Strip Seal Expansion Joint N-Type vs W-Type Profile Selection Guide

Strip seal expansion joints are available in N-type and W-type profiles, named after the shape of the seal cross-section. Each profile has different movement range capabilities and performance characteristics that make them suitable for different applications. The N-type profile has a single arch shape that accommodates movement by flexing the arch. It is suitable for movement ranges of 25-80 mm and is the most commonly used profile for medium-movement highway bridges. The N-type seal is relatively simple to install and replace, and its single arch design provides good waterproofing performance. The W-type profile has a double arch shape that provides greater flexibility and accommodates larger movement ranges of 50-120 mm. The double arch design distributes the strain more evenly across the seal cross-section, resulting in longer fatigue life for the same movement range. W-type seals are preferred for bridges with larger thermal movements or where a longer seal service life is required. For movement ranges up to 60 mm, the N-type profile is generally the most economical choice. For movement ranges of 60-100 mm, the W-type profile provides better performance and longer service life. For movement ranges exceeding 100 mm, a modular joint system is typically required. Both N-type and W-type seals are available in EPDM or neoprene rubber, with EPDM being the preferred material for most applications. The seal dimensions must be matched to the steel edge beam groove dimensions, which are standardized for each profile type. Using the correct seal dimensions is critical for waterproofing performance and seal retention. Installation of both profile types follows the same basic procedure: clean the groove surfaces, apply lubricant, and push the seal into the grooves. The seal must be installed without stretching or twisting. A seal installation tool is recommended to ensure correct installation without damage to the seal.