Foam Density Distribution Analysis in Pre-insulated Pipes Using Non-destructive X-Ray Microscopy

Pakdad Langroudi; Ingo Weidlich

doi:10.1007/978-3-032-09844-3_16

Foam Density Distribution Analysis in Pre-insulated Pipes Using Non-destructive X-Ray Microscopy

^*Corresponding author for this work

Abstract

Pre-insulated bonded pipes used in district heating systems are engineered for a service life of at least 30 years. The longevity of these systems is primarily influenced by the properties of the polyurethane (PUR) foam insulation. While operational and installation parameters contribute to overall durability, the characterization of the foam layer is critical for service life prediction. According to EN 253, pipe manufacturers are required to maintain a minimum foam density of 55 kg/m³. However, the foaming process leads to a non-uniform density distribution across the pipe cross-section—from the steel carrier pipe to the high-density polyethylene (HDPE) casing. Determining the foam density distribution function enables normalization of measurement data, which is essential for subsequent analysis using spectroscopic techniques such as Laser Induced Breakdown Spectroscopy (LIBS) and Fourier Transform Infrared (FT-IR) Spectroscopy. Traditional methods for density determination, including liquid displacement, and the cut-and-weigh method, are often labor-intensive and prone to inaccuracies. To address these limitations, a methodology has been developed that utilizes nanoscale X-ray microscopy and computer vision techniques to analyze foam density distribution.

Original language	English
Title of host publication	Proceedings of the 19th International Symposium on District Heating and Cooling
Subtitle of host publication	The International Research Conference on Heating and Cooling Networks - Under the Supervision of IEA DHC
Editors	Dirk Vanhoudt
Pages	163-171
Number of pages	9
Volume	1700
DOIs	https://doi.org/10.1007/978-3-032-09844-3_16
Publication status	Published - 24 Jan 2026
Event	19th International Symposium of District Heating and Cooling, IEA DHC 2025 - Genk, Belgium Duration: 7 Sept 2025 → 10 Sept 2025

Publication series

Name	Lecture Notes in Networks and Systems
Volume	1700
ISSN (Print)	2367-3370
ISSN (Electronic)	2367-3389

Conference

Conference	19th International Symposium of District Heating and Cooling, IEA DHC 2025
Country/Territory	Belgium
City	Genk
Period	7/09/25 → 10/09/25

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

SDG 07 Affordable and Clean Energy

Keywords

Computer vision
Data normalization
Distribution function
Rigid polyurethane foam
X-Ray scan

Access to Document

10.1007/978-3-032-09844-3_16Licence: CC BY

Cite this

Langroudi, P., & Weidlich, I. (2026). Foam Density Distribution Analysis in Pre-insulated Pipes Using Non-destructive X-Ray Microscopy. In D. Vanhoudt (Ed.), Proceedings of the 19th International Symposium on District Heating and Cooling: The International Research Conference on Heating and Cooling Networks - Under the Supervision of IEA DHC (Vol. 1700, pp. 163-171). (Lecture Notes in Networks and Systems; Vol. 1700 ). https://doi.org/10.1007/978-3-032-09844-3_16

Langroudi, Pakdad ; Weidlich, Ingo. / Foam Density Distribution Analysis in Pre-insulated Pipes Using Non-destructive X-Ray Microscopy. Proceedings of the 19th International Symposium on District Heating and Cooling: The International Research Conference on Heating and Cooling Networks - Under the Supervision of IEA DHC. editor / Dirk Vanhoudt. Vol. 1700 2026. pp. 163-171 (Lecture Notes in Networks and Systems).

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title = "Foam Density Distribution Analysis in Pre-insulated Pipes Using Non-destructive X-Ray Microscopy",

abstract = "Pre-insulated bonded pipes used in district heating systems are engineered for a service life of at least 30 years. The longevity of these systems is primarily influenced by the properties of the polyurethane (PUR) foam insulation. While operational and installation parameters contribute to overall durability, the characterization of the foam layer is critical for service life prediction. According to EN 253, pipe manufacturers are required to maintain a minimum foam density of 55 kg/m3. However, the foaming process leads to a non-uniform density distribution across the pipe cross-section—from the steel carrier pipe to the high-density polyethylene (HDPE) casing. Determining the foam density distribution function enables normalization of measurement data, which is essential for subsequent analysis using spectroscopic techniques such as Laser Induced Breakdown Spectroscopy (LIBS) and Fourier Transform Infrared (FT-IR) Spectroscopy. Traditional methods for density determination, including liquid displacement, and the cut-and-weigh method, are often labor-intensive and prone to inaccuracies. To address these limitations, a methodology has been developed that utilizes nanoscale X-ray microscopy and computer vision techniques to analyze foam density distribution.",

keywords = "Computer vision, Data normalization, Distribution function, Rigid polyurethane foam, X-Ray scan",

author = "Pakdad Langroudi and Ingo Weidlich",

note = "Publisher Copyright: {\textcopyright} The Author(s) 2026.; 19th International Symposium of District Heating and Cooling, IEA DHC 2025 ; Conference date: 07-09-2025 Through 10-09-2025",

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Langroudi, P & Weidlich, I 2026, Foam Density Distribution Analysis in Pre-insulated Pipes Using Non-destructive X-Ray Microscopy. in D Vanhoudt (ed.), Proceedings of the 19th International Symposium on District Heating and Cooling: The International Research Conference on Heating and Cooling Networks - Under the Supervision of IEA DHC. vol. 1700, Lecture Notes in Networks and Systems, vol. 1700 , pp. 163-171, 19th International Symposium of District Heating and Cooling, IEA DHC 2025, Genk, Belgium, 7/09/25. https://doi.org/10.1007/978-3-032-09844-3_16

Foam Density Distribution Analysis in Pre-insulated Pipes Using Non-destructive X-Ray Microscopy. / Langroudi, Pakdad ; Weidlich, Ingo.
Proceedings of the 19th International Symposium on District Heating and Cooling: The International Research Conference on Heating and Cooling Networks - Under the Supervision of IEA DHC. ed. / Dirk Vanhoudt. Vol. 1700 2026. p. 163-171 (Lecture Notes in Networks and Systems; Vol. 1700 ).

Research output: Chapter in Book (Inbook) /Conference Proceeding › Conference Paper › Research Article/Contribution › peer-review

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AU - Langroudi, Pakdad

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PY - 2026/1/24

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N2 - Pre-insulated bonded pipes used in district heating systems are engineered for a service life of at least 30 years. The longevity of these systems is primarily influenced by the properties of the polyurethane (PUR) foam insulation. While operational and installation parameters contribute to overall durability, the characterization of the foam layer is critical for service life prediction. According to EN 253, pipe manufacturers are required to maintain a minimum foam density of 55 kg/m3. However, the foaming process leads to a non-uniform density distribution across the pipe cross-section—from the steel carrier pipe to the high-density polyethylene (HDPE) casing. Determining the foam density distribution function enables normalization of measurement data, which is essential for subsequent analysis using spectroscopic techniques such as Laser Induced Breakdown Spectroscopy (LIBS) and Fourier Transform Infrared (FT-IR) Spectroscopy. Traditional methods for density determination, including liquid displacement, and the cut-and-weigh method, are often labor-intensive and prone to inaccuracies. To address these limitations, a methodology has been developed that utilizes nanoscale X-ray microscopy and computer vision techniques to analyze foam density distribution.

AB - Pre-insulated bonded pipes used in district heating systems are engineered for a service life of at least 30 years. The longevity of these systems is primarily influenced by the properties of the polyurethane (PUR) foam insulation. While operational and installation parameters contribute to overall durability, the characterization of the foam layer is critical for service life prediction. According to EN 253, pipe manufacturers are required to maintain a minimum foam density of 55 kg/m3. However, the foaming process leads to a non-uniform density distribution across the pipe cross-section—from the steel carrier pipe to the high-density polyethylene (HDPE) casing. Determining the foam density distribution function enables normalization of measurement data, which is essential for subsequent analysis using spectroscopic techniques such as Laser Induced Breakdown Spectroscopy (LIBS) and Fourier Transform Infrared (FT-IR) Spectroscopy. Traditional methods for density determination, including liquid displacement, and the cut-and-weigh method, are often labor-intensive and prone to inaccuracies. To address these limitations, a methodology has been developed that utilizes nanoscale X-ray microscopy and computer vision techniques to analyze foam density distribution.

KW - Computer vision

KW - Data normalization

KW - Distribution function

KW - Rigid polyurethane foam

KW - X-Ray scan

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BT - Proceedings of the 19th International Symposium on District Heating and Cooling

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Y2 - 7 September 2025 through 10 September 2025

ER -

Langroudi P , Weidlich I. Foam Density Distribution Analysis in Pre-insulated Pipes Using Non-destructive X-Ray Microscopy. In Vanhoudt D, editor, Proceedings of the 19th International Symposium on District Heating and Cooling: The International Research Conference on Heating and Cooling Networks - Under the Supervision of IEA DHC. Vol. 1700. 2026. p. 163-171. (Lecture Notes in Networks and Systems). doi: 10.1007/978-3-032-09844-3_16