Extra topcoat on stainless steel Tubtara® prevents bolt / rivet nut gripping problem

A manufacturer of systems for mounting solar panels reduces assembly costs by using Tubtara‘s with Seal Inox® topcoat reducing friction and preventing galling between the stainless steel bolt and thread of the Tubtara®.

Customer profile

Manufacturer of systems for mounting PV solar modules on (flat) roofs


The customer uses power tools to assemble bolts in Tubtara® blind rivet nuts at high speeds. During assembly the increased friction between the threaded connection of the stainless steel bolt and Tubtara® causes gripping, also called ‘galling’.  The bolt cannot be disassembled anymore as the two sliding surfaces are adhering. 

Tubtara® solution

Stainless steel 304 M8 HUKO 55 with a thin, drylayer of Seal Inox® topcoat.  Colour: grey.
The integrated lubricant additive in the Seal Inox® topcoat reduces friction and prevents gripping.  To exclude any assembly problem, we changed the hexagonal hole tolerance from 0 -0.1 mm to 0.05 -0.15 mm.


  • No galling between the stainless steel bolt and thread of the Tubtara® anymore
  • Full torque is used for the connection (not lost because of the internal friction between the threaded parts)
  • Reduced assembly time
  • Different colours possible for aesthetic requirements


Reduction of man-hours: faster assembly possible
Strong assembly and after-service possible

Cross market opportunities 

Every assembly of Tubtara® blind rivet nuts in stainless steel at high speeds e.g. in aerospace, telecom, lighting, medical, metal furniture, food, marine, pulp & paper, white goods, railways, chemical, offshore, road infrastructure, construction etc.