manufacturers do not have engineering design capability. The intensity and flexibility coefficients used to scale up bigger and higher pressure fittings were based on work done, mostly on four-inch Schedule 40 pipes with standard wall thicknesses, in the 1940's and 1950's. Dimensional information was obtained on a number of as-built fittings. Finite element analysis (FEA) was used to calculate stress concentration factors. Two burst tests were performed that validated the FEA model. Purchase specifications were recommended. Guidelines for fitting design and selection, material testing and requirements for material strengths were provided.
Benefit: The immediate benefit of this work was that the member company that initiated the project was able to determine that his system fittings were not at risk and did not have to be replaced. In the long term, members can now be comfortable in the purchase of pipe fittings using the information available from this project.
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