NGA and FGIA Jointly Publish Update to Guidelines for Use of Capillary Tubes

Updated Glass Technical Resource Jointly Published
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Date: 3 June 2024

Newest Edition Reflects Advances in Insulating Glass

The Fenestration and Glazing Industry Alliance (FGIA) and the National Glass Association (NGA) are proud to announce the joint publication of an updated technical resource, NGA/FGIA TB-1601, Guidelines for Use of Capillary Tubes.

This eight-page guide addresses the use of capillary tubes in insulating glass units, including proper manufacture and design, glazing methodologies, as well as advantages and disadvantages of their use.

“This is an excellent resource covering the use of capillary tubes; everything from design guidance to glazing considerations,” shared Aaron Thompson, Principal Research Engineer at Viracon. “The volunteers comprising the task group have worked over the past two years to bring the material up to date and in line with expanded knowledge and use since its original publication in 2014.”

The resource further expands on environmental conditions, discussing how gas fill, temperature and pressure impact IGU behavior.

“The use of capillary tubes in insulating glass units (IGUs) has long been established as a means to accommodate changes in elevation of an IGU from the point of IGU manufacture to the point of installation,” said Amy Becker, FGIA Glass Products Specialist. “Such elevation changes create pressure differentials between the IGU cavity and the exterior environment that, unless alleviated, can cause glass deflection, excessive edge seal stress, and/or glass breakage.”

Guidelines for Use of Capillary Tubes can be downloaded from the FGIA Online Store or the NGA Store.

FGIA and NGA thank the task group members who developed this resource for the industry.

Task Group Members

  • Rob Carlson, Tristar Glass
  • Scott Corley, ODL
  • William Davis, Vitro Architectural Glass
  • Rob Grommesh, Cardinal
  • Jim Gulnick, McGrory Glass
  • Jeff Haberer, Trulite
  • Douglas Hauck, Quanex Building Products
  • Mark Hutchinson, INTIGRAL
  • Brett Jones, Manko Windows
  • Drew Pavlacky, Andersen Corporation
  • Raymond Roy, Guardian Glass
  • Bryan Smith, Garibaldi Glass
  • Melissa Szotkowski, Oldcastle BuildingEnvelope
  • Garth Tait, Hartung
  • Nathalie Thibault, Lepage Millwork
  • Aaron Thompson, Viracon
  • Matthew Waldren, Pella Corporation
  • DJ Weil, Cardinal
  • Rick Wright, Oldcastle BuildingEnvelope

About NGA

NGA represents all aspects of the glazing and glass building products industry, including contract glaziers, full-service glass companies, fabricators, manufacturers and suppliers. For more information about NGA and its activities, visit

About FGIA

FGIA is dedicated to improving home and building performance through better glass, window, door and skylight technology and standards. For more information about FGIA and its activities, visit

600450 NGA and FGIA Jointly Publish Update to Guidelines for Use of Capillary Tubes

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